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  <xsd:element id="alxo_LineOfCreditFacilityAvailableBorrowingCapacityUponAchievementOfMilestones" name="LineOfCreditFacilityAvailableBorrowingCapacityUponAchievementOfMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="alxo_LeaseOperatingLeaseCommencementPeriod" name="LeaseOperatingLeaseCommencementPeriod" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="alxo_CommitmentsAndContingenciesTable" name="CommitmentsAndContingenciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <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_CashEquivalentsAvailableForSale" name="CashEquivalentsAvailableForSale" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <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_StockOptionsIssuedAndOutstandingMember" name="StockOptionsIssuedAndOutstandingMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="alxo_AccruedContractManufacturingCurrent" name="AccruedContractManufacturingCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <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_LesseeOperatingLeasesExpirationYear" name="LesseeOperatingLeasesExpirationYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <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_LongTermInvestmentCorporateDebtSecuritiesMember" name="LongTermInvestmentCorporateDebtSecuritiesMember" 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:schema>
