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<!-- RRD ActiveDisclosure(SM) XBRL Linkbase Document - http://www.financial.rrd.com/ -->
<!-- Creation Date      : 2015-11-12T02:49:52.8648803+00:00 -->
<!-- Version            : 2.0.12.1 -->
<!-- Package ID         : C7EB874A2DC1D687253D89DE0CB2C979-0001326110-001510 -->
<!-- Copyright (c) 2015 R. R. Donnelley &amp; Sons Company. All Rights Reserved. -->
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:type="locator" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill" />
    <label xml:lang="en-US" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intangible assets, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:to="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IntangibleAssetsNetExcludingGoodwill_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Intangible Assets Net Excluding Goodwill</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:type="locator" xlink:label="us-gaap_OtherAssetsNoncurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherAssetsNoncurrent" xlink:to="us-gaap_OtherAssetsNoncurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherAssetsNoncurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Assets Noncurrent</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Assets" xlink:type="locator" xlink:label="us-gaap_Assets" />
    <label xml:lang="en-US" xlink:label="us-gaap_Assets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Assets" xlink:to="us-gaap_Assets_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_Assets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Assets</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">LIABILITIES AND STOCKHOLDERS&#8217; EQUITY</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:to="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities And Stockholders Equity [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrentAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Current liabilities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrentAbstract" xlink:to="us-gaap_LiabilitiesCurrentAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrentAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities Current [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccountsPayableCurrent" xlink:type="locator" xlink:label="us-gaap_AccountsPayableCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccountsPayableCurrent" xlink:to="us-gaap_AccountsPayableCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_AccountsPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accounts Payable Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_AccruedLiabilitiesCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_AccruedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccruedLiabilitiesCurrent" xlink:to="us-gaap_AccruedLiabilitiesCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_AccruedLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accrued Liabilities Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DueToRelatedPartiesCurrent" xlink:type="locator" xlink:label="us-gaap_DueToRelatedPartiesCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_DueToRelatedPartiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Due to related parties (See Note 6)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DueToRelatedPartiesCurrent" xlink:to="us-gaap_DueToRelatedPartiesCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DueToRelatedPartiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Due To Related Parties Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NotesPayableCurrent" xlink:type="locator" xlink:label="us-gaap_NotesPayableCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_NotesPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Notes payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NotesPayableCurrent" xlink:to="us-gaap_NotesPayableCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NotesPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Notes Payable Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_DerivativeLiabilitiesCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_DerivativeLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrant derivative liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeLiabilitiesCurrent" xlink:to="us-gaap_DerivativeLiabilitiesCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DerivativeLiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Liabilities Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:type="locator" xlink:label="us-gaap_LiabilitiesCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total current liabilities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesCurrent" xlink:to="us-gaap_LiabilitiesCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredRentCreditCurrent" xlink:type="locator" xlink:label="us-gaap_DeferredRentCreditCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_DeferredRentCreditCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred rent</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredRentCreditCurrent" xlink:to="us-gaap_DeferredRentCreditCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DeferredRentCreditCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Rent Credit Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredRevenueCurrent" xlink:type="locator" xlink:label="us-gaap_DeferredRevenueCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_DeferredRevenueCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DeferredRevenueCurrent" xlink:to="us-gaap_DeferredRevenueCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DeferredRevenueCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Revenue Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Liabilities" xlink:type="locator" xlink:label="us-gaap_Liabilities" />
    <label xml:lang="en-US" xlink:label="us-gaap_Liabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_Liabilities" xlink:to="us-gaap_Liabilities_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_Liabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:type="locator" xlink:label="us-gaap_CommitmentsAndContingencies" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commitments and contingencies (See Note 5)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommitmentsAndContingencies" xlink:to="us-gaap_CommitmentsAndContingencies_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommitmentsAndContingencies_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Commitments And Contingencies</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:type="locator" xlink:label="us-gaap_StockholdersEquityAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stockholders&#8217; equity</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityAbstract" xlink:to="us-gaap_StockholdersEquityAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockValue" xlink:type="locator" xlink:label="us-gaap_CommonStockValue" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockValue" xlink:to="us-gaap_CommonStockValue_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Value</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdditionalPaidInCapitalCommonStock" xlink:type="locator" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock" />
    <label xml:lang="en-US" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional paid-in capital</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdditionalPaidInCapitalCommonStock" xlink:to="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_AdditionalPaidInCapitalCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Additional Paid In Capital Common Stock</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" />
    <label xml:lang="en-US" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accumulated other comprehensive loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Accumulated Other Comprehensive Income Loss Net Of Tax</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:type="locator" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit" />
    <label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accumulated deficit</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RetainedEarningsAccumulatedDeficit" xlink:to="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_RetainedEarningsAccumulatedDeficit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Retained Earnings Accumulated Deficit</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquity" xlink:type="locator" xlink:label="us-gaap_StockholdersEquity" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total stockholders&#8217; equity</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquity" xlink:to="us-gaap_StockholdersEquity_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:type="locator" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity" />
    <label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total liabilities and stockholders&#8217; equity</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LiabilitiesAndStockholdersEquity" xlink:to="us-gaap_LiabilitiesAndStockholdersEquity_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LiabilitiesAndStockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liabilities And Stockholders Equity</label>
    <loc xlink:href="nk-20150930.xsd#nk_CommonStockClassUndefinedMember" xlink:type="locator" xlink:label="nk_CommonStockClassUndefinedMember" />
    <label xml:lang="en-US" xlink:label="nk_CommonStockClassUndefinedMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock class undefined.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CommonStockClassUndefinedMember" xlink:to="nk_CommonStockClassUndefinedMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_CommonStockClassUndefinedMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common Stock Class Undefined</label>
    <label xml:lang="en-US" xlink:label="nk_CommonStockClassUndefinedMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Class Undefined [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:type="locator" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, par value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockParOrStatedValuePerShare" xlink:to="us-gaap_CommonStockParOrStatedValuePerShare_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockParOrStatedValuePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Par Or Stated Value Per Share</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:type="locator" xlink:label="us-gaap_CommonStockSharesAuthorized" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares authorized</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesAuthorized" xlink:to="us-gaap_CommonStockSharesAuthorized_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Shares Authorized</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:type="locator" xlink:label="us-gaap_CommonStockSharesIssued" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesIssued" xlink:to="us-gaap_CommonStockSharesIssued_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Shares Issued</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonStockSharesOutstanding" xlink:type="locator" xlink:label="us-gaap_CommonStockSharesOutstanding" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock, shares outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonStockSharesOutstanding" xlink:to="us-gaap_CommonStockSharesOutstanding_lbl" />
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    <label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement [Abstract]</label>
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_Revenues" xlink:type="locator" xlink:label="us-gaap_Revenues" />
    <label xml:lang="en-US" xlink:label="us-gaap_Revenues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Revenue</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_Revenues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenues</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:type="locator" xlink:label="us-gaap_OperatingExpensesAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_OperatingExpensesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Operating expenses:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingExpensesAbstract" xlink:to="us-gaap_OperatingExpensesAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OperatingExpensesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Expenses [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentExpense" />
    <label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research and development</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentExpense" xlink:to="us-gaap_ResearchAndDevelopmentExpense_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Research And Development Expense</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:type="locator" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense" />
    <label xml:lang="en-US" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Selling, general and administrative</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SellingGeneralAndAdministrativeExpense" xlink:to="us-gaap_SellingGeneralAndAdministrativeExpense_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Selling General And Administrative Expense</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingExpenses" xlink:type="locator" xlink:label="us-gaap_OperatingExpenses" />
    <label xml:lang="en-US" xlink:label="us-gaap_OperatingExpenses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total operating expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingExpenses" xlink:to="us-gaap_OperatingExpenses_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OperatingExpenses_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Expenses</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:type="locator" xlink:label="us-gaap_OperatingIncomeLoss" />
    <label xml:lang="en-US" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Loss from operations</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingIncomeLoss" xlink:to="us-gaap_OperatingIncomeLoss_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OperatingIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Income Loss</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpenseAbstract" xlink:type="locator" xlink:label="us-gaap_OtherNonoperatingIncomeExpenseAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherNonoperatingIncomeExpenseAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other income (expense):</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherNonoperatingIncomeExpenseAbstract" xlink:to="us-gaap_OtherNonoperatingIncomeExpenseAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherNonoperatingIncomeExpenseAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Nonoperating Income Expense [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestIncomeExpenseNet" xlink:type="locator" xlink:label="us-gaap_InterestIncomeExpenseNet" />
    <label xml:lang="en-US" xlink:label="us-gaap_InterestIncomeExpenseNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Interest income (expense), net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestIncomeExpenseNet" xlink:to="us-gaap_InterestIncomeExpenseNet_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_InterestIncomeExpenseNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Income Expense Net</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:type="locator" xlink:label="us-gaap_OtherNonoperatingIncomeExpense" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherNonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other income, net</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherNonoperatingIncomeExpense" xlink:to="us-gaap_OtherNonoperatingIncomeExpense_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherNonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Nonoperating Income Expense</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueAdjustmentOfWarrants" xlink:type="locator" xlink:label="us-gaap_FairValueAdjustmentOfWarrants" />
    <label xml:lang="en-US" xlink:label="us-gaap_FairValueAdjustmentOfWarrants_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Fair value adjustment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueAdjustmentOfWarrants" xlink:to="us-gaap_FairValueAdjustmentOfWarrants_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_FairValueAdjustmentOfWarrants_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Adjustment Of Warrants</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:type="locator" xlink:label="us-gaap_NonoperatingIncomeExpense" />
    <label xml:lang="en-US" xlink:label="us-gaap_NonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total other income (expense)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NonoperatingIncomeExpense" xlink:to="us-gaap_NonoperatingIncomeExpense_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NonoperatingIncomeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Nonoperating Income Expense</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Loss before income taxes</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:to="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:type="locator" xlink:label="us-gaap_IncomeTaxExpenseBenefit" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income tax expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeTaxExpenseBenefit" xlink:to="us-gaap_IncomeTaxExpenseBenefit_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeTaxExpenseBenefit_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Tax Expense Benefit</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetIncomeLoss" xlink:type="locator" xlink:label="us-gaap_NetIncomeLoss" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetIncomeLoss" xlink:to="us-gaap_NetIncomeLoss_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Income Loss</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:type="locator" xlink:label="us-gaap_EarningsPerShareAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_EarningsPerShareAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss per share:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EarningsPerShareAbstract" xlink:to="us-gaap_EarningsPerShareAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_EarningsPerShareAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EarningsPerShareBasicAndDiluted" xlink:type="locator" xlink:label="us-gaap_EarningsPerShareBasicAndDiluted" />
    <label xml:lang="en-US" xlink:label="us-gaap_EarningsPerShareBasicAndDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basic and diluted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EarningsPerShareBasicAndDiluted" xlink:to="us-gaap_EarningsPerShareBasicAndDiluted_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_EarningsPerShareBasicAndDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Earnings Per Share Basic And Diluted</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract" xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted average number of shares during the period:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract" xlink:to="us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number Of Shares Outstanding Diluted Disclosure Items [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" xlink:type="locator" xlink:label="us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" />
    <label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basic and diluted</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted" xlink:to="us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_WeightedAverageNumberOfShareOutstandingBasicAndDiluted_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Weighted Average Number Of Share Outstanding Basic And Diluted</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:type="locator" xlink:label="us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Of Income And Comprehensive Income [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract" xlink:to="us-gaap_StatementOfIncomeAndComprehensiveIncomeAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetIncomeLoss_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Net loss</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTranslationAdjustmentTaxPortionAttributableToParent" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeForeignCurrencyTranslationAdjustmentTaxPortionAttributableToParent" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherComprehensiveIncomeForeignCurrencyTranslationAdjustmentTaxPortionAttributableToParent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Changes in foreign currency translation adjustment</label>
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:type="locator" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Other comprehensive loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:to="us-gaap_OtherComprehensiveIncomeLossNetOfTax_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Comprehensive Income Loss Net Of Tax</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:type="locator" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax" />
    <label xml:lang="en-US" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Comprehensive loss</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ComprehensiveIncomeNetOfTax" xlink:to="us-gaap_ComprehensiveIncomeNetOfTax_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ComprehensiveIncomeNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Comprehensive Income Net Of Tax</label>
    <loc xlink:href="nk-20150930.xsd#nk_StockIssuedDuringPeriodValueWarrantsExercised" xlink:type="locator" xlink:label="nk_StockIssuedDuringPeriodValueWarrantsExercised" />
    <label xml:lang="en-US" xlink:label="nk_StockIssuedDuringPeriodValueWarrantsExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock issued during period value warrants exercised.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_StockIssuedDuringPeriodValueWarrantsExercised" xlink:to="nk_StockIssuedDuringPeriodValueWarrantsExercised_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_StockIssuedDuringPeriodSharesWarrantsExercised" xlink:type="locator" xlink:label="nk_StockIssuedDuringPeriodSharesWarrantsExercised" />
    <label xml:lang="en-US" xlink:label="nk_StockIssuedDuringPeriodSharesWarrantsExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock issued during period shares warrants exercised.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_StockIssuedDuringPeriodSharesWarrantsExercised" xlink:to="nk_StockIssuedDuringPeriodSharesWarrantsExercised_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_ReclassificationOfWarrantLiabilitiesDueToExercise" xlink:type="locator" xlink:label="nk_ReclassificationOfWarrantLiabilitiesDueToExercise" />
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ReclassificationOfWarrantLiabilitiesDueToExercise" xlink:to="nk_ReclassificationOfWarrantLiabilitiesDueToExercise_lbl" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IPOMember" xlink:type="locator" xlink:label="us-gaap_IPOMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_IPOMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Initial Public Offering</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_IPOMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">I P O [Member]</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_PrivatePlacementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Private Placement</label>
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestructuringCostAndReserveAxis" xlink:type="locator" xlink:label="us-gaap_RestructuringCostAndReserveAxis" />
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    <label xml:lang="en-US" xlink:label="us-gaap_SpinoffMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Spinout</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Beginning Balance</label>
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:type="locator" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" />
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    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting of restricted stock units</label>
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockValueSharesIssuedNetOfTaxWithholdings" xlink:type="locator" xlink:label="us-gaap_RestrictedStockValueSharesIssuedNetOfTaxWithholdings" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings" xlink:type="locator" xlink:label="us-gaap_RestrictedStockSharesIssuedNetOfSharesForTaxWithholdings" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalStockSplit" xlink:type="locator" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalStockSplit" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued" xlink:type="locator" xlink:label="us-gaap_AdjustmentsToAdditionalPaidInCapitalWarrantIssued" />
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    <label xml:lang="en-US" xlink:label="nk_StockIssuedDuringPeriodSharesWarrantsExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares Warrants Exercised</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodValue" xlink:type="locator" xlink:label="us-gaap_StockRepurchasedDuringPeriodValue" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Repurchase of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockRepurchasedDuringPeriodValue" xlink:to="us-gaap_StockRepurchasedDuringPeriodValue_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Repurchased During Period Value</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:type="locator" xlink:label="us-gaap_StockRepurchasedDuringPeriodShares" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Repurchase of common stock, Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockRepurchasedDuringPeriodShares" xlink:to="us-gaap_StockRepurchasedDuringPeriodShares_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Repurchased During Period Shares</label>
    <label xml:lang="en-US" xlink:label="nk_ReclassificationOfWarrantLiabilitiesDueToExercise_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reclassification of warrant liability due to exercise</label>
    <label xml:lang="en-US" xlink:label="nk_ReclassificationOfWarrantLiabilitiesDueToExercise_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Reclassification Of Warrant Liabilities Due To Exercise</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Conversion of Class A common stock to common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities" xlink:to="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value Conversion Of Convertible Securities</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Conversion of Class A common stock to common stock, Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities" xlink:to="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares Conversion Of Convertible Securities</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:to="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodValueNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Value New Issues</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance of common stock, Shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:to="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesNewIssues_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares New Issues</label>
    <label xml:lang="en-US" xlink:label="nk_RestructuringOfEntity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Spinout of Brink Biologics, Inc.</label>
    <label xml:lang="en-US" xlink:label="nk_RestructuringOfEntity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restructuring Of Entity</label>
    <label xml:lang="en-US" xlink:label="us-gaap_OtherComprehensiveIncomeLossNetOfTax_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other comprehensive loss</label>
    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Beginning Balance</label>
    <label xml:lang="en-US" xlink:label="us-gaap_CommonStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel">Beginning Balance, Shares</label>
    <loc xlink:href="nk-20150930.xsd#nk_StockIssuanceCosts" xlink:type="locator" xlink:label="nk_StockIssuanceCosts" />
    <label xml:lang="en-US" xlink:label="nk_StockIssuanceCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock issuance costs.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_StockIssuanceCosts" xlink:to="nk_StockIssuanceCosts_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquityNoteStockSplitConversionRatio1" xlink:type="locator" xlink:label="us-gaap_StockholdersEquityNoteStockSplitConversionRatio1" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Forward stock split of its outstanding common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityNoteStockSplitConversionRatio1" xlink:to="us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityNoteStockSplitConversionRatio1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity Note Stock Split Conversion Ratio1</label>
    <label xml:lang="en-US" xlink:label="nk_StockIssuanceCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock issuance costs</label>
    <label xml:lang="en-US" xlink:label="nk_StockIssuanceCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issuance Costs</label>
    <loc xlink:href="nk-20150930.xsd#nk_ChangesInOperatingAssetsAndLiabilitiesNetOfEffectOfAcquisitionsAbstract" xlink:type="locator" xlink:label="nk_ChangesInOperatingAssetsAndLiabilitiesNetOfEffectOfAcquisitionsAbstract" />
    <label xml:lang="en-US" xlink:label="nk_ChangesInOperatingAssetsAndLiabilitiesNetOfEffectOfAcquisitionsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Changes in operating assets and liabilities net of effect of acquisitions.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ChangesInOperatingAssetsAndLiabilitiesNetOfEffectOfAcquisitionsAbstract" xlink:to="nk_ChangesInOperatingAssetsAndLiabilitiesNetOfEffectOfAcquisitionsAbstract_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_IncreaseDecreaseInDeferredRent" xlink:type="locator" xlink:label="nk_IncreaseDecreaseInDeferredRent" />
    <label xml:lang="en-US" xlink:label="nk_IncreaseDecreaseInDeferredRent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Increase decrease in deferred rent.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_IncreaseDecreaseInDeferredRent" xlink:to="nk_IncreaseDecreaseInDeferredRent_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_BusinessCombinationConsiderationTransferredWarrantsFairValue" xlink:type="locator" xlink:label="nk_BusinessCombinationConsiderationTransferredWarrantsFairValue" />
    <label xml:lang="en-US" xlink:label="nk_BusinessCombinationConsiderationTransferredWarrantsFairValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business combination consideration transferred warrants fair value.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_BusinessCombinationConsiderationTransferredWarrantsFairValue" xlink:to="nk_BusinessCombinationConsiderationTransferredWarrantsFairValue_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_PriceChangeInParValue" xlink:type="locator" xlink:label="nk_PriceChangeInParValue" />
    <label xml:lang="en-US" xlink:label="nk_PriceChangeInParValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Price change in par value.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PriceChangeInParValue" xlink:to="nk_PriceChangeInParValue_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_CashlessExerciseOfWarrants" xlink:type="locator" xlink:label="nk_CashlessExerciseOfWarrants" />
    <label xml:lang="en-US" xlink:label="nk_CashlessExerciseOfWarrants_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Cashless exercise of warrants.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CashlessExerciseOfWarrants" xlink:to="nk_CashlessExerciseOfWarrants_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementOfCashFlowsAbstract" xlink:type="locator" xlink:label="us-gaap_StatementOfCashFlowsAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_StatementOfCashFlowsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Of Cash Flows [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementOfCashFlowsAbstract" xlink:to="us-gaap_StatementOfCashFlowsAbstract_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business Acquisition</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionAxis" xlink:to="us-gaap_BusinessAcquisitionAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:type="locator" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Business Acquisition Acquiree</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessAcquisitionAcquireeDomain" xlink:to="us-gaap_BusinessAcquisitionAcquireeDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_BusinessAcquisitionAcquireeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Acquisition Acquiree [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_OtherOwnerOfInexBioIncMember" xlink:type="locator" xlink:label="nk_OtherOwnerOfInexBioIncMember" />
    <label xml:lang="en-US" xlink:label="nk_OtherOwnerOfInexBioIncMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Owner Of Inex Bio Inc</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_OtherOwnerOfInexBioIncMember" xlink:to="nk_OtherOwnerOfInexBioIncMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_OtherOwnerOfInexBioIncMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Owner Of Inex Bio Inc [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash flows used in operating activities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided By Used In Operating Activities Continuing Operations [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:type="locator" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Adjustments to reconcile net loss to net cash used in operating activities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:to="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DepreciationDepletionAndAmortization" xlink:type="locator" xlink:label="us-gaap_DepreciationDepletionAndAmortization" />
    <label xml:lang="en-US" xlink:label="us-gaap_DepreciationDepletionAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Depreciation and amortization</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DepreciationDepletionAndAmortization" xlink:to="us-gaap_DepreciationDepletionAndAmortization_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DepreciationDepletionAndAmortization_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Depreciation Depletion And Amortization</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensation" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-based compensation expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensation" xlink:to="us-gaap_ShareBasedCompensation_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation</label>
    <label xml:lang="en-US" xlink:label="us-gaap_FairValueAdjustmentOfWarrants_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in fair value of warrant derivative liability</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInNotesPayableCurrent" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInNotesPayableCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInNotesPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Change in value of note payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInNotesPayableCurrent" xlink:to="us-gaap_IncreaseDecreaseInNotesPayableCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInNotesPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Notes Payable Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInNotesReceivableRelatedParties" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInNotesReceivableRelatedParties" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInNotesReceivableRelatedParties_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Forgiveness of note receivable from related party</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInNotesReceivableRelatedParties" xlink:to="us-gaap_IncreaseDecreaseInNotesReceivableRelatedParties_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInNotesReceivableRelatedParties_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Notes Receivable Related Parties</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProvisionForDoubtfulAccounts" xlink:type="locator" xlink:label="us-gaap_ProvisionForDoubtfulAccounts" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProvisionForDoubtfulAccounts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Bad debt expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProvisionForDoubtfulAccounts" xlink:to="us-gaap_ProvisionForDoubtfulAccounts_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProvisionForDoubtfulAccounts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Provision For Doubtful Accounts</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeLossFromEquityMethodInvestments" xlink:type="locator" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeLossFromEquityMethodInvestments_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Loss incurred by Inex Bio</label>
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" />
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    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Prepaid Deferred Expense And Other Assets</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Other assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets" xlink:to="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInOtherNoncurrentAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Other Noncurrent Assets</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayable" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accounts payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccountsPayable" xlink:to="us-gaap_IncreaseDecreaseInAccountsPayable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInAccountsPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Accounts Payable</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilities" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued expenses</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInAccruedLiabilities" xlink:to="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInAccruedLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Accrued Liabilities</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInDueToRelatedPartiesCurrent" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInDueToRelatedPartiesCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInDueToRelatedPartiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Due to related parties</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInDueToRelatedPartiesCurrent" xlink:to="us-gaap_IncreaseDecreaseInDueToRelatedPartiesCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInDueToRelatedPartiesCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Due To Related Parties Current</label>
    <label xml:lang="en-US" xlink:label="nk_IncreaseDecreaseInDeferredRent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred rent</label>
    <label xml:lang="en-US" xlink:label="nk_IncreaseDecreaseInDeferredRent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Deferred Rent</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:type="locator" xlink:label="us-gaap_IncreaseDecreaseInDeferredRevenue" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInDeferredRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncreaseDecreaseInDeferredRevenue" xlink:to="us-gaap_IncreaseDecreaseInDeferredRevenue_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncreaseDecreaseInDeferredRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Increase Decrease In Deferred Revenue</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash used in operating activities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations" xlink:to="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInOperatingActivitiesContinuingOperations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided By Used In Operating Activities Continuing Operations</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash flows used in investing activities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided By Used In Investing Activities Continuing Operations [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Purchases of property and equipment</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment" xlink:to="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payments To Acquire Property Plant And Equipment</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Purchase of Inex Bio Inc., net of cash acquired</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:to="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payments To Acquire Businesses Net Of Cash Acquired</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsToAcquireIntangibleAssets" xlink:type="locator" xlink:label="us-gaap_PaymentsToAcquireIntangibleAssets" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsToAcquireIntangibleAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Investment in intangible assets</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsToAcquireIntangibleAssets" xlink:to="us-gaap_PaymentsToAcquireIntangibleAssets_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsToAcquireIntangibleAssets_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payments To Acquire Intangible Assets</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Net cash used in investing activities</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations" xlink:to="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInInvestingActivitiesContinuingOperations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided By Used In Investing Activities Continuing Operations</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract" xlink:type="locator" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash flows provided by financing activities:</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract" xlink:to="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NetCashProvidedByUsedInFinancingActivitiesContinuingOperationsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Net Cash Provided By Used In Financing Activities Continuing Operations [Abstract]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOrSaleOfEquity" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOrSaleOfEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from equity offerings, net of issuance costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOrSaleOfEquity" xlink:to="us-gaap_ProceedsFromIssuanceOrSaleOfEquity_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOrSaleOfEquity_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Issuance Or Sale Of Equity</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RepaymentsOfNotesPayable" xlink:type="locator" xlink:label="us-gaap_RepaymentsOfNotesPayable" />
    <label xml:lang="en-US" xlink:label="us-gaap_RepaymentsOfNotesPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Payments on notes payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RepaymentsOfNotesPayable" xlink:to="us-gaap_RepaymentsOfNotesPayable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_RepaymentsOfNotesPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Repayments Of Notes Payable</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from exercise of Class B common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:to="us-gaap_ProceedsFromIssuanceOfCommonStock_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Issuance Of Common Stock</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromWarrantExercises" xlink:type="locator" xlink:label="us-gaap_ProceedsFromWarrantExercises" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromWarrantExercises_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from exercise of warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromWarrantExercises" xlink:to="us-gaap_ProceedsFromWarrantExercises_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromWarrantExercises_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Warrant Exercises</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:type="locator" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Repurchase of common stock</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsForRepurchaseOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payments For Repurchase Of Common Stock</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:type="locator" xlink:label="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Employee payroll taxes paid related to net share settlement of restricted stock units</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payments Related To Tax Withholding For Share Based Compensation</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:type="locator" xlink:label="us-gaap_ProceedsFromStockOptionsExercised" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromStockOptionsExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from exercise of stock options</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionsDisclosureTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Transactions Disclosure [Text Block]</label>
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    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">License agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_LicensingAgreementTextBlock" xlink:to="nk_LicensingAgreementTextBlock_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_LicensingAgreementAbstract" xlink:type="locator" xlink:label="nk_LicensingAgreementAbstract" />
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Licensing agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_LicensingAgreementAbstract" xlink:to="nk_LicensingAgreementAbstract_lbl" />
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Licensing Agreement [Abstract]</label>
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Out-Licensing Agreement</label>
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Licensing Agreement [Text Block]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract" xlink:type="locator" xlink:label="us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Discontinued Operations And Disposal Groups [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract" xlink:to="us-gaap_DiscontinuedOperationsAndDisposalGroupsAbstract_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock" xlink:type="locator" xlink:label="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock" />
    <label xml:lang="en-US" xlink:label="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Spinout of Brink Biologics and Coneksis</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock" xlink:to="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DisposalGroupsIncludingDiscontinuedOperationsDisclosureTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Disposal Groups Including Discontinued Operations Disclosure [Text Block]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EquityAbstract" xlink:type="locator" xlink:label="us-gaap_EquityAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_EquityAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Equity [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EquityAbstract" xlink:to="us-gaap_EquityAbstract_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:type="locator" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stockholders&apos; Equity</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:to="us-gaap_StockholdersEquityNoteDisclosureTextBlock_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockholdersEquityNoteDisclosureTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stockholders Equity Note Disclosure [Text Block]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:type="locator" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract" xlink:to="us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" xlink:type="locator" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock" />
    <label xml:lang="en-US" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock-Based Compensation</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_DisclosureOfCompensationRelatedCostsShareBasedPaymentsTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Disclosure Of Compensation Related Costs Share Based Payments [Text Block]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueDisclosuresAbstract" xlink:type="locator" xlink:label="us-gaap_FairValueDisclosuresAbstract" />
    <label xml:lang="en-US" xlink:label="us-gaap_FairValueDisclosuresAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Disclosures [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueDisclosuresAbstract" xlink:to="us-gaap_FairValueDisclosuresAbstract_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueMeasurementInputsDisclosureTextBlock" xlink:type="locator" xlink:label="us-gaap_FairValueMeasurementInputsDisclosureTextBlock" />
    <label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementInputsDisclosureTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair Value Measurement</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_FairValueMeasurementInputsDisclosureTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Measurement Inputs Disclosure [Text Block]</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventsAbstract_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Events [Abstract]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventsAbstract" xlink:to="us-gaap_SubsequentEventsAbstract_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventsTextBlock" xlink:type="locator" xlink:label="us-gaap_SubsequentEventsTextBlock" />
    <label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventsTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Events</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventsTextBlock" xlink:to="us-gaap_SubsequentEventsTextBlock_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventsTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Events [Text Block]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConsolidationPolicyTextBlock" xlink:type="locator" xlink:label="us-gaap_ConsolidationPolicyTextBlock" />
    <label xml:lang="en-US" xlink:label="us-gaap_ConsolidationPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Principles of Consolidation</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConsolidationPolicyTextBlock" xlink:to="us-gaap_ConsolidationPolicyTextBlock_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ConsolidationPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Consolidation Policy [Text Block]</label>
    <loc xlink:href="nk-20150930.xsd#nk_LiquidityPolicyTextBlock" xlink:type="locator" xlink:label="nk_LiquidityPolicyTextBlock" />
    <label xml:lang="en-US" xlink:label="nk_LiquidityPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Liquidity.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_LiquidityPolicyTextBlock" xlink:to="nk_LiquidityPolicyTextBlock_lbl" />
    <label xml:lang="en-US" xlink:label="nk_LiquidityPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Liquidity</label>
    <label xml:lang="en-US" xlink:label="nk_LiquidityPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Liquidity Policy [Text Block]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_UseOfEstimates" xlink:type="locator" xlink:label="us-gaap_UseOfEstimates" />
    <label xml:lang="en-US" xlink:label="us-gaap_UseOfEstimates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Use of Estimates</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_UseOfEstimates" xlink:to="us-gaap_UseOfEstimates_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_UseOfEstimates_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Use Of Estimates</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConcentrationRiskCreditRisk" xlink:type="locator" xlink:label="us-gaap_ConcentrationRiskCreditRisk" />
    <label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskCreditRisk_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Risks and Uncertainties</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_ConcentrationRiskCreditRisk_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Concentration Risk Credit Risk</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CashAndCashEquivalentsPolicyTextBlock" xlink:type="locator" xlink:label="us-gaap_CashAndCashEquivalentsPolicyTextBlock" />
    <label xml:lang="en-US" xlink:label="us-gaap_CashAndCashEquivalentsPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash and Cash Equivalents</label>
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" xlink:type="locator" xlink:label="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock" />
    <label xml:lang="en-US" xlink:label="us-gaap_GoodwillAndIntangibleAssetsPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intangible Assets</label>
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:type="locator" xlink:label="us-gaap_FairValueOfFinancialInstrumentsPolicy" />
    <label xml:lang="en-US" xlink:label="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fair Value of Financial Instruments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:to="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_FairValueOfFinancialInstrumentsPolicy_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fair Value Of Financial Instruments Policy</label>
    <loc xlink:href="nk-20150930.xsd#nk_DeferredRentPolicyTextBlock" xlink:type="locator" xlink:label="nk_DeferredRentPolicyTextBlock" />
    <label xml:lang="en-US" xlink:label="nk_DeferredRentPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Deferred rent.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_DeferredRentPolicyTextBlock" xlink:to="nk_DeferredRentPolicyTextBlock_lbl" />
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    <label xml:lang="en-US" xlink:label="nk_DeferredRentPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Rent Policy [Text Block]</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_CompensationRelatedCostsPolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Compensation Related Costs Policy [Text Block]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EarningsPerSharePolicyTextBlock" xlink:type="locator" xlink:label="us-gaap_EarningsPerSharePolicyTextBlock" />
    <label xml:lang="en-US" xlink:label="us-gaap_EarningsPerSharePolicyTextBlock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Basic and Diluted Net Loss Per Share of Common Stock</label>
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeByNatureAxis" xlink:type="locator" xlink:label="us-gaap_DerivativeByNatureAxis" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeNameDomain" xlink:type="locator" xlink:label="us-gaap_DerivativeNameDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_DerivativeNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Derivative Name</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_DerivativeNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Name [Domain]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_WarrantMember" xlink:type="locator" xlink:label="us-gaap_WarrantMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_WarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Outstanding Warrants</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_WarrantMember" xlink:to="us-gaap_WarrantMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_WarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Warrant [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AwardTypeAxis" xlink:type="locator" xlink:label="us-gaap_AwardTypeAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Award Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AwardTypeAxis" xlink:to="us-gaap_AwardTypeAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_AwardTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Award Type [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangements By Share Based Payment Award Award Type And Plan Name [Domain]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeStockOptionMember" xlink:type="locator" xlink:label="us-gaap_EmployeeStockOptionMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee Stock Option</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeStockOptionMember" xlink:to="us-gaap_EmployeeStockOptionMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_EmployeeStockOptionMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Stock Option [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:type="locator" xlink:label="us-gaap_RestrictedStockUnitsRSUMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockUnitsRSUMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Outstanding Restricted Stock Units</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RestrictedStockUnitsRSUMember" xlink:to="us-gaap_RestrictedStockUnitsRSUMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_RestrictedStockUnitsRSUMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Restricted Stock Units R S U [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_SeriesBConvertiblePreferredStockMember" xlink:type="locator" xlink:label="nk_SeriesBConvertiblePreferredStockMember" />
    <label xml:lang="en-US" xlink:label="nk_SeriesBConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series B convertible preferred stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_SeriesBConvertiblePreferredStockMember" xlink:to="nk_SeriesBConvertiblePreferredStockMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_SeriesBConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Series B Convertible Preferred Stock</label>
    <label xml:lang="en-US" xlink:label="nk_SeriesBConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series B Convertible Preferred Stock [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_SeriesCConvertiblePreferredStockMember" xlink:type="locator" xlink:label="nk_SeriesCConvertiblePreferredStockMember" />
    <label xml:lang="en-US" xlink:label="nk_SeriesCConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Series C convertible preferred stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_SeriesCConvertiblePreferredStockMember" xlink:to="nk_SeriesCConvertiblePreferredStockMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_SeriesCConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Series C Convertible Preferred Stock</label>
    <label xml:lang="en-US" xlink:label="nk_SeriesCConvertiblePreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series C Convertible Preferred Stock [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CommonClassBMember" xlink:type="locator" xlink:label="us-gaap_CommonClassBMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonClassBMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class B Common Shares Not Exercised</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CommonClassBMember" xlink:to="us-gaap_CommonClassBMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_CommonClassBMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Class B [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" />
    <label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:type="locator" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" />
    <label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Antidilutive securities excluded from computation of earnings per share, amount</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount</label>
    <loc xlink:href="nk-20150930.xsd#nk_MilestonePaymentAmount" xlink:type="locator" xlink:label="nk_MilestonePaymentAmount" />
    <label xml:lang="en-US" xlink:label="nk_MilestonePaymentAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Milestone payment amount.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_MilestonePaymentAmount" xlink:to="nk_MilestonePaymentAmount_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_PercentageOfRoyaltyOnNetSales" xlink:type="locator" xlink:label="nk_PercentageOfRoyaltyOnNetSales" />
    <label xml:lang="en-US" xlink:label="nk_PercentageOfRoyaltyOnNetSales_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of royalty on net sales.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PercentageOfRoyaltyOnNetSales" xlink:to="nk_PercentageOfRoyaltyOnNetSales_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationsAbstract" xlink:type="locator" xlink:label="us-gaap_BusinessCombinationsAbstract" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="locator" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="locator" xlink:label="us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain" />
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    <loc xlink:href="nk-20150930.xsd#nk_InexLicenseAgreementMember" xlink:type="locator" xlink:label="nk_InexLicenseAgreementMember" />
    <label xml:lang="en-US" xlink:label="nk_InexLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Inex license agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_InexLicenseAgreementMember" xlink:to="nk_InexLicenseAgreementMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_InexLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inex license agreement</label>
    <label xml:lang="en-US" xlink:label="nk_InexLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Inex License Agreement [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeAxis" xlink:type="locator" xlink:label="us-gaap_DeferredRevenueArrangementTypeAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_DeferredRevenueArrangementTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred Revenue Arrangement Type</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_DeferredRevenueArrangementTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Revenue Arrangement Type [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DeferredRevenueArrangementTypeDomain" xlink:type="locator" xlink:label="us-gaap_DeferredRevenueArrangementTypeDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_DeferredRevenueArrangementTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Deferred Revenue Arrangement Type</label>
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    <label xml:lang="en-US" xlink:label="us-gaap_DeferredRevenueArrangementTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Deferred Revenue Arrangement Type [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_UpFrontFeeMember" xlink:type="locator" xlink:label="nk_UpFrontFeeMember" />
    <label xml:lang="en-US" xlink:label="nk_UpFrontFeeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Up front fee.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_UpFrontFeeMember" xlink:to="nk_UpFrontFeeMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_UpFrontFeeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Up front fee</label>
    <label xml:lang="en-US" xlink:label="nk_UpFrontFeeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Up Front Fee [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_InexBioHoldingsMember" xlink:type="locator" xlink:label="nk_InexBioHoldingsMember" />
    <label xml:lang="en-US" xlink:label="nk_InexBioHoldingsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Inex bio holdings.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_InexBioHoldingsMember" xlink:to="nk_InexBioHoldingsMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_InexBioHoldingsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Inex Bio Holdings</label>
    <label xml:lang="en-US" xlink:label="nk_InexBioHoldingsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Inex Bio Holdings [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_EragonVenturesLLCMember" xlink:type="locator" xlink:label="nk_EragonVenturesLLCMember" />
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    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationConsiderationTransferredOther1" xlink:type="locator" xlink:label="us-gaap_BusinessCombinationConsiderationTransferredOther1" />
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    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Current Liabilities Accounts Payable</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:type="locator" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" />
    <label xml:lang="en-US" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/totalLabel">Total assets acquired and liabilities assumed</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:to="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Recognized Identifiable Assets Acquired And Liabilities Assumed Net</label>
    <loc xlink:href="nk-20150930.xsd#nk_ReacquiredRightsPeriod" xlink:type="locator" xlink:label="nk_ReacquiredRightsPeriod" />
    <label xml:lang="en-US" xlink:label="nk_ReacquiredRightsPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Reacquired rights period.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ReacquiredRightsPeriod" xlink:to="nk_ReacquiredRightsPeriod_lbl" />
    <label xml:lang="en-US" xlink:label="nk_ReacquiredRightsPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Reacquired rights period</label>
    <label xml:lang="en-US" xlink:label="nk_ReacquiredRightsPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Reacquired Rights Period</label>
    <loc xlink:href="nk-20150930.xsd#nk_BusinessCombinationConsiderationCashPaidToAcquireShares" xlink:type="locator" xlink:label="nk_BusinessCombinationConsiderationCashPaidToAcquireShares" />
    <label xml:lang="en-US" xlink:label="nk_BusinessCombinationConsiderationCashPaidToAcquireShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Business combination consideration transferred cash paid to acquire shares.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_BusinessCombinationConsiderationCashPaidToAcquireShares" xlink:to="nk_BusinessCombinationConsiderationCashPaidToAcquireShares_lbl" />
    <label xml:lang="en-US" xlink:label="nk_BusinessCombinationConsiderationCashPaidToAcquireShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Less cash paid to acquire shares in Inex Bio</label>
    <label xml:lang="en-US" xlink:label="nk_BusinessCombinationConsiderationCashPaidToAcquireShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Business Combination Consideration Cash Paid To Acquire Shares</label>
    <loc xlink:href="nk-20150930.xsd#nk_CashBasedCompensation" xlink:type="locator" xlink:label="nk_CashBasedCompensation" />
    <label xml:lang="en-US" xlink:label="nk_CashBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Cash based compensation.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CashBasedCompensation" xlink:to="nk_CashBasedCompensation_lbl" />
    <label xml:lang="en-US" xlink:label="nk_CashBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash based compensation</label>
    <label xml:lang="en-US" xlink:label="nk_CashBasedCompensation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cash Based Compensation</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentTable" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentTable" xlink:to="us-gaap_DebtInstrumentTable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Table]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:type="locator" xlink:label="us-gaap_ShortTermDebtTypeAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short Term Debt Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermDebtTypeAxis" xlink:to="us-gaap_ShortTermDebtTypeAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Debt Type [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:type="locator" xlink:label="us-gaap_ShortTermDebtTypeDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short Term Debt Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShortTermDebtTypeDomain" xlink:to="us-gaap_ShortTermDebtTypeDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShortTermDebtTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Short Term Debt Type [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_PromissoryNoteMember" xlink:type="locator" xlink:label="nk_PromissoryNoteMember" />
    <label xml:lang="en-US" xlink:label="nk_PromissoryNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">2013 promissory note.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PromissoryNoteMember" xlink:to="nk_PromissoryNoteMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_PromissoryNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2013 Promissory Note</label>
    <label xml:lang="en-US" xlink:label="nk_PromissoryNoteMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Promissory Note [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SeriesCPreferredStockMember" xlink:type="locator" xlink:label="us-gaap_SeriesCPreferredStockMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_SeriesCPreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Series C Preferred Stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SeriesCPreferredStockMember" xlink:to="us-gaap_SeriesCPreferredStockMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SeriesCPreferredStockMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Series C Preferred Stock [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_TwoThousandNineConvertibleNotesMember" xlink:type="locator" xlink:label="nk_TwoThousandNineConvertibleNotesMember" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandNineConvertibleNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand nine convertible notes</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_TwoThousandNineConvertibleNotesMember" xlink:to="nk_TwoThousandNineConvertibleNotesMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandNineConvertibleNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2009 Convertible Notes</label>
    <label xml:lang="en-US" xlink:label="nk_TwoThousandNineConvertibleNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Nine Convertible Notes [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_TwoThousandThirteenSecuritiesPurchaseAgreementMember" xlink:type="locator" xlink:label="nk_TwoThousandThirteenSecuritiesPurchaseAgreementMember" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandThirteenSecuritiesPurchaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand thirteen securities purchase agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_TwoThousandThirteenSecuritiesPurchaseAgreementMember" xlink:to="nk_TwoThousandThirteenSecuritiesPurchaseAgreementMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandThirteenSecuritiesPurchaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2013 Securities Purchase Agreement</label>
    <label xml:lang="en-US" xlink:label="nk_TwoThousandThirteenSecuritiesPurchaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Thirteen Securities Purchase Agreement [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_ClassOfWarrantOrRightAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class Of Warrant Or Right</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightAxis" xlink:to="us-gaap_ClassOfWarrantOrRightAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ClassOfWarrantOrRightAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Class Of Warrant Or Right [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_ClassOfWarrantOrRightDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class Of Warrant Or Right</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightDomain" xlink:to="us-gaap_ClassOfWarrantOrRightDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ClassOfWarrantOrRightDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Class Of Warrant Or Right [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_CorporateAdvisoryWarrantMember" xlink:type="locator" xlink:label="nk_CorporateAdvisoryWarrantMember" />
    <label xml:lang="en-US" xlink:label="nk_CorporateAdvisoryWarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Corporate advisory warrant .</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CorporateAdvisoryWarrantMember" xlink:to="nk_CorporateAdvisoryWarrantMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_CorporateAdvisoryWarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">CA Warrant</label>
    <label xml:lang="en-US" xlink:label="nk_CorporateAdvisoryWarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Corporate Advisory Warrant [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_PurchaseAgreementWarrantMember" xlink:type="locator" xlink:label="nk_PurchaseAgreementWarrantMember" />
    <label xml:lang="en-US" xlink:label="nk_PurchaseAgreementWarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Purchase agreement warrant.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PurchaseAgreementWarrantMember" xlink:to="nk_PurchaseAgreementWarrantMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_PurchaseAgreementWarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">PA Warrant</label>
    <label xml:lang="en-US" xlink:label="nk_PurchaseAgreementWarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Purchase Agreement Warrant [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_SideAgreementNotesMember" xlink:type="locator" xlink:label="nk_SideAgreementNotesMember" />
    <label xml:lang="en-US" xlink:label="nk_SideAgreementNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Side agreement notes.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_SideAgreementNotesMember" xlink:to="nk_SideAgreementNotesMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_SideAgreementNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Side Agreement Notes</label>
    <label xml:lang="en-US" xlink:label="nk_SideAgreementNotesMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Side Agreement Notes [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentLineItems" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt Instrument [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentLineItems" xlink:to="us-gaap_DebtInstrumentLineItems_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument [Line Items]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConvertibleNotesPayableCurrent" xlink:type="locator" xlink:label="us-gaap_ConvertibleNotesPayableCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_ConvertibleNotesPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Convertible notes payable current</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConvertibleNotesPayableCurrent" xlink:to="us-gaap_ConvertibleNotesPayableCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ConvertibleNotesPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Convertible Notes Payable Current</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:type="locator" xlink:label="us-gaap_PreferredStockSharesIssued" />
    <label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Preferred stock shares issued</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PreferredStockSharesIssued" xlink:to="us-gaap_PreferredStockSharesIssued_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_PreferredStockSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Preferred Stock Shares Issued</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock" xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from issuance of preferred stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock" xlink:to="us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Issuance Of Preferred Stock And Preference Stock</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of accrued interest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:to="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentInterestRateStatedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Interest Rate Stated Percentage</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentMaturityDate" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentMaturityDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Short term debt maturity date</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentMaturityDate" xlink:to="us-gaap_DebtInstrumentMaturityDate_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentMaturityDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Maturity Date</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromNotesPayable" xlink:type="locator" xlink:label="us-gaap_ProceedsFromNotesPayable" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromNotesPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from security purchase agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromNotesPayable" xlink:to="us-gaap_ProceedsFromNotesPayable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromNotesPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Notes Payable</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_AmortizationOfDebtDiscountPremium" xlink:type="locator" xlink:label="us-gaap_AmortizationOfDebtDiscountPremium" />
    <label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfDebtDiscountPremium_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Amortization of financing costs and discounts</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_AmortizationOfDebtDiscountPremium" xlink:to="us-gaap_AmortizationOfDebtDiscountPremium_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_AmortizationOfDebtDiscountPremium_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Amortization Of Debt Discount Premium</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_NotesPayable" xlink:type="locator" xlink:label="us-gaap_NotesPayable" />
    <label xml:lang="en-US" xlink:label="us-gaap_NotesPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Notes payable</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_NotesPayable" xlink:to="us-gaap_NotesPayable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_NotesPayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Notes Payable</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:type="locator" xlink:label="us-gaap_DebtConversionConvertedInstrumentSharesIssued1" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtConversionConvertedInstrumentSharesIssued1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Promissory note agreed to convert</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtConversionConvertedInstrumentSharesIssued1" xlink:to="us-gaap_DebtConversionConvertedInstrumentSharesIssued1_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtConversionConvertedInstrumentSharesIssued1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Conversion Converted Instrument Shares Issued1</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestPaid" xlink:type="locator" xlink:label="us-gaap_InterestPaid" />
    <label xml:lang="en-US" xlink:label="us-gaap_InterestPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued interest paid</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestPaid" xlink:to="us-gaap_InterestPaid_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_InterestPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Paid</label>
    <loc xlink:href="nk-20150930.xsd#nk_Payables" xlink:type="locator" xlink:label="nk_Payables" />
    <label xml:lang="en-US" xlink:label="nk_Payables_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Payables.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_Payables" xlink:to="nk_Payables_lbl" />
    <label xml:lang="en-US" xlink:label="nk_Payables_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Notes payable and accounts payable, total</label>
    <label xml:lang="en-US" xlink:label="nk_Payables_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payables</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentConvertibleConversionPrice1" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentConvertibleConversionPrice1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Conversion price of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:to="us-gaap_DebtInstrumentConvertibleConversionPrice1_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentConvertibleConversionPrice1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Convertible Conversion Price1</label>
    <loc xlink:href="nk-20150930.xsd#nk_OutstandingConvertibleNotePayable" xlink:type="locator" xlink:label="nk_OutstandingConvertibleNotePayable" />
    <label xml:lang="en-US" xlink:label="nk_OutstandingConvertibleNotePayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Outstanding convertible note payable.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_OutstandingConvertibleNotePayable" xlink:to="nk_OutstandingConvertibleNotePayable_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_InterestPayableCurrent" xlink:type="locator" xlink:label="us-gaap_InterestPayableCurrent" />
    <label xml:lang="en-US" xlink:label="us-gaap_InterestPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued interest outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_InterestPayableCurrent" xlink:to="us-gaap_InterestPayableCurrent_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_InterestPayableCurrent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Interest Payable Current</label>
    <label xml:lang="en-US" xlink:label="nk_OutstandingConvertibleNotePayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Outstanding convertible note payable</label>
    <label xml:lang="en-US" xlink:label="nk_OutstandingConvertibleNotePayable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Outstanding Convertible Note Payable</label>
    <loc xlink:href="nk-20150930.xsd#nk_WarrantExercisableAsPercentageOfSharesIssued" xlink:type="locator" xlink:label="nk_WarrantExercisableAsPercentageOfSharesIssued" />
    <label xml:lang="en-US" xlink:label="nk_WarrantExercisableAsPercentageOfSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Warrant exercisable as a percentage of shares issued.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_WarrantExercisableAsPercentageOfSharesIssued" xlink:to="nk_WarrantExercisableAsPercentageOfSharesIssued_lbl" />
    <label xml:lang="en-US" xlink:label="nk_WarrantExercisableAsPercentageOfSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrant exercisable as a percentage of shares issued</label>
    <label xml:lang="en-US" xlink:label="nk_WarrantExercisableAsPercentageOfSharesIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Warrant Exercisable As Percentage Of Shares Issued</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:type="locator" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" />
    <label xml:lang="en-US" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exchanged warrants, in share</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights" xlink:to="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Class Of Warrant Or Right Number Of Securities Called By Warrants Or Rights</label>
    <loc xlink:href="nk-20150930.xsd#nk_WarrantShareIssuedPercentage" xlink:type="locator" xlink:label="nk_WarrantShareIssuedPercentage" />
    <label xml:lang="en-US" xlink:label="nk_WarrantShareIssuedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Warrant share issued percentage.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_WarrantShareIssuedPercentage" xlink:to="nk_WarrantShareIssuedPercentage_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_ClassOfWarrantOrRightExpirationDate" xlink:type="locator" xlink:label="nk_ClassOfWarrantOrRightExpirationDate" />
    <label xml:lang="en-US" xlink:label="nk_ClassOfWarrantOrRightExpirationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Class of warrant or right expiration date.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ClassOfWarrantOrRightExpirationDate" xlink:to="nk_ClassOfWarrantOrRightExpirationDate_lbl" />
    <label xml:lang="en-US" xlink:label="nk_WarrantShareIssuedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrant percentage</label>
    <label xml:lang="en-US" xlink:label="nk_WarrantShareIssuedPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Warrant Share Issued Percentage</label>
    <label xml:lang="en-US" xlink:label="nk_ClassOfWarrantOrRightExpirationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrant expiration date</label>
    <label xml:lang="en-US" xlink:label="nk_ClassOfWarrantOrRightExpirationDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Class Of Warrant Or Right Expiration Date</label>
    <loc xlink:href="nk-20150930.xsd#nk_PercentageOfDilutedSharesOutstanding" xlink:type="locator" xlink:label="nk_PercentageOfDilutedSharesOutstanding" />
    <label xml:lang="en-US" xlink:label="nk_PercentageOfDilutedSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of diluted shares outstanding.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PercentageOfDilutedSharesOutstanding" xlink:to="nk_PercentageOfDilutedSharesOutstanding_lbl" />
    <label xml:lang="en-US" xlink:label="nk_PercentageOfDilutedSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Diluted stock outstanding, percentage</label>
    <label xml:lang="en-US" xlink:label="nk_PercentageOfDilutedSharesOutstanding_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Diluted Shares Outstanding</label>
    <loc xlink:href="nk-20150930.xsd#nk_WarrantExchanged" xlink:type="locator" xlink:label="nk_WarrantExchanged" />
    <label xml:lang="en-US" xlink:label="nk_WarrantExchanged_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Warrant exchanged.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_WarrantExchanged" xlink:to="nk_WarrantExchanged_lbl" />
    <label xml:lang="en-US" xlink:label="nk_WarrantExchanged_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrant exchanged</label>
    <label xml:lang="en-US" xlink:label="nk_WarrantExchanged_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Warrant Exchanged</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:type="locator" xlink:label="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock issued for placement agent commission</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:to="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockIssuedDuringPeriodSharesIssuedForServices_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Issued During Period Shares Issued For Services</label>
    <loc xlink:href="nk-20150930.xsd#nk_SettlementAgreementPaymentCashPaid" xlink:type="locator" xlink:label="nk_SettlementAgreementPaymentCashPaid" />
    <label xml:lang="en-US" xlink:label="nk_SettlementAgreementPaymentCashPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Settlement agreement payment cash paid.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_SettlementAgreementPaymentCashPaid" xlink:to="nk_SettlementAgreementPaymentCashPaid_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_SettlementAgreementWithConversionOfCommonStock" xlink:type="locator" xlink:label="nk_SettlementAgreementWithConversionOfCommonStock" />
    <label xml:lang="en-US" xlink:label="nk_SettlementAgreementWithConversionOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Settlement agreement with conversion of common stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_SettlementAgreementWithConversionOfCommonStock" xlink:to="nk_SettlementAgreementWithConversionOfCommonStock_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_CommonStockConversionPrice" xlink:type="locator" xlink:label="nk_CommonStockConversionPrice" />
    <label xml:lang="en-US" xlink:label="nk_CommonStockConversionPrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock conversion price.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CommonStockConversionPrice" xlink:to="nk_CommonStockConversionPrice_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_CashSettlementExchangeForRetiringNotes" xlink:type="locator" xlink:label="nk_CashSettlementExchangeForRetiringNotes" />
    <label xml:lang="en-US" xlink:label="nk_CashSettlementExchangeForRetiringNotes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Cash settlement exchange for retiring notes.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CashSettlementExchangeForRetiringNotes" xlink:to="nk_CashSettlementExchangeForRetiringNotes_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_CommonStockExerciseOfWarrantsPurchaseOfShare" xlink:type="locator" xlink:label="nk_CommonStockExerciseOfWarrantsPurchaseOfShare" />
    <label xml:lang="en-US" xlink:label="nk_CommonStockExerciseOfWarrantsPurchaseOfShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock exercise of warrants purchase of share.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CommonStockExerciseOfWarrantsPurchaseOfShare" xlink:to="nk_CommonStockExerciseOfWarrantsPurchaseOfShare_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_CommonStockExerciseOfWarrantsPurchasePricePerShare" xlink:type="locator" xlink:label="nk_CommonStockExerciseOfWarrantsPurchasePricePerShare" />
    <label xml:lang="en-US" xlink:label="nk_CommonStockExerciseOfWarrantsPurchasePricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock exercise of warrants purchase price per share.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CommonStockExerciseOfWarrantsPurchasePricePerShare" xlink:to="nk_CommonStockExerciseOfWarrantsPurchasePricePerShare_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_DifferenceAmountOfNotesPayableAndAmountPaidToRetire" xlink:type="locator" xlink:label="nk_DifferenceAmountOfNotesPayableAndAmountPaidToRetire" />
    <label xml:lang="en-US" xlink:label="nk_DifferenceAmountOfNotesPayableAndAmountPaidToRetire_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Difference amount of notes payable and amount paid to retire.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_DifferenceAmountOfNotesPayableAndAmountPaidToRetire" xlink:to="nk_DifferenceAmountOfNotesPayableAndAmountPaidToRetire_lbl" />
    <label xml:lang="en-US" xlink:label="nk_SettlementAgreementPaymentCashPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Settlement agreement payment cash paid</label>
    <label xml:lang="en-US" xlink:label="nk_SettlementAgreementPaymentCashPaid_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Settlement Agreement Payment Cash Paid</label>
    <label xml:lang="en-US" xlink:label="nk_SettlementAgreementWithConversionOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Settlement agreement with conversion of common stock</label>
    <label xml:lang="en-US" xlink:label="nk_SettlementAgreementWithConversionOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Settlement Agreement With Conversion Of Common Stock</label>
    <label xml:lang="en-US" xlink:label="nk_CommonStockConversionPrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock conversion price</label>
    <label xml:lang="en-US" xlink:label="nk_CommonStockConversionPrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Conversion Price</label>
    <label xml:lang="en-US" xlink:label="nk_CashSettlementExchangeForRetiringNotes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Cash settlement exchange for retiring notes</label>
    <label xml:lang="en-US" xlink:label="nk_CashSettlementExchangeForRetiringNotes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Cash Settlement Exchange For Retiring Notes</label>
    <label xml:lang="en-US" xlink:label="nk_CommonStockExerciseOfWarrantsPurchaseOfShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock exercise of warrants purchase of share</label>
    <label xml:lang="en-US" xlink:label="nk_CommonStockExerciseOfWarrantsPurchaseOfShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Exercise Of Warrants Purchase Of Share</label>
    <label xml:lang="en-US" xlink:label="nk_CommonStockExerciseOfWarrantsPurchasePricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock exercise of warrants purchase price per share</label>
    <label xml:lang="en-US" xlink:label="nk_CommonStockExerciseOfWarrantsPurchasePricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Exercise Of Warrants Purchase Price Per Share</label>
    <label xml:lang="en-US" xlink:label="nk_DifferenceAmountOfNotesPayableAndAmountPaidToRetire_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Difference amount of notes payable and amount paid to retire</label>
    <label xml:lang="en-US" xlink:label="nk_DifferenceAmountOfNotesPayableAndAmountPaidToRetire_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Difference Amount Of Notes Payable And Amount Paid To Retire</label>
    <loc xlink:href="nk-20150930.xsd#nk_LicenseAgreementAndMiscellaneousOtherObligation" xlink:type="locator" xlink:label="nk_LicenseAgreementAndMiscellaneousOtherObligation" />
    <label xml:lang="en-US" xlink:label="nk_LicenseAgreementAndMiscellaneousOtherObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">License agreement and miscellaneous other obligation.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_LicenseAgreementAndMiscellaneousOtherObligation" xlink:to="nk_LicenseAgreementAndMiscellaneousOtherObligation_lbl" />
    <label xml:lang="en-US" xlink:label="nk_LicenseAgreementAndMiscellaneousOtherObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License agreement and miscellaneous other obligation</label>
    <label xml:lang="en-US" xlink:label="nk_LicenseAgreementAndMiscellaneousOtherObligation_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License Agreement And Miscellaneous Other Obligation</label>
    <loc xlink:href="nk-20150930.xsd#nk_ConversionPeriod" xlink:type="locator" xlink:label="nk_ConversionPeriod" />
    <label xml:lang="en-US" xlink:label="nk_ConversionPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Conversion period.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ConversionPeriod" xlink:to="nk_ConversionPeriod_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtAndCapitalLeaseObligations" xlink:type="locator" xlink:label="us-gaap_DebtAndCapitalLeaseObligations" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtAndCapitalLeaseObligations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt and capital lease obligations</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtAndCapitalLeaseObligations" xlink:to="us-gaap_DebtAndCapitalLeaseObligations_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtAndCapitalLeaseObligations_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt And Capital Lease Obligations</label>
    <label xml:lang="en-US" xlink:label="nk_ConversionPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Conversion period</label>
    <label xml:lang="en-US" xlink:label="nk_ConversionPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Conversion Period</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ConversionOfStockAmountIssued1" xlink:type="locator" xlink:label="us-gaap_ConversionOfStockAmountIssued1" />
    <label xml:lang="en-US" xlink:label="us-gaap_ConversionOfStockAmountIssued1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Financing closing cost</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ConversionOfStockAmountIssued1" xlink:to="us-gaap_ConversionOfStockAmountIssued1_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ConversionOfStockAmountIssued1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Conversion Of Stock Amount Issued1</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentFaceAmount" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt instrument, face amount</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentFaceAmount" xlink:to="us-gaap_DebtInstrumentFaceAmount_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentFaceAmount_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Face Amount</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentIncreaseAccruedInterest" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentIncreaseAccruedInterest" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentIncreaseAccruedInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Debt instrument, increase, accrued interest</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentIncreaseAccruedInterest" xlink:to="us-gaap_DebtInstrumentIncreaseAccruedInterest_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentIncreaseAccruedInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Increase Accrued Interest</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherLongTermDebt" xlink:type="locator" xlink:label="us-gaap_OtherLongTermDebt" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherLongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other creditors holding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherLongTermDebt" xlink:to="us-gaap_OtherLongTermDebt_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherLongTermDebt_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Long Term Debt</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PrincipalAmountOutstandingOnLoansSecuritized" xlink:type="locator" xlink:label="us-gaap_PrincipalAmountOutstandingOnLoansSecuritized" />
    <label xml:lang="en-US" xlink:label="us-gaap_PrincipalAmountOutstandingOnLoansSecuritized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other creditors outstanding principal</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PrincipalAmountOutstandingOnLoansSecuritized" xlink:to="us-gaap_PrincipalAmountOutstandingOnLoansSecuritized_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_PrincipalAmountOutstandingOnLoansSecuritized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Principal Amount Outstanding On Loans Securitized</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentPrincipal" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentPrincipal_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other creditors outstanding principal</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentPeriodicPaymentPrincipal" xlink:to="us-gaap_DebtInstrumentPeriodicPaymentPrincipal_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentPrincipal_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Periodic Payment Principal</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:type="locator" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentInterest" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Accrued interest were repaid by cash</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DebtInstrumentPeriodicPaymentInterest" xlink:to="us-gaap_DebtInstrumentPeriodicPaymentInterest_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DebtInstrumentPeriodicPaymentInterest_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Debt Instrument Periodic Payment Interest</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesTable" xlink:type="locator" xlink:label="us-gaap_LossContingenciesTable" />
    <label xml:lang="en-US" xlink:label="us-gaap_LossContingenciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Loss Contingencies [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LossContingenciesTable" xlink:to="us-gaap_LossContingenciesTable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LossContingenciesTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Loss Contingencies [Table]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LeaseArrangementTypeAxis" xlink:type="locator" xlink:label="us-gaap_LeaseArrangementTypeAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_LeaseArrangementTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease Arrangement Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseArrangementTypeAxis" xlink:to="us-gaap_LeaseArrangementTypeAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LeaseArrangementTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Arrangement Type [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LeaseArrangementTypeDomain" xlink:type="locator" xlink:label="us-gaap_LeaseArrangementTypeDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_LeaseArrangementTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease Arrangement Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseArrangementTypeDomain" xlink:to="us-gaap_LeaseArrangementTypeDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LeaseArrangementTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Arrangement Type [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_SubLeaseAgreementsMember" xlink:type="locator" xlink:label="nk_SubLeaseAgreementsMember" />
    <label xml:lang="en-US" xlink:label="nk_SubLeaseAgreementsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Sub lease agreements.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_SubLeaseAgreementsMember" xlink:to="nk_SubLeaseAgreementsMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_SubLeaseAgreementsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sub Lease Agreements</label>
    <label xml:lang="en-US" xlink:label="nk_SubLeaseAgreementsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sub Lease Agreements [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:type="locator" xlink:label="us-gaap_StatementScenarioAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_StatementScenarioAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Statement Scenario</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_StatementScenarioAxis" xlink:to="us-gaap_StatementScenarioAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StatementScenarioAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Statement Scenario [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:type="locator" xlink:label="us-gaap_ScenarioUnspecifiedDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScenarioUnspecifiedDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Scenario Unspecified</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScenarioUnspecifiedDomain" xlink:to="us-gaap_ScenarioUnspecifiedDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScenarioUnspecifiedDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Scenario Unspecified [Domain]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScenarioForecastMember" xlink:type="locator" xlink:label="us-gaap_ScenarioForecastMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScenarioForecastMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Scenario Forecast</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScenarioForecastMember" xlink:to="us-gaap_ScenarioForecastMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScenarioForecastMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Scenario Forecast [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_PrivatePlacementOneMember" xlink:type="locator" xlink:label="nk_PrivatePlacementOneMember" />
    <label xml:lang="en-US" xlink:label="nk_PrivatePlacementOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Private placement one.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PrivatePlacementOneMember" xlink:to="nk_PrivatePlacementOneMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_PrivatePlacementOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Private Placement One</label>
    <label xml:lang="en-US" xlink:label="nk_PrivatePlacementOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Private Placement One [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_PrivatePlacementTwoMember" xlink:type="locator" xlink:label="nk_PrivatePlacementTwoMember" />
    <label xml:lang="en-US" xlink:label="nk_PrivatePlacementTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Private placement two.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PrivatePlacementTwoMember" xlink:to="nk_PrivatePlacementTwoMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_PrivatePlacementTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Private Placement Two</label>
    <label xml:lang="en-US" xlink:label="nk_PrivatePlacementTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Private Placement Two [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RelatedPartyTransactionAxis" xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Related Party Transaction</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionAxis" xlink:to="us-gaap_RelatedPartyTransactionAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Transaction [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RelatedPartyTransactionDomain" xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Related Party Transaction</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionDomain" xlink:to="us-gaap_RelatedPartyTransactionDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Transaction [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_SorrentoMember" xlink:type="locator" xlink:label="nk_SorrentoMember" />
    <label xml:lang="en-US" xlink:label="nk_SorrentoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Sorrento.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_SorrentoMember" xlink:to="nk_SorrentoMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_SorrentoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Sorrento</label>
    <label xml:lang="en-US" xlink:label="nk_SorrentoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sorrento [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherCommitmentsAxis" xlink:type="locator" xlink:label="us-gaap_OtherCommitmentsAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherCommitmentsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Commitments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherCommitmentsAxis" xlink:to="us-gaap_OtherCommitmentsAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherCommitmentsAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Commitments [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OtherCommitmentsDomain" xlink:type="locator" xlink:label="us-gaap_OtherCommitmentsDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherCommitmentsDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Other Commitments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OtherCommitmentsDomain" xlink:to="us-gaap_OtherCommitmentsDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OtherCommitmentsDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Other Commitments [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_FoxChaseCancerCenterLicenseAgreementMember" xlink:type="locator" xlink:label="nk_FoxChaseCancerCenterLicenseAgreementMember" />
    <label xml:lang="en-US" xlink:label="nk_FoxChaseCancerCenterLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Fox chase cancer center license agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_FoxChaseCancerCenterLicenseAgreementMember" xlink:to="nk_FoxChaseCancerCenterLicenseAgreementMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_FoxChaseCancerCenterLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Fox Chase Cancer Center License Agreement</label>
    <label xml:lang="en-US" xlink:label="nk_FoxChaseCancerCenterLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Fox Chase Cancer Center License Agreement [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_RushUniversityMedicalCenterLicenseAgreementMember" xlink:type="locator" xlink:label="nk_RushUniversityMedicalCenterLicenseAgreementMember" />
    <label xml:lang="en-US" xlink:label="nk_RushUniversityMedicalCenterLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Rush university medical center license agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_RushUniversityMedicalCenterLicenseAgreementMember" xlink:to="nk_RushUniversityMedicalCenterLicenseAgreementMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_RushUniversityMedicalCenterLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Rush University Medical Center License Agreement</label>
    <label xml:lang="en-US" xlink:label="nk_RushUniversityMedicalCenterLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Rush University Medical Center License Agreement [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationAxis" xlink:to="us-gaap_IncomeStatementLocationAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:type="locator" xlink:label="us-gaap_IncomeStatementLocationDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Location</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementLocationDomain" xlink:to="us-gaap_IncomeStatementLocationDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementLocationDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Location [Domain]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:type="locator" xlink:label="us-gaap_LossContingenciesLineItems" />
    <label xml:lang="en-US" xlink:label="us-gaap_LossContingenciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Loss Contingencies [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LossContingenciesLineItems" xlink:to="us-gaap_LossContingenciesLineItems_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LossContingenciesLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Loss Contingencies [Line Items]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LeaseExpirationDate1" xlink:type="locator" xlink:label="us-gaap_LeaseExpirationDate1" />
    <label xml:lang="en-US" xlink:label="us-gaap_LeaseExpirationDate1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Lease Expiration Date</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LeaseExpirationDate1" xlink:to="us-gaap_LeaseExpirationDate1_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LeaseExpirationDate1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Expiration Date1</label>
    <loc xlink:href="nk-20150930.xsd#nk_NumberOfSquareFootOfFacilityLeased" xlink:type="locator" xlink:label="nk_NumberOfSquareFootOfFacilityLeased" />
    <label xml:lang="en-US" xlink:label="nk_NumberOfSquareFootOfFacilityLeased_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of square foot of facility leased.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_NumberOfSquareFootOfFacilityLeased" xlink:to="nk_NumberOfSquareFootOfFacilityLeased_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_LeaseAgreementExtendedLeaseTerm" xlink:type="locator" xlink:label="nk_LeaseAgreementExtendedLeaseTerm" />
    <label xml:lang="en-US" xlink:label="nk_LeaseAgreementExtendedLeaseTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Lease agreement extended lease term.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_LeaseAgreementExtendedLeaseTerm" xlink:to="nk_LeaseAgreementExtendedLeaseTerm_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_BaseRent" xlink:type="locator" xlink:label="nk_BaseRent" />
    <label xml:lang="en-US" xlink:label="nk_BaseRent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Base rent.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_BaseRent" xlink:to="nk_BaseRent_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_AnnualPercentageIncreasesToBaseRent" xlink:type="locator" xlink:label="nk_AnnualPercentageIncreasesToBaseRent" />
    <label xml:lang="en-US" xlink:label="nk_AnnualPercentageIncreasesToBaseRent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Annual percentage increases to base rent.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_AnnualPercentageIncreasesToBaseRent" xlink:to="nk_AnnualPercentageIncreasesToBaseRent_lbl" />
    <label xml:lang="en-US" xlink:label="nk_NumberOfSquareFootOfFacilityLeased_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of square foot of facility leased.</label>
    <label xml:lang="en-US" xlink:label="nk_NumberOfSquareFootOfFacilityLeased_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Square Foot Of Facility Leased</label>
    <label xml:lang="en-US" xlink:label="nk_LeaseAgreementExtendedLeaseTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Extended lease term</label>
    <label xml:lang="en-US" xlink:label="nk_LeaseAgreementExtendedLeaseTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Lease Agreement Extended Lease Term</label>
    <label xml:lang="en-US" xlink:label="nk_BaseRent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Base rent</label>
    <label xml:lang="en-US" xlink:label="nk_BaseRent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Base Rent</label>
    <label xml:lang="en-US" xlink:label="nk_AnnualPercentageIncreasesToBaseRent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of annual increase of base rent</label>
    <label xml:lang="en-US" xlink:label="nk_AnnualPercentageIncreasesToBaseRent_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Annual Percentage Increases To Base Rent</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OperatingLeasesRentExpenseNet" xlink:type="locator" xlink:label="us-gaap_OperatingLeasesRentExpenseNet" />
    <label xml:lang="en-US" xlink:label="us-gaap_OperatingLeasesRentExpenseNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Rent expense</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OperatingLeasesRentExpenseNet" xlink:to="us-gaap_OperatingLeasesRentExpenseNet_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OperatingLeasesRentExpenseNet_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Operating Leases Rent Expense Net</label>
    <loc xlink:href="nk-20150930.xsd#nk_ProceedsFromIssuanceOfPrivatePlacementGross" xlink:type="locator" xlink:label="nk_ProceedsFromIssuanceOfPrivatePlacementGross" />
    <label xml:lang="en-US" xlink:label="nk_ProceedsFromIssuanceOfPrivatePlacementGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Proceeds From Issuance Of Private Placement Gross.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ProceedsFromIssuanceOfPrivatePlacementGross" xlink:to="nk_ProceedsFromIssuanceOfPrivatePlacementGross_lbl" />
    <label xml:lang="en-US" xlink:label="nk_ProceedsFromIssuanceOfPrivatePlacementGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from issuance of common stock gross of issuance costs</label>
    <label xml:lang="en-US" xlink:label="nk_ProceedsFromIssuanceOfPrivatePlacementGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Issuance Of Private Placement Gross</label>
    <loc xlink:href="nk-20150930.xsd#nk_WarrantExerciseTerm" xlink:type="locator" xlink:label="nk_WarrantExerciseTerm" />
    <label xml:lang="en-US" xlink:label="nk_WarrantExerciseTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Warrant exercise term.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_WarrantExerciseTerm" xlink:to="nk_WarrantExerciseTerm_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_ClassOfWarrantOrRightOutstandingNumberOfSharesExercised" xlink:type="locator" xlink:label="nk_ClassOfWarrantOrRightOutstandingNumberOfSharesExercised" />
    <label xml:lang="en-US" xlink:label="nk_ClassOfWarrantOrRightOutstandingNumberOfSharesExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Class of warrant or right outstanding number of shares exercised.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ClassOfWarrantOrRightOutstandingNumberOfSharesExercised" xlink:to="nk_ClassOfWarrantOrRightOutstandingNumberOfSharesExercised_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LicensesRevenue" xlink:type="locator" xlink:label="us-gaap_LicensesRevenue" />
    <label xml:lang="en-US" xlink:label="us-gaap_LicensesRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Consideration for the sale of the licensed patents</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LicensesRevenue" xlink:to="us-gaap_LicensesRevenue_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LicensesRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Licenses Revenue</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VariableInterestEntityOwnershipPercentage" xlink:type="locator" xlink:label="us-gaap_VariableInterestEntityOwnershipPercentage" />
    <label xml:lang="en-US" xlink:label="us-gaap_VariableInterestEntityOwnershipPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Ownership interest of the total outstanding common shares</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VariableInterestEntityOwnershipPercentage" xlink:to="us-gaap_VariableInterestEntityOwnershipPercentage_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_VariableInterestEntityOwnershipPercentage_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Variable Interest Entity Ownership Percentage</label>
    <label xml:lang="en-US" xlink:label="nk_WarrantExerciseTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrant exercise term</label>
    <label xml:lang="en-US" xlink:label="nk_WarrantExerciseTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Warrant Exercise Term</label>
    <label xml:lang="en-US" xlink:label="nk_ClassOfWarrantOrRightOutstandingNumberOfSharesExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class of warrant or right outstanding number of shares exercised</label>
    <label xml:lang="en-US" xlink:label="nk_ClassOfWarrantOrRightOutstandingNumberOfSharesExercised_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Class Of Warrant Or Right Outstanding Number Of Shares Exercised</label>
    <loc xlink:href="nk-20150930.xsd#nk_WarrantExchangeToPurchaseOfCommonStock" xlink:type="locator" xlink:label="nk_WarrantExchangeToPurchaseOfCommonStock" />
    <label xml:lang="en-US" xlink:label="nk_WarrantExchangeToPurchaseOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Warrant exchange to purchase of common stock.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_WarrantExchangeToPurchaseOfCommonStock" xlink:to="nk_WarrantExchangeToPurchaseOfCommonStock_lbl" />
    <label xml:lang="en-US" xlink:label="nk_WarrantExchangeToPurchaseOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrants exchange to purchase common stock</label>
    <label xml:lang="en-US" xlink:label="nk_WarrantExchangeToPurchaseOfCommonStock_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Warrant Exchange To Purchase Of Common Stock</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Purchase of fully-vested incentive stock option</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding Number</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceOfPrivatePlacement" xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceOfPrivatePlacement" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from issuance of common stock net of issuance costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceOfPrivatePlacement" xlink:to="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Issuance Of Private Placement</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RoyaltyExpense" xlink:type="locator" xlink:label="us-gaap_RoyaltyExpense" />
    <label xml:lang="en-US" xlink:label="us-gaap_RoyaltyExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Expense earned or paid</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RoyaltyExpense" xlink:to="us-gaap_RoyaltyExpense_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_RoyaltyExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Royalty Expense</label>
    <loc xlink:href="nk-20150930.xsd#nk_PeriodOfLicenseAgreement" xlink:type="locator" xlink:label="nk_PeriodOfLicenseAgreement" />
    <label xml:lang="en-US" xlink:label="nk_PeriodOfLicenseAgreement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Period of license agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PeriodOfLicenseAgreement" xlink:to="nk_PeriodOfLicenseAgreement_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_MinimumAnnualRoyaltyPayment" xlink:type="locator" xlink:label="nk_MinimumAnnualRoyaltyPayment" />
    <label xml:lang="en-US" xlink:label="nk_MinimumAnnualRoyaltyPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Minimum annual royalty payment.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_MinimumAnnualRoyaltyPayment" xlink:to="nk_MinimumAnnualRoyaltyPayment_lbl" />
    <label xml:lang="en-US" xlink:label="nk_PeriodOfLicenseAgreement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Period of license agreement</label>
    <label xml:lang="en-US" xlink:label="nk_PeriodOfLicenseAgreement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Period Of License Agreement</label>
    <label xml:lang="en-US" xlink:label="nk_MinimumAnnualRoyaltyPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Minimum annual royalty payment</label>
    <label xml:lang="en-US" xlink:label="nk_MinimumAnnualRoyaltyPayment_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Minimum Annual Royalty Payment</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LicenseCosts" xlink:type="locator" xlink:label="us-gaap_LicenseCosts" />
    <label xml:lang="en-US" xlink:label="us-gaap_LicenseCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Payments in license agreement</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LicenseCosts" xlink:to="us-gaap_LicenseCosts_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LicenseCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License Costs</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized" xlink:type="locator" xlink:label="us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized" />
    <label xml:lang="en-US" xlink:label="us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Milestone payments</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized" xlink:to="us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_RevenueRecognitionMilestoneMethodRevenueRecognized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Revenue Recognition Milestone Method Revenue Recognized</label>
    <loc xlink:href="nk-20150930.xsd#nk_LicenseAgreementTerminationNoticePeriod" xlink:type="locator" xlink:label="nk_LicenseAgreementTerminationNoticePeriod" />
    <label xml:lang="en-US" xlink:label="nk_LicenseAgreementTerminationNoticePeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">License agreement termination notice period.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_LicenseAgreementTerminationNoticePeriod" xlink:to="nk_LicenseAgreementTerminationNoticePeriod_lbl" />
    <label xml:lang="en-US" xlink:label="nk_LicenseAgreementTerminationNoticePeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License agreement termination notice period</label>
    <label xml:lang="en-US" xlink:label="nk_LicenseAgreementTerminationNoticePeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License Agreement Termination Notice Period</label>
    <loc xlink:href="nk-20150930.xsd#nk_RelatedPartyTransactionInitialTermOfAgreement" xlink:type="locator" xlink:label="nk_RelatedPartyTransactionInitialTermOfAgreement" />
    <label xml:lang="en-US" xlink:label="nk_RelatedPartyTransactionInitialTermOfAgreement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Related party transaction initial term of agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_RelatedPartyTransactionInitialTermOfAgreement" xlink:to="nk_RelatedPartyTransactionInitialTermOfAgreement_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_RelatedPartyAgreementRenewalTerm" xlink:type="locator" xlink:label="nk_RelatedPartyAgreementRenewalTerm" />
    <label xml:lang="en-US" xlink:label="nk_RelatedPartyAgreementRenewalTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Related party agreement renewal term.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_RelatedPartyAgreementRenewalTerm" xlink:to="nk_RelatedPartyAgreementRenewalTerm_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Related Party Transactions By Related Party [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Related Party Transactions By Related Party [Table]</label>
    <loc xlink:href="nk-20150930.xsd#nk_NantOmicsLLCMember" xlink:type="locator" xlink:label="nk_NantOmicsLLCMember" />
    <label xml:lang="en-US" xlink:label="nk_NantOmicsLLCMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">NantOmics, LLC.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_NantOmicsLLCMember" xlink:to="nk_NantOmicsLLCMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_NantOmicsLLCMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">NantOmics</label>
    <label xml:lang="en-US" xlink:label="nk_NantOmicsLLCMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Nant Omics L L C [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_NanoCavLLCMember" xlink:type="locator" xlink:label="nk_NanoCavLLCMember" />
    <label xml:lang="en-US" xlink:label="nk_NanoCavLLCMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">NanoCav, LLC.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_NanoCavLLCMember" xlink:to="nk_NanoCavLLCMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_NanoCavLLCMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">NanoCav</label>
    <label xml:lang="en-US" xlink:label="nk_NanoCavLLCMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Nano Cav L L C [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_NantCellIncMember" xlink:type="locator" xlink:label="nk_NantCellIncMember" />
    <label xml:lang="en-US" xlink:label="nk_NantCellIncMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">NantCell, Inc.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_NantCellIncMember" xlink:to="nk_NantCellIncMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_NantCellIncMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">NantCell</label>
    <label xml:lang="en-US" xlink:label="nk_NantCellIncMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Nant Cell Inc [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finite Lived Intangible Assets By Major Class</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets By Major Class [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="locator" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Finite Lived Intangible Assets Major Class Name</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Finite Lived Intangible Assets Major Class Name [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_SharedServicesAgreementMember" xlink:type="locator" xlink:label="nk_SharedServicesAgreementMember" />
    <label xml:lang="en-US" xlink:label="nk_SharedServicesAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Shared services agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_SharedServicesAgreementMember" xlink:to="nk_SharedServicesAgreementMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_SharedServicesAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shared Services Agreement</label>
    <label xml:lang="en-US" xlink:label="nk_SharedServicesAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Shared Services Agreement [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventTypeAxis" xlink:to="us-gaap_SubsequentEventTypeAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:type="locator" xlink:label="us-gaap_SubsequentEventTypeDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventTypeDomain" xlink:to="us-gaap_SubsequentEventTypeDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event Type [Domain]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SubsequentEventMember" xlink:type="locator" xlink:label="us-gaap_SubsequentEventMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Subsequent Event</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SubsequentEventMember" xlink:to="us-gaap_SubsequentEventMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SubsequentEventMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Subsequent Event [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_NantworksLimitedLiabilityCompanyMember" xlink:type="locator" xlink:label="nk_NantworksLimitedLiabilityCompanyMember" />
    <label xml:lang="en-US" xlink:label="nk_NantworksLimitedLiabilityCompanyMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">NantWorks LLC.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_NantworksLimitedLiabilityCompanyMember" xlink:to="nk_NantworksLimitedLiabilityCompanyMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_NantworksLimitedLiabilityCompanyMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">NantWorks</label>
    <label xml:lang="en-US" xlink:label="nk_NantworksLimitedLiabilityCompanyMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Nantworks Limited Liability Company [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RelatedPartyTransactionLineItems" xlink:type="locator" xlink:label="us-gaap_RelatedPartyTransactionLineItems" />
    <label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Related Party Transaction [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RelatedPartyTransactionLineItems" xlink:to="us-gaap_RelatedPartyTransactionLineItems_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_RelatedPartyTransactionLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Transaction [Line Items]</label>
    <label xml:lang="en-US" xlink:label="nk_RelatedPartyTransactionInitialTermOfAgreement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Initial term of agreement entered into with the related party by the entity</label>
    <label xml:lang="en-US" xlink:label="nk_RelatedPartyTransactionInitialTermOfAgreement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Transaction Initial Term Of Agreement</label>
    <label xml:lang="en-US" xlink:label="nk_RelatedPartyAgreementRenewalTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Related party, agreement renewal term</label>
    <label xml:lang="en-US" xlink:label="nk_RelatedPartyAgreementRenewalTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Related Party Agreement Renewal Term</label>
    <loc xlink:href="nk-20150930.xsd#nk_UpfrontPaymentToRelatedParty" xlink:type="locator" xlink:label="nk_UpfrontPaymentToRelatedParty" />
    <label xml:lang="en-US" xlink:label="nk_UpfrontPaymentToRelatedParty_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Upfront payment to related party.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_UpfrontPaymentToRelatedParty" xlink:to="nk_UpfrontPaymentToRelatedParty_lbl" />
    <label xml:lang="en-US" xlink:label="nk_UpfrontPaymentToRelatedParty_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non refundable upfront payment</label>
    <label xml:lang="en-US" xlink:label="nk_UpfrontPaymentToRelatedParty_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Upfront Payment To Related Party</label>
    <loc xlink:href="nk-20150930.xsd#nk_AgreementEffectiveDate" xlink:type="locator" xlink:label="nk_AgreementEffectiveDate" />
    <label xml:lang="en-US" xlink:label="nk_AgreementEffectiveDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Agreement effective date.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_AgreementEffectiveDate" xlink:to="nk_AgreementEffectiveDate_lbl" />
    <label xml:lang="en-US" xlink:label="nk_AgreementEffectiveDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Agreement Effective Date</label>
    <label xml:lang="en-US" xlink:label="nk_AgreementEffectiveDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Agreement Effective Date</label>
    <loc xlink:href="nk-20150930.xsd#nk_AnnualPercentageIncreasesToBaseRentCommencementDate" xlink:type="locator" xlink:label="nk_AnnualPercentageIncreasesToBaseRentCommencementDate" />
    <label xml:lang="en-US" xlink:label="nk_AnnualPercentageIncreasesToBaseRentCommencementDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Annual percentage increases to base rent commencement date.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_AnnualPercentageIncreasesToBaseRentCommencementDate" xlink:to="nk_AnnualPercentageIncreasesToBaseRentCommencementDate_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_PeriodOfLicenseAgreementDescription" xlink:type="locator" xlink:label="nk_PeriodOfLicenseAgreementDescription" />
    <label xml:lang="en-US" xlink:label="nk_PeriodOfLicenseAgreementDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Period of license agreement description.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PeriodOfLicenseAgreementDescription" xlink:to="nk_PeriodOfLicenseAgreementDescription_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_CostsIncurredDevelopmentCosts" xlink:type="locator" xlink:label="us-gaap_CostsIncurredDevelopmentCosts" />
    <label xml:lang="en-US" xlink:label="us-gaap_CostsIncurredDevelopmentCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Costs incurred</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_CostsIncurredDevelopmentCosts" xlink:to="us-gaap_CostsIncurredDevelopmentCosts_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_CostsIncurredDevelopmentCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Costs Incurred Development Costs</label>
    <label xml:lang="en-US" xlink:label="nk_AnnualPercentageIncreasesToBaseRentCommencementDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Annual percentage increases to base rent commencement date</label>
    <label xml:lang="en-US" xlink:label="nk_AnnualPercentageIncreasesToBaseRentCommencementDate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Annual Percentage Increases To Base Rent Commencement Date</label>
    <label xml:lang="en-US" xlink:label="nk_PeriodOfLicenseAgreementDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Period of agreement</label>
    <label xml:lang="en-US" xlink:label="nk_PeriodOfLicenseAgreementDescription_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Period Of License Agreement Description</label>
    <loc xlink:href="nk-20150930.xsd#nk_LicenseAgreementTerm" xlink:type="locator" xlink:label="nk_LicenseAgreementTerm" />
    <label xml:lang="en-US" xlink:label="nk_LicenseAgreementTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">License agreement term.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_LicenseAgreementTerm" xlink:to="nk_LicenseAgreementTerm_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_AgreementOneTimeFee" xlink:type="locator" xlink:label="nk_AgreementOneTimeFee" />
    <label xml:lang="en-US" xlink:label="nk_AgreementOneTimeFee_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Agreement one time fee.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_AgreementOneTimeFee" xlink:to="nk_AgreementOneTimeFee_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_LicensingAgreementLineItems" xlink:type="locator" xlink:label="nk_LicensingAgreementLineItems" />
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Licensing agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_LicensingAgreementLineItems" xlink:to="nk_LicensingAgreementLineItems_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_LicensingAgreementTable" xlink:type="locator" xlink:label="nk_LicensingAgreementTable" />
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Licensing agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_LicensingAgreementTable" xlink:to="nk_LicensingAgreementTable_lbl" />
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Licensing Agreement [Table]</label>
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Licensing Agreement [Table]</label>
    <loc xlink:href="nk-20150930.xsd#nk_IntrexonLicenseAgreementMember" xlink:type="locator" xlink:label="nk_IntrexonLicenseAgreementMember" />
    <label xml:lang="en-US" xlink:label="nk_IntrexonLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Intrexon license agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_IntrexonLicenseAgreementMember" xlink:to="nk_IntrexonLicenseAgreementMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_IntrexonLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Intrexon Corporation</label>
    <label xml:lang="en-US" xlink:label="nk_IntrexonLicenseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Intrexon License Agreement [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research And Development Arrangement Contract To Perform For Others By Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis" xlink:to="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersByTypeAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Research And Development Arrangement Contract To Perform For Others By Type [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:type="locator" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Research And Development Arrangement Contract To Perform For Others Type</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain" xlink:to="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ResearchAndDevelopmentArrangementContractToPerformForOthersTypeDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Research And Development Arrangement Contract To Perform For Others Type [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_INDFilingMember" xlink:type="locator" xlink:label="nk_INDFilingMember" />
    <label xml:lang="en-US" xlink:label="nk_INDFilingMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">IND filing.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_INDFilingMember" xlink:to="nk_INDFilingMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_INDFilingMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">First IND Filing</label>
    <label xml:lang="en-US" xlink:label="nk_INDFilingMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">I N D Filing [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_PhaseTwoMember" xlink:type="locator" xlink:label="nk_PhaseTwoMember" />
    <label xml:lang="en-US" xlink:label="nk_PhaseTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Phase two.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PhaseTwoMember" xlink:to="nk_PhaseTwoMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_PhaseTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">First Phase II Clinical Trial</label>
    <label xml:lang="en-US" xlink:label="nk_PhaseTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Phase Two [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_PhaseThreeMember" xlink:type="locator" xlink:label="nk_PhaseThreeMember" />
    <label xml:lang="en-US" xlink:label="nk_PhaseThreeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Phase three.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PhaseThreeMember" xlink:to="nk_PhaseThreeMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_PhaseThreeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">First Phase III Clinical Trial</label>
    <label xml:lang="en-US" xlink:label="nk_PhaseThreeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Phase Three [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_CommercialSaleRelatedToLicensedProductsMember" xlink:type="locator" xlink:label="nk_CommercialSaleRelatedToLicensedProductsMember" />
    <label xml:lang="en-US" xlink:label="nk_CommercialSaleRelatedToLicensedProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Commercial sale related to licensed products.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CommercialSaleRelatedToLicensedProductsMember" xlink:to="nk_CommercialSaleRelatedToLicensedProductsMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_CommercialSaleRelatedToLicensedProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commercial Sale Related to Licensed Products</label>
    <label xml:lang="en-US" xlink:label="nk_CommercialSaleRelatedToLicensedProductsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Commercial Sale Related To Licensed Products [Member]</label>
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Licensing Agreement [Line Items]</label>
    <label xml:lang="en-US" xlink:label="nk_LicensingAgreementLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Licensing Agreement [Line Items]</label>
    <label xml:lang="en-US" xlink:label="nk_LicenseAgreementTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">License agreement term (years)</label>
    <label xml:lang="en-US" xlink:label="nk_LicenseAgreementTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License Agreement Term</label>
    <label xml:lang="en-US" xlink:label="nk_AgreementOneTimeFee_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Agreement one time fee</label>
    <label xml:lang="en-US" xlink:label="nk_AgreementOneTimeFee_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Agreement One Time Fee</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:type="locator" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Table]</label>
    <loc xlink:href="nk-20150930.xsd#nk_ConeksisIncMember" xlink:type="locator" xlink:label="nk_ConeksisIncMember" />
    <label xml:lang="en-US" xlink:label="nk_ConeksisIncMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Coneksis Inc.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ConeksisIncMember" xlink:to="nk_ConeksisIncMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_ConeksisIncMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Coneksis</label>
    <label xml:lang="en-US" xlink:label="nk_ConeksisIncMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Coneksis Inc [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:type="locator" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_RoyaltyRevenue" xlink:type="locator" xlink:label="us-gaap_RoyaltyRevenue" />
    <label xml:lang="en-US" xlink:label="us-gaap_RoyaltyRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Royalty revenue</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_RoyaltyRevenue" xlink:to="us-gaap_RoyaltyRevenue_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_RoyaltyRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Royalty Revenue</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_LicenseAndServicesRevenue" xlink:type="locator" xlink:label="us-gaap_LicenseAndServicesRevenue" />
    <label xml:lang="en-US" xlink:label="us-gaap_LicenseAndServicesRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Invoiced for services</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_LicenseAndServicesRevenue" xlink:to="us-gaap_LicenseAndServicesRevenue_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_LicenseAndServicesRevenue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">License And Services Revenue</label>
    <label xml:lang="en-US" xlink:label="us-gaap_SellingGeneralAndAdministrativeExpense_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Selling, general and administrative expense</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfStockByClassTable" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfStockByClassTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Stock By Class [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfStockByClassTable" xlink:to="us-gaap_ScheduleOfStockByClassTable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfStockByClassTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Stock By Class [Table]</label>
    <loc xlink:href="nk-20150930.xsd#nk_TwoThousandFourteenSecuritiesPurchaseAgreementMember" xlink:type="locator" xlink:label="nk_TwoThousandFourteenSecuritiesPurchaseAgreementMember" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandFourteenSecuritiesPurchaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand fourteen securities purchase agreement.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_TwoThousandFourteenSecuritiesPurchaseAgreementMember" xlink:to="nk_TwoThousandFourteenSecuritiesPurchaseAgreementMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandFourteenSecuritiesPurchaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2014 Securities Purchase Agreement</label>
    <label xml:lang="en-US" xlink:label="nk_TwoThousandFourteenSecuritiesPurchaseAgreementMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Fourteen Securities Purchase Agreement [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_CommonStockWarrantMember" xlink:type="locator" xlink:label="nk_CommonStockWarrantMember" />
    <label xml:lang="en-US" xlink:label="nk_CommonStockWarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common stock warrant.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CommonStockWarrantMember" xlink:to="nk_CommonStockWarrantMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_CommonStockWarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common Stock Warrant</label>
    <label xml:lang="en-US" xlink:label="nk_CommonStockWarrantMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Warrant [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:type="locator" xlink:label="us-gaap_ClassOfStockLineItems" />
    <label xml:lang="en-US" xlink:label="us-gaap_ClassOfStockLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Class Of Stock [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ClassOfStockLineItems" xlink:to="us-gaap_ClassOfStockLineItems_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ClassOfStockLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Class Of Stock [Line Items]</label>
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceOfPrivatePlacement_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/verboseLabel">Proceeds from issuance of common stock net of issuance costs</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PaymentsOfStockIssuanceCosts" xlink:type="locator" xlink:label="us-gaap_PaymentsOfStockIssuanceCosts" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsOfStockIssuanceCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Issuance costs</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PaymentsOfStockIssuanceCosts" xlink:to="us-gaap_PaymentsOfStockIssuanceCosts_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_PaymentsOfStockIssuanceCosts_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Payments Of Stock Issuance Costs</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ProceedsFromIssuanceInitialPublicOffering" xlink:type="locator" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Proceeds from sale of common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ProceedsFromIssuanceInitialPublicOffering" xlink:to="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ProceedsFromIssuanceInitialPublicOffering_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Proceeds From Issuance Initial Public Offering</label>
    <loc xlink:href="nk-20150930.xsd#nk_NumberOfBoardOfDirectors" xlink:type="locator" xlink:label="nk_NumberOfBoardOfDirectors" />
    <label xml:lang="en-US" xlink:label="nk_NumberOfBoardOfDirectors_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Number of board of directors.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_NumberOfBoardOfDirectors" xlink:to="nk_NumberOfBoardOfDirectors_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SaleOfStockPricePerShare" xlink:type="locator" xlink:label="us-gaap_SaleOfStockPricePerShare" />
    <label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockPricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock issued, par value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SaleOfStockPricePerShare" xlink:to="us-gaap_SaleOfStockPricePerShare_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SaleOfStockPricePerShare_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sale Of Stock Price Per Share</label>
    <label xml:lang="en-US" xlink:label="nk_NumberOfBoardOfDirectors_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Number of board of directors</label>
    <label xml:lang="en-US" xlink:label="nk_NumberOfBoardOfDirectors_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Number Of Board Of Directors</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SalesCommissionsAndFees" xlink:type="locator" xlink:label="us-gaap_SalesCommissionsAndFees" />
    <label xml:lang="en-US" xlink:label="us-gaap_SalesCommissionsAndFees_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Commissions</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SalesCommissionsAndFees" xlink:to="us-gaap_SalesCommissionsAndFees_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SalesCommissionsAndFees_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sales Commissions And Fees</label>
    <loc xlink:href="nk-20150930.xsd#nk_CommonStockWarrantIssued" xlink:type="locator" xlink:label="nk_CommonStockWarrantIssued" />
    <label xml:lang="en-US" xlink:label="nk_CommonStockWarrantIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Common Stock Warrant Issued.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_CommonStockWarrantIssued" xlink:to="nk_CommonStockWarrantIssued_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_ClassOfWarrantOrRightsExercisablePeriodFromDateOfIssuance" xlink:type="locator" xlink:label="nk_ClassOfWarrantOrRightsExercisablePeriodFromDateOfIssuance" />
    <label xml:lang="en-US" xlink:label="nk_ClassOfWarrantOrRightsExercisablePeriodFromDateOfIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Class of warrant or rights exercisable period from date of issuance.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ClassOfWarrantOrRightsExercisablePeriodFromDateOfIssuance" xlink:to="nk_ClassOfWarrantOrRightsExercisablePeriodFromDateOfIssuance_lbl" />
    <loc xlink:href="nk-20150930.xsd#nk_PercentageOfConsentOfShareholdersForNewTransaction" xlink:type="locator" xlink:label="nk_PercentageOfConsentOfShareholdersForNewTransaction" />
    <label xml:lang="en-US" xlink:label="nk_PercentageOfConsentOfShareholdersForNewTransaction_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Percentage of consent of shareholders for new transaction.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_PercentageOfConsentOfShareholdersForNewTransaction" xlink:to="nk_PercentageOfConsentOfShareholdersForNewTransaction_lbl" />
    <label xml:lang="en-US" xlink:label="nk_CommonStockWarrantIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrants issued to purchase common shares</label>
    <label xml:lang="en-US" xlink:label="nk_CommonStockWarrantIssued_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Common Stock Warrant Issued</label>
    <label xml:lang="en-US" xlink:label="nk_ClassOfWarrantOrRightsExercisablePeriodFromDateOfIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrant exercisable period</label>
    <label xml:lang="en-US" xlink:label="nk_ClassOfWarrantOrRightsExercisablePeriodFromDateOfIssuance_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Class Of Warrant Or Rights Exercisable Period From Date Of Issuance</label>
    <label xml:lang="en-US" xlink:label="nk_PercentageOfConsentOfShareholdersForNewTransaction_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Percentage of shareholders consent</label>
    <label xml:lang="en-US" xlink:label="nk_PercentageOfConsentOfShareholdersForNewTransaction_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Percentage Of Consent Of Shareholders For New Transaction</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_DerivativeLiabilities" xlink:type="locator" xlink:label="us-gaap_DerivativeLiabilities" />
    <label xml:lang="en-US" xlink:label="us-gaap_DerivativeLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Derivative Liability</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_DerivativeLiabilities" xlink:to="us-gaap_DerivativeLiabilities_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_DerivativeLiabilities_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Derivative Liabilities</label>
    <loc xlink:href="nk-20150930.xsd#nk_StockRepurchasedDuringPeriodPerShareValue" xlink:type="locator" xlink:label="nk_StockRepurchasedDuringPeriodPerShareValue" />
    <label xml:lang="en-US" xlink:label="nk_StockRepurchasedDuringPeriodPerShareValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Stock repurchased during period per share value.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_StockRepurchasedDuringPeriodPerShareValue" xlink:to="nk_StockRepurchasedDuringPeriodPerShareValue_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Repurchase of common stock, shares</label>
    <label xml:lang="en-US" xlink:label="nk_StockRepurchasedDuringPeriodPerShareValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Repurchase of common stock, par value</label>
    <label xml:lang="en-US" xlink:label="nk_StockRepurchasedDuringPeriodPerShareValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Stock Repurchased During Period Per Share Value</label>
    <label xml:lang="en-US" xlink:label="us-gaap_StockRepurchasedDuringPeriodValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Repurchase of common stock, value</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="locator" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanNameAxis" xlink:type="locator" xlink:label="us-gaap_PlanNameAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameAxis" xlink:to="us-gaap_PlanNameAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_PlanNameAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_PlanNameDomain" xlink:type="locator" xlink:label="us-gaap_PlanNameDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Plan Name</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_PlanNameDomain" xlink:to="us-gaap_PlanNameDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_PlanNameDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Plan Name [Domain]</label>
    <loc xlink:href="nk-20150930.xsd#nk_TwoThousandFourteenEquityIncentivePlanMember" xlink:type="locator" xlink:label="nk_TwoThousandFourteenEquityIncentivePlanMember" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandFourteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand fourteen equity incentive plan.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_TwoThousandFourteenEquityIncentivePlanMember" xlink:to="nk_TwoThousandFourteenEquityIncentivePlanMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandFourteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2014 Equity Incentive Plan</label>
    <label xml:lang="en-US" xlink:label="nk_TwoThousandFourteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Fourteen Equity Incentive Plan [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_TwoThousandFifteenEquityIncentivePlanMember" xlink:type="locator" xlink:label="nk_TwoThousandFifteenEquityIncentivePlanMember" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandFifteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Two thousand fifteen equity incentive plan.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_TwoThousandFifteenEquityIncentivePlanMember" xlink:to="nk_TwoThousandFifteenEquityIncentivePlanMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_TwoThousandFifteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">2015 Equity Incentive Plan</label>
    <label xml:lang="en-US" xlink:label="nk_TwoThousandFifteenEquityIncentivePlanMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Two Thousand Fifteen Equity Incentive Plan [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:type="locator" xlink:label="us-gaap_TitleOfIndividualAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_TitleOfIndividualAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Title Of Individual</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TitleOfIndividualAxis" xlink:to="us-gaap_TitleOfIndividualAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_TitleOfIndividualAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Title Of Individual [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:type="locator" xlink:label="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Title Of Individual With Relationship To Entity</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:to="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Title Of Individual With Relationship To Entity [Domain]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_OfficerMember" xlink:type="locator" xlink:label="us-gaap_OfficerMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_OfficerMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Officer</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_OfficerMember" xlink:to="us-gaap_OfficerMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_OfficerMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Officer [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VestingAxis" xlink:type="locator" xlink:label="us-gaap_VestingAxis" />
    <label xml:lang="en-US" xlink:label="us-gaap_VestingAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VestingAxis" xlink:to="us-gaap_VestingAxis_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_VestingAxis_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Vesting [Axis]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_VestingDomain" xlink:type="locator" xlink:label="us-gaap_VestingDomain" />
    <label xml:lang="en-US" xlink:label="us-gaap_VestingDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vesting</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_VestingDomain" xlink:to="us-gaap_VestingDomain_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_VestingDomain_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Vesting [Domain]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheOneMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vest over a 40-month service period beginning on April 1, 2015</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationAwardTrancheOneMember" xlink:to="us-gaap_ShareBasedCompensationAwardTrancheOneMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Award Tranche One [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheTwoMember" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Vest based on the achievement of various milestones</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationAwardTrancheTwoMember" xlink:to="us-gaap_ShareBasedCompensationAwardTrancheTwoMember_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationAwardTrancheTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Award Tranche Two [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_NonEmployeeStockOptionsMember" xlink:type="locator" xlink:label="nk_NonEmployeeStockOptionsMember" />
    <label xml:lang="en-US" xlink:label="nk_NonEmployeeStockOptionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Non employee stock options.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_NonEmployeeStockOptionsMember" xlink:to="nk_NonEmployeeStockOptionsMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_NonEmployeeStockOptionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non Employee Stock Options</label>
    <label xml:lang="en-US" xlink:label="nk_NonEmployeeStockOptionsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Non Employee Stock Options [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share Based Compensation Arrangement By Share Based Payment Award [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award [Line Items]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Common stock reserved for issuance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" />
    <label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Maximum expiration period of grant date fair value of incentive plan</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Expiration Period</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares reserved for issuance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Authorized</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Additional Shares reserved for issuance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Number Of Additional Shares Authorized</label>
    <loc xlink:href="nk-20150930.xsd#nk_WarrantTerm" xlink:type="locator" xlink:label="nk_WarrantTerm" />
    <label xml:lang="en-US" xlink:label="nk_WarrantTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Warrant Term.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_WarrantTerm" xlink:to="nk_WarrantTerm_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares granted to employee</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Shares granted at an exercise price</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Option vesting period</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1</label>
    <label xml:lang="en-US" xlink:label="nk_WarrantTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Warrant Term</label>
    <label xml:lang="en-US" xlink:label="nk_WarrantTerm_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Warrant Term</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" />
    <label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Option vested</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:to="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested Number Of Shares</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Granted option to purchase common stock</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Grants of restricted stock</label>
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    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Exercise price range one.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ExercisePriceRangeOneMember" xlink:to="nk_ExercisePriceRangeOneMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">$0.22</label>
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeOneMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Exercise Price Range One [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_ExercisePriceRangeTwoMember" xlink:type="locator" xlink:label="nk_ExercisePriceRangeTwoMember" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Exercise price range two.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ExercisePriceRangeTwoMember" xlink:to="nk_ExercisePriceRangeTwoMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">$0.42</label>
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeTwoMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Exercise Price Range Two [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_ExercisePriceRangeThreeMember" xlink:type="locator" xlink:label="nk_ExercisePriceRangeThreeMember" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeThreeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Exercise price range three.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ExercisePriceRangeThreeMember" xlink:to="nk_ExercisePriceRangeThreeMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeThreeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">$1.76</label>
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeThreeMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Exercise Price Range Three [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_ExercisePriceRangeFourMember" xlink:type="locator" xlink:label="nk_ExercisePriceRangeFourMember" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeFourMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Exercise price range four.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ExercisePriceRangeFourMember" xlink:to="nk_ExercisePriceRangeFourMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeFourMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">$2.00</label>
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeFourMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Exercise Price Range Four [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_ExercisePriceRangeFiveMember" xlink:type="locator" xlink:label="nk_ExercisePriceRangeFiveMember" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeFiveMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Exercise price range five.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ExercisePriceRangeFiveMember" xlink:to="nk_ExercisePriceRangeFiveMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeFiveMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">$2.20</label>
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeFiveMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Exercise Price Range Five [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_ExercisePriceRangeSixMember" xlink:type="locator" xlink:label="nk_ExercisePriceRangeSixMember" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeSixMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Exercise price range six.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ExercisePriceRangeSixMember" xlink:to="nk_ExercisePriceRangeSixMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeSixMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">$ 25.00</label>
    <label xml:lang="en-US" xlink:label="nk_ExercisePriceRangeSixMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Exercise Price Range Six [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" />
    <label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Exercise Prices</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:to="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Exercisable Options Weighted Average Exercise Price1</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Options Outstanding, Number Outstanding</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:to="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Number Of Outstanding Options</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:type="locator" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" />
    <label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Options Outstanding, Weighted-Average Life (in Years)</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:to="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Sharebased Compensation Shares Authorized Under Stock Option Plans Exercise Price Range Outstanding Options Weighted Average Remaining Contractual Term2</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Aggregate intrinsic value of stock options exercised</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" />
    <label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Unrecognized compensation cost related to non-vested stock options</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:type="locator" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" />
    <label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average period for recognition</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:to="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1</label>
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Stock option outstanding</label>
    <loc xlink:href="nk-20150930.xsd#nk_EmployeeGrantsMember" xlink:type="locator" xlink:label="nk_EmployeeGrantsMember" />
    <label xml:lang="en-US" xlink:label="nk_EmployeeGrantsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Employee grants.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_EmployeeGrantsMember" xlink:to="nk_EmployeeGrantsMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_EmployeeGrantsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Employee Grants</label>
    <label xml:lang="en-US" xlink:label="nk_EmployeeGrantsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Employee Grants [Member]</label>
    <loc xlink:href="nk-20150930.xsd#nk_NonEmployeeGrantsMember" xlink:type="locator" xlink:label="nk_NonEmployeeGrantsMember" />
    <label xml:lang="en-US" xlink:label="nk_NonEmployeeGrantsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Non employee grants.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_NonEmployeeGrantsMember" xlink:to="nk_NonEmployeeGrantsMember_lbl" />
    <label xml:lang="en-US" xlink:label="nk_NonEmployeeGrantsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Non-Employee Grants</label>
    <label xml:lang="en-US" xlink:label="nk_NonEmployeeGrantsMember_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Non Employee Grants [Member]</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Risk-free interest rate</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Risk Free Interest Rate</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Dividend yield</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Expected Dividend Rate</label>
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/terseLabel">Weighted-average grant date fair value</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExercisePrice_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Exercise Price</label>
    <loc xlink:href="nk-20150930.xsd#nk_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNetOfSharesWithheldForEmployeePayrollTaxes" xlink:type="locator" xlink:label="nk_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNetOfSharesWithheldForEmployeePayrollTaxes" />
    <label xml:lang="en-US" xlink:label="nk_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNetOfSharesWithheldForEmployeePayrollTaxes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/documentation">Share based compensation arrangement by share based payment award equity instruments other than options vested net of shares withheld for employee payroll taxes.</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="nk_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNetOfSharesWithheldForEmployeePayrollTaxes" xlink:to="nk_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNetOfSharesWithheldForEmployeePayrollTaxes_lbl" />
    <loc xlink:href="http://xbrl.fasb.org/us-gaap/2015/elts/us-gaap-2015-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:type="locator" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel">Number of Shares, Unvested, Beginning balance</label>
    <labelArc xlink:type="arc" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:to="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" />
    <label xml:lang="en-US" xlink:label="us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Nonvested Number</label>
    <label xml:lang="en-US" xlink:label="nk_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNetOfSharesWithheldForEmployeePayrollTaxes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2009/role/negatedLabel">Number of Shares, Vested, net of shares withheld for employee payroll taxes</label>
    <label xml:lang="en-US" xlink:label="nk_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedNetOfSharesWithheldForEmployeePayrollTaxes_lbl" xlink:type="resource" xlink:role="http://www.xbrl.org/2003/role/label">Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vested Net Of Shares Withheld For Employee Payroll Taxes</label>
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    <loc xlink:href="nk-20150930.xsd#nk_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsSharesWithheldForEmployeePayrollTaxesWeightedAverageGrantDateFairValue" xlink:type="locator" xlink:label="nk_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsSharesWithheldForEmployeePayrollTaxesWeightedAverageGrantDateFairValue" />
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