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<!--Created on: 4/27/2015 11:00:13 PM-->
<!--Modified on: 4/27/2015 11:00:13 PM-->
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  <element id="cldx_AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsGrossUnrealizedGain" name="AvailableForSaleSecuritiesDebtMaturitiesAfterOneThroughThreeYearsGrossUnrealizedGain" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <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="EmployeeConsultantAndNonEmployeeDirectorStockOptionMember" id="cldx_EmployeeConsultantAndNonEmployeeDirectorStockOptionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="CollaborativeArrangementAgreementTerm" id="cldx_CollaborativeArrangementAgreementTerm" 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="AccumulatedOtherComprehensiveIncomeLossRollForward" id="cldx_AccumulatedOtherComprehensiveIncomeLossRollForward" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" 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:element name="ReimbursementOfExternalCostsIncurredPercentage" id="cldx_ReimbursementOfExternalCostsIncurredPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ScheduleOfOtherLongTermLiabilitiesTableTextBlock" id="cldx_ScheduleOfOtherLongTermLiabilitiesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <element id="cldx_UnderwrittenPublicOfferingMember" name="UnderwrittenPublicOfferingMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
</xsd:schema>
