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  <xsd:element name="DebtInstrumentPaymentFeePayableOnRepayment" id="cldx_DebtInstrumentPaymentFeePayableOnRepayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="DebtInstrumentNumberOfEqualConsecutiveMonthlyInstallments" id="cldx_DebtInstrumentNumberOfEqualConsecutiveMonthlyInstallments" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="DebtInstrumentCovenantRateOfPrepaymentPremiumInYearThree" id="cldx_DebtInstrumentCovenantRateOfPrepaymentPremiumInYearThree" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="NoticePeriodForTerminationOfAgreement" id="cldx_NoticePeriodForTerminationOfAgreement" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CommonStockExerciseOfFullOverAllotmentOptionToPurchaseAdditionalSharesByUnderwriter" id="cldx_CommonStockExerciseOfFullOverAllotmentOptionToPurchaseAdditionalSharesByUnderwriter" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract" id="cldx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="StockholdersEquityTable" id="cldx_StockholdersEquityTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="StockholdersEquityLineItems" id="cldx_StockholdersEquityLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="USGovernmentAndMunicipalObligationsMember" id="cldx_USGovernmentAndMunicipalObligationsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsAmortizedCost" id="cldx_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsAmortizedCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearGrossUnrealizedGain" id="cldx_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearGrossUnrealizedGain" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsGrossUnrealizedGain" id="cldx_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsGrossUnrealizedGain" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="AvailableForSaleSecuritiesGrossUnrealizedLossesAbstract" id="cldx_AvailableForSaleSecuritiesGrossUnrealizedLossesAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearGrossUnrealizedLosses" id="cldx_AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearGrossUnrealizedLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsGrossUnrealizedLosses" id="cldx_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsGrossUnrealizedLosses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsFairValue" id="cldx_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsFairValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="FixedRateOfCommissionOnSaleOfStock" id="cldx_FixedRateOfCommissionOnSaleOfStock" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CommonStockIssuanceOfAdditionalSharesAggregateOfferingPrice" id="cldx_CommonStockIssuanceOfAdditionalSharesAggregateOfferingPrice" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="ScheduleOfNatureOfBusinessAndOverviewTable" id="cldx_ScheduleOfNatureOfBusinessAndOverviewTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="EmployeeConsultantAndNonEmployeeDirectorStockOptionMember" id="cldx_EmployeeConsultantAndNonEmployeeDirectorStockOptionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShelfRegistrationStatementAmount" id="cldx_ShelfRegistrationStatementAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="ClassOfWarrantOrRightNumberOfRightsPerCommonStockShare" id="cldx_ClassOfWarrantOrRightNumberOfRightsPerCommonStockShare" type="xbrli:decimalItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ClassOfWarrantOrRightConditionOnExerciseOfRightsPercentageOfCommonStockAcquired" id="cldx_ClassOfWarrantOrRightConditionOnExerciseOfRightsPercentageOfCommonStockAcquired" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ClassOfWarrantOrRightConditionOnExerciseOfRightsPercentageOfCommonStockAcquiredThroughTender" id="cldx_ClassOfWarrantOrRightConditionOnExerciseOfRightsPercentageOfCommonStockAcquiredThroughTender" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="NumberOfMultiplesClassOfWarrantOrRightConditionOnExerciseOfRightsOfExercisePriceHolderCanReceiveInValueIfFifteenPercentOrMoreOfCommonStockIsAcquired" id="cldx_NumberOfMultiplesClassOfWarrantOrRightConditionOnExerciseOfRightsOfExercisePriceHolderCanReceiveInValueIfFifteenPercentOrMoreOfCommonStockIsAcquired" type="xbrli:integerItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ClassOfWarrantOrRightConditionOnExerciseOfRightsPercentageOfAssetsOrEarningPowerSoldForHolderRightToReceiveCommonStockOfAcquiringCompany" id="cldx_ClassOfWarrantOrRightConditionOnExerciseOfRightsPercentageOfAssetsOrEarningPowerSoldForHolderRightToReceiveCommonStockOfAcquiringCompany" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="LudwigInstituteForCancerResearchMember" id="cldx_LudwigInstituteForCancerResearchMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="AlterisTherapeuticsIncMember" id="cldx_AlterisTherapeuticsIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ThomasJeffersonUniversityMember" id="cldx_ThomasJeffersonUniversityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="UniversityOfSouthamptonUKMember" id="cldx_UniversityOfSouthamptonUKMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="AmgenIncMember" id="cldx_AmgenIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="SeattleGeneticIncMember" id="cldx_SeattleGeneticIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="NonRefundableLicenseFee" id="cldx_NonRefundableLicenseFee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementRoyaltyPaymentPeriodFromFirstCommercialSaleOfLicensedProduct" id="cldx_CollaborativeArrangementRoyaltyPaymentPeriodFromFirstCommercialSaleOfLicensedProduct" type="xbrli:durationItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementTotalPotentialMilestonePayments" id="cldx_CollaborativeArrangementTotalPotentialMilestonePayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="CollaborativeArrangementAgreementTerm" id="cldx_CollaborativeArrangementAgreementTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementNumberOfAgreements" id="cldx_CollaborativeArrangementNumberOfAgreements" type="xbrli:integerItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="IncomeTaxReconciliationExpirationOfNetOperatingLossesAndResearchAndDevelopmentTaxCredits" id="cldx_IncomeTaxReconciliationExpirationOfNetOperatingLossesAndResearchAndDevelopmentTaxCredits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="DeferredTaxLiabilitiesOtherAcquiredIntangibleAssets" id="cldx_DeferredTaxLiabilitiesOtherAcquiredIntangibleAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="DeferredTaxLiabilitiesDeferredLicenseCostsAndOtherExpense" id="cldx_DeferredTaxLiabilitiesDeferredLicenseCostsAndOtherExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="DeferredTaxAssetsLiabilitiesGross" id="cldx_DeferredTaxAssetsLiabilitiesGross" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="DeferredTaxAssetsInProcessResearchAndDevelopmentIntangibleAssets" id="cldx_DeferredTaxAssetsInProcessResearchAndDevelopmentIntangibleAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="CollaborativeArrangementMilestonePaymentsReceived" id="cldx_CollaborativeArrangementMilestonePaymentsReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="AVANTMember" id="cldx_AVANTMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OperatingLossAndTaxCreditCarryforwardsLineItems" id="cldx_OperatingLossAndTaxCreditCarryforwardsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OperatingLossCarryforwardsAnnualLimitationAmount" id="cldx_OperatingLossCarryforwardsAnnualLimitationAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="OperatingLossCarryforwardsExpired" id="cldx_OperatingLossCarryforwardsExpired" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="OperatingLossCarryforwardsNetOfExpirationsAndUtilization" id="cldx_OperatingLossCarryforwardsNetOfExpirationsAndUtilization" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="OperatingLossCarryforwardsWithLimitationsOnUse" id="cldx_OperatingLossCarryforwardsWithLimitationsOnUse" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="OperatingLossCarryforwardsRemotelyLikelyToBeUtilized" id="cldx_OperatingLossCarryforwardsRemotelyLikelyToBeUtilized" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="OwnershipChangeAxis" id="cldx_OwnershipChangeAxis" type="xbrli:stringItemType" substitutionGroup="xbrldt:dimensionItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OwnershipChangeDomain" id="cldx_OwnershipChangeDomain" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OwnershipChangeInOctober2007Member" id="cldx_OwnershipChangeInOctober2007Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OwnershipChangesInJune2009AndDecember2009Member" id="cldx_OwnershipChangesInJune2009AndDecember2009Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="PeriodOfRecognitionOfUnrealizedGainLossAfterOwnershipChange" id="cldx_PeriodOfRecognitionOfUnrealizedGainLossAfterOwnershipChange" type="xbrli:durationItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="PriorToAcquisitionMember" id="cldx_PriorToAcquisitionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="PriorToMergerMember" id="cldx_PriorToMergerMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="StatusOfMergerAndAcquisitionAxis" id="cldx_StatusOfMergerAndAcquisitionAxis" type="xbrli:stringItemType" substitutionGroup="xbrldt:dimensionItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="StatusOfMergerAndAcquisitionDomain" id="cldx_StatusOfMergerAndAcquisitionDomain" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="TaxCreditCarryforwardAmountWithSubstantialLimitationsOnUse" id="cldx_TaxCreditCarryforwardAmountWithSubstantialLimitationsOnUse" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="OperatingLossAndTaxCreditCarryforwardsTable" id="cldx_OperatingLossAndTaxCreditCarryforwardsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementForDevelopmentAndCommercializationOfProductMember" id="cldx_CollaborativeArrangementForDevelopmentAndCommercializationOfProductMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="RoyaltyAgreementMember" id="cldx_RoyaltyAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CincinnatiChildrensHospitalMedicalCenterMember" id="cldx_CincinnatiChildrensHospitalMedicalCenterMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="DukeUniversityAndThomasJeffersonUniversityMember" id="cldx_DukeUniversityAndThomasJeffersonUniversityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CommonStockSharesAvailableForSale" id="cldx_CommonStockSharesAvailableForSale" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <xsd:element name="ExpirationOfNetOperatingLossesAndResearchAndDevelopmentTaxCredits" id="cldx_ExpirationOfNetOperatingLossesAndResearchAndDevelopmentTaxCredits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="CommonStockAvailableForSaleLockUpPeriodToBeWaivedByUnderwriters" id="cldx_CommonStockAvailableForSaleLockUpPeriodToBeWaivedByUnderwriters" type="xbrli:durationItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ValueAtWhichTaxBenefitsSold" id="cldx_ValueAtWhichTaxBenefitsSold" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="FairValueAssetsAmountTransfersBetweenMeasurementLevels" id="cldx_FairValueAssetsAmountTransfersBetweenMeasurementLevels" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="FairValueLiabilitiesAmountTransfersBetweenMeasurementLevels" id="cldx_FairValueLiabilitiesAmountTransfersBetweenMeasurementLevels" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="AvailableForSaleSecuritiesConsideredToBeOtherThanTemporarilyImpaired" id="cldx_AvailableForSaleSecuritiesConsideredToBeOtherThanTemporarilyImpaired" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="DebtInstrumentCovenantRateOfPrepaymentPremiumInYearFour" id="cldx_DebtInstrumentCovenantRateOfPrepaymentPremiumInYearFour" type="num:percentItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="AccumulatedOtherComprehensiveIncomeLossRollForward" id="cldx_AccumulatedOtherComprehensiveIncomeLossRollForward" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OperatingLeasesTermOfLease" id="cldx_OperatingLeasesTermOfLease" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OperatingLeasesPeriodOfRenewalOptions" id="cldx_OperatingLeasesPeriodOfRenewalOptions" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OperatingLeasesCommencementPeriodOfRentalObligations" id="cldx_OperatingLeasesCommencementPeriodOfRentalObligations" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OperatingLeasesNumberOfRenewalOptions" id="cldx_OperatingLeasesNumberOfRenewalOptions" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <xsd:element name="RepaymentOfLongTermDebtPrincipalAmount" id="cldx_RepaymentOfLongTermDebtPrincipalAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="DebtInstrumentInterestAndPrepaymentFees" id="cldx_DebtInstrumentInterestAndPrepaymentFees" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element name="AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments" id="cldx_AvailableForSaleSecuritiesGrossUnrealizedGainAccumulatedInInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element name="AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments" id="cldx_AvailableForSaleSecuritiesGrossUnrealizedLossAccumulatedInInvestments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="IncomeTaxExpenseBenefitBeforeChangeInValuationAllowance" id="cldx_IncomeTaxExpenseBenefitBeforeChangeInValuationAllowance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementNumberOfAntiHIVAntibodies" id="cldx_CollaborativeArrangementNumberOfAntiHIVAntibodies" type="xbrli:integerItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementEstimatedCostForDevelopmentServices" id="cldx_CollaborativeArrangementEstimatedCostForDevelopmentServices" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementUpfrontPaymentAmount" id="cldx_CollaborativeArrangementUpfrontPaymentAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" abstract="false" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" />
</xsd:schema>
