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  <xsd:import namespace="http://www.xbrl.org/dtr/type/non-numeric" schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/dei/2014-01-31" schemaLocation="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" />
  <xsd:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" />
  <import namespace="http://fasb.org/us-gaap/2017-01-31" schemaLocation="http://xbrl.fasb.org/us-gaap/2017/elts/us-gaap-2017-01-31.xsd" xmlns="http://www.w3.org/2001/XMLSchema" />
  <import namespace="http://xbrl.sec.gov/country/2017-01-31" schemaLocation="http://xbrl.sec.gov/country/2017/country-2017-01-31.xsd" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="CollaborativeArrangementNonrefundableUpfrontFees" id="xncr_CollaborativeArrangementNonrefundableUpfrontFees" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementAnnualMaintenanceFees" id="xncr_CollaborativeArrangementAnnualMaintenanceFees" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementMilestonePayment" id="xncr_CollaborativeArrangementMilestonePayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementNumberOfTargetPrograms" id="xncr_CollaborativeArrangementNumberOfTargetPrograms" type="xbrli:integerItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementResearchLicenseTerm" id="xncr_CollaborativeArrangementResearchLicenseTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementAdditionalResearchTerm" id="xncr_CollaborativeArrangementAdditionalResearchTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementExtensionFee" id="xncr_CollaborativeArrangementExtensionFee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementNumberOfTechnologiesToWhichResearchLicenseProvided" id="xncr_CollaborativeArrangementNumberOfTechnologiesToWhichResearchLicenseProvided" type="xbrli:integerItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementNumberOfCommercialOptions" id="xncr_CollaborativeArrangementNumberOfCommercialOptions" type="xbrli:integerItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborationResearchAndLicensingAgreementsDisclosureAbstract" id="xncr_CollaborationResearchAndLicensingAgreementsDisclosureAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element id="xncr_CollaborationsLicensesAndMilestonesRevenue" name="CollaborationsLicensesAndMilestonesRevenue" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="SupplementalCashFlowInformationCashPaidAbstract" id="xncr_SupplementalCashFlowInformationCashPaidAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="PotentialMilestonesTypeAxis" id="xncr_PotentialMilestonesTypeAxis" type="xbrli:stringItemType" substitutionGroup="xbrldt:dimensionItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="MorphoSysMember" id="xncr_MorphoSysMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="PotentialMilestonesTypeDomain" id="xncr_PotentialMilestonesTypeDomain" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="DevelopmentBasedMilestonesMember" id="xncr_DevelopmentBasedMilestonesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="RegulatoryBasedMilestonesMember" id="xncr_RegulatoryBasedMilestonesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="SalesBasedMilestonesMember" id="xncr_SalesBasedMilestonesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="EquityIncentivePlan2010Member" id="xncr_EquityIncentivePlan2010Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="EquityIncentivePlan2013Member" id="xncr_EquityIncentivePlan2013Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="DocumentAndEntityInformationAbstract" id="xncr_DocumentAndEntityInformationAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualPercentageIncreaseInSharesAuthorized" id="xncr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualPercentageIncreaseInSharesAuthorized" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualIncreaseInSharesAuthorized" id="xncr_ShareBasedCompensationArrangementByShareBasedPaymentAwardAnnualIncreaseInSharesAuthorized" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="LicenseAgreementMember" id="xncr_LicenseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OptionAndLicenseAgreementMember" id="xncr_OptionAndLicenseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ResearchLicenseAndCommercialization2009AgreementMember" id="xncr_ResearchLicenseAndCommercialization2009AgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="AmgenIncMember" id="xncr_AmgenIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="MerckSharpAndDohmeCorpMember" id="xncr_MerckSharpAndDohmeCorpMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="AlexionPharmaceuticalsIncMember" id="xncr_AlexionPharmaceuticalsIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CSLLimitedMember" id="xncr_CSLLimitedMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementAnnualMaintenanceFeesDuringExtensionOfResearchTerm" id="xncr_CollaborativeArrangementAnnualMaintenanceFeesDuringExtensionOfResearchTerm" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <element id="xncr_RevenueRecognitionMilestoneMethodPending" name="RevenueRecognitionMilestoneMethodPending" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_CollaborationAndLicenseAgreementMember" name="CollaborationAndLicenseAgreementMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="CollaborativeResearchAndLicensingAgreementsPolicyPolicyTextBlock" id="xncr_CollaborativeResearchAndLicensingAgreementsPolicyPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ScheduleOfStockOptionsOutstandingTableTextBlock" id="xncr_ScheduleOfStockOptionsOutstandingTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="xncr_NovoNordiskMember" name="NovoNordiskMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_BoehringerIngelheimInternationalGmbhMember" name="BoehringerIngelheimInternationalGmbhMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="CollaborativeArrangementNumberOfCompounds" id="xncr_CollaborativeArrangementNumberOfCompounds" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="DeferredTaxLiabilitiesCapitalizedLegalCosts" id="xncr_DeferredTaxLiabilitiesCapitalizedLegalCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="DeferredTaxLiabilitiesLicenseCosts" id="xncr_DeferredTaxLiabilitiesLicenseCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="IncreaseDecreaseInDeferredRent" id="xncr_IncreaseDecreaseInDeferredRent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <element id="xncr_MarketableSecuritiesMember" name="MarketableSecuritiesMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="RevenueRecognitionContractPeriod" id="xncr_RevenueRecognitionContractPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="xncr_ResearchAndLicenseAgreement2015Member" name="ResearchAndLicenseAgreement2015Member" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="PreviousTargetsWhichBispecificTechnologyWillBeApplied" id="xncr_PreviousTargetsWhichBispecificTechnologyWillBeApplied" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <xsd:element name="CollaborationAndLicensingProgramsAxis" id="xncr_CollaborationAndLicensingProgramsAxis" type="xbrli:stringItemType" substitutionGroup="xbrldt:dimensionItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element id="xncr_CollaborationAndLicensingProgramsDomain" name="CollaborationAndLicensingProgramsDomain" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_Cd38ProgramMember" name="Cd38ProgramMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_DiscoveryProgramMember" name="DiscoveryProgramMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="NumberOfPreviousIdentifiedProductsInWhichSubstitutionCanOccur" id="xncr_NumberOfPreviousIdentifiedProductsInWhichSubstitutionCanOccur" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="SaleOfAdditionalCommonStockTextblock" id="xncr_SaleOfAdditionalCommonStockTextblock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ScheduleOfRevenueByMajorLicenseesTableTextBlock" id="xncr_ScheduleOfRevenueByMajorLicenseesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="PropertyPlantAndEquipmentUsefulLifeTableTextBlock" id="xncr_PropertyPlantAndEquipmentUsefulLifeTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="xncr_ResearchLicenseAndOptionAgreementMember" name="ResearchLicenseAndOptionAgreementMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_ResearchLicenseeAndCollaborationAgreement2007AgreementMember" name="ResearchLicenseeAndCollaborationAgreement2007AgreementMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_JanssenMember" name="JanssenMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="BIMember" id="xncr_BIMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OtherCustomerMember" id="xncr_OtherCustomerMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element id="xncr_NonUnitedStatesMember" name="NonUnitedStatesMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="NumberOfServiceProviders" id="xncr_NumberOfServiceProviders" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="NumberOfCriticalSuppliers" id="xncr_NumberOfCriticalSuppliers" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ComputersSoftwareAndEquipmentMember" id="xncr_ComputersSoftwareAndEquipmentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="PatentsDefiniteLifeMember" id="xncr_PatentsDefiniteLifeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="PatentsPendingIssuanceMember" id="xncr_PatentsPendingIssuanceMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="LicensesAndOtherIntangibleAssetsMember" id="xncr_LicensesAndOtherIntangibleAssetsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CapitalizedPatentAndLicensingMember" id="xncr_CapitalizedPatentAndLicensingMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element id="xncr_InProcessIntangibleAssetsMember" name="InProcessIntangibleAssetsMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="FiniteLivedAndIndefiniteLivedIntangibleAssetsByMajorClassLineItems" id="xncr_FiniteLivedAndIndefiniteLivedIntangibleAssetsByMajorClassLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="NumberOfPrimaryCriteriasToDetermineCapitalizationOfPatent" id="xncr_NumberOfPrimaryCriteriasToDetermineCapitalizationOfPatent" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="IncomeTaxTable" id="xncr_IncomeTaxTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="IncomeTaxesLineItems" id="xncr_IncomeTaxesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="EmployeeAndNonEmployeeStockOptionMember" id="xncr_EmployeeAndNonEmployeeStockOptionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfCompensationWithheldToPurchaseSharesAtDiscount" id="xncr_ShareBasedCompensationArrangementByShareBasedPaymentAwardPercentageOfCompensationWithheldToPurchaseSharesAtDiscount" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardInitialTermOfPlan" id="xncr_ShareBasedCompensationArrangementByShareBasedPaymentAwardInitialTermOfPlan" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardSubsequentTermOfPlan" id="xncr_ShareBasedCompensationArrangementByShareBasedPaymentAwardSubsequentTermOfPlan" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="SharebasedCompensationArrangementBySharebasedPaymentAwardNumberOfPurchasePeriods" id="xncr_SharebasedCompensationArrangementBySharebasedPaymentAwardNumberOfPurchasePeriods" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <xsd:element name="SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePeriod" id="xncr_SharebasedCompensationArrangementBySharebasedPaymentAwardPurchasePeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePriceOfCommonStockPercentageOnInitialOfferingDate" id="xncr_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePriceOfCommonStockPercentageOnInitialOfferingDate" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="SharesAuthorizedUnderStockOptionPlansExercisePriceRangeOneMember" id="xncr_SharesAuthorizedUnderStockOptionPlansExercisePriceRangeOneMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="SharesAuthorizedUnderStockOptionPlansExercisePriceRangeTwoMember" id="xncr_SharesAuthorizedUnderStockOptionPlansExercisePriceRangeTwoMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="SharesAuthorizedUnderStockOptionPlansExercisePriceRangeThreeMember" id="xncr_SharesAuthorizedUnderStockOptionPlansExercisePriceRangeThreeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <element id="xncr_SharesAuthorizedUnderStockOptionPlansExercisePriceRangeFourMember" name="SharesAuthorizedUnderStockOptionPlansExercisePriceRangeFourMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <xsd:element name="ShareBasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsCommonStockFairValuePerShareMinimum" id="xncr_ShareBasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsCommonStockFairValuePerShareMinimum" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsCommonStockFairValuePerShareMaximum" id="xncr_ShareBasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsCommonStockFairValuePerShareMaximum" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="xncr_MonroviaMember" name="MonroviaMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_SanDiegoMember" name="SanDiegoMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_DepintoVsJohnSStaffordLitigationCaseMember" name="DepintoVsJohnSStaffordLitigationCaseMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_NovartisMember" name="NovartisMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_GlobalDiscoveryProgramMember" name="GlobalDiscoveryProgramMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_FcLicensesMember" name="FcLicensesMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_Xmab14045ProductMember" name="Xmab14045ProductMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_Xmab13676ProductMember" name="Xmab13676ProductMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_NumberOfDevelopmentStageProducts" name="NumberOfDevelopmentStageProducts" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_CollaborativeAgreementBispecificTechnologyAppliedNumberOfAntibodyTargets" name="CollaborativeAgreementBispecificTechnologyAppliedNumberOfAntibodyTargets" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_CollaborativeAgreementNonExclusiveLicenseProvidedNumberOfFcTechnologiesTargets" name="CollaborativeAgreementNonExclusiveLicenseProvidedNumberOfFcTechnologiesTargets" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_CollaborativeAgreementPercentageOfResponsibilityAssumedForDevelopmentCosts" name="CollaborativeAgreementPercentageOfResponsibilityAssumedForDevelopmentCosts" nillable="true" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_CollaborativeAgreementPercentageOfResponsibilityAssumedForCommercializationCosts" name="CollaborativeAgreementPercentageOfResponsibilityAssumedForCommercializationCosts" nillable="true" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_CollaborativeAgreementPercentageOfProfitOnNetSales" name="CollaborativeAgreementPercentageOfProfitOnNetSales" nillable="true" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_CollaborativeAgreementBispecificTechnologyAppliedNumberOfTargetsDelivered" name="CollaborativeAgreementBispecificTechnologyAppliedNumberOfTargetsDelivered" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_BispecificFcTechnologiesMember" name="BispecificFcTechnologiesMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_CollaborativeAgreementNumberOfPrograms" name="CollaborativeAgreementNumberOfPrograms" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_NumberOfDeliveredDiscoverPrograms" name="NumberOfDeliveredDiscoverPrograms" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_PiperJaffrayMember" name="PiperJaffrayMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_AggregateValueStockSold" name="AggregateValueStockSold" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_AccruedInterestOnMarketableSecurities" name="AccruedInterestOnMarketableSecurities" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_NumberOfVendors" name="NumberOfVendors" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_IncomeTaxExpenseBenefitNet" name="IncomeTaxExpenseBenefitNet" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_AccountingStandardUpdate201609Member" name="AccountingStandardUpdate201609Member" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_NumberOfSubstitutedAntibodyCandidates" name="NumberOfSubstitutedAntibodyCandidates" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_RevenueRecognitionMilestoneMethodPayment" name="RevenueRecognitionMilestoneMethodPayment" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_LitigationSettlementPaidNotCoveredByInsurance" name="LitigationSettlementPaidNotCoveredByInsurance" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_FiniteLivedAndIndefiniteLivedIntangibleAssetsByMajorClassTable" name="FiniteLivedAndIndefiniteLivedIntangibleAssetsByMajorClassTable" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_TaxCutsAndJobsActOf2017IncomeTaxExpenseBenefit" name="TaxCutsAndJobsActOf2017IncomeTaxExpenseBenefit" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_DeferredTaxLiabilitiesStateTaxes" name="DeferredTaxLiabilitiesStateTaxes" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_NumberOfProgramsRightToParticipate" name="NumberOfProgramsRightToParticipate" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Amount" name="EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017Amount" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="xncr_IncomeTaxReconciliationResearchAndDevelopmentCredit" name="IncomeTaxReconciliationResearchAndDevelopmentCredit" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
</xsd:schema>
