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  <xs:element id="cccc_TransactionPriceFromClosingOfTheStockPurchaseAgreement" abstract="false" name="TransactionPriceFromClosingOfTheStockPurchaseAgreement" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_CollaborativeArrangementRegulatoryMilestoneAchieved" abstract="false" name="CollaborativeArrangementRegulatoryMilestoneAchieved" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_ExpectedConsiderationToBeReceivedFromManufacturedClinicalSupply" abstract="false" name="ExpectedConsiderationToBeReceivedFromManufacturedClinicalSupply" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_AdditionalUpfrontConsideration" abstract="false" name="AdditionalUpfrontConsideration" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_NumberOfPotentialTargets" abstract="false" name="NumberOfPotentialTargets" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="cccc_NumberOfTargets" abstract="false" name="NumberOfTargets" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="cccc_OptionExerciseFee" abstract="false" name="OptionExerciseFee" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_NumberOfTargetedProteinDegradation" abstract="false" name="NumberOfTargetedProteinDegradation" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="cccc_ResearchAndDevelopmentAgreementPeriod" abstract="false" name="ResearchAndDevelopmentAgreementPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="cccc_NonRefundableUpfrontPayment" abstract="false" name="NonRefundableUpfrontPayment" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_ResearchTerm" abstract="false" name="ResearchTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="cccc_ResearchExtendedTerm" abstract="false" name="ResearchExtendedTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="cccc_AnnualPayments" abstract="false" name="AnnualPayments" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_AnnualResearchPlanPaymentsReceivables" abstract="false" name="AnnualResearchPlanPaymentsReceivables" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_UpfrontFees" abstract="false" name="UpfrontFees" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_AmountPayableForExtendResearchTermOption" abstract="false" name="AmountPayableForExtendResearchTermOption" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_ResearchAndDevelopmentTargetsMember" abstract="true" name="ResearchAndDevelopmentTargetsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_OptionRightsMember" abstract="true" name="OptionRightsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_TransactionPriceUnsatisfiedToPerformanceObligation" abstract="false" name="TransactionPriceUnsatisfiedToPerformanceObligation" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_RocheAgreementMember" abstract="true" name="RocheAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_BiogenAgreementMember" abstract="true" name="BiogenAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_CalicoAgreementMember" abstract="true" name="CalicoAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_LongTermDebtAndWarrantLiabilityTable" abstract="true" name="LongTermDebtAndWarrantLiabilityTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="cccc_CreditAgreementWithPerceptiveLifeSciencesMasterFundLTDMember" abstract="true" name="CreditAgreementWithPerceptiveLifeSciencesMasterFundLTDMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_TermLoanMember" abstract="true" name="TermLoanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_TrancheOneMember" abstract="true" name="TrancheOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_TrancheTwoMember" abstract="true" name="TrancheTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_LongTermDebtAndWarrantLiabilityLineItems" abstract="true" name="LongTermDebtAndWarrantLiabilityLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="cccc_AtmOfferingsMember" abstract="true" name="AtmOfferingsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_EquityDistributionAgreementWithCowenAndCompanyLLCMember" abstract="true" name="EquityDistributionAgreementWithCowenAndCompanyLLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_EquityDistributionAgreementWithTDSecuritiesUSALLCMember" abstract="true" name="EquityDistributionAgreementWithTDSecuritiesUSALLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="cccc_TwoThousandFifteenIncentiveStockOptionAndGrantPlanMember" abstract="true" name="TwoThousandFifteenIncentiveStockOptionAndGrantPlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_TwoThousandAndTwentyStockOptionAndIncentivePlanMember" abstract="true" name="TwoThousandAndTwentyStockOptionAndIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_TwoThousandTwentyEmployeeStockPurchasePlanMember" abstract="true" name="TwoThousandTwentyEmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_InducementGrantsMember" abstract="true" name="InducementGrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="cccc_TimeBasedRestrictedStockUnitsMember" abstract="true" name="TimeBasedRestrictedStockUnitsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="cccc_ShareBasedCompensationAwardTrancheFourMember" abstract="true" name="ShareBasedCompensationAwardTrancheFourMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="cccc_ShareBasedCompensationArrangementByShareBasedPaymentAwardCliffVestingPeriod" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardCliffVestingPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="cccc_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNewExercisePricePerShareTrancheTwo" abstract="false" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardNewExercisePricePerShareTrancheTwo" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="cccc_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNewExercisePricePerShareTrancheOne" abstract="false" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardNewExercisePricePerShareTrancheOne" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="cccc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfCommonSharesIssuablePerVested" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfCommonSharesIssuablePerVested" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="cccc_NumberOfEmployeesGrantedNonQualifiedStockOptions" abstract="false" name="NumberOfEmployeesGrantedNonQualifiedStockOptions" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="cccc_MaximumAuthorizedPayrollDeductionPercentageOfEligibleCompensationForEligibleEmployees" abstract="false" name="MaximumAuthorizedPayrollDeductionPercentageOfEligibleCompensationForEligibleEmployees" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="cccc_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAnnualOfferingPeriods" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAnnualOfferingPeriods" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="cccc_PercentageOfOutstandingSharesOfCommonStock" abstract="false" name="PercentageOfOutstandingSharesOfCommonStock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="cccc_EffectiveIncomeTaxRateReconciliationFederalTaxCredit" abstract="false" name="EffectiveIncomeTaxRateReconciliationFederalTaxCredit" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="cccc_EffectiveIncomeTaxRateReconciliationStateTaxCredit" abstract="false" name="EffectiveIncomeTaxRateReconciliationStateTaxCredit" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="cccc_EffectiveIncomeTaxRateReconciliationWithholdingTax" abstract="false" name="EffectiveIncomeTaxRateReconciliationWithholdingTax" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="cccc_IncomeTaxTable" abstract="true" name="IncomeTaxTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="cccc_IncomeTaxLineItems" abstract="true" name="IncomeTaxLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="cccc_EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActPercent" abstract="false" name="EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActPercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="cccc_NetOperatingLossCarryforwardsLimitedAndExpiredDueToOwnershipChanges" abstract="false" name="NetOperatingLossCarryforwardsLimitedAndExpiredDueToOwnershipChanges" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_DeferredTaxAssetsCapitalizedResearchAndDevelopmentExpenditures" abstract="false" name="DeferredTaxAssetsCapitalizedResearchAndDevelopmentExpenditures" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_DeferredTaxAssetsOperatingLeaseLiability" abstract="false" name="DeferredTaxAssetsOperatingLeaseLiability" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_DeferredTaxAssetsCapitalizedStartUpCosts" abstract="false" name="DeferredTaxAssetsCapitalizedStartUpCosts" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_DeferredTaxLiabilitiesRightOfUseAsset" abstract="false" name="DeferredTaxLiabilitiesRightOfUseAsset" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_OptionsToPurchaseCommonStockMember" abstract="true" name="OptionsToPurchaseCommonStockMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="cccc_DefinedContributionPlanEmployerMatchingContributionAdditionalPercentOfEmployeesGrossPay" abstract="false" name="DefinedContributionPlanEmployerMatchingContributionAdditionalPercentOfEmployeesGrossPay" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="cccc_DefinedContributionPlanEmployerMatchingContributionAdditionalPercentOfMatch" abstract="false" name="DefinedContributionPlanEmployerMatchingContributionAdditionalPercentOfMatch" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="cccc_ReportableSegmentMember" abstract="true" name="ReportableSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="cccc_DevelopmentExpenses" abstract="false" name="DevelopmentExpenses" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="cccc_ResearchExpenses" abstract="false" name="ResearchExpenses" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
