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  <xsd:element id="alxo_OperatingLeaseAnnualLeaseExpense" name="OperatingLeaseAnnualLeaseExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="alxo_OperatingLeaseLiabilityCurrentIncludingPayableAndAccruedLiabilitiesDueToRelatedParty" name="OperatingLeaseLiabilityCurrentIncludingPayableAndAccruedLiabilitiesDueToRelatedParty" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_OperatingLossCarryforwardsExpirationPeriod" name="OperatingLossCarryforwardsExpirationPeriod" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_PaymentForOfferingCost" name="PaymentForOfferingCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_PercentageOfFeeAmountPaidUponFinalPayment" name="PercentageOfFeeAmountPaidUponFinalPayment" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_PercentageOfIncreaseOfAnnualRent" name="PercentageOfIncreaseOfAnnualRent" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_PermittedIssuanceOfCommonStock" name="PermittedIssuanceOfCommonStock" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ProceedsFromRepaymentsOfNoteAndAccruedInterest" name="ProceedsFromRepaymentsOfNoteAndAccruedInterest" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="alxo_RelatedPartyAgreementAutomaticallyRenewalAdditionalTermUnlessTerminated" name="RelatedPartyAgreementAutomaticallyRenewalAdditionalTermUnlessTerminated" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_RelatedPartyMarkupCostPercentage" name="RelatedPartyMarkupCostPercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="alxo_RenewalPeriodsOfAgreement" name="RenewalPeriodsOfAgreement" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_RetentionMilestonePayment" name="RetentionMilestonePayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_ShareBasedCompensationArrangementByShareBasedPaymentAwardAuthorizedAmount" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAuthorizedAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantAuthorized" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantAuthorized" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantCanceled" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantCanceled" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantGranted" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantGranted" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedExercised" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsNonvestedExercised" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchaseOfCommonSockAtLowerOfClosingPricePercentage" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchaseOfCommonSockAtLowerOfClosingPricePercentage" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_StockIssuedDuringPeriodSharesWarrantExercise" name="StockIssuedDuringPeriodSharesWarrantExercise" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_StockIssuedDuringPeriodValueVestingOfEarlyExercisedStockOptions" name="StockIssuedDuringPeriodValueVestingOfEarlyExercisedStockOptions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_TaxCreditCarryforwardExpirationPeriod" name="TaxCreditCarryforwardExpirationPeriod" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_TemporaryEquityStockIssuedDuringPeriodShareNewIssues" name="TemporaryEquityStockIssuedDuringPeriodShareNewIssues" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_TermLoanFinalPaymentCost" name="TermLoanFinalPaymentCost" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_TermLoanFinalPaymentCosts" name="TermLoanFinalPaymentCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="alxo_TermLoanNonCurrent" name="TermLoanNonCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_TermLoanUnamortizedFinalPayment" name="TermLoanUnamortizedFinalPayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_TypeOfRevenueDescription" name="TypeOfRevenueDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_UnrecognizedTaxBenefitsIncreasesDecreasesResultingFromPriorPeriodTaxPositions" name="UnrecognizedTaxBenefitsIncreasesDecreasesResultingFromPriorPeriodTaxPositions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_VariableLeaseCostAndOtherNet" name="VariableLeaseCostAndOtherNet" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="alxo_VestingOfEarlyExercisedStockOptions" name="VestingOfEarlyExercisedStockOptions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="alxo_CommitmentsAndContingenciesLineItems" name="CommitmentsAndContingenciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_NetOperatingLossAndTaxCreditCarryforwardsLineItems" name="NetOperatingLossAndTaxCreditCarryforwardsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ScheduleOfBalanceSheetComponentsLineItems" name="ScheduleOfBalanceSheetComponentsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_SignificantAccountingPoliciesLineItems" name="SignificantAccountingPoliciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_AmendedAndRestatedTwoThousandTwentyEquityIncentivePlanMember" name="AmendedAndRestatedTwoThousandTwentyEquityIncentivePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_CollaborationAgreementsMember" name="CollaborationAgreementsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_CommercialAntibodyAgreementMember" name="CommercialAntibodyAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_CommercialLicenseAgreementMember" name="CommercialLicenseAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_CommonStockSubjectToRepurchaseMember" name="CommonStockSubjectToRepurchaseMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_CompoundDerivativeLiabilityMember" name="CompoundDerivativeLiabilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ComputerHardwareAndSoftwareMember" name="ComputerHardwareAndSoftwareMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_CrystalBioscienceIncMember" name="CrystalBioscienceIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_EmployeeStockPurchasePlanSharesAuthorizedForFutureIssuanceMember" name="EmployeeStockPurchasePlanSharesAuthorizedForFutureIssuanceMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ExclusiveEquityAgreementMember" name="ExclusiveEquityAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_FixedRateMember" name="FixedRateMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_FollowOnPublicOfferingMember" name="FollowOnPublicOfferingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_LabEquipmentAndOtherAssetsMember" name="LabEquipmentAndOtherAssetsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_LongTermInvestmentAssetBackedSecuritiesMember" name="LongTermInvestmentAssetBackedSecuritiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_LongTermInvestmentsMember" name="LongTermInvestmentsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_LongTermInvestmentUSGovernmentAgenciesDebtSecuritiesMember" name="LongTermInvestmentUSGovernmentAgenciesDebtSecuritiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_LongTermInvestmentUsTreasurySecuritiesMember" name="LongTermInvestmentUsTreasurySecuritiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_MasterServiceAgreementMember" name="MasterServiceAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_OfficeAndLaboratorySpaceOneMember" name="OfficeAndLaboratorySpaceOneMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_OfficeSpaceMember" name="OfficeSpaceMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_OfficeSpaceOneMember" name="OfficeSpaceOneMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_OxfordFinanceAndSiliconValleyBankLoanAgreementMember" name="OxfordFinanceAndSiliconValleyBankLoanAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_PrepaidClinicalExpensesMember" name="PrepaidClinicalExpensesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_PrepaidContractManufacturingCostsMember" name="PrepaidContractManufacturingCostsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ResearchAndDevelopmentServicesAgreementMember" name="ResearchAndDevelopmentServicesAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_RestrictedStockIssuedAndOutstandingMember" name="RestrictedStockIssuedAndOutstandingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ScalmiBioIncMember" name="ScalmiBioIncMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_SecuredTermLoanFacilityMember" name="SecuredTermLoanFacilityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_SelexisSAMember" name="SelexisSAMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_SeriesAConvertiblePreferredStockMember" name="SeriesAConvertiblePreferredStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_SeriesBAndCConvertiblePreferredStockMember" name="SeriesBAndCConvertiblePreferredStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_SeriesBConvertiblePreferredStockMember" name="SeriesBConvertiblePreferredStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ShortTermInvestmentAssetBackedSecuritiesMember" name="ShortTermInvestmentAssetBackedSecuritiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ShortTermInvestmentCommercialPaperMember" name="ShortTermInvestmentCommercialPaperMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ShortTermInvestmentCorporateDebtSecuritiesMember" name="ShortTermInvestmentCorporateDebtSecuritiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ShortTermInvestmentUSGovernmentAgenciesDebtSecuritiesMember" name="ShortTermInvestmentUSGovernmentAgenciesDebtSecuritiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ShortTermInvestmentUSTreasurySecuritiesMember" name="ShortTermInvestmentUSTreasurySecuritiesMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_SiliconValleyBankAndWestRiverLoanAgreementMember" name="SiliconValleyBankAndWestRiverLoanAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_StanfordJuniorUniversityMember" name="StanfordJuniorUniversityMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_StockOptionModificationMember" name="StockOptionModificationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_StockOptionsAuthorizedForFutureIssuanceMember" name="StockOptionsAuthorizedForFutureIssuanceMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_StockOptionsIssuedAndOutstandingMember" name="StockOptionsIssuedAndOutstandingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TallacTherapeuticsMember" name="TallacTherapeuticsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TermLoanMember" name="TermLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TollnineMember" name="TollnineMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TrancheAMember" name="TrancheAMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TrancheBMember" name="TrancheBMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TrancheCMember" name="TrancheCMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TrancheDMember" name="TrancheDMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TwentyThousandAndTwentyEmployeeStockPurchasePlanMember" name="TwentyThousandAndTwentyEmployeeStockPurchasePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TwentyThousandAndTwentyEquityIncentivePlanMember" name="TwentyThousandAndTwentyEquityIncentivePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_TwoThousandAndFifteenShareAwardSchemeMember" name="TwoThousandAndFifteenShareAwardSchemeMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_UndesignatedPreferredStockMember" name="UndesignatedPreferredStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_CommitmentsAndContingenciesTable" name="CommitmentsAndContingenciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_NetOperatingLossAndTaxCreditCarryforwardsTable" name="NetOperatingLossAndTaxCreditCarryforwardsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ScheduleOfBalanceSheetComponentsTable" name="ScheduleOfBalanceSheetComponentsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_SignificantAccountingPoliciesTable" name="SignificantAccountingPoliciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_ClinicalAndContractManufacturingAccrualsPolicyTextBlock" name="ClinicalAndContractManufacturingAccrualsPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ConcentrationOfCreditRiskCreditLossesAndOtherRisksAndUncertaintiesPolicyTextBlock" name="ConcentrationOfCreditRiskCreditLossesAndOtherRisksAndUncertaintiesPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ConvertiblePreferredStockWarrantLiabilityPolicyTextBlock" name="ConvertiblePreferredStockWarrantLiabilityPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_CostOfServicesForRelatedPartyRevenuePolicyTextBlock" name="CostOfServicesForRelatedPartyRevenuePolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_DeferredOfferingCostPolicyTextBlock" name="DeferredOfferingCostPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_LesseeOperatingAndFinancingLeaseLiabilityMaturityTableTextBlock" name="LesseeOperatingAndFinancingLeaseLiabilityMaturityTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_LesseeOperatingAndFinancingLeasesTextBlock" name="LesseeOperatingAndFinancingLeasesTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ReverseStockSplitPolicyTextBlock" name="ReverseStockSplitPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesTableTextBlock" name="ScheduleOfAccruedExpensesAndOtherCurrentLiabilitiesTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_ScheduleOfCommonStockReservedForFutureIssuanceTableTextBlock" name="ScheduleOfCommonStockReservedForFutureIssuanceTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_SummaryOfNetOperatingLossAndTaxCreditCarryforwardsTextBlock" name="SummaryOfNetOperatingLossAndTaxCreditCarryforwardsTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" name="SupplementalCashFlowInformationRelatedToLeasesTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
</xsd:schema>
