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  <xs:element id="mgnx_CostOfManufacturingServices" abstract="false" name="CostOfManufacturingServices" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="mgnx_NonRefundableUpfrontFees" abstract="false" name="NonRefundableUpfrontFees" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="mgnx_AtTheMarketOfferingMember" abstract="true" name="AtTheMarketOfferingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="mgnx_EmployeeStockPurchasePlanMaximumAnnualContributionsPerEmployeePercent" abstract="false" name="EmployeeStockPurchasePlanMaximumAnnualContributionsPerEmployeePercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="mgnx_IncyteCommercialSupplyAgreementMember" abstract="true" name="IncyteCommercialSupplyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="mgnx_RevenuesFromGrantsMember" abstract="true" name="RevenuesFromGrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="mgnx_NumberOfPerformanceObligations" abstract="false" name="NumberOfPerformanceObligations" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="mgnx_NetProceedsFromSaleOfFutureRoyalties" abstract="false" name="NetProceedsFromSaleOfFutureRoyalties" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="mgnx_NationalInstituteOfAllergyAndInfectiousDiseasesMember" abstract="true" name="NationalInstituteOfAllergyAndInfectiousDiseasesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="mgnx_PotentialTargetNominationOptionFeesAndMilestonePayments" abstract="false" name="PotentialTargetNominationOptionFeesAndMilestonePayments" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="mgnx_GileadFirstResearchProgramMember" abstract="true" name="GileadFirstResearchProgramMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="mgnx_RevenueFromCollaborativeAgreementsMember" abstract="true" name="RevenueFromCollaborativeAgreementsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="mgnx_RevenuePerformanceObligationExtensionTerm" abstract="false" name="RevenuePerformanceObligationExtensionTerm" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="mgnx_A2022GileadCollaborationAndLicenseAgreementMember" abstract="true" name="A2022GileadCollaborationAndLicenseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="mgnx_ThomasSpitznagelMember" abstract="true" name="ThomasSpitznagelMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="mgnx_InLicensingArrangementTable" abstract="true" name="InLicensingArrangementTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="mgnx_ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOfferingPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="mgnx_RevenueFromRoyalityAgreementsMemberMember" abstract="true" name="RevenueFromRoyalityAgreementsMemberMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="mgnx_TotalAnnualFixedPayments" abstract="false" name="TotalAnnualFixedPayments" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="mgnx_AdditionalAnnualFixedPayments" abstract="false" name="AdditionalAnnualFixedPayments" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="mgnx_TwoThousandSixteenEmployeeStockPurchasePlanMember" abstract="true" name="TwoThousandSixteenEmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
</xs:schema>
