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CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Current assets: |  |
Cash and cash equivalents | $ 87,288 | $ 10,315
Other receivables | 1,011 | 304
Tax incentive receivables, current | 1,932 |
Prepaid expenses and other current assets | 1,828 | 1,253
Total current assets | 92,059 | 11,872
Tax incentive receivables |  | 144
Property and equipment, net | 1,164 | 1,500
Deposits | 206 | 206
Restricted cash | 50 | 50
Total assets | 93,479 | 13,772
Current liabilities: |  |
Accounts payable | 3,470 | 1,139
Accrued expenses and other current liabilities | 4,321 | 2,928
Derivative liabilities | 223 | 2,708
Deferred rent | 143 | 143
Total current liabilities | 8,157 | 6,918
Deferred rent, net of current portion | 365 | 493
Total liabilities | 8,522 | 7,411
Commitments and contingencies (Note 11) |  |
Stockholders' equity (deficit): |  |
Common units, zero and 335,281 units issued and outstanding as of December 31, 2017 and 2016, respectively | 0 | 0
Preferred stock, $0.001 par value; 10,000,000 and zero shares authorized as of December 31, 2017 and 2016, respectively |  |
Common stock, $0.001 par value; 60,000,000 shares authorized as of December 31, 3017; 14,369,182 shares issued and outstanding as of December 31, 2017; no shares authorized, issued or outstanding as of December 31, 2016 | 14 |
Additional paid-in capital | 181,428 |
Accumulated deficit | (96,840) | (45,440)
Total Spero Therapeutics, Inc. stockholders' equity (deficit) | 84,602 | (45,440)
Non-controlling interests | 355 | (3,808)
Total stockholders' equity (deficit) | 84,957 | (49,248)
Total liabilities, redeemable convertible preferred units, and stockholders' equity (deficit) | $ 93,479 | 13,772
Bridge Units [Member] |  |
Current liabilities: |  |
Convertible preferred stock |  | 7,924
Redeemable Convertible Preferred Units [Member] |  |
Current liabilities: |  |
Convertible preferred stock |  | $ 47,685

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- Definition Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(17)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3044-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 4 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6812-107765 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586 + Details
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