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  <xs:element id="fhtx_InterestIncomeAndOtherIncomeExpense" abstract="false" name="InterestIncomeAndOtherIncomeExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_PreFundedWarrantMember" abstract="true" name="PreFundedWarrantMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_Series1WarrantsMember" abstract="true" name="Series1WarrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_Series2WarrantsMember" abstract="true" name="Series2WarrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_NonCashLeaseExpense" abstract="false" name="NonCashLeaseExpense" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_NonCashOfferingCost" abstract="false" name="NonCashOfferingCost" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_MarketableSecuritiesAndFairValueMeasurementsTextBlock" abstract="false" name="MarketableSecuritiesAndFairValueMeasurementsTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="fhtx_CollaborationAgreementAbstract" abstract="true" name="CollaborationAgreementAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="fhtx_LeasesBalanceSheetLocationTableTextBlock" abstract="false" name="LeasesBalanceSheetLocationTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <xs:element id="fhtx_USGovernmentAgenciesDueWithinOneYearMember" abstract="true" name="USGovernmentAgenciesDueWithinOneYearMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_CorporateDebtSecuritiesDueWithinOneYearMember" abstract="true" name="CorporateDebtSecuritiesDueWithinOneYearMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_CorporateDebtSecuritiesDueAfterOneYearThroughTwoYearsMember" abstract="true" name="CorporateDebtSecuritiesDueAfterOneYearThroughTwoYearsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_AccruedResearchAndDevelopmentExpenses" abstract="false" name="AccruedResearchAndDevelopmentExpenses" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_January2026OfferingMember" abstract="true" name="January2026OfferingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_AtTheMarketOfferingMember" abstract="true" name="AtTheMarketOfferingMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_Series1AndSeries2WarrantMember" abstract="true" name="Series1AndSeries2WarrantMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_Series1WarrantMember" abstract="true" name="Series1WarrantMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_Series2WarrantMember" abstract="true" name="Series2WarrantMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_SeriesWarrantMember" abstract="true" name="SeriesWarrantMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_SeriesWarrantsMember" abstract="true" name="SeriesWarrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_CommonStockVotingRightsVotes" abstract="false" name="CommonStockVotingRightsVotes" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="fhtx_WarrantWeightedAveragePricePerShare" abstract="false" name="WarrantWeightedAveragePricePerShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="fhtx_MinimumWarrantAdjustedExercisePricePerShare" abstract="false" name="MinimumWarrantAdjustedExercisePricePerShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="fhtx_ExerciseOfWarrantsLowerLimitAfterExerciseAsPercentageOfCommonStock" abstract="false" name="ExerciseOfWarrantsLowerLimitAfterExerciseAsPercentageOfCommonStock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="fhtx_MaximumBeneficialOwnershipLimitationPercentage" abstract="false" name="MaximumBeneficialOwnershipLimitationPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="fhtx_FairValueOfWarrants" abstract="false" name="FairValueOfWarrants" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_SaleOfStockMaximumNumberOfSharesIssuedInTransactionValue" abstract="false" name="SaleOfStockMaximumNumberOfSharesIssuedInTransactionValue" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_SaleOfStockCommissionFeesPayablePercentage" abstract="false" name="SaleOfStockCommissionFeesPayablePercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="fhtx_ClassOfWarrantOrRightPreFundedWarrantsExercised" abstract="false" name="ClassOfWarrantOrRightPreFundedWarrantsExercised" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="fhtx_TwoThousandTwentyEquityIncentivePlanMember" abstract="true" name="TwoThousandTwentyEquityIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_A2016StockIncentivePlanMember" abstract="true" name="A2016StockIncentivePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_TwoThousandTwentyEmployeeStockPurchasePlanMember" abstract="true" name="TwoThousandTwentyEmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_ShareBasedCompensationArrangementByShareBasedPaymentAutomaticAnnualIncreasePercentage" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAutomaticAnnualIncreasePercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="fhtx_ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumFutureIncreaseShares" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardMaximumFutureIncreaseShares" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="fhtx_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfOfferingPeriods" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfOfferingPeriods" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="fhtx_EliLillyMember" abstract="true" name="EliLillyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_JointProgramsMember" abstract="true" name="JointProgramsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_DiscoveryProgramsMember" abstract="true" name="DiscoveryProgramsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_ResearchDevelopmentAndRegulatoryMember" abstract="true" name="ResearchDevelopmentAndRegulatoryMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_SalesBasedMilestoneMember" abstract="true" name="SalesBasedMilestoneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_LilyCollaborationAgreementMember" abstract="true" name="LilyCollaborationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_NumberOfPrograms" abstract="false" name="NumberOfPrograms" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="fhtx_NumberOfTargets" abstract="false" name="NumberOfTargets" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="fhtx_NumberOfAdditionalTargets" abstract="false" name="NumberOfAdditionalTargets" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="fhtx_CostSharingRate" abstract="false" name="CostSharingRate" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="fhtx_MilestoneReceivableUponAchievement" abstract="false" name="MilestoneReceivableUponAchievement" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_OptOutMilestoneReceivableUponAchievement" abstract="false" name="OptOutMilestoneReceivableUponAchievement" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" abstract="false" name="LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_StanfordLicenseAgreementMember" abstract="true" name="StanfordLicenseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_AnnualLicenseMaintenanceFees" abstract="false" name="AnnualLicenseMaintenanceFees" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_MilestonesPayableUponEvent" abstract="false" name="MilestonesPayableUponEvent" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_ScientificFounderMember" abstract="true" name="ScientificFounderMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_FlagshipPioneeringInc.Member" abstract="true" name="FlagshipPioneeringInc.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_BVFPartnersLPMember" abstract="true" name="BVFPartnersLPMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_DeerfieldManagementCo.LPMember" abstract="true" name="DeerfieldManagementCo.LPMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_FMRLLCMember" abstract="true" name="FMRLLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_SharePurchaseAgreementMember" abstract="true" name="SharePurchaseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_FoghornTherapeuticsMember" abstract="true" name="FoghornTherapeuticsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_PrefundedWarrantsMember" abstract="true" name="PrefundedWarrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_ServiceAgreementTerm" abstract="false" name="ServiceAgreementTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="fhtx_ServiceAgreementRenewalTerm" abstract="false" name="ServiceAgreementRenewalTerm" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="fhtx_PersonnelMember" abstract="true" name="PersonnelMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_FHD286Member" abstract="true" name="FHD286Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_LillyPartneredProgramsMember" abstract="true" name="LillyPartneredProgramsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_ProprietaryProgramsMember" abstract="true" name="ProprietaryProgramsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_OperatingAndAdministrativeCostsMember" abstract="true" name="OperatingAndAdministrativeCostsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_TheSegmentMember" abstract="true" name="TheSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="fhtx_FacilitiesAndInformationRelatedExpensesNetSubleaseIncome" abstract="false" name="FacilitiesAndInformationRelatedExpensesNetSubleaseIncome" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="fhtx_CollaborationRevenueMember" abstract="true" name="CollaborationRevenueMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
</xs:schema>
