false 2025 Q3 0001501697--12-31 0.0333 0.0667 0.0333 0.0333 xbrli:shares iso4217:USD iso4217:USD xbrli:shares xbrli:pure xfor:employee iso4217:EUR xfor:performanceObligation utr:sqm 0001501697 2025-01-01 2025-09-30 0001501697 2025-10-31 0001501697 2025-09-30 0001501697 2024-12-31 0001501697 xfor:LicenseAndOtherRevenueMember 2025-07-01 2025-09-30 0001501697 xfor:LicenseAndOtherRevenueMember 2024-07-01 2024-09-30 0001501697 xfor:LicenseAndOtherRevenueMember 2025-01-01 2025-09-30 0001501697 xfor:LicenseAndOtherRevenueMember 2024-01-01 2024-09-30 0001501697 2025-07-01 2025-09-30 0001501697 2024-07-01 2024-09-30 0001501697 us-gaap:ProductMember 2025-01-01 2025-09-30 0001501697 us-gaap:ProductMember 2024-01-01 2024-09-30 0001501697 2024-01-01 2024-09-30 0001501697 us-gaap:RetainedEarningsMember 2024-07-01 2024-09-30 0001501697 us-gaap:CommonStockMember 2024-12-31 0001501697 us-gaap:AdditionalPaidInCapitalMember 2024-12-31 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2024-12-31 0001501697 us-gaap:RetainedEarningsMember 2024-12-31 0001501697 us-gaap:CommonStockMember 2025-01-01 2025-03-31 0001501697 2025-01-01 2025-03-31 0001501697 us-gaap:AdditionalPaidInCapitalMember 2025-01-01 2025-03-31 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2025-01-01 2025-03-31 0001501697 us-gaap:RetainedEarningsMember 2025-01-01 2025-03-31 0001501697 us-gaap:CommonStockMember 2025-03-31 0001501697 us-gaap:AdditionalPaidInCapitalMember 2025-03-31 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2025-03-31 0001501697 us-gaap:RetainedEarningsMember 2025-03-31 0001501697 2025-03-31 0001501697 us-gaap:CommonStockMember 2025-04-01 2025-06-30 0001501697 us-gaap:AdditionalPaidInCapitalMember 2025-04-01 2025-06-30 0001501697 2025-04-01 2025-06-30 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2025-04-01 2025-06-30 0001501697 us-gaap:RetainedEarningsMember 2025-04-01 2025-06-30 0001501697 us-gaap:CommonStockMember 2025-06-30 0001501697 us-gaap:AdditionalPaidInCapitalMember 2025-06-30 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2025-06-30 0001501697 us-gaap:RetainedEarningsMember 2025-06-30 0001501697 2025-06-30 0001501697 us-gaap:CommonStockMember 2025-07-01 2025-09-30 0001501697 us-gaap:AdditionalPaidInCapitalMember 2025-07-01 2025-09-30 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2025-07-01 2025-09-30 0001501697 us-gaap:RetainedEarningsMember 2025-07-01 2025-09-30 0001501697 us-gaap:CommonStockMember 2025-09-30 0001501697 us-gaap:AdditionalPaidInCapitalMember 2025-09-30 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2025-09-30 0001501697 us-gaap:RetainedEarningsMember 2025-09-30 0001501697 us-gaap:CommonStockMember 2023-12-31 0001501697 us-gaap:AdditionalPaidInCapitalMember 2023-12-31 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2023-12-31 0001501697 us-gaap:RetainedEarningsMember 2023-12-31 0001501697 2023-12-31 0001501697 us-gaap:CommonStockMember 2024-01-01 2024-03-31 0001501697 2024-01-01 2024-03-31 0001501697 us-gaap:AdditionalPaidInCapitalMember 2024-01-01 2024-03-31 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2024-01-01 2024-03-31 0001501697 us-gaap:RetainedEarningsMember 2024-01-01 2024-03-31 0001501697 us-gaap:CommonStockMember 2024-03-31 0001501697 us-gaap:AdditionalPaidInCapitalMember 2024-03-31 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2024-03-31 0001501697 us-gaap:RetainedEarningsMember 2024-03-31 0001501697 2024-03-31 0001501697 us-gaap:CommonStockMember 2024-04-01 2024-06-30 0001501697 us-gaap:AdditionalPaidInCapitalMember 2024-04-01 2024-06-30 0001501697 2024-04-01 2024-06-30 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2024-04-01 2024-06-30 0001501697 us-gaap:RetainedEarningsMember 2024-04-01 2024-06-30 0001501697 us-gaap:CommonStockMember 2024-06-30 0001501697 us-gaap:AdditionalPaidInCapitalMember 2024-06-30 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2024-06-30 0001501697 us-gaap:RetainedEarningsMember 2024-06-30 0001501697 2024-06-30 0001501697 us-gaap:CommonStockMember 2024-07-01 2024-09-30 0001501697 us-gaap:AdditionalPaidInCapitalMember 2024-07-01 2024-09-30 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2024-07-01 2024-09-30 0001501697 us-gaap:CommonStockMember 2024-09-30 0001501697 us-gaap:AdditionalPaidInCapitalMember 2024-09-30 0001501697 us-gaap:AccumulatedOtherComprehensiveIncomeMember 2024-09-30 0001501697 us-gaap:RetainedEarningsMember 2024-09-30 0001501697 2024-09-30 0001501697 xfor:Q32023PrivatePlacementMember 2025-08-13 2025-08-13 0001501697 us-gaap:SubsequentEventMember xfor:PublicOfferingMember 2025-10-23 2025-10-27 0001501697 xfor:ViennaLeaseAgreementMember us-gaap:LetterOfCreditMember 2025-09-30 0001501697 xfor:ViennaLeaseAgreementMember us-gaap:LetterOfCreditMember 2024-12-31 0001501697 xfor:AllstonLeaseAgreementMember us-gaap:LetterOfCreditMember 2025-09-30 0001501697 xfor:AllstonLeaseAgreementMember us-gaap:LetterOfCreditMember 2024-12-31 0001501697 xfor:HerculesSecondAmendedLoanAgreementMember xfor:MinCashTestDate1Member 2025-09-30 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:MoneyMarketFundsMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:MoneyMarketFundsMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:MoneyMarketFundsMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MoneyMarketFundsMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:USTreasuryBillSecuritiesMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:USTreasuryBillSecuritiesMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:USTreasuryBillSecuritiesMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasuryBillSecuritiesMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:MoneyMarketFundsMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:MoneyMarketFundsMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:MoneyMarketFundsMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueMeasurementsRecurringMember us-gaap:MoneyMarketFundsMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:USTreasuryBillSecuritiesMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:USTreasuryBillSecuritiesMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:USTreasuryBillSecuritiesMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueMeasurementsRecurringMember us-gaap:USTreasuryBillSecuritiesMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:USTreasurySecuritiesMember 2025-09-30 0001501697 us-gaap:USGovernmentCorporationsAndAgenciesSecuritiesMember 2025-09-30 0001501697 us-gaap:USTreasurySecuritiesMember 2024-12-31 0001501697 us-gaap:USGovernmentCorporationsAndAgenciesSecuritiesMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:EmbeddedDerivativeFinancialInstrumentsMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:EmbeddedDerivativeFinancialInstrumentsMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:EmbeddedDerivativeFinancialInstrumentsMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueMeasurementsRecurringMember us-gaap:EmbeddedDerivativeFinancialInstrumentsMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:WarrantMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:WarrantMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:WarrantMember us-gaap:FairValueMeasurementsRecurringMember 2025-09-30 0001501697 us-gaap:FairValueMeasurementsRecurringMember us-gaap:WarrantMember 2025-09-30 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:EmbeddedDerivativeFinancialInstrumentsMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:EmbeddedDerivativeFinancialInstrumentsMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:EmbeddedDerivativeFinancialInstrumentsMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueMeasurementsRecurringMember us-gaap:EmbeddedDerivativeFinancialInstrumentsMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel1Member us-gaap:WarrantMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel2Member us-gaap:WarrantMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueInputsLevel3Member us-gaap:WarrantMember us-gaap:FairValueMeasurementsRecurringMember 2024-12-31 0001501697 us-gaap:FairValueMeasurementsRecurringMember us-gaap:WarrantMember 2024-12-31 0001501697 us-gaap:EmbeddedDerivativeFinancialInstrumentsMember 2024-12-31 0001501697 us-gaap:WarrantMember 2024-12-31 0001501697 us-gaap:EmbeddedDerivativeFinancialInstrumentsMember 2025-01-01 2025-09-30 0001501697 us-gaap:WarrantMember 2025-01-01 2025-09-30 0001501697 us-gaap:WarrantMember 2025-09-30 0001501697 us-gaap:MeasurementInputDiscountRateMember 2025-09-30 0001501697 us-gaap:EmbeddedDerivativeFinancialInstrumentsMember 2025-09-30 0001501697 us-gaap:WarrantMember 2025-09-30 0001501697 us-gaap:WarrantMember 2024-12-31 0001501697 us-gaap:WarrantMember 2025-06-30 2025-06-30 0001501697 us-gaap:WarrantMember 2024-12-31 2024-12-31 0001501697 us-gaap:RestrictedStockMember 2025-07-01 2025-09-30 0001501697 us-gaap:RestrictedStockMember 2024-07-01 2024-09-30 0001501697 us-gaap:RestrictedStockMember 2025-01-01 2025-09-30 0001501697 us-gaap:RestrictedStockMember 2024-01-01 2024-09-30 0001501697 us-gaap:EmployeeStockMember 2025-07-01 2025-09-30 0001501697 us-gaap:EmployeeStockMember 2024-07-01 2024-09-30 0001501697 us-gaap:EmployeeStockMember 2025-01-01 2025-09-30 0001501697 us-gaap:EmployeeStockMember 2024-01-01 2024-09-30 0001501697 xfor:PreFundedWarrantMember srt:MaximumMember 2025-09-30 0001501697 us-gaap:EmployeeStockOptionMember 2025-07-01 2025-09-30 0001501697 us-gaap:EmployeeStockOptionMember 2024-07-01 2024-09-30 0001501697 us-gaap:EmployeeStockOptionMember 2025-01-01 2025-09-30 0001501697 us-gaap:EmployeeStockOptionMember 2024-01-01 2024-09-30 0001501697 us-gaap:RestrictedStockUnitsRSUMember 2025-07-01 2025-09-30 0001501697 us-gaap:RestrictedStockUnitsRSUMember 2024-07-01 2024-09-30 0001501697 us-gaap:RestrictedStockUnitsRSUMember 2025-01-01 2025-09-30 0001501697 us-gaap:RestrictedStockUnitsRSUMember 2024-01-01 2024-09-30 0001501697 us-gaap:WarrantMember 2025-07-01 2025-09-30 0001501697 us-gaap:WarrantMember 2024-07-01 2024-09-30 0001501697 us-gaap:WarrantMember 2025-01-01 2025-09-30 0001501697 us-gaap:WarrantMember 2024-01-01 2024-09-30 0001501697 us-gaap:CommonStockMember 2025-04-28 2025-04-28 0001501697 xfor:Q12025StrategicRestructuringPlanMember 2025-01-01 2025-09-30 0001501697 xfor:Q12025StrategicRestructuringPlanMember 2025-09-30 0001501697 us-gaap:ResearchAndDevelopmentExpenseMember xfor:Q12025StrategicRestructuringPlanMember 2025-01-01 2025-09-30 0001501697 us-gaap:SellingGeneralAndAdministrativeExpensesMember xfor:Q12025StrategicRestructuringPlanMember 2025-01-01 2025-09-30 0001501697 xfor:September2025StrategicRestructuringPlanMember 2025-09-30 0001501697 xfor:September2025StrategicRestructuringPlanMember 2025-07-01 2025-09-30 0001501697 xfor:September2025StrategicRestructuringPlanMember 2025-01-01 2025-09-30 0001501697 us-gaap:ResearchAndDevelopmentExpenseMember xfor:September2025StrategicRestructuringPlanMember 2025-07-01 2025-09-30 0001501697 us-gaap:ResearchAndDevelopmentExpenseMember xfor:September2025StrategicRestructuringPlanMember 2025-01-01 2025-09-30 0001501697 us-gaap:SellingGeneralAndAdministrativeExpensesMember xfor:September2025StrategicRestructuringPlanMember 2025-07-01 2025-09-30 0001501697 us-gaap:SellingGeneralAndAdministrativeExpensesMember xfor:September2025StrategicRestructuringPlanMember 2025-01-01 2025-09-30 0001501697 xfor:NorgineAgreementMember 2025-01-13 2025-01-13 0001501697 xfor:RegulatoryMilestoneMember 2025-01-13 2025-01-13 0001501697 xfor:RegulatoryMilestoneMember 2025-01-13 0001501697 xfor:CommercialMilestoneMember 2025-01-13 0001501697 xfor:SalesMilestoneMember 2025-01-13 0001501697 xfor:NorgineAgreementMember 2025-01-13 0001501697 xfor:RebatesAndDiscountsMember 2024-12-31 0001501697 xfor:CoPayAssistanceMember 2024-12-31 0001501697 xfor:ProductReturnsMember 2024-12-31 0001501697 xfor:RebatesAndDiscountsMember 2025-01-01 2025-09-30 0001501697 xfor:CoPayAssistanceMember 2025-01-01 2025-09-30 0001501697 xfor:ProductReturnsMember 2025-01-01 2025-09-30 0001501697 xfor:RebatesAndDiscountsMember 2025-09-30 0001501697 xfor:CoPayAssistanceMember 2025-09-30 0001501697 xfor:ProductReturnsMember 2025-09-30 0001501697 xfor:NorgineAgreementMember 2025-09-30 0001501697 xfor:NorgineAgreementLicenseMember 2025-01-01 2025-09-30 0001501697 xfor:NorgineAgreementMember 2025-01-01 2025-09-30 0001501697 xfor:NorgineAgreementLicenseMember 2025-09-30 0001501697 xfor:NorgineAgreementLicenseMember 2024-01-01 2024-09-30 0001501697 xfor:NorgineAgreementRDWHIMMember 2025-09-30 0001501697 xfor:NorgineAgreementRDWHIMMember 2025-01-01 2025-09-30 0001501697 xfor:NorgineAgreementRDWHIMMember 2024-01-01 2024-09-30 0001501697 xfor:NorgineAgreementRDCNMember 2025-09-30 0001501697 xfor:NorgineAgreementRDCNMember 2025-01-01 2025-09-30 0001501697 xfor:NorgineAgreementRDCNMember 2024-01-01 2024-09-30 0001501697 xfor:NorgineAgreementMember 2024-01-01 2024-09-30 0001501697 us-gaap:PatentsMember 2025-09-30 0001501697 us-gaap:PatentsMember 2025-07-01 2025-09-30 0001501697 us-gaap:PatentsMember 2024-07-01 2024-09-30 0001501697 xfor:HerculesLoanAgreementMember 2025-09-30 0001501697 xfor:HerculesLoanAgreementMember 2018-10-01 2021-03-31 0001501697 xfor:HerculesLoanAgreementMember 2025-01-01 2025-09-30 0001501697 xfor:HerculesLoanAgreementMember 2025-07-01 2025-09-30 0001501697 xfor:HerculesLoanAgreementMember 2024-07-01 2024-07-01 0001501697 xfor:HerculesSecondAmendedLoanAgreementMember 2025-09-30 0001501697 xfor:HerculesLoanAgreementMember 2024-07-01 2024-09-30 0001501697 xfor:HerculesLoanAgreementMember 2024-01-01 2024-09-30 0001501697 xfor:ViennaAustriaLeaseMember 2025-01-01 2025-09-30 0001501697 xfor:ViennaAustriaLeaseMember 2025-09-30 0001501697 xfor:IndemnificationAgreementsMember 2025-09-30 0001501697 xfor:IndemnificationAgreementsMember 2024-12-31 0001501697 xfor:ATMSalesAgreementMember 2020-08-07 2025-09-30 0001501697 xfor:ATMSalesAgreementMember 2025-01-01 2025-09-30 0001501697 xfor:ATMSalesAgreementMember 2023-08-24 0001501697 xfor:LincolnParkCapitalFundLLCMember 2025-06-23 0001501697 xfor:LincolnParkCapitalFundLLCMember 2025-06-23 2025-06-23 0001501697 xfor:LincolnParkCapitalFundLLCMember 2025-06-23 2025-06-30 0001501697 xfor:Q32023PrivatePlacementMember 2025-08-11 2025-08-12 0001501697 xfor:Q32023PrivatePlacementMember 2025-08-12 0001501697 xfor:PreFundedWarrantMember xfor:Q32023PrivatePlacementMember 2025-08-12 0001501697 us-gaap:CommonStockMember srt:MinimumMember 2025-04-17 2025-04-17 0001501697 us-gaap:CommonStockMember srt:MaximumMember 2025-04-17 2025-04-17 0001501697 xfor:TwoThousandNineteenEquityIncentivePlanMember 2025-09-30 0001501697 xfor:TwoThousandSeventeenEquityIncentivePlanMember 2025-09-30 0001501697 us-gaap:EmployeeStockOptionMember 2025-07-01 2025-09-30 0001501697 us-gaap:EmployeeStockOptionMember 2024-07-01 2024-09-30 0001501697 us-gaap:EmployeeStockOptionMember 2025-01-01 2025-09-30 0001501697 us-gaap:EmployeeStockOptionMember 2024-01-01 2024-09-30 0001501697 2024-01-01 2024-12-31 0001501697 us-gaap:RestrictedStockUnitsRSUMember 2024-12-31 0001501697 us-gaap:RestrictedStockUnitsRSUMember 2025-01-01 2025-09-30 0001501697 us-gaap:RestrictedStockUnitsRSUMember 2025-09-30 0001501697 xfor:PerformanceBasedRestrictedStockUnitsMember 2025-01-01 2025-09-30 0001501697 us-gaap:ResearchAndDevelopmentExpenseMember 2025-07-01 2025-09-30 0001501697 us-gaap:ResearchAndDevelopmentExpenseMember 2024-07-01 2024-09-30 0001501697 us-gaap:ResearchAndDevelopmentExpenseMember 2025-01-01 2025-09-30 0001501697 us-gaap:ResearchAndDevelopmentExpenseMember 2024-01-01 2024-09-30 0001501697 us-gaap:GeneralAndAdministrativeExpenseMember 2025-07-01 2025-09-30 0001501697 us-gaap:GeneralAndAdministrativeExpenseMember 2024-07-01 2024-09-30 0001501697 us-gaap:GeneralAndAdministrativeExpenseMember 2025-01-01 2025-09-30 0001501697 us-gaap:GeneralAndAdministrativeExpenseMember 2024-01-01 2024-09-30 0001501697 us-gaap:StockAppreciationRightsSARSMember 2022-11-07 0001501697 us-gaap:StockAppreciationRightsSARSMember 2025-09-30 0001501697 us-gaap:StockAppreciationRightsSARSMember 2024-12-31 0001501697 us-gaap:StockAppreciationRightsSARSMember 2025-01-01 2025-09-30 0001501697 xfor:U.S.SpecialtyPharmacyCustomerMember 2025-07-01 2025-09-30 0001501697 xfor:U.S.SpecialtyPharmacyCustomerMember 2025-01-01 2025-09-30 0001501697 xfor:UnitedKingdomSpecialPharmacyCustomerMember 2025-07-01 2025-09-30 0001501697 xfor:UnitedKingdomSpecialPharmacyCustomerMember 2025-01-01 2025-09-30 0001501697 xfor:U.S.SpecialtyPharmacyCustomerMember 2024-07-01 2024-09-30 0001501697 xfor:U.S.SpecialtyPharmacyCustomerMember 2024-01-01 2024-09-30 0001501697 us-gaap:NonUsMember 2024-07-01 2024-09-30 0001501697 us-gaap:NonUsMember 2024-01-01 2024-09-30 0001501697 xfor:ReportableSegmentMember 2025-07-01 2025-09-30 0001501697 xfor:ReportableSegmentMember 2024-07-01 2024-09-30 0001501697 xfor:ReportableSegmentMember 2025-01-01 2025-09-30 0001501697 xfor:ReportableSegmentMember 2024-01-01 2024-09-30 0001501697 xfor:ReportableSegmentMember 2025-09-30 0001501697 xfor:ReportableSegmentMember 2024-12-31 0001501697 country:US xfor:ReportableSegmentMember 2024-12-31 0001501697 country:AT xfor:ReportableSegmentMember 2024-12-31 0001501697 us-gaap:SubsequentEventMember xfor:PublicOfferingMember 2025-10-27 0001501697 xfor:PreFundedWarrantMember us-gaap:SubsequentEventMember xfor:PublicOfferingMember 2025-10-27 0001501697 us-gaap:SubsequentEventMember us-gaap:OverAllotmentOptionMember 2025-10-23 2025-10-27 0001501697 xfor:PreFundedWarrantMember us-gaap:SubsequentEventMember xfor:PublicOfferingMember 2025-10-23 2025-10-27 0001501697 xfor:MarkBaldryMember 2025-07-01 2025-09-30 0001501697 xfor:Dr.PaulaRaganMember 2025-07-01 2025-09-30 0001501697 xfor:Dr.PaulaRaganTradingArrangementCommonStockRestrictedMember xfor:Dr.PaulaRaganMember 2025-09-30 0001501697 xfor:Dr.PaulaRaganTradingArrangementCommonStockTaxWithholdingMember xfor:Dr.PaulaRaganMember 2025-09-30 0001501697 xfor:AdamMostafaMember 2025-01-01 2025-09-30 0001501697 xfor:AdamMostafaMember 2025-07-01 2025-09-30 0001501697 xfor:AdamMostafaTradingArrangementCommonStockTaxWithholdingMember xfor:AdamMostafaMember 2025-09-30

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 10-Q
(Mark One)

☒ | QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended September 30, 2025
or

☐ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from __________ to __________
Commission File Number: 001-38295
_____________________________________________________________________________________
X4 PHARMACEUTICALS, INC.
(Exact name of registrant as specified in its charter)
_____________________________________________________________________________________

Delaware (State or other jurisdiction of incorporation or organization) | 27-3181608 (I.R.S. Employer Identification No.)
61 North Beacon Street, 4th Floor Boston, Massachusetts (Address of principal executive offices) | 02134 (Zip Code)

(857) 529-8300
(Registrant’s telephone number, including area code)
____________________________________________________________________________
Securities registered pursuant to Section 12(b) of the Act:

Title of each class |  | Trading Symbol(s) |  | Name of each exchange on which registered
Common Stock, par value $0.001 per share |  | XFOR |  | The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No ☐
Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No ☐
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer | ☐ |  | Accelerated filer | ☐
Non-accelerated filer | ☒ |  | Smaller reporting company | ☒
|  |  | Emerging growth company | ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐
Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes ☐ No ☒
As of October 31, 2025, the registrant had 87,436,688 shares of common stock, $0.001 par value per share, outstanding.

X4 PHARMACEUTICALS INC. TABLE OF CONTENTS
PART I: FINANCIAL INFORMATION |
| ITEM 1: FINANCIAL STATEMENTS | 3
| Condensed Consolidated Balance Sheets (unaudited) | 3
| Condensed Consolidated Statements of Operations and Comprehensive (Loss) Income (unaudited) | 4
| Condensed Consolidated Statements Stockholders’ Equity (unaudited) | 5
| Condensed Consolidated Statements of Cash Flows (unaudited) | 7
| Notes to Condensed Consolidated Financial Statements | 8
| ITEM 2: Management’s Discussion and Analysis of Financial Condition and Results of Operations | 27
| ITEM 3: Q uan titative and Q ual itative D isclosures A bout M arket Risk | 34
| ITEM 4: Controls and Procedures | 34
PART II: OTHER INFORMATION |
| ITEM 1: Legal Proceedings | 35
| ITEM 1A: Risk Factors | 35
| ITEM 2: Unregistered Sales of Equity Securities and Use of Proceeds | 35
| ITEM 3: Defaults upon Senior Securities | 35
| ITEM 4: M ine S afety Disclosures | 35
| ITEM 5: O ther Information | 35
| ITEM 6: Exhibits | 37
Signatures | 39

EXPLANATORY NOTE
On April 28, 2025, X4 Pharmaceuticals, Inc. (the “Company”), effected a 1-for-30 reverse stock split of its common stock (the “Reverse Stock Split”). Unless otherwise noted, all references to common stock share and per share amounts in this Quarterly Report on Form 10-Q have been retroactively adjusted to reflect the Reverse Stock Split.
See Note 13 of the condensed consolidated financial statements for a description of the Reverse Stock Split.
2

PART I FINANCIAL INFORMATION
Item 1. Financial Statements.
X4 PHARMACEUTICALS, INC.
CONDENSED CONSOLIDATED BALANCE SHEETS
(In thousands, except share and per share amounts)
(unaudited)

| September 30, 2025 |  | December 31, 2024
ASSETS |  |  |
Current assets: |  |  |
Cash and cash equivalents | $ | 69,632 |  |  | $ | 55,699 |
Accounts receivable | 891 |  |  | 1,070 |
Marketable securities | 52,562 |  |  | 46,361 |
Research and development incentive receivable | 715 |  |  | 640 |
Inventory | 4,080 |  |  | 2,817 |
Prepaid expenses and other current assets | 4,925 |  |  | 5,588 |
Total current assets | 132,805 |  |  | 112,175 |
Property and equipment, net | 218 |  |  | 776 |
Goodwill | 17,351 |  |  | 17,351 |
Intangible asset, net | 9,438 |  |  | 10,000 |
Right-of-use assets | 1,775 |  |  | 4,065 |
Other assets | 1,968 |  |  | 2,080 |
Total assets | $ | 163,555 |  |  | $ | 146,447 |
LIABILITIES AND STOCKHOLDERS’ EQUITY |  |  |
Current liabilities: |  |  |
Accounts payable | $ | 5,053 |  |  | $ | 8,621 |
Accrued expenses | 16,661 |  |  | 23,005 |
Deferred revenue | 592 |  |  | — |
Current portion of lease liability | 1,200 |  |  | 1,251 |
Total current liabilities | 23,506 |  |  | 32,877 |
Long-term debt, including accretion, net of discount | 76,062 |  |  | 75,425 |
Lease liabilities | 95 |  |  | 1,410 |
Warrant liability | 959 |  |  | 13,755 |
Deferred revenue | 789 |  |  | — |
Other liabilities | 525 |  |  | 831 |
Total liabilities | 101,936 |  |  | 124,298 |
Commitments and contingencies (Note 10) |  |  |
Stockholders’ equity: |  |  |
Preferred stock, $0.001 par value. 10,000,000 shares authorized and no shares issued and outstanding as of September 30, 2025 and December 31, 2024, respectively | — |  |  | — |
Common stock, $0.001 par value, 500,000,000 shares authorized as of September 30, 2025 and December 31, 2024, respectively; 25,146,411 and 5,698,231 shares issued and outstanding as of September 30, 2025 and December 31, 2024, respectively | 25 |  |  | 6 |
Additional paid-in capital | 632,341 |  |  | 537,620 |
Accumulated other comprehensive loss | (118) |  |  | (122) |
Accumulated deficit | (570,629) |  |  | (515,355) |
Total stockholders’ equity | 61,619 |  |  | 22,149 |
Total liabilities and stockholders’ equity | $ | 163,555 |  |  | $ | 146,447 |

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.
3

X4 PHARMACEUTICALS, INC.
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE (LOSS) INCOME
(In thousands, except share and per share amounts)
(unaudited)

| Three Months Ended September 30, |  | Nine Months Ended September 30,
| 2025 |  | 2024 |  | 2025 |  | 2024
License and other revenue | $ | 199 |  |  | $ | — |  |  | $ | 28,293 |  |  | $ | — |
Product revenue, net | 1,566 |  |  | 560 |  |  | 4,252 |  |  | 1,123 |
Total revenue | 1,765 |  |  | 560 |  |  | 32,545 |  |  | 1,123 |
Costs and operating expenses: |  |  |  |  |  |  |
Cost of revenue | 351 |  |  | 227 |  |  | 5,393 |  |  | 495 |
Research and development | 17,337 |  |  | 19,173 |  |  | 54,202 |  |  | 59,941 |
Selling, general and administrative | 11,586 |  |  | 15,660 |  |  | 36,134 |  |  | 46,373 |
Gain on sale of non-financial asset | — |  |  | — |  |  | — |  |  | (105,000) |
Total operating expense | 29,274 |  |  | 35,060 |  |  | 95,729 |  |  | 1,809 |
Loss from operations | (27,509) |  |  | (34,500) |  |  | (63,184) |  |  | (686) |
Other (expense) income, net: |  |  |  |  |  |  |
Interest income | 901 |  |  | 1,871 |  |  | 2,591 |  |  | 4,502 |
Interest expense | (2,257) |  |  | (2,414) |  |  | (6,690) |  |  | (6,464) |
Change in fair value of warrant liability | (676) |  |  | (1,864) |  |  | 12,796 |  |  | 4,596 |
Other (expense) income, net | (304) |  |  | 226 |  |  | (746) |  |  | 475 |
Total other (expense) income, net | (2,336) |  |  | (2,181) |  |  | 7,951 |  |  | 3,109 |
(Loss) income before provision for income taxes | (29,845) |  |  | (36,681) |  |  | (55,233) |  |  | 2,423 |
Provision for income taxes | (30) |  |  | 15 |  |  | 41 |  |  | 52 |
Net (loss) income | $ | (29,815) |  |  | $ | (36,696) |  |  | $ | (55,274) |  |  | $ | 2,371 |
Net (loss) income per share: basic | $ | (0.69) |  |  | $ | (5.48) |  |  | $ | (2.87) |  |  | $ | 0.35 |
Weighted average shares outstanding: basic | 43,272,773 |  |  | 6,695,509 |  |  | 19,242,848 |  |  | 6,681,134 |
Net (loss) income per share: diluted | $ | (0.69) |  |  | $ | (5.48) |  |  | $ | (2.87) |  |  | $ | 0.35 |
Weighted average shares outstanding: diluted | 43,272,773 |  |  | 6,695,509 |  |  | 19,242,848 |  |  | 6,687,041 |
Other comprehensive (loss) income, net of tax: |  |  |  |  |  |  |
Net (loss) income | $ | (29,815) |  |  | $ | (36,696) |  |  | $ | (55,274) |  |  | $ | 2,371 |
Change in net unrealized gains on marketable debt securities | 20 |  |  | 45 |  |  | 4 |  |  | 5 |
Comprehensive (loss) income | $ | (29,795) |  |  | $ | (36,651) |  |  | $ | (55,270) |  |  | $ | 2,376 |

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.
4

X4 PHARMACEUTICALS, INC.
CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY
(In thousands, except share amounts)
(Unaudited)

| Common Stock |  | Additional Paid-In Capital |  | Accumulated Other Comprehensive Loss |  | Accumulated Deficit |  | Total Stockholders’ Equity
| Shares |  | Amount
Balance at December 31, 2024 | 5,698,231 |  |  | $ | 6 |  |  | $ | 537,620 |  |  | $ | (122) |  |  | $ | (515,355) |  |  | $ | 22,149 |
Vesting of restricted stock units | 90,514 |  |  | — |  |  | — |  |  |  |  |  |  | — |
Stock-based compensation expense |  |  |  |  | 519 |  |  |  |  |  |  | 519 |
Unrealized loss on marketable securities |  |  |  |  |  |  | (6) |  |  |  |  | (6) |
Net income |  |  |  |  |  |  |  |  | 282 |  |  | 282 |
Balance at March 31, 2025 | 5,788,745 |  |  | $ | 6 |  |  | $ | 538,139 |  |  | $ | (128) |  |  | $ | (515,073) |  |  | $ | 22,944 |
Proceeds from the sale of common stock, less discounts | 2,140,729 |  |  | 2 |  |  | 5,982 |  |  |  |  |  |  | 5,984 |
Issuance of common stock under employee stock purchase plan | 18,473 |  |  | — |  |  | 46 |  |  |  |  |  |  | 46 |
Vesting of restricted stock units | 12,000 |  |  | — |  |  | — |  |  |  |  |  |  | — |
Stock-based compensation expense |  |  |  |  | 748 |  |  |  |  |  |  | 748 |
Unrealized loss on marketable securities |  |  |  |  |  |  | (10) |  |  |  |  | (10) |
Net loss |  |  |  |  |  |  |  |  | (25,741) |  |  | (25,741) |
Balance at June 30, 2025 | 7,959,947 |  |  | $ | 8 |  |  | $ | 544,915 |  |  | $ | (138) |  |  | $ | (540,814) |  |  | $ | 3,971 |
Sale of common stock, net of issuance costs | 14,504,156 |  |  | 15 |  |  | 86,666 |  |  |  |  |  |  | 86,681 |
Vesting of restricted stock units | 112,692 |  |  | — |  |  | — |  |  |  |  |  |  | — |
Exercise of pre-funded warrants | 2,569,616 |  |  | 2 |  |  | — |  |  |  |  |  |  | 2 |
Stock-based compensation expense |  |  |  |  | 760 |  |  |  |  |  |  | 760 |
Unrealized gains on marketable securities |  |  |  |  |  |  | 20 |  |  |  |  | 20 |
Net loss |  |  |  |  |  |  |  |  | (29,815) |  |  | (29,815) |
Balance at September 30, 2025 | 25,146,411 |  |  | $ | 25 |  |  | $ | 632,341 |  |  | $ | (118) |  |  | $ | (570,629) |  |  | $ | 61,619 |

5

X4 PHARMACEUTICALS, INC.
CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY
(In thousands, except share amounts)
(Unaudited)

| Common Stock |  | Additional Paid-In Capital |  | Accumulated Other Comprehensive Loss |  | Accumulated Deficit |  | Total Stockholders’ Equity
| Shares |  | Amount
Balance at December 31, 2023 | 5,581,153 |  |  | $ | 6 |  |  | $ | 529,117 |  |  | $ | (119) |  |  | $ | (477,905) |  |  | $ | 51,099 |
Vesting of restricted stock units | 16,773 |  |  | — |  |  | — |  |  |  |  |  |  | — |
Stock-based compensation expense |  |  |  |  | 1,739 |  |  |  |  |  |  | 1,739 |
Unrealized loss on marketable securities |  |  |  |  |  |  | (36) |  |  |  |  | (36) |
Net loss |  |  |  |  |  |  |  |  | (51,766) |  |  | (51,766) |
Balance at March 31, 2024 | 5,597,926 |  |  | $ | 6 |  |  | $ | 530,856 |  |  | $ | (155) |  |  | $ | (529,671) |  |  | $ | 1,036 |
Issuance of common stock under employee stock purchase plan | 7,835 |  |  | — |  |  | 158 |  |  |  |  |  |  | 158 |
Vesting of restricted stock units | 777 |  |  | — |  |  | — |  |  |  |  |  |  | — |
Stock-based compensation |  |  |  |  | 2,428 |  |  |  |  |  |  | 2,428 |
Unrealized loss on marketable securities |  |  |  |  |  |  | (4) |  |  |  |  | (4) |
Net loss |  |  |  |  |  |  |  |  | 90,833 |  |  | 90,833 |
Balance at June 30, 2024 | 5,606,538 |  |  | $ | 6 |  |  | $ | 533,442 |  |  | $ | (159) |  |  | $ | (438,838) |  |  | $ | 94,451 |
Vesting of restricted stock units | 10,504 |  |  |  |  | 1 |  |  |  |  |  |  | 1 |
Stock-based compensation expense |  |  |  |  | 1,820 |  |  |  |  |  |  | 1,820 |
Unrealized gains on marketable securities |  |  |  |  |  |  | 45 |  |  |  |  | 45 |
Net loss |  |  |  |  |  |  |  |  | (36,696) |  |  | (36,696) |
Balance at September 30, 2024 | 5,617,042 |  |  | $ | 6 |  |  | $ | 535,263 |  |  | $ | (114) |  |  | $ | (475,534) |  |  | $ | 59,621 |

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.
6

X4 PHARMACEUTICALS, INC.
CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS
(In thousands)
(Unaudited)

| Nine Months Ended September 30,
| 2025 |  | 2024
Cash flows from operating activities: |  |  |
Net (loss) income | $ | (55,274) |  |  | $ | 2,371 |
Adjustments to reconcile net (loss) income to net cash used in operating activities: |  |  |
Stock-based compensation expense | 2,027 |  |  | 5,987 |
Depreciation and amortization expense | 1,054 |  |  | 523 |
Gain on sale of non-financial asset | — |  |  | (105,000) |
Non-cash lease expense | 2,290 |  |  | 1,179 |
Accretion of debt discount | 658 |  |  | 655 |
Change in fair value of warrant liability | (12,796) |  |  | (4,596) |
Other | 44 |  |  | (504) |
Changes in operating assets and liabilities: |  |  |
Accounts receivable | 179 |  |  | — |
Inventory | (1,263) |  |  | (2,445) |
Prepaid expenses, other current and non-current assets and research and development incentive receivable | 862 |  |  | 1,197 |
Accounts payable | (3,621) |  |  | (364) |
Accrued expenses and other long-term liabilities | (4,190) |  |  | 3,832 |
Deferred revenue | 1,381 |  |  | — |
Lease liabilities | (1,442) |  |  | (741) |
Net cash used in operating activities | (70,091) |  |  | (97,906) |
Cash flows from investing activities: |  |  |
Acquisition of intangible asset | (3,000) |  |  | (7,000) |
Proceeds from sale of non-financial asset | — |  |  | 105,000 |
Purchase of marketable securities | (61,487) |  |  | (34,354) |
Sales and maturities of marketable securities | 55,792 |  |  | 12,250 |
Acquisition of property and equipment | — |  |  | (285) |
Net cash (used in) provided by investing activities | (8,695) |  |  | 75,611 |
Cash flows from financing activities: |  |  |
Proceeds from issuance of shares of common stock under employee stock purchase plan | 46 |  |  | 159 |
Proceed from borrowings under loan and security agreement | — |  |  | 20,000 |
Proceeds from sale of shares of common stock, less issuance costs | 92,490 |  |  | — |
Net cash provided by financing activities | 92,536 |  |  | 20,159 |
Effect of exchange rate changes on cash, cash equivalents and restricted cash | 210 |  |  | 88 |
Net increase (decrease) in cash, cash equivalents and restricted cash | 13,960 |  |  | (2,048) |
Cash, cash equivalents and restricted cash at beginning of period | 56,475 |  |  | 100,248 |
Cash, cash equivalents and restricted cash at end of period | $ | 70,435 |  |  | $ | 98,200 |
Issuance costs not yet paid related to sale of shares of common stock and pre-funded warrants | $ | 222 |  |  | $ | — |
Acquisition of intangible assets included in accrued expenses | $ | — |  |  | $ | 3,500 |

The accompanying notes are an integral part of these unaudited condensed consolidated financial statements.
7

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
1. Description of Business and Summary of Significant Accounting Policies
X4 Pharmaceuticals Inc., together with its subsidiaries, also referred to in these financial statements as “we,” “us,” “our,” the “Company” and “X4,” is a biopharmaceutical company developing and commercializing novel therapeutics for the treatment of rare hematology diseases. We continue to progress our global, pivotal Phase 3 clinical trial, (the “4WARD” trial) to evaluate the efficacy, safety, and tolerability of oral, once-daily mavorixafor (with or without stable doses of G-CSF) in people with congenital, acquired primary autoimmune, or idiopathic chronic neutropenia who are experiencing recurrent and/or serious infections. The 52-week trial is a randomized, double-blind, placebo-controlled, multicenter study aiming to enroll up to 176 patients, with full enrollment expected in the third quarter of 2026. The FDA has granted Fast Track designation to mavorixafor for the treatment of chronic neutropenia. Chronic neutropenia is defined as periods lasting more than three months persistently or intermittently where there are abnormally low levels of neutrophils circulating in the blood, and may be idiopathic (of unknown origin), cyclic (episodes typically occurring every three weeks), or congenital (of genetic causation). Chronic neutropenia disorders are rare blood conditions similarly characterized by increased risks of infections and cancer due to abnormally low levels of neutrophils in the body. In all cases, the CXCL12/CXCR4 pathway is the key regulator of neutrophil release from the bone marrow. We have one commercially approved product, XOLREMDI ® (mavorixafor), which has received accelerated approval in the United States from the U.S. Food and Drug Administration (“FDA”) for use as an oral, once-daily therapy in patients 12 years of age and older with WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome, to increase the number of circulating mature neutrophils and lymphocytes. WHIM syndrome is a rare combined primary immunodeficiency and chronic neutropenic disorder. In connection with the Company’s long term strategy to successfully complete the 4WARD Phase 3 trial in patients with moderate and severe chronic neutropenia, the Company is no longer prioritizing investment in the WHIM indication. The Company is headquartered in Boston, Massachusetts.
Basis of Presentation
On April 28, 2025 the Company effected a 1-for-30 reverse stock split of its common stock (the “Reverse Stock Split”). Unless otherwise noted, all references to common stock share and per share amounts in this Quarterly Report on Form 10-Q have been retroactively adjusted to reflect the Reverse Stock Split.
The accompanying unaudited interim condensed consolidated financial statements as of and for the nine months ended September 30, 2025 and 2024, respectively have been prepared in accordance with accounting principles generally accepted in the U.S. for interim financial information and with the instructions to the Quarterly Report on Form 10-Q and Article 10 of Regulation S-X. In the opinion of management, such financial information includes all adjustments (consisting only of normal recurring adjustments) considered necessary for a fair presentation of our financial position at such dates and the operating results and cash flows for such periods. Operating results for the three and nine months ended September 30, 2025 are not necessarily indicative of the results that may be expected for the entire year or for any other subsequent interim period.
Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted pursuant to such rules and regulations. These unaudited interim condensed consolidated financial statements should be read in conjunction with the Company’s audited financial statements and the notes thereto for the year ended December 31, 2024 included in its Annual Report on Form 10-K filed with the SEC on March 26, 2025.
The condensed consolidated balance sheet at December 31, 2024 that is presented in these interim condensed consolidated financial statements was derived from audited financial statements but does not include all disclosures required by GAAP.
Principles of Consolidation
The condensed consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries, including X4 Pharmaceuticals (Austria) GmbH, which is incorporated in Vienna, Austria, and X4 Therapeutics, Inc. All intercompany accounts and transactions have been eliminated.
Use of Estimates
The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of expenses during the
8

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
reporting period. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses, the accrual of operational and financial license milestones, the accrual of reserves for variable consideration related to product revenue, and the impairment or lack of impairment of long-lived assets including operating lease right-of-use assets and goodwill. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates when there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. As of the date of issuance of these condensed consolidated financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. Actual results could differ from those estimates, and any such differences may be material to the Company’s condensed consolidated financial statements.
Liquidity
The Company has evaluated whether there are certain conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the condensed consolidated financial statements are issued. Although the Company has an approved drug product, licensing and sales of the Company’s drug product over the next 12 months will not be sufficient to fund the Company’s operating expenses. Since inception, the Company has incurred significant operating losses and negative cash flows from operations, and the Company expects to continue to generate operating losses and negative cash flows from operations for the foreseeable future. For the nine months ended September 30, 2025, the Company’s net loss was $55.3 million and net cash used in operating activities was $70.1 million. As of September 30, 2025, the Company had $122.2 million of cash, cash equivalents and short-term marketable securities, and an accumulated deficit of $570.6 million.
On August 13, 2025, the Company closed a private placement of shares of its common stock and, in lieu of common stock to certain investors, prefunded warrants to purchase shares of its common stock, for net proceeds of approximately $81.0 million, after deducting placement agent fees and other estimated expenses. See Note 11 for further information on this transaction. Also, on October 27, 2025, the Company closed an underwritten offering of shares of its common stock and, in lieu of common stock to certain investors, prefunded warrants to purchase shares of its common stock, for net proceeds of approximately $145.6 million, after deducting the Underwriters’ (as defined below) discounts and commissions and estimated offering expenses, which offering further extends the Company’s ability to fund its operations and financial obligations.
The Company must continue to comply with covenants under its Second Amended and Restated Loan and Security Agreement, as amended, (the “Hercules Loan Agreement”) with Hercules Capital Inc. (“Hercules”). Such covenants are described in Note 8 to these condensed consolidated financial statements. As of September 30, 2025, the Company was in compliance with all covenants under the Hercules Loan Agreement.
Based on its current operating plan, the Company believes (a) that its current cash, cash equivalents and short-term marketable will be sufficient to fund its operations for at least the next 12 months and (b) it will continue to comply with all covenants under the Hercules Loan Agreement through at least the 12-month period from the issuance date of these condensed consolidated financial statements.
The Company is subject to risks common to companies in the biopharmaceutical industry including, but not limited to, uncertainties relating to conducting preclinical and clinical research and development, the manufacture and supply of products and product candidates for clinical and commercial use, obtaining and maintaining regulatory approvals and pricing and reimbursement for the Company’s products and product candidates, market acceptance, managing global growth and operating expenses, availability of additional capital, competition, obtaining and enforcing patents, stock price volatility, dependence on collaborative relationships and third-party service providers, dependence on key personnel, and from time to time government investigations, litigation, and potential product liability claims.
Significant Accounting Policies
The Company’s significant accounting policies are disclosed in the audited consolidated financial statements and the notes thereto in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024 filed with the SEC on March 26, 2025. Since the date of those consolidated financial statements, there have been no material changes to the Company’s significant accounting policies other than as follows:
9

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
Revenue Recognition
The Company records revenue using the guidance of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”), as amended. Upon the approval by the FDA of the sales and marketing of the Company’s lead product candidate, revenue related to its sale and distribution is accounted for under ASC 606. The Company recognizes revenue when its customer obtains control of promised goods, services or licensed rights, in an amount that reflects the consideration that the Company determines it expects to receive in exchange for those goods, services or licensed rights. To determine revenue recognition for arrangements that the Company determines are within the scope of ASC 606, the Company performs the following five steps: (1) identify the customer and contract with the customer; (2) identify the performance obligations in the contract; (3) determine the transaction price, adjusted for variable consideration resulting from potential returns, rebates, discounts, down-stream charges and the probability of achievement of future milestones; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when the Company satisfies its performance obligations, which is upon delivery of the finished product to the customer, delivery of services or delivery of licensed rights.
The Company currently sells its product to a specialty pharmacy, which dispenses the Company’s drug product to patients in the U.S. The Company records revenue when the specialty pharmacy obtains control over the promised good, which occurs at a point in time, typically upon delivery to the specialty pharmacy. The Company has concluded that it provides one performance obligation in its contract with the specialty pharmacy customer and for other customers in this class: the delivery of drug product that has been approved for sale and distribution by the applicable regulatory authority.
The Company has also entered into a license and supply agreement with Norgine Pharma UK Limited (the “Norgine Agreement”) (Note 3). The terms of this agreement contain multiple performance obligations, which include a) the delivery of a license, b) WHIM research and development services and c) CN research and development services. Payments to the Company under this arrangement include non-refundable, upfront license fees; regulatory and sales-based milestone payments and royalties on future product sales.
As part of the accounting for its contract arrangements, the Company makes significant judgments, primarily related to the estimation of the amount of variable consideration to include in the transaction price upon delivery of the Company’s drug product or licensed rights.
•The variable consideration for product sales typically includes estimates for discounts, product returns, rebates due to U.S. federal and state payors, such as Medicaid, based on agreements that the Company has with these payors who provide medical insurance to the end patient, and estimated co-pay assistance payments for patients who enroll in the Company’s patient assistance program. These variable payments are considered a reduction of the Company’s transaction price with its customer and are estimated using the expected value method at the time the Company’s product is delivered to the customer.
•The consideration in license agreements typically includes future regulatory milestone payments, sales-based milestone payments, and royalties on future product sales. The Company has elected to exclude sale-based milestone payments and sales-based royalties from the transaction price under the applicable practical expedient. As such, the remaining variable consideration is generally comprised of future regulatory or operational milestone payments, which are considered for inclusion in the transaction price at the outset of the arrangement and at each reporting period using the most-likely-amount method.
For arrangements which contain multiple performance obligations, the Company allocates the transaction price to each performance obligation based on the estimated relative standalone selling price. The Company estimates the standalone selling price with the objective of determining the price at which the Company would sell such an item if it were to be sold regularly on a standalone basis.
Net revenue recognized for each period is the amount for which, based on management’s estimate, it is probable that a significant reversal of cumulative revenue recognized will not occur. At the end of each subsequent reporting period, the Company re-evaluates these estimates based on new information and actual operational trends and if necessary, adjusts these variable consideration estimates. Any such adjustments are recorded on a cumulative catch-up basis in the period of the adjustment.
10

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
Cost of Revenue
Cost of revenue consists of drug product costs, including capitalized internal direct and overhead costs associated with the manufacturing, lot release and distribution of XOLREMDI, amortization of intangible assets associated with license agreements and royalty expense. Cost of revenue may also include costs related to excess or obsolete inventory adjustment charges and abnormal manufacturing costs.
Restricted Cash

(in thousands) | As of September 30, 2025 |  | As of December 31, 2024
Letter of credit security: Vienna Austria lease | $ | 224 |  |  | $ | 199 |
Letter of credit security: Boston lease | 579 |  |  | 577 |
Total restricted cash | $ | 803 |  |  | $ | 776 |

As of September 30, 2025, restricted cash related to the Vienna Austria lease is included in other current assets and restricted cash related to the Boston lease is included in other assets.
In connection with the Company’s lease agreements for its facilities in Boston, Massachusetts and Vienna, Austria, the Company maintains letters of credit, which are secured by restricted cash, for the benefit of the respective landlord. In accordance with the Company’s Hercules Loan Agreement and as further described in Note 10, the Company at all times must maintain a minimum level of cash of $15.0 million in an account or accounts in which Hercules has a first priority security interest as further described in Note 10.
The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed consolidated balance sheets to the sum to the total of amounts shown in the Company’s condensed consolidated statements of cash flows as of September 30, 2025 and December 31, 2024:
Cash, Cash Equivalents, Restricted Cash and Marketable Securities

(in thousands) | September 30, 2025 |  | December 31, 2024 |  |  |  |
Cash and cash equivalents | $ | 69,632 |  |  | $ | 55,699 |  |  |  |  |
Restricted cash | 803 |  |  | 776 |  |  |  |  |
Total cash, cash equivalents and restricted cash | $ | 70,435 |  |  | $ | 56,475 |  |  |  |  |

The Company’s cash equivalents consisted of money market funds invested in U.S. Treasury securities. The money market funds were valued based on quoted prices in active markets for identical assets, which represents a Level 1 measurement. All marketable securities are classified as short-term investments as all are due within one year and include investments in U.S. Treasury notes, U.S. Treasury bills and federal government agency notes. The amortized cost of each investment, individually and in aggregate, approximated fair value. The Company evaluated each marketable security for impairment that is other-than-temporary and concluded that no marketable security was impaired as of September 30, 2025 and December 31, 2024.

| Fair Value Measurements as of September 30, 2025 Using:
(in thousands) | Level 1 |  | Level 2 |  | Level 3 |  | Total
Cash equivalents—money market funds | $ | 50,423 |  |  | $ | — |  |  | $ | — |  |  | $ | 50,423 |
Marketable securities— U.S. Treasury notes, U.S. Treasury bills, and federal government agency notes | — |  |  | 52,562 |  |  | — |  |  | 52,562 |
| $ | 50,423 |  |  | $ | 52,562 |  |  | $ | — |  |  | $ | 102,985 |

11

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)

| Fair Value Measurements as of December 31, 2024 Using:
(in thousands) | Level 1 |  | Level 2 |  | Level 3 |  | Total
Cash equivalents—money market funds | $ | 40,983 |  |  | $ | — |  |  | $ | — |  |  | $ | 40,983 |
Marketable securities—U.S. Treasury notes, U.S. Treasury bills, and federal government agency notes | — |  |  | 46,361 |  |  | — |  |  | 46,361 |
| $ | 40,983 |  |  | $ | 46,361 |  |  | $ | — |  |  | $ | 87,344 |

All marketable securities are classified as short-term investments as all are due within one year and include investments in U.S. Treasury notes, U.S. Treasury bills and federal government agency notes. The amortized cost of each investment, individually and in aggregate, approximated fair value. The Company evaluated each marketable security for impairment that is other-than-temporary and concluded that no marketable security was impaired as of September 30, 2025 and December 31, 2024. The Company’s cash equivalents consisted of money market funds invested in U.S. Treasury securities. The money market funds were valued based on quoted prices in active markets for identical assets, which represents a Level 1 measurement.
The following table provides amortized cost, unrealized gains and losses and the carrying amount of available-for-sale debt marketable securities as of September 30, 2025:

(in thousands) | Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Fair Value
U.S. Treasury securities | $ | 17,352 |  |  | $ | 1 |  |  | $ | 3 |  |  | $ | 17,350 |
Federal Government Agency securities | 35,210 |  |  | 11 |  |  | 9 |  |  | 35,212 |
Total available-for-sale debt securities | $ | 52,562 |  |  | $ | 12 |  |  | $ | 12 |  |  | $ | 52,562 |

The following table provides amortized cost, unrealized gains and losses and the carrying amount of available-for-sale debt marketable securities as of December 31, 2024:

(in thousands) | Amortized Cost |  | Gross Unrealized Gains |  | Gross Unrealized Losses |  | Fair Value
U.S. Treasury securities | $ | 18,928 |  |  | $ | 5 |  |  | $ | 3 |  |  | $ | 18,930 |
Federal Government Agency securities | 27,436 |  |  | 9 |  |  | 14 |  |  | 27,431 |
Total available-for-sale debt securities | $ | 46,364 |  |  | $ | 14 |  |  | $ | 17 |  |  | $ | 46,361 |

Liabilities Measured at Fair Value
The following tables present information about the Company’s financial liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy used to determine such fair values:

| Fair Value Measurements as of September 30, 2025 Using:
(in thousands) | Level 1 |  | Level 2 |  | Level 3 |  | Total
Liabilities: |  |  |  |  |  |  |
Embedded derivative liability | $ | — |  |  | $ | — |  |  | $ | 10 |  |  | $ | 10 |
Class C warrant liability | — |  |  | — |  |  | 959 |  |  | 959 |
| $ | — |  |  | $ | — |  |  | $ | 969 |  |  | $ | 969 |

12

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)

| Fair Value Measurements as of December 31, 2024 Using:
(in thousands) | Level 1 |  | Level 2 |  | Level 3 |  | Total
Liabilities: |  |  |  |  |  |  |
Embedded derivative liability | $ | — |  |  | $ | — |  |  | $ | 10 |  |  | $ | 10 |
Class C warrant liability | — |  |  | — |  |  | 13,755 |  |  | 13,755 |
| $ | — |  |  | $ | — |  |  | $ | 13,765 |  |  | $ | 13,765 |

The following table provides a roll-forward for the nine months ended September 30, 2025, of the aggregate fair values financial instruments for which fair values are determined using Level 3 inputs:

(in thousands) | Embedded Derivative Liability |  |  |  | Class C Warrant Liability |  | Total |  |
Balance as of December 31, 2024 | $ | 10 |  |  |  |  | $ | 13,755 |  |  | $ | 13,765 |  |  |
Change in fair value | — |  |  |  |  | (12,796) |  |  | (12,796) |  |  |
Balance as of September 30, 2025 | $ | 10 |  |  |  |  | $ | 959 |  |  | $ | 969 |  |  |

Valuation of Embedded Derivative Liability— The fair value of the embedded derivative liability recognized in connection with the Company’s Hercules Loan Agreement, which is associated with additional fees due to Hercules upon non-credit related events of default, was determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair value of this embedded derivative liability, which is reported within other non-current liabilities on the condensed consolidated balance sheets, is estimated by the Company at each reporting date based, in part, on the results of third-party valuations, which were prepared based on a discounted cash flow model that considered the timing and probability of occurrence of a redemption upon an event of default, the potential amount of prepayment fees or contingent interest upon an event of default and the Company’s risk-adjusted discount rate of 17%. As of September 30, 2025 and December 31, 2024, the fair value of this derivative liability was $10 thousand.
Class C Warrant Liability— In December 2022, the Company issued Class C Warrants for the purchase of shares of its common stock in a public offering. The Class C Warrants are accounted for as a liability on the condensed consolidated balance sheet and are adjusted to fair value at period end through “change in fair value of warrant liability” on the condensed consolidated statements of operations and comprehensive (loss) income.
The Company calculated the fair value of the Class C Warrants using the Black-Scholes option pricing model, with the following inputs:

|  | September 30, 2025 |  | December 31, 2024
Common stock price |  | $3.42 |  | $21.90
Risk-free interest rate |  | 3.6 | % |  | 4.2 | %
Expected term (in years) |  | 2.2 |  | 2.9
Expected volatility |  | 136.4 | % |  | 117.5 | %
Expected dividend yield |  | — | % |  | — | %

Net (Loss) Income Per Share
Basic net (loss) income per common share is calculated based on the net (loss) income attributable to common stockholders divided by the weighted average number of shares outstanding for the period. The calculation of diluted net (loss) income per common share excludes the potential conversion of securities, such as stock awards and warrants, using the treasury stock method, as their inclusion would have an anti-dilutive effect.
13

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
Basic and diluted net (loss) income per share was calculated as follows:

| Three Months Ended September 30, |  | Nine Months Ended September 30, |  |
(in thousands, except share and per share data) | 2025 |  | 2024 |  | 2025 |  | 2024 |  |  |  |
Numerator: |  |  |  |  |  |  |  |  |  |  |
Net (loss) income | $ | (29,815) |  |  | $ | (36,696) |  |  | $ | (55,274) |  |  | $ | 2,371 |  |  |  |  |
Denominator: |  |  |  |  |  |  |  |  |  |  |
Weighted average shares of common stock outstanding—basic | 43,272,773 |  |  | 6,695,509 |  |  | 19,242,848 |  |  | 6,681,134 |  |  |  |  |
Net (loss) income per share— basic | $ | (0.69) |  |  | $ | (5.48) |  |  | $ | (2.87) |  |  | $ | 0.35 |  |  |  |  |
Effective of dilutive securities |  |  |  |  |  |  |  |  |  |  |
Time-based restricted stock units | — |  |  | — |  |  | — |  |  | 3,698 |  |  |  |  |
Employee stock purchase plan | — |  |  | — |  |  | — |  |  | 2,209 |  |  |  |  |
Dilutive potential common shares | — |  |  | — |  |  | — |  |  | 5,907 |  |  |  |  |
Weighted average shares of common stock outstanding—diluted | 43,272,773 |  |  | 6,695,509 |  |  | 19,242,848 |  |  | 6,687,041 |  |  |  |  |
Net (loss) income per share— diluted | $ | (0.69) |  |  | $ | (5.48) |  |  | $ | (2.87) |  |  | $ | 0.35 |  |  |  |  |

Basic and diluted weighted average shares of common stock outstanding for the three and nine months ended September 30, 2025 and 2024 includes the weighted average effect of pre-funded warrants for the purchase of shares of common stock, for which the remaining unfunded exercise price is less than or equal to $0.30 per share.
For the three and nine months ended September 30, 2025 and for the three months ended September 30, 2024, during which the Company recorded net loss, the Company’s potentially dilutive securities included outstanding stock options, employee stock purchase plan shares, unvested restricted stock units and warrants to purchase shares of common stock. These potentially dilutive securities have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share, and thus they are considered “anti-dilutive.” Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same for these periods.
For the nine months ended September 30, 2024, during which the Company recorded net income, the dilutive effect of outstanding stock options, restricted stock units, employee stock purchase plan shares and warrants were calculated using the treasury stock method, whereby all such awards were assumed to be exercised at the beginning of the period. The hypothetical proceeds from such exercises, including the average unrecognized stock compensation expense for outstanding stock options and restricted stock units, were assumed to be used to purchase outstanding common stock at the average price during the period. The net share impact of dilutive securities was added to the weighted average basic common shares outstanding to calculate weighted average diluted shares outstanding.
The Company excluded the following potential shares of common stock from the computation of diluted net (loss) income per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect:

| Three Months Ended September 30, |  | Nine Months Ended September 30, |
(in thousands) | 2025 |  | 2024 |  | 2025 |  | 2024 |
Options to purchase shares of common stock | 12,988 |  |  | 386 |  |  | 12,988 |  |  | 386 |  |
Unvested restricted stock units | 99 |  |  | 271 |  |  | 99 |  |  | 266 |  |
Warrants to purchase shares of common stock (excluding prefunded warrants, which are included in basic shares outstanding) | 2,546 |  |  | 2,546 |  |  | 2,546 |  |  | 2,546 |  |
| 15,633 |  |  | 3,203 |  |  | 15,633 |  |  | 3,198 |  |

14

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
Recently Announced Accounting Standards Not Yet Adopted
In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740) Improvements to Income Tax Disclosures (“ASU 2023-09”). The amendments in ASU 2023-09 require that entities on an annual basis disclose specific categories in the income tax rate reconciliation and provide additional information for reconciling items if the effect of those reconciling items that exceed a certain threshold. ASU 2023-09 also requires more disaggregated disclosures related to income taxes paid. The amendments in ASU 2023-09 become effective for the Company in its December 31, 2025 consolidated financial statements. The Company does not expect that the adoption of ASU 2023-09 will have a material impact on its consolidated financial statements when adopted.
In November 2024, the FASB issued ASU 2024-03, Disaggregation of Income Statement Expenses (Topic 220) (“ASU 2024-03”) requiring that public business entities disclose additional information about specific expense categories in the notes to financial statements at interim and annual reporting periods. The amendments in ASU 2024-03 are effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. The requirements in ASU 2024-03 may be applied either prospectively to financial statements issued for reporting periods after the effective date or retrospectively to any or all prior periods presented in the financial statements. The Company continues to evaluate the impact of ASU 2024-03.
2. Strategic Restructurings
In the first quarter of 2025, we implemented a strategic restructuring of our business operations, workforce and capital spending to focus efforts on advancing mavorixafor to treat patients with chronic neutropenia. As part of this restructuring, we (i) implemented a net reduction of our employee headcount by 43 employees, or approximately 30% of our total workforce as of February 2025, including our U.S. commercial field team, (ii) commenced the closure of our research and development facility in Vienna, Austria, (iii) paused our pre-clinical drug candidate programs and (iv) streamlined other spending to support the ongoing clinical development of mavorixafor for the larger population of patients with chronic neutropenia. We incurred charges of approximately $2.3 million for severance and other employee termination-related costs related to this strategic restructuring, of which $0.7 million is included in research and development and $1.6 million is included in selling, general and administrative expense on the accompanying condensed consolidated income statements for the nine months ended September 30, 2025.
On September 17, 2025, we announced an additional strategic restructuring designed to sharpen operational focus and align resources with the Company’s long‑term strategy to successfully complete the 4WARD Phase 3 trial in patients with moderate and severe chronic neutropenia. As part of this initiative, we have further reduced our workforce by an additional approximately 50%. This workforce reduction was substantially completed in the third quarter of 2025. As part of this strategic restructuring, we incurred expenses of approximately $4.9 million for severance and other employee termination-related costs, of which $1.5 million is included in research and development and $3.4 million is included in selling, general and administrative expense on the accompanying condensed consolidated income statements for the three and nine months ended September 30, 2025.
Approximately $3.7 million of accrued severance and other employee termination-related costs are included in accrued expenses on the condensed consolidated balance sheet as of September 30, 2025. These remaining severance obligation payments are expected to be substantially completed in the fourth quarter of 2025.
The following table summarizes the Company’s liability recognized in connection with these headcount reductions:

(in thousands) |  |
Balance as of January 1, 2025 |  | $ | 522 |
Severance and other employee-related expenses |  | 7,203 |
Cash payments |  | (4,019) |
Balance as of September 30, 2025 |  | $ | 3,706 |

3. License Agreements
15

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
Norgine Agreement
On January 13, 2025, the Company entered into a License and Supply Agreement (the “Norgine Agreement”) with Norgine Pharma UK Limited (“Norgine”), pursuant to which Norgine was granted an exclusive license to seek regulatory approval and distribute, market and sell the Company’s product mavorixafor (marketed by the Company as XOLREMDI in the United States) within the Field (as defined in the Norgine Agreement), in the European Economic Area, Switzerland, the United Kingdom, Australia and New Zealand (collectively, the “Territory”), following regulatory approval in the Territory. Additionally, Norgine was granted a co-exclusive license to manufacture mavorixafor for the Territory. The Company retains all rights to mavorixafor outside the Territory and specific reserved rights within the Territory. Norgine may grant sublicenses to its affiliates and certain third parties subject to the terms of the Norgine Agreement, except that it may not sublicense the commercial rights granted under the Norgine Agreement for certain countries without X4’s explicit consent.
Pursuant to the terms of the Norgine Agreement, the Company received a one-time, non-refundable, upfront payment of €28.5 million and a regulatory milestone payment of €0.5 million. The Company could receive up to approximately €20.6 million, €20.0 million and €185.0 million upon the achievement of certain regulatory, commercial, and sales milestones, respectively, or €225.6 million in aggregate. The Norgine Agreement also includes escalating double-digit royalties of up to mid-twenties on any future net sales in the Territory. The tiered royalty payments are subject to royalty stacking, and to a material reduction on a country-by-country basis if a generic version of mavorixafor becomes available in the applicable country. The Company and Norgine will collaborate closely on regulatory filings, with the Company continuing to be responsible for the ongoing global, pivotal Phase 3 4WARD clinical trial evaluating mavorixafor in chronic neutropenia and certain components of pediatric studies for WHIM. Norgine will be responsible for all market access and commercialization activities. The Company also agreed to manufacture and supply mavorixafor to Norgine. Norgine shall be required to pay a supply price to the Company for the licensed product derived from the Company’s manufacturing costs plus margin in the low teens.
Subject to customary rights of each party to earlier terminate the Norgine Agreement, the term of the Norgine Agreement continues, on a country-by-country basis, until the later of: (i) the tenth (10th) anniversary of the first commercial sale of mavorixafor, (ii) expiration of regulatory market exclusivity of mavorixafor or (iii) expiration of the last-to-expire licensed patent in such country. The term of the Norgine Agreement shall be automatically renewed for additional three-year terms unless either party provides the other party written notice of its intent not to renew the Norgine Agreement at least one year prior to the applicable termination date of the Norgine Agreement. In the event of automatic renewal, the royalty payment rate drops to a single digit royalty.
4. Revenue
Product Revenue, Net
During the three and nine months ended September 30, 2025, the Company recorded net revenue $1.6 million and $4.3 million, respectively, for the sale of the Company’s drug product in the U.S. Net product revenue was $0.6 million and $1.1 million and for the three and nine months ended September 30, 2024 following the commercial launch of the Company’s product during the second quarter of 2024.
The following table summarizes the balances and activity in each of the product reserve accounts for the nine months ended September 30, 2025.

(in thousands) | Rebates and Discounts |  | Co-Pay Assistance |  | Product Returns |  | Total
Beginning balance at December 31, 2024 | $ | 99 |  |  | $ | 29 |  |  | $ | 11 |  |  | $ | 139 |
Provision related to revenue associated with sales processed in the nine month period ended September 30, 2025 | 413 |  |  | 69 |  |  | 38 |  |  | 520 |
Adjustments related to revenue associated with sales processed in prior periods | (16) |  |  | — |  |  | (41) |  |  | (57) |
Credits and payments made during the period | (169) |  |  | (100) |  |  | — |  |  | (269) |
Balance as of September 30, 2025 | $ | 327 |  |  | $ | (2) |  |  | $ | 8 |  |  | $ | 333 |

16

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
The provision for contractual discounts provided to the Company’s customer is recorded as a reduction of accounts receivable. The provisions for co-pay assistance payments, contractual rebates and product returns are classified within accrued expenses.
The following table provides a rollforward of accounts receivable for the nine months ended September 30, 2025.

(in thousands) | Accounts Receivable
Beginning balance at December 31, 2024 | $ | 1,070 |
Increase in accounts receivable for drug product sales | 4,581 |
Decrease in accounts receivable for cash collections | (4,760) |
Balance as of September 30, 2025 | $ | 891 |

License and Other
During the first quarter of 2025, the Company entered into the Norgine Agreement. The Company analyzed the activities required under the Norgine Agreement and concluded that the arrangement was indicative of a vendor-customer relationship and would be accounted for under ASC 606. During the nine months ended September 30, 2025, the Company received a one-time, non-refundable, up-front payment of €28.5 million and a regulatory milestone payment of €0.5 million, which are included the transaction price. All other future regulatory-based milestone payments, which represent variable consideration, have been fully constrained as these are not yet considered probable. The Company has also excluded from the transaction price future royalty payments that are based on units sold by Norgine and future cumulative revenue-based milestone payments under the applicable practical expedient.
Under the Norgine Agreement, the Company’s promises include a) the delivery of a license, b) research and development services for certain components of WHIM clinical studies, c) research and development services for the global Phase 3 trial of XOLREMDI for CN, and d) the option for delivery of commercial drug supply pursuant to a manufacturing agreement. The Company assessed the above promises and determined that the option for delivery of commercial drug supply is priced at fair value, and therefore is not a material right or a performance obligation. Revenue from the delivery of manufacturing supply will be recorded when delivered at the pricing agreed to in the contract. The license was considered functional intellectual property as of the inception of the Norgine Agreement and distinct from other promises under the contract, as Norgine can benefit from the license on its own or together with other readily available resources. Each of the research and development services were considered distinct as the customer can benefit from these services together with the license transferred at the inception of the agreement. The research and development services will not modify or customize the initial intellectual property transferred at contract inception due to the late stage of development of the intellectual property. As a result, the Company identified three performance obligations: a) the delivery of the license, b) research and development services for certain components of WHIM clinical studies, and c) research and development services for the global Phase 3 trial of XOLREMDI for CN.
The Company allocated the transaction price of $29.7 million among these three performance obligations based on the Company’s best estimate of stand-alone selling price for each distinct performance obligation. The Company developed the estimated standalone selling price, at inception, for each of the three performance obligations with the objective of determining the price at which the Company would sell such an item if it were to be sold regularly on a standalone basis. The Company developed the estimated standalone selling price for the license primarily based on the probability-weighted present value of expected future cash flows. In developing such estimates, the Company applied judgment in determining the forecasted revenues, taking into consideration the applicable market conditions and relevant entity-specific factors, the probability of success, the time needed to develop XOLREMDI and the discount rate. The Company developed the estimated standalone selling price for the research and development services based on the amount a third party would pay for these services, which contemplates the level of efforts necessary to perform these services and the costs for full-time equivalent employees and expected resources to be committed plus a reasonable margin.
During the nine months ended September 30, 2025, the Company recognized $27.6 million for the delivery of the license and $0.7 million for research and development services. The license performance obligation was satisfied at a point in time upon transfer of the license to Norgine. Control of the license was transferred on the effective date of the Norgine Agreement as Norgine could begin to use and benefit from the license. For the research and development performance obligations, the Company recognizes revenue over time using an input method based on cost incurred during the period relative to the total estimated cost of the obligation. This method, in management’s judgment, is the best measure of progress towards satisfying the performance obligation as the transfer of control occurs as services are performed. The amounts received that have not yet been
17

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
recognized as revenue are recorded as deferred revenue on the condensed consolidated balance sheet and will be recognized over the remaining period as the performance obligation is satisfied.
The following table summarizes the allocation of transaction price to the three performance obligations in the Norgine Agreement based on the weighting of estimated stand-alone selling price for these performance obligations at the inception of the agreement.

|  |  |  |  | Allocation of Transaction Price |  | Revenue Recognized
(in thousands) |  |  |  | Nine Months Ended September 30,
Performance Obligation: |  |  |  | 2025 |  | 2024
License |  |  |  |  | $ | 27,639 |  |  | $ | 27,639 |  |  | $ | — |
Research and development services: WHIM |  |  |  |  | 312 |  |  | 25 |  | — |
Research and development services: CN |  |  |  |  | 1,724 |  |  | 629 |  | — |
Total |  |  |  |  | $ | 29,675 |  |  | $ | 28,293 |  |  | $ | — |

As of September 30, 2025, deferred revenue related to the Norgine Agreement was $1.4 million, of which $0.6 million was current.
5. Inventory
Inventory consists of the following:

(in thousands) | September 30, 2025 |  | December 31, 2024
Raw materials | $ | 1,397 |  |  | 1,529 |
Work in process | 2,111 |  |  | 608 |
Finished goods | 572 |  |  | 680 |
Total inventory | $ | 4,080 |  |  | $ | 2,817 |

6. Intangible Assets, Net
As of September 30, 2025, the Company’s net definite-lived intangible asset, which resulted from the capitalization of certain milestone payments made or accrued related to its license agreement for the intellectual property contained in its drug product, included a gross intangible asset of $10.5 million, less accumulated amortization of $1.1 million for a net intangible asset of $9.4 million. The Company amortizes the intangible asset to cost of revenue over the remaining life of the underlying patent protecting the intellectual property through 2038.
As of September 30, 2025, amortization expense for the next five years and beyond is summarized as follows (in thousands):

Year | Amortization expense
2025 (remainder of year) | $ | 188 |
2026 | 750 |
2027 | 750 |
2028 | 750 |
2029 | 750 |
Thereafter | 6,250 |
Total | $ | 9,438 |

18

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
The Company began amortizing its finite-lived intangible assets in April 2024 over a 14-year period based on the expected patent exclusivity period for XOLREMDI. Amortization expense totaled $0.2 million and $0.6 million for the three and nine months ended September 30, 2025, respectively, and $0.2 million and $0.3 million for the comparable prior year periods. Amortization expense is recorded as a component of cost of revenue on the condensed consolidated statements of operations and comprehensive (loss) income.
7. Accrued Expenses
Accrued expenses consisted of the following:

(in thousands) | September 30, 2025 |  | December 31, 2024
Accrued employee compensation and benefits | $ | 8,344 |  |  | 13,053 |
Accrued external research and development expenses | 5,923 |  |  | 3,727 |
Accrued royalty and milestone payments | 100 |  |  | 3,092 |
Accrued professional fees | 908 |  |  | 1,825 |
Accrued deferred financing fees | 222 |  |  | — |
Other | 1,164 |  |  | 1,308 |
| $ | 16,661 |  |  | $ | 23,005 |

8. Long-Term Debt
Long-term debt consisted of the following:

(in thousands) | September 30, 2025 |  | December 31, 2024
Principal amount of long-term debt | $ | 75,000 |  |  | $ | 75,000 |
Debt discount, net of accretion | (475) |  |  | (650) |
Cumulative accrual of end of term payments | 1,537 |  |  | 1,075 |
Long-term debt | $ | 76,062 |  |  | $ | 75,425 |

Hercules Loan Agreement
The Company is party to the Hercules Loan Agreement, which provides for an aggregate term loan facility of up to $107.5 million, under which the Company has borrowed an aggregate of $75.0 million of term loans, representing the maximum borrowings allowable as of September 30, 2025. Additional borrowings are available subject to approval of the Lender (as defined in the Hercules Loan Agreement) in its sole discretion.
Borrowings under the Hercules Loan Agreement accrue interest at a variable rate equal to the greater of (i) 10.15% or (ii) The Wall Street Journal prime rate plus 3.15%. In an event of default and until such event is no longer continuing, the interest rate applicable to borrowings would be increased by 4.0%. Borrowings are repayable in monthly interest-only payments through July 1, 2027, which is the maturity date of the Hercules Loan Agreement. At the Company’s option, the Company may prepay all, but not less than all, of the outstanding borrowings, subject to a prepayment premium of 1%. In addition, the Hercules Loan Agreement provides for payment of end-of-term fees of $2.8 million plus 3.5% of the aggregate principal amount of loans drawn, if any, subsequent to the most recent amendment in August 2023, payable upon the earlier of maturity or the repayment in full of all obligations under the Hercules Loan Agreement. Borrowings under the Hercules Loan Agreement are collateralized by substantially all of the Company’s personal property and other assets except for its intellectual property (but including rights to payment and proceeds from the sale, licensing or disposition of the intellectual property).
Under the Hercules Loan Agreement, the Company has agreed to affirmative and negative covenants. The Company must maintain cash, cash equivalents or liquid assets in an account or accounts in which Hercules has a first priority security interest
19

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
(“Qualified Cash”) in an aggregate amount equal to at least 20% of the aggregate principal amount of loans outstanding under the Hercules Loan Agreement, which equals $15.0 million as of the issuance of these condensed consolidated financial statements. The Company must also continue to achieve a performance covenant, which includes maintaining a trailing six-month net product revenue of at least 55% of its forecast as approved by the Company’s Board of Directors (the “Performance Covenant”). Such Performance Covenant is waived during any period in which:
(i.) the Company maintains Qualified Cash, as defined in the Hercules Loan Agreement, in an aggregate amount equal to at least 75% of loans outstanding under the Hercules Loan Agreement or
(ii.) both (x.) the Company maintains a Market Capitalization (as defined in the Hercules Loan Agreement) of at least $450.0 million and (y.) the Company maintains Qualified Cash in an aggregate amount equal to at least 45% of loans outstanding.
The Hercules Loan Agreement also restricts the Company’s ability to incur additional indebtedness, pay dividends, encumber its intellectual property, or engage in certain fundamental business transactions, such as mergers or acquisitions of other businesses, with certain exceptions.
The Company recognized interest expense under the Hercules Loan Agreement as follows:

(in thousands) | Three Months Ended September 30, |  | Nine Months Ended September 30,
| 2025 |  | 2024 |  | 2025 |  | 2024
Total interest expense | $ | 2,256 |  |  | $ | 2,414 |  |  | $ | 6,687 |  |  | $ | 6,463 |
Non-cash interest expense | $ | 221 |  |  | $ | 194 |  |  | $ | 637 |  |  | $ | 655 |

The annual effective interest rate on the Hercules Loan Agreement as of September 30, 2025 was 11.4%. There were no principal payments due or paid under the Hercules Loan Agreement during the three and nine months ended September 30, 2025 and 2024.
As of September 30, 2025, future principal and accrued end-of-term payments of $76.5 million under the Hercules Loan Agreement are due on July 1, 2027.

(in thousands), |  |
Year Ending December 31, |  | Total
2025 |  | — |
2026 |  | — |
2027 |  | 76,537 |
Long-term debt, including end-of-term payments |  | $ | 76,537 |

9. Leases
The Company has lease agreements for its facilities in Boston, Massachusetts, which is the Company’s principal executive offices, and in Vienna, Austria, which was previously the Company’s research and development center. There are no restrictions or financial covenants associated with any of the lease agreements.
Vienna Austria Lease Update
The Company has an operating lease for approximately 1,200 square meters of laboratory and office space in Vienna, Austria (“Vienna Lease”), that commenced in February 2021 for a term of seven years. On February 6, 2025, the Company announced a plan to vacate the lease and close operations. As of September 30, 2025, the Company has abandoned the Vienna Lease and has entered into an agreement with the landlord to terminate the lease effective November 30, 2025. Accordingly, the Company has accelerated the amortization of the right of use asset to zero and adjusted the remaining lease obligation to reflect the Company’s remaining lease obligation as of September 30, 2025.
20

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
The components of lease expense for the three and nine months ended September 30, 2025 and 2024 were as follows:

(dollars in thousands) | Three Months Ended September 30, |  | Nine Months Ended September 30, |  |
Lease Cost | 2025 |  | 2024 |  | 2025 |  | 2024 |  |  |  |
Fixed operating lease cost | $ | 142 |  | $ | 495 |  | $ | 1,714 |  | $ | 1,473 |  |  |  |
Total lease expense | $ | 142 |  | $ | 495 |  | $ | 1,714 |  | $ | 1,473 |  |  |  |
Other information |  |  |  |  |  |  |  |  |  |  |
Operating cash outflows from operating leases | $ | 363 |  | 345 |  | $ | 1,065 |  | $ | 1,032 |  |  |  |
Weighted-average remaining lease term—operating leases | 1.1 |  | 2.5 |  | 1.1 |  | 2.5 |  |  |  |
Weighted-average discount rate—operating leases | 11.5 | % |  | 11.5 | % |  | 11.5 | % |  | 11.5 | % |  |  |  |

Maturities of lease liabilities due under lease agreements that have commenced as of September 30, 2025 are as follows (in thousands):

Maturity of lease liabilities | Operating Leases
2025 (remainder of the year) | $ | 333 |
2026 | 1,053 |
Total lease payments | 1,386 |
Less: interest | (91) |
Total operating lease liabilities as of September 30, 2025 | $ | 1,295 |

10. Commitments and Contingencies
The Company has agreements with contract research organizations (“CROs”) pursuant to which the Company and the CROs are conducting clinical trials. The Company may terminate these agreements by providing notice pursuant to the contractual provisions of such agreements and would incur early termination fees. The Company has agreements with contract manufacturing organizations (“CMOs”) for the production of mavorixafor for use in clinical trials and for the commercial supply of XOLREMDI. The Company’s agreement with the CMO who produces batches of drug substance for use in the Company’s clinical and commercial drug supply contains cancellation provisions that would require the Company to pay up to the full contract value upon cancellation. As of September 30, 2025, the Company has approximately $0.6 million of such commitments in place subject to cancellation provisions.
License Agreements
See Note 5 to the Company’s Annual Report on Form 10-K filed with the SEC on March 26, 2025 for a description of licensing agreements, which commit the Company to contingent milestone and royalty fees based on future operational events.
Indemnification Agreements
In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners, and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and its executive officers that will require the Company to, among other things, indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnification obligations. The Company is not currently aware of any indemnification claims and has not accrued any liabilities related to such obligations in its condensed consolidated financial statements as of September 30, 2025 or December 31, 2024.
21

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
Legal Proceedings
The Company is not a party to any litigation and does not have contingency reserves established for any litigation liabilities. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of the authoritative guidance that addresses accounting for contingencies. The Company expenses as incurred the costs related to any legal proceedings.
11. Equity Transactions
Reverse Stock Split
On April 17, 2025, the Company’s stockholders approved an amendment to its Restated Certificate of Incorporation, as amended (“Certificate of Incorporation”) to combine outstanding shares of the Company’s common stock into a lesser number of outstanding shares, by a ratio of not less than one-for-fifteen and not more than one-for-thirty, with the exact ratio to be set within this range by the Board of Directors in its sole discretion. On April 17, 2025, the Board of Directors approved the Reverse Stock Split. On April 24, 2025, the Company filed an amendment to its Certificate of Incorporation to effectuate the Reverse Stock Split effective as of 12:01 a.m. Eastern Time on April 28, 2025. As a result of the Reverse Stock Split, every 30 shares of the Company’s common stock issued or outstanding were automatically reclassified into one validly issued, fully-paid and non-assessable new share of common stock, subject to the treatment of fractional shares as described below, without any action on the part of the holders. Proportional adjustments were made to the number of shares of common stock awarded and available for issuance under the Company’s equity incentive plans, as well as the exercise price and the number of shares issuable upon the exercise or conversion of the Company’s outstanding stock options and other equity securities under the Company’s equity incentive plans. All outstanding warrants were also adjusted in accordance with their terms, which resulted, among other changes to the warrant terms, in proportionate adjustments being made to the number of shares issuable upon exercise of such warrants and to the exercise and redemption prices of such warrants. The shares of common stock outstanding following the Reverse Stock Split remain fully paid and non-assessable. The Reverse Stock Split did not affect the number of authorized shares of common stock or the par value of the common stock.
No fractional shares were issued in connection with the Reverse Stock Split. Stockholders who would otherwise be entitled to receive fractional shares were automatically entitled to receive cash in lieu of such fractional share. On April 28, 2025, the Company effected a 1-for-30 Reverse Stock Split. Unless otherwise noted, all references to common stock share and per share amounts in this Quarterly Report on Form 10-Q have been retroactively adjusted to reflect the Reverse Stock Split.
ATM Sales Agreement
We are party to a Controlled Equity Offering SM Sales Agreement (“ATM”), dated as of August 7, 2020, pursuant to which we may offer and sell shares of our common stock through one or more investment banks. To date and for the nine months ended September 30, 2025, we have sold $23.6 million and $9.0 million, respectively, of our common stock, net of offering costs, under the ATM. Pursuant to our Registration Statement on Form S-3 that became effective on August 24, 2023 and the related ATM prospectus contained therein, we may offer and sell shares of our common stock having an aggregate offering price of up to an additional $66.0 million.
Purchase Agreement
In June 2025, we entered into a common stock purchase agreement (“Purchase Agreement”) with Lincoln Park Capital Fund LLC pursuant to which Lincoln Park committed to purchase, at our request from time to time over a 24-month period, shares of our common stock having an aggregate offering price of up to $40.0 million, subject to certain limitations including a common share cap that will require shareholder approval to exceed (the “Purchase Shares”). In consideration for entering into the Purchase Agreement, the Company issued 137,099 shares of common stock (the “Commitment Shares”) to Lincoln Park as a commitment fee. The fair value of the Commitment Shares, which was consideration given to Lincoln Park in exchange for entering into the agreement and was not significant, was measured on the issuance date as determined based on the closing price of the Company’s common stock. Through September 30, 2025, the Company sold 1,297,936 common shares to Lincoln Park for aggregate proceeds of $2.2 million. The issuance of the Purchase Shares and Commitment Shares were registered pursuant to the Company’s effective shelf registration statement on Form S-3 (the “Registration Statement”), and the related base prospectus included in the Registration Statement, as supplemented by a prospectus supplement filed on June 23, 2025. During the third quarter of 2025, the Company terminated the Purchase Agreement.
22

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
Q3 2025 Private Placement
On August 11, 2025 and August 12, 2025, the Company entered into securities purchase agreements pursuant to which it agreed to issue and sell to several institutional and accredited investors (the “Investors”), in a private placement (the “Q3 2025 Private Placement”), 11,040,776 shares of common stock at a price of $1.42 per share and pre-funded warrants to purchase 48,852,772 shares of common stock at a purchase price of $1.419 per pre-funded warrant (representing the price of $1.42 per share minus the $0.001 per share exercise price of each such prefunded warrant). The pre-funded warrants are exercisable, subject to certain beneficial ownership restrictions, at any time after their original issuance and will not expire. The Q3 2025 Private Placement closed on August 13, 2025. The net proceeds of $81.0 million, after deducting placement agent fees and offering expenses paid by the Company, received for the shares of common stock and the pre-funded warrants was recorded as permanent equity as the Company concluded that the shares of common stock and pre-funded warrants met the criteria for permanent equity classification.
Also, on August 11, 2025 and August 12, 2025, the Company entered into registration rights agreements with the Investors, pursuant to which the Company agreed to register for resale the common shares issued in the Q3 2025 Private Placement and the issuance of the shares of common stock underlying the pre-funded warrants held by the Investors. Such registration statement was filed on September 10, 2025 and was declared effective by the SEC on September 17, 2025. The Company has agreed to use commercially reasonable efforts to keep such registration statement effective until the date the shares of common stock sold in the Q3 2025 Private Placement and the shares of common stock underlying the pre-funded warrants covered by such registration statement have been sold or may be resold pursuant to Rule 144 without restriction.
12. Stock-Based Compensation
As of September 30, 2025, there is an aggregate of approximately 0.2 million shares of common stock available for issuance under the Company’s equity incentive plans, including 0.1 million shares of common stock remain available for issuance under the Amended and Restated 2017 Employee Stock Purchase Plan.
Stock Option Valuation
The following table presents, on a weighted average basis, the assumptions used in the Black-Scholes option-pricing model to determine the grant-date fair value of stock options granted:

| Three Months Ended September 30, |  | Nine Months Ended September 30,
| 2025 |  | 2024 |  | 2025 |  | 2024
Risk-free interest rate | 3.9 | % |  | 3.8 | % |  | 3.9 | % |  | 4.1 | %
Expected term (in years) | 5.8 |  | 6.1 |  | 5.8 |  | 6.1
Expected volatility | 108.9 | % |  | 101.4 | % |  | 108.9 | % |  | 97.6 | %
Expected dividend yield | 0 | % |  | 0 | % |  | 0 | % |  | 0 | %

Stock Options
The following table summarizes the Company’s stock option activity for the nine months ended September 30, 2025:

| Number of Shares |  | Weighted Average Exercise Price |  | Weighted Average Contractual Term (Years) |  | Aggregate Intrinsic Value (in thousands)
Outstanding as of December 31, 2024 | 394,493 |  |  | $ | 57.09 |  |  | 8.6 |  | $ | 269 |
Granted | 12,792,811 |  |  | 1.63 |  |  |  |  |
Forfeited and expired | (199,059) |  |  | 32.73 |  |  |  |  | $ | — |
Outstanding as of September 30, 2025 | 12,988,245 |  |  | $ | 2.84 |  |  | 9.8 |  | $ | — |
Exercisable as of September 30, 2025 | 140,512 |  |  | $ | 99.19 |  |  | 6.9 |  | $ | — |
Vested and expected to vest as of September 30, 2025 | 9,576,307 |  |  | $ | 3.24 |  |  | 9.8 |  | $ | 16,880 |

23

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
The aggregate intrinsic value of options is calculated as the difference between the exercise price of the stock options and the fair value of the Company’s common stock to the extent the stock option had a lower exercise price. There were no options exercised in 2025 and 2024. The weighted average grant-date fair value per share of stock options granted during the nine months ended September 30, 2025 and 2024 was $1.35 and $23.40, respectively.
Restricted Stock Units
The following table summarizes the Company’s restricted stock unit activity for the nine months ended September 30, 2025:

| Number of Shares
Unvested as of December 31, 2024 | 198,995 |
Granted | 278,209 |
Vested | (224,616) |
Forfeited | (153,356) |
Unvested as of September 30, 2025 | 99,232 |

During the nine months ended September 30, 2025, the Company granted 0.3 million time-based restricted stock units to employees at the grant date fair value of $12.65 per share. These awards vest as the employee provides services to the Company over a three-year vesting period. Also during the nine months ended September 30, 2025, 0.1 million outstanding performance-based restricted stock units (“PRSUs”) vested based on the achievement of an operational milestone. The Company considers the achievement of the remaining operational milestone related to outstanding PRSUs to be probable. Stock-based compensation expense has been recognized for these awards using the accelerated attribution model based on the fair value of the awards as of the date of grant and management’s best estimate of the date the probable operational milestone will be achieved. The Company updates its estimates related to the probability and timing of achievement of the operational milestones each period until the award either vests or is forfeited.
Stock-Based Compensation
Stock-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive(loss) income as follows:

| Three Months Ended September 30, |  | Nine Months Ended September 30, |  |
(in thousands) | 2025 |  | 2024 |  | 2025 |  | 2024 |  |  |  |
Research and development expense | $ | 179 |  |  | $ | 1,143 |  |  | $ | 778 |  |  | $ | 3,108 |  |  |  |  |
Selling, general and administrative expense | 581 |  |  | 677 |  |  | 1,249 |  |  | 2,879 |  |  |  |  |
Total stock-based compensation | $ | 760 |  |  | $ | 1,820 |  |  | $ | 2,027 |  |  | $ | 5,987 |  |  |  |  |

Stock Appreciation Rights
The following table summarizes the Company’s stock appreciation right (“SARs”) balances and activity as of September 30, 2025. The weighted average target (exercise) price of the SARs is $45.71. During the third quarter of 2025, all participants to whom SARs were granted were terminated and the vesting of certain unvested SARs was accelerated. The vested SARs of 313,856 as of September 30, 2025 are exercisable for 90 days from the termination date and will forfeit if not exercised.

| Number of Shares |  |  |  |
Outstanding as of December 31, 2024 | 347,068 |  |  |  |  |
Forfeited | (22,099) |  |  |  |  |
Outstanding as of September 30, 2025 | 324,969 |  |  |  |  |
Vested as of September 30, 2025 | 313,856 |  |  |  |  |

24

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
13. Segment Information
We have defined our Chief Operating Decision Maker (“CODM”) as our Executive Chairman. The CODM manages the Company’s operations as a single operating segment, which comprises its single reportable segment, for the purposes of assessing performance and making operating decisions. The Company’s focus is on the research, development and commercialization of novel therapeutics for the treatment of rare diseases. The Company’s research, development and commercialization efforts are focused on its lead molecule, mavorixafor, which is being marketed in the U.S. under the trade name XOLREMDI. The CODM uses the Company’s condensed consolidated net (loss) income to monitor actual results as compared to forecast in assessing segment performance and allocation of resources.
We derive our revenue from the sale of XOLREMDI in the U.S. and from licensed rights to mavorixafor for other non-U.S. territories. We recognized $1.6 million and $4.3 million of revenue from our U.S. customer and $0.2 million and $28.3 million of revenue from our customer in the United Kingdom for the three and nine months ended September 30, 2025, respectively. The Company recognized $0.6 million and $1.1 million of revenue from its U.S. customer for the three and nine months ended September 30, 2024, respectively, and no non-U.S. revenue for the three and nine months ended September 30, 2024.
The measure of profit for the segment is net (loss) income and consisted of the following for the three and nine months ended September 30, 2025, and 2024:

| Three Months Ended September 30, |  | Nine Months Ended September 30,
(in thousands) | 2025 |  | 2024 |  | 2025 |  | 2024
Revenue from external customers | $ | 1,765 |  |  | $ | 560 |  |  | $ | 32,545 |  |  | $ | 1,123 |
Compensation expense, excluding stock-based compensation, SARs compensation expense and severance expense | 6,932 |  |  | 11,717 |  |  | 28,405 |  |  | 33,941 |
Direct research and development program expenses (X4P-001, mavorixafor) | 10,314 |  |  | 9,665 |  |  | 28,139 |  |  | 31,073 |
Gain on sale of non-financial assets | — |  |  | — |  |  | — |  |  | (105,000) |
Other segment items (a) | 14,334 |  |  | 15,874 |  |  | 31,275 |  |  | 38,738 |
Net (loss) income (measure of segment profit) | $ | (29,815) |  |  | $ | (36,696) |  |  | $ | (55,274) |  |  | $ | 2,371 |

(a) Other segment items primarily include cost of revenue, non-compensation departmental costs within sales, general and administrative departments, certain unallocated external costs within research and development, stock-based compensation expense, SARs compensation expense, severance expense, other income (expense), and provision for income taxes.
The CODM only receives and reviews information regarding segment assets at the consolidated level. Certain other entity-wide disclosures are included elsewhere in these condensed consolidated financials statements. As of September 30, 2025, the Company’s single operating segment had long-lived assets, including property and equipment and right-of-use assets, of $2.0 million, which were located in the U.S. As of December 31, 2024, the operating segment’s long-lived assets were $4.8 million, of which $3.2 million and $1.6 million were located in the U.S. and Austria, respectively.
14. Subsequent Events
On October 23, 2025, the Company entered into an underwriting agreement with Leerink Partners LLC, Stifel, Nicolaus & Company, Incorporated and Guggenheim Securities, LLC, as the representatives of the underwriters named therein (the “Underwriters”), to issue and sell 45,860,000 shares of the Company’s common stock at a public offering price of $2.90 per share and, in lieu of common stock to certain investors, pre-funded warrants to purchase 700,000 shares of the Company’s common stock (the “Pre-Funded Warrants”) at a public offering price of $2.899 per share, which represents the per share public offering price for the common stock less the $0.001 per share exercise price for each Pre-Funded Warrant (the “Offering”). In addition, the Company granted the Underwriters an option for a period of 30 days to purchase up to an additional 6,984,000 shares of its common stock at the public offering price, less the underwriting discounts and commissions, which the Underwriters exercised in full on October 24, 2025. The Offering closed on October 27, 2025.
25

X4 PHARMACEUTICALS, INC.
NOTES TO CONDENSED CONSOLIDATED FINANCIAL STATEMENTS
(Unaudited)
The Pre-Funded Warrants will be exercisable at any time after the date of issuance. A holder of Pre-Funded Warrants may not exercise the warrant if the holder, together with its affiliates, would beneficially own more than 4.99% or 9.99%, as applicable, of the number of shares of common stock outstanding immediately after giving effect to such exercise. A holder of Pre-Funded Warrants may increase or decrease this percentage to a percentage not in excess of 19.99% by providing prior notice to the Company, provided that any increase will not be effective until the 61st day after such notice is delivered to the Company.
The net proceeds from the Offering, including proceeds from the exercise in full of the Underwriters’ option to purchase additional shares, were approximately $145.6 million, after deducting the Underwriters’ discounts and commissions and estimated offering expenses.
26

Item 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
The following discussion and analysis should be read in conjunction with our condensed consolidated financial statements and related notes in “Item 1. Financial Statements.” References in this report to “X4,” the “Company,” “we,” “our” and “us” are references to X4 Pharmaceuticals, Inc. and its subsidiaries.
Forward-Looking Statements
This Quarterly Report on Form 10-Q contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), that relate to future events or to our future operations or financial performance. All statements, other than statements of historical facts, contained in this Quarterly Report on Form 10-Q, including statements regarding our strategy, future operations, future financial position, future revenues, projected costs, prospects, plans and objectives of management, are forward-looking statements. These statements may be identified by such forward-looking terminology as “may,” “should,” “expects,” “intends,” “plans,” “anticipates,” “believes,” “estimates,” “predicts,” “potential,” “continue” or the negative of these terms or other comparable terminology. Our forward-looking statements are based on a series of expectations, assumptions, estimates and projections about our company, are not guarantees of future results or performance and involve substantial risks and uncertainty. We may not actually achieve the plans, intentions, or expectations disclosed in these forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in these forward-looking statements. These forward-looking statements are subject to a number of known and unknown risks, uncertainties and assumptions, including risks described in the section titled “Risk Factors” and elsewhere in this report, regarding, among other things:
•our ability to raise additional capital or achieve sufficient revenue to properly fund our business and operating plan as well as our ability to continue as a going concern;
•our expectations and goals for commercialization of XOLREMDI® , which has been approved for use as an oral, once-daily therapy to increase the number of circulating mature neutrophils and lymphocytes in patients 12 years of age and older with WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome in the U.S. and that XOLREMDI, our one product approved for commercial sale, upon which we depend almost entirely on to produce revenue faces an unknown market size and growth potential and we have not generated significant revenue from product sales to date, and we may never achieve profitability;
•our expectations that the intended effects of the reverse stock split will occur and that we will be able to maintain compliance with Nasdaq’s listing requirements and this will positively impact our ability to raise capital;
•the initiation, timing, progress and results of our current and future preclinical studies and clinical trials and related preparatory work and the period during which the results of the trials will become available, as well as our research and development programs;
•the timing of enrollment in, and our ability to successfully enroll, our clinical trials, including our Phase 3 4WARD clinical trial;
•the potential benefits, including clinical utility, that may be derived from XOLREMDI or any of our product candidates;
•the timing of and our ability to obtain and maintain regulatory approval of our existing product XOLREMDI (mavorixafor) or any product candidates that we may develop in the future, and any related restrictions, limitations, or warnings in the label of any approved product candidates;
•our plans to research, develop, manufacture and commercialize XOLREMDI or our product candidates;
•the timing of our regulatory filings for our product candidates, along with regulatory developments in the United States and other foreign countries;
•the size and growth potential of the markets for XOLREMDI and our product candidates, if approved, and the rate and degree of market acceptance of XOLREMDI and our product candidates, including reimbursement that may be received from payors;
•the benefits of U.S. Food and Drug Administration and European Commission designations, including, without limitation, Fast Track, orphan and Breakthrough Therapy;
•our commercialization, marketing and manufacturing capabilities and strategy;
27

•our ability to execute and realize benefits from the strategic restructurings announced in February 2025 and September 2025, or any similar actions taken in the future;
•our ability to attract and retain qualified employees and key personnel;
•our competitive position and the development of and projections relating to our competitors or our industry;
•our expectations regarding our ability to obtain and maintain intellectual property protection;
•the success of competing therapies that are or may become available;
•our estimates and expectations regarding future operations, financial position, revenues, costs, expenses, uses of cash, capital requirements or our need for additional financing;
•our plans to in-license, acquire, develop and commercialize additional product candidates;
•the impact of laws and regulations;
•our plans to identify additional product candidates with significant commercial potential that are consistent with our commercial objectives;
•our strategies, prospects, plans, expectations or objectives; and
•other risks and uncertainties, including those listed under the section titled “Risk Factors” in this Quarterly Report.
OVERVIEW
We are a biopharmaceutical company developing, and commercializing novel therapeutics for the treatment of rare hematology diseases. We continue to progress our global, pivotal Phase 3 clinical trial, (the “4WARD” trial) to evaluate the efficacy, safety, and tolerability of oral, once-daily mavorixafor (with or without stable doses of G-CSF) in people with congenital, acquired primary autoimmune, or idiopathic chronic neutropenia who are experiencing recurrent and/or serious infections. The 52-week trial is a randomized, double-blind, placebo-controlled, multicenter study aiming to enroll up to 176 patients, with full enrollment expected in Q3 2026. The FDA has granted Fast Track designation to mavorixafor for the treatment of chronic neutropenia. Chronic neutropenia is defined as periods lasting more than three months persistently or intermittently where there are abnormally low levels of neutrophils circulating in the blood, and may be idiopathic (of unknown origin), cyclic (episodes typically occurring every three weeks), or congenital (of genetic causation). Chronic neutropenia disorders are rare blood conditions similarly characterized by increased risks of infections and cancer due to abnormally low levels of neutrophils in the body. In all cases, the CXCL12/CXCR4 pathway is the key regulator of neutrophil release from the bone marrow.
We have one commercially approved product, XOLREMDI ® (mavorixafor), which has received accelerated approval in the United States from the U.S. Food and Drug Administration (“FDA”) for use as an oral, once-daily therapy in patients 12 years of age and older with WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome, to increase the number of circulating mature neutrophils and lymphocytes. WHIM syndrome is a rare combined primary immunodeficiency and chronic neutropenic disorder. In connection with the our long term strategy to successfully complete the 4WARD Phase 3 trial in patients with moderate and severe chronic neutropenia, we are no longer prioritizing investment in the WHIM indication.
Private Placement Financing and Management Changes
During the third quarter of 2025, we sold shares of common stock and pre-funded warrants to purchase common stock in a private placement that resulted in net proceeds of approximately $81.0 million, after deducting placement agent fees and other expenses. Pursuant to registration rights agreements, we registered the shares of common stock issued and issuable under pre-funded warrants under a registration statement on Form S-3 that was declared effective by the SEC on September 17, 2025.
Concurrent with the financing and effective August 12, 2025, our former President and Chief Executive Officer Paula Ragan, PhD, and Chief Financial Officer Adam Mostafa stepped down from their respective roles. Dr. Ragan also resigned from the Company’s Board of Directors (the “Board”), and Michael Wyzga transitioned from Board Chair to Lead Independent Director. In their place, the Board appointed Adam R. Craig, M.D., Ph.D, as Executive Chair and Board Chair; John Volpone as President, and David Kirske as Chief Financial Officer.
Q4 2025 Equity Financing
In October 2025, we closed an underwritten public offering of our common stock and, in lieu of common stock to certain investors, pre-funded warrants, raising proceeds of $145.6 million, net of underwriting discounts and estimated offering
28

expenses.
Strategic Restructurings
In the first quarter of 2025, we implemented a strategic restructuring of our business operations, workforce and capital spending to focus efforts on advancing mavorixafor to treat those with chronic neutropenia. As part of this restructuring, we (i) implemented a net reduction of our employee headcount by 43 employees, or approximately 30% of our total workforce, including our U.S. commercial field team, (ii) commenced the closure of our research and development facility in Vienna, Austria, (iii) paused our pre-clinical drug candidate programs and (iv) streamlined other spending to support the ongoing clinical development of mavorixafor for the larger population of those with chronic neutropenia. We incurred charges of approximately $2.5 million for severance and other employee termination-related costs related to this strategic restructuring. We believe that this strategic restructuring will decrease our annual spending by $30 million to $35 million per year.
In September 2025, we announced an additional strategic restructuring designed to further sharpen operational focus and align resources with our long‑term strategy to successfully complete the 4WARD Phase 3 trial in patients with moderate and severe chronic neutropenia. As part of this initiative, we further reduced our workforce by approximately 50%, a step anticipated to result in additional annualized cost savings of approximately $13 million. We incurred expenses of approximately $4.9 million during the third quarter for severance and other employee termination-related costs related to this strategic restructuring. This workforce reduction was substantially completed in the third quarter of 2025.
The estimate of costs that we expect to incur related to these workforce reduction as well as the decrease in spending, and the timing thereof are subject to a number of assumptions and actual results may differ. We may also incur additional costs not currently contemplated due to events that may occur as a result of, or that are associated with, the actions described above.
Regulatory Update and Out-License Agreements
In early 2025, we submitted a Marketing Authorization Application (“MAA”) to the EMA seeking regulatory approval to commercialize mavorixafor for WHIM syndrome in the European Union. Such MAA was validated for processing by the EMA in January 2025. O n January 13, 2025, we announced a License and Supply Agreement (the “Norgine Agreement”) with Norgine Pharma UK (“Norgine”), pursuant to which Norgine was granted an exclusive license to distribute, market and sell our drug product for all indications in the European Economic Area, Switzerland, the United Kingdom, Australia, and New Zealand.
RESULTS OF OPERATIONS
The following table summarizes the results of our operations for the three and nine months ended September 30, 2025 and 2024:

| Three Months Ended September 30, |  | Nine Months Ended September 30, |  |
(in millions) | 2025 |  | 2024 |  | Change |  | 2025 |  | 2024 |  | Change |  |  |  |  |  |
Revenue | $ | 1.8 |  |  | $ | 0.6 |  |  | $ | 1.2 |  |  | $ | 32.5 |  |  | $ | 1.1 |  |  | $ | 31.4 |  |  |  |  |  |  |
Cost and operating expenses: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cost of revenue | 0.4 |  |  | 0.2 |  |  | 0.2 |  |  | 5.4 |  |  | 0.5 |  |  | 4.9 |  |  |  |  |  |  |
Research and development | 17.3 |  |  | 19.2 |  |  | (1.9) |  |  | 54.2 |  |  | 59.9 |  |  | (5.7) |  |  |  |  |  |  |
Selling, general and administrative | 11.6 |  |  | 15.7 |  |  | (4.1) |  |  | 36.1 |  |  | 46.4 |  |  | (10.3) |  |  |  |  |  |  |
Gain on sale of non-financial asset | — |  |  | — |  |  | — |  |  | — |  |  | (105.0) |  |  | 105.0 |  |  |  |  |  |  |
Total operating expenses | 29.3 |  |  | 35.1 |  |  | (5.8) |  |  | 95.7 |  |  | 1.8 |  |  | 93.9 |  |  |  |  |  |  |
Loss from operations | (27.5) |  |  | (34.5) |  |  | 7.0 |  |  | (63.2) |  |  | (0.7) |  |  | (62.5) |  |  |  |  |  |  |
Total other (expense) income, net | (2.3) |  |  | (2.2) |  |  | (0.1) |  |  | 8.0 |  |  | 3.1 |  |  | 4.9 |  |  |  |  |  |  |
(Loss) income before income taxes | (29.8) |  |  | (36.7) |  |  | 6.9 |  |  | (55.2) |  |  | 2.4 |  |  | (57.6) |  |  |  |  |  |  |
Provision for income taxes | — |  |  | — |  |  | — |  |  | (0.1) |  |  | — |  |  | (0.1) |  |  |  |  |  |  |
Net (loss) income | $ | (29.8) |  |  | $ | (36.7) |  |  | $ | 6.9 |  |  | $ | (55.3) |  |  | $ | 2.4 |  |  | $ | (57.7) |  |  |  |  |  |  |

Revenue
License and Other
During the nine months ended September 30, 2025, we granted an exclusive license to Norgine to distribute, market and sell our product for all indications in the European Economic Area, Switzerland, the United Kingdom, Australia and Ne w Zealand following regulatory approval. For the nine months ended September, 2025, we recognized $27.6 million for the delivery of the
29

license and $0.7 million for the provision of research and development services. We had no license or other revenue during the three or nine months ended September 30, 2024.
Product Revenue, Net
We began recognizing product sales in June 2024 following FDA approval of XOLREMDI on April 29, 2024 and its subsequent commercial launch in the United States. Net product sales were as follows for the nine months ended September 30, 2025 and for each of the quarterly periods therein and the comparative quarter in the prior year.

(in thousands) | 2025 |  | 2024
First quarter | $ | 942 |  |  | $ | — |
Second quarter | 1,744 |  |  | 563 |
Third quarter | 1,566 |  |  | 560 |
Nine months ended September 30, | $ | 4,252 |  |  | $ | 1,123 |

Co-pay assistance payments and rebates to U.S. government payors have comprised the majority of our gross-to-net revenue adjustments. Gross-to-net adjustments have been approximately 10% in 2025 year to date.
Operating Cost and Expenses:
Cost of Revenue
Cost of revenue primarily consists of amortization of an intangible asset related to accrued and paid milestone payments associated with our Genzyme license agreement, and sales and sublicense-based royalty payments due under our Genzyme license agreement. Cost of revenue increased $4.9 million in the nine months ended September 30, 2025, as compared to the same period in the prior year, primarily due to additional royalties in the current nine period associated with sublicense income from our Norgine Agreement.
Research and Development Expenses
Research and development expenses consist primarily of costs incurred in connection with the development of our product candidates, including employee salaries and related expenses, clinical development expenses, internal and third-party costs of manufacturing our drug products for use in our clinical trials. Research and development expenses also include costs related to compliance with regulatory requirements; and prior to the FDA’s approval of our drug product in the U.S. in the second quarter of 2024, payments made under third-party licensing agreements were charged to research and development expense.
Following our strategic restructuring announced during the first quarter of 2025, substantially all of our research and development has been focused on our one product candidate, mavorixafor (X4P-001). The following table shows external costs incurred by product candidate (primarily external CRO costs) and unallocated research and development costs, primarily consisting of employee salaries and related expense for our research and development organization.

| Three Months Ended September 30, |  | Nine Months Ended September 30,
| 2025 |  | 2024 |  | Change |  | 2025 |  | 2024 |  | Change
(in millions) |  |  |  |  |  |  |  |  |  |  |
Direct research and development expenses by product candidate:
Mavorixafor (X4P-001) | $ | 10.3 |  |  | $ | 9.7 |  |  | $ | 0.6 |  |  | $ | 28.2 |  |  | $ | 31.1 |  |  | $ | (2.9) |
X4P-002 | — |  |  | — |  |  | — |  |  | — |  |  | 0.2 |  |  | (0.2) |
X4P-003 | — |  |  | — |  |  | — |  |  | — |  |  | 0.1 |  |  | (0.1) |
Unallocated expense | 7.0 |  |  | 9.5 |  |  | (2.5) |  |  | 26.0 |  |  | 28.5 |  |  | (2.5) |
Total research and development expenses | $ | 17.3 |  |  | $ | 19.2 |  |  | $ | (1.9) |  |  | $ | 54.2 |  |  | $ | 59.9 |  |  | $ | (5.7) |

Research and development expenses decreased by $1.9 million and $5.7 million in the three and nine months ended September 30, 2025, respectively, as compared to the same periods in the prior year primarily due to decreases in spending associated with our 2025 strategic restructurings, including lower spending on non-clinical programs, lower consulting fees, lower drug substance manufacturing costs, and lower regulatory costs. For the three and nine months ended September 30, 2025, unallocated expense includes $1.5 million and $2.2 million, respectively, in severance charges for terminated employees.
30

Decreases in research and development expenses in the current three month period were partially offset by higher clinical costs associated with our 4WARD trial.
Selling, General and Administrative Expenses
Selling, general and administrative expenses consist primarily of salaries and related costs, including stock-based compensation, for personnel in sales and marketing, executive, finance, and administrative functions. Selling, general and administrative expenses also include direct and allocated facility-related costs as well as professional fees for legal, patent, consulting, investor and public relations, accounting, and audit services.
Selling, general and administrative expenses decreased by approximately $4.1 million and $10.3 million in the three and nine months ended September 30, 2025, respectively, as compared to the same periods in the prior year. Selling, general and administrative expenses include $3.4 million and $5.0 million in severance charges for terminated employees in the three and nine month periods ended September 30, 2025, respectively. Decreases to selling, general and administrative expense in each period were primarily due to a decreases in compensation expense due to lower head count in our general and administrative functions, a significant decrease in sales and marketing expenses in the current three and nine month periods as compared to the prior year, during which we incurred commercialization sales and marketing launch costs related to our drug product. These decreases in selling, general and administrative expenses were partially offset by higher severance costs associated with our 2025 strategic restructurings and higher legal costs in the current three and nine month periods.
Other (Expense) Income, Net

| Three Months Ended September 30, |  | Nine Months Ended September 30,
| 2025 |  | 2024 |  | change |  | 2025 |  | 2024 |  | change
(in millions) |  |  |
Interest income | $ | 0.9 |  |  | $ | 1.9 |  |  | $ | (1.0) |  |  | $ | 2.6 |  |  | $ | 4.5 |  |  | $ | (1.9) |
Interest expense | (2.3) |  |  | (2.4) |  |  | 0.1 |  |  | (6.7) |  |  | (6.5) |  |  | (0.2) |
Change in fair value of Class C warrant liability | (0.7) |  |  | (1.9) |  |  | 1.2 |  |  | 12.8 |  |  | 4.6 |  |  | 8.2 |
Other (expense) income, net | (0.2) |  |  | 0.2 |  |  | (0.4) |  |  | (0.7) |  |  | 0.5 |  |  | (1.2) |
Total other (expense) income, net | $ | (2.3) |  |  | $ | (2.2) |  |  | $ | (0.1) |  |  | $ | 8.0 |  |  | $ | 3.1 |  |  | $ | 4.9 |

Other expense, net, increased approximately $0.1 million in the three months ended September 30, 2025 as compared to the same period in the prior year primarily due to lower interest income earned on our marketable securities, partially offset by lower losses in the current period on fair value adjustments related to our Class C warrants. Other expense, net, de creased $4.9 million in the nine months ended September 30, 2025 as compared to the same period in the prior year primarily due to higher gains on fair value adjustments related to our Class C warrants in the current period, partially offset by lower interest income on our marketable security investment portfolio.
Provision for Income Taxes
Income tax provisions recorded for the three and nine months ended September 30, 2025 and 2024 were not significant and were primarily related to our Austrian subsidiary. We will continue to maintain a full valuation allowance against net deferred tax assets, including net operating loss carryforwards, until we are able to consistently generate sufficient taxable income to realize the benefit of our net deferred tax assets.
Liquidity and Capital Resources
Sources of Liquidity
To date, we have funded our operations primarily with proceeds from sales of common stock, warrants and prefunded warrants for the purchase of our preferred stock and our common stock, sales of preferred stock, proceeds from the issuance of convertible debt and borrowings under loan and security agreements.
31

Public and Private Equity Offerings. Over the past several years we have funded our operations primarily from sales of common stock, warrants and prefunded warrants through both public offerings and private placements. Most
recently in August 2025, we sold shares of common stock and, in lieu of common stock to certain investors, pre-funded warrants to purchase shares of common stock in a private placement (“Q3 2025 PIPE”) offering for net proceeds of $81.0 million, after placement agent fees and offering expenses. In addition, in Q4 2025 we completed an underwritten public offering of 52,844,000 shares of our common stock (inclusive of 6,984,000 shares pursuant to the exercise in full of the underwriters’ option to purchase additional shares) at a public offering price of $2.90 per share and, in lieu of common stock to certain investors, prefunded warrants to purchase up to 700,000 shares of our common stock at a price of $2.899 per pre-funded warrant, for net proceeds of $145.6 million, after underwriting discounts and offering expenses.
ATM Sales Agreement. We are party to a Controlled Equity Offering SM Sales Agreement (“ATM”), dated as of August 7, 2020, pursuant to which we may offer and sell shares of our common stock through one or more investment banks. To date and for the nine months ended September 30, 2025, we have sold $23.6 million and $9.0 million, respectively, of our common stock, net of offering costs, under the ATM. Pursuant to our Registration Statement on Form S-3 that became effective on August 24, 2023 and the related ATM prospectus contained therein, we may offer and sell shares of our common stock having an aggregate offering price of up to an additional $66.0 million.
Product Sales and License Revenue. We commercially launched XOLREMDI in the second quarter of 2024 following the approval of XOLREMDI by the FDA on April 29, 2024. To date, we have generated $6.8 million of net product revenue from the sale of XOLREMDI. In the first quarter of 2025, we generated $27.6 million in license revenue from the Norgine Agreement.
Hercules Loan Agreement. We are a party to a loan and security agreement (the “Hercules Loan Agreement”), which provides for a term loan facility of up to $107.5 million, under which we have borrowed an aggregate of $75.0 million of term loans to date, representing the maximum borrowings as of September 30, 2025. The term loan facility requires that we make interest-only payments through maturity on July 1, 2027 and requires that we meet certain operational and financial covenants. See Note 8 to the condensed, consolidated financial statements contained herein for a full description of our Hercules Loan Agreement.
Historical Cash Flows
The following table summarizes our cash flow activities for each of the periods presented:

| Nine Months Ended September 30,
| 2025 |  | 2024
| (in thousands)
Net (loss) income | $ | (55.3) |  |  | $ | 2.4 |
Adjustments to reconcile net (loss) income to net cash used in operating activities | (6.7) |  |  | (101.8) |
Changes in operating assets and liabilities | (8.1) |  |  | 1.5 |
Net cash used in operating activities | (70.1) |  |  | (97.9) |
Net cash (used in) provided by investing activities | (8.7) |  |  | 75.6 |
Net cash provided by financing activities | 92.5 |  |  | 20.3 |
Effect of exchange rate changes on cash, cash equivalents and restricted cash | 0.1 |  |  | — |
Net increase in cash, cash equivalents and restricted cash | 13.9 |  |  | (2.0) |
Cash, cash equivalents and restricted cash, beginning of period | 56.5 |  |  | 100.2 |
Cash, cash equivalents and restricted cash, end of period | $ | 70.4 |  |  | $ | 98.2 |

Operating Activities
During the nine months ended September 30, 2025, net cash used in operating activities was $70.1 million, primarily resulting from net losses of $55.3 million adjusted for net non-cash income of $6.7 million, primarily related to gains on changes to the fair value of our Class C warrants that are measured quarterly at fair value, and $8.1 million of changes to operating assets and liabilities primarily related to a reduction in accounts payable and accrued expenses. Net cash used in operating activities for the nine months ended September 30, 2024 was $97.9 million, primarily resulting from costs and operating expenses of $106.8 million, adjusted for non-cash expenses of $7.7 million and changes in our operating assets and liabilities of $1.5 million. Net cash used in operations for the nine months ended September 30, 2025 also excludes the gain on sale of a priority review
32

voucher, which is included in investing activities. Non-cash expenses primarily include stock-based compensation expense, non-cash lease expense, non-cash interest expense and change in fair value of financial liabilities.
Investing Activities
During the nine months ended September 30, 2025, cash used in investing activities of $8.7 million, primarily include net sales of short-term marketable securities. During the nine months ended September 30, 2024, cash provided by investing activities of $75.6 million included $105.0 million in cash proceeds from the sale of a priority review voucher obtained as a result of the approval of our drug product by the FDA, partially offset by cash outflows of $7.0 million in license payments classified as the acquisition of an intangible assets, $22.1 million of net investments of short-term marketable securities and the acquisition of equipment.
Financing Activities
During the nine months ended September 30, 2025, cash provided by financing activities of $92.5 million was primarily due to proceeds of $81.2 million, net of cash paid for issuance costs, for the sale our common stock and pre-funded warrants in our Q3 2025 PIPE, $9.0 million in sales of our common stock through our ATM program and $2.2 million in sales of our common stock through our common stock purchase agreement with Lincoln Park Capital Fund LLC. Cash provided by financing activities for the nine months ended September 30, 2024 included $20.0 million of new borrowings on our loan facility.
Capital Resources
Based on our cash, cash equivalents and marketable securities on hand as of November 5, 2025 and our current operating plan, we believe that our cash, cash equivalents and marketable securities will allow us to fund operations for at least the next 12 months.
Capital Requirements
October 27, 2025, we closed an underwritten offering of shares of our common stock and, in lieu of common stock to certain investors, pre-funded warrants to purchase shares of our common stock, for net proceeds of approximately $145.6 million, after deducting underwriting discounts and commissions and estimated offering expenses, which further extends our ability to fund our operations and financial obligations. Until we reach profitability, we will need to raise additional capital, which cannot be assured, to fund our operations and meet our financial obligations beyond this period. Such additional capital could be raised through a combination of equity offerings, debt financings, other third-party funding, marketing and distribution arrangements, or other collaborations and strategic alliances. If we are unable to obtain funding, we could be forced to delay, reduce, or eliminate some or all of our research and development programs, product portfolio expansion or commercialization efforts, which would adversely affect our business prospects, or we may be unable to continue operations and may need to restructure our obligations in a court-supervised process or otherwise.
Due to the numerous risks and uncertainties associated with the future sale of our approved drug product and the research, development, and commercialization of future product candidates, we are unable to estimate the exact amount of our funding requirements. Our short-term and long-term funding requirements will depend on and could increase significantly as a result of many factors, including:
•the scope, number, initiation, progress, timing, costs, design, duration, any potential delays, and results of clinical trials and nonclinical studies for our current or future product candidates, particularly our Phase 3 clinical trial of mavorixafor for the treatment of individuals with chronic neutropenic disorders;
•the outcome, timing and cost of regulatory reviews, approvals or other actions to meet regulatory requirements established by the FDA and comparable foreign regulatory authorities, including the potential for the FDA or comparable foreign regulatory authorities to require that we perform more studies for our product candidates than those that we currently expect;
•our ability to obtain marketing approval for our product candidates;
•the cost of filing, prosecuting, defending and enforcing our patent claims and other intellectual property rights covering our product and product candidates, including any such patent claims and intellectual property rights that we have licensed from Genzyme pursuant to the terms of our license agreement with Genzyme;
•our ability to maintain, expand and defend the scope of our intellectual property portfolio, including the cost of defending intellectual property disputes, including patent infringement actions brought by third parties against us or our product or product candidates;
•our ability to establish and maintain licensing, collaboration or similar arrangements on favorable terms and whether and to what extent we retain development or commercialization responsibilities under any new licensing, collaboration or similar arrangement;
33

•the success of any other business, product or technology that we acquire or in which we invest;
•the costs of acquiring, licensing or investing in businesses, product candidates and technologies;
•the effect of competing technological and market developments; and
•the costs to continue operating as a public company
CRITICAL ACCOUNTING POLICIES AND SIGNIFICANT JUDGMENTS AND ESTIMATES
Our condensed consolidated financial statements are prepared in accordance with generally accepted accounting principles in the United States. The preparation of our condensed consolidated financial statements and related disclosures requires us to make estimates and judgments that affect the reported amounts of assets, liabilities, costs and expenses, and the disclosure of contingent assets and liabilities in our condensed consolidated financial statements. We base our estimates on historical experience, known trends and events and various other factors that we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. We evaluate our estimates and assumptions on an ongoing basis. Our actual results may differ from these estimates under different assumptions or conditions.
During the three months ended September 30, 2025, there were no material changes to our critical accounting policies as reported for the year ended December 31, 2024 as part of our Annual Report on Form 10-K other than as updated in Note 2 of these condensed consolidated financial statements. Also see Note 2 under the heading “Recently Adopted Accounting Pronouncements” for new accounting pronouncements or changes to the accounting pronouncements during the three months ended September 30, 2025.
Smaller Reporting Company Status
We are a smaller reporting company (“SRC”) as defined by Rule 12b-2 of the Exchange Act and Item 10(f)(1) of Regulation S-K. We may take advantage of certain of the scaled disclosures available to smaller reporting companies for so long as (i) our voting and non-voting common stock held by non-affiliates is less than $250.0 million measured on the last business day of our second fiscal quarter or (ii) our annual revenue is less than $100.0 million during the most recently completed fiscal year and our voting and non-voting common stock held by non-affiliates is less than $700.0 million measured on the last business day of our second fiscal quarter.
Item 3. Quantitative and Qualitative Disclosures About Market Risk
As an SRC, we are not required to provide the information requested by this Item.
Item 4. Controls and Procedures
Evaluation of Disclosure Controls and Procedures
We maintain disclosure controls and procedures that are designed to ensure that information required to be disclosed in the reports that we file or submit under the Exchange Act is recorded, processed, summarized, and reported within the time periods specified in the SEC’s rules and forms and accumulated and communicated to our management, including our principal executive officer and principal financial officer, to allow timely decisions regarding required disclosure.
Our management, with the participation of our principal executive officer and principal financial officer, evaluated the effectiveness of our disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) as of September 30, 2025, and have concluded that, based on such evaluation, our disclosure controls and procedures were effective as of September 30, 2025 at the reasonable assurance level. Our management recognizes that any controls and procedures, no matter how well designed and operated, can provide only reasonable assurance of achieving their objectives, and management necessarily applies its judgment in evaluating the cost-benefit relationship of possible controls and procedures.
Changes in Internal Control Over Financial Reporting
There were no changes in our internal control over financial reporting that occurred during the three months ended September 30, 2025 that have materially affected, or are reasonably likely to materially affect, our internal control over financial reporting.
34

PART II: OTHER INFORMATION
Item 1. Legal Proceedings
From time to time, we may become involved in legal proceedings or be subject to claims arising in the ordinary course of our business. We are not currently a party to any material legal proceedings and we are not aware of any pending or threatened legal proceedings against us that we believe could have a material adverse effect on our business, operating results or financial condition.
Item 1A. Risk Factors
Our business is subject to various risks, including those described in Part II, Item 1A, “Risk Factors” of our Quarterly Report on Form 10-Q for the quarter ended June 30, 2025. There have been no material changes from the risk factors disclosed in Item 1A of our Quarterly Report on Form 10-Q for the quarter ended June 30, 2025.
This report contains forward-looking statements that involve risks and uncertainties. The occurrence of any of the risks described in our Quarterly Report on Form 10-Q for the quarter ended June 30, 2025 could materially adversely affect our business, financial condition, liquidity, operating results or prospects and the trading price of our securities. Additional risks and uncertainties that we do not presently know or that we currently deem immaterial may also harm our business, financial condition, operating results and prospects and the trading price of our securities.
Item 2. Unregistered Sales of Equity Securities and Use of Proceeds
None.
Item 3. Defaults upon Senior Securities
None.
Item 4. Mine Safety Disclosures
Not applicable.
Item 5. Other Information
Rule 10b5-1 Trading Plans
During the quarter ended September 30, 2025, no director or Section 16 officer adopted, modified or terminated any Rule 10b5-1 trading arrangements or non-Rule 10b5-1 trading arrangements (in each case, as defined in Item 408(a) of Regulation S-K), except as described below:
In connection with her departure from the Company, Dr. Paula Ragan, the Company’s former President and Chief Executive Officer and a former director, terminated a Rule 10b5-1 trading arrangement on August 14, 2025. The terminated Rule 10b5-1 trading arrangement was originally adopted on June 28, 2024, and provided for the sale of up to 313,794 shares of common stock and (ii) 25,682 shares of our common stock to satisfy tax withholding obligation upon the vesting of performance-based restricted stock units.
In connection with his departure from the Company, Adam Mostafa, the Company’s former Chief Financial Officer, terminated a Rule 10b5-1 trading arrangement on August 14, 2025. The terminated Rule 10b5-1 trading arrangement was originally adopted on June 28, 2024, and provided for the sale 11,229 shares of our common stock to satisfy tax withholding obligation upon the vesting of performance-based restricted stock units.
On September 4, 2025, Mark Baldry, the Company’s former Chief Commercial Officer, adopted a written trading arrangement for the sale of Company securities intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). In connection with his departure from the Company, Mr. Baldry terminated the 10b5-1 trading arrangement on September 25, 2025. This trading arrangement was subject to a 90-day “cooling off” period before any trades could be conducted thereunder, would have expired on February 28, 2026 and provided for the sale of an indeterminable (1) number of shares of our common stock.
(1) The number of shares that were to be sold in accordance with these trading arrangements was indeterminable at the time of the filing of this Quarterly Report on Form 10-Q for the period ended September 30, 2025. Upon vesting of performance-
35

based restricted stock units, a sell-to-cover trade would have occurred to satisfy any applicable tax withholding obligations on behalf of the employee. The number of shares sold in the sell-to-cover would have varied based on the market price of the Company’s common stock at the time of settlement and the employee’s minimum tax withholding obligation.
36

Item 6. Exhibits

|  |  |  | Incorporated by Reference to:
Exhibit No. |  | Exhibit Description |  | Form |  | Exhibit No. |  | Filing Date |  | File No.
3.1 |  | Restated Certificate of Incorporation, as amended, as of September 1, 2022. |  | 8-K |  | 3.1 |  | 09/01/2022 |  | 001-38295
3.2 |  | Certificate of Amendment to the Restated Certificate of Incorporation of X4 Pharmaceuticals, Inc. |  | 8-K |  | 3.1 |  | 04/24/2025 |  | 001-38295
3.3 |  | Amended and Restated By-laws of the Company |  | 8-K |  | 3.2 |  | 11/20/2017 |  | 001-38295
4.1 |  | Form of Common Stock Certificate |  | 8-K |  | 4.1 |  | 3/13/2019 |  | 001-38295
4.2 |  | Form of August 2025 Pre-Funded Warrant. |  | 8-K |  | 4.1 |  | 8/12/2025 |  | 001-38295
4.3 |  | Form of Pre-Funded Warrant. |  | 8-K |  | 4.1 |  | 10/27/2025 |  | 001-38295
4.4 |  | Form of Registration Rights Agreement, dated August 11, 2025. |  | 8-K |  | 10.2 |  | 8/12/2025 |  | 001-38295
4.5 |  | Form of Registration Rights Agreement, dated August 12, 2025. |  | 8-K |  | 10.2 |  | 8/13/2025 |  | 001-38295
10.1@ |  | Amendment No. 1 to X4 Pharmaceuticals Inc., Amended and Restated 2019 Inducement Equity Incentive Plan. |  | 8-K |  | 10.3 |  | 8/12/2025 |  | 001-38295
10.2*@ |  | Employment Agreement, dated as of August 11, 2025, by and between X4 Pharmaceuticals, Inc. and Adam Craig. |  |  |  |  |  |  |  |
10.3*@ |  | Employment Agreement, dated as of August 11, 2025, by and between X4 Pharmaceuticals, Inc. and David Kirske. |  |  |  |  |  |  |  |
10.4*@ |  | Employment Agreement, dated as of August 11, 2025, by and between X4 Pharmaceuticals, Inc. and John Volpone. |  |  |  |  |  |  |  |
31.1* |  | Certification of Principal Executive Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |  |  |  |  |  |  |  |
31.2* |  | Certification of Principal Financial Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |  |  |  |  |  |  |  |
32.1** |  | Certification of Principal Executive Officer and Principal Financial Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. |  |  |  |  |  |  |  |
101.INS* |  | Inline XBRL Instance Document |  |  |  |  |  |  |  |
101.SCH* |  | Inline XBRL Taxonomy Extension Schema Document |  |  |  |  |  |  |  |
101.CAL* |  | Inline XBRL Taxonomy Extension Calculation Linkbase Document |  |  |  |  |  |  |  |
101.DEF* |  | Inline XBRL Taxonomy Extension Definition Linkbase Document |  |  |  |  |  |  |  |
101.LAB* |  | Inline XBRL Taxonomy Extension Label Linkbase Document |  |  |  |  |  |  |  |

37

101.PRE* |  | Inline XBRL Taxonomy Extension Presentation Linkbase Document |  |  |  |  |  |  |  |
104 |  | Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101) |  |  |  |  |  |  |  |

* Filed herewith
** The certification attached as Exhibit 32.1 accompanying this Quarterly Report on Form 10-Q is not deemed filed with the Securities and Exchange Commission and is not to be incorporated by reference into any filing of the Company under the Securities Act of 1933, as amended, or the Securities Exchange Act of 1934, as amended, whether made before or after the date of this Quarterly Report on Form 10-Q, irrespective of any general incorporation language contained in such filing.
@ Indicates management contract or compensatory plan.
38

SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

| X4 PHARMACEUTICALS, INC.
Date: November 5, 2025 | By: | /s/ Adam R. Craig
|  | Adam R. Craig, M.D., Ph.D. Executive Chairman (Principal Executive Officer)

Date: November 5, 2025 | By: | /s/ David Kirske
|  | David Kirske Chief Financial Officer and Treasurer (Principal Financial and Accounting Officer)

39