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  <xs:element id="pths_ThirdPartyFacilityMember" abstract="true" name="ThirdPartyFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_NumberOfFDAApprovedProducts" abstract="false" name="NumberOfFDAApprovedProducts" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_NumberOfCommercialProductsActivelyPromoted" abstract="false" name="NumberOfCommercialProductsActivelyPromoted" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_ProceedsFromPIPEGross" abstract="false" name="ProceedsFromPIPEGross" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_NumberOfAdditionalPIPEInvestors" abstract="false" name="NumberOfAdditionalPIPEInvestors" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_PreferredStockConvertibleDenominator" abstract="false" name="PreferredStockConvertibleDenominator" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_PreferredStockConversionMaximumOwnershipPercentage" abstract="false" name="PreferredStockConversionMaximumOwnershipPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_PreferredStockChangeToMaximumPercentageOwnershipNoticePeriod" abstract="false" name="PreferredStockChangeToMaximumPercentageOwnershipNoticePeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_BusinessAcquisitionPercentageOfBusinessOwnedAfterMerger" abstract="false" name="BusinessAcquisitionPercentageOfBusinessOwnedAfterMerger" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtConversionToEquityValue" abstract="false" name="DebtConversionToEquityValue" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_LineOfCreditFacilityNumberOfThirdPartyLenders" abstract="false" name="LineOfCreditFacilityNumberOfThirdPartyLenders" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_BusinessCombinationConsiderationTransferredLiabilitiesSettled" abstract="false" name="BusinessCombinationConsiderationTransferredLiabilitiesSettled" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_PreferredASharesIssuedRollForward" abstract="true" name="PreferredASharesIssuedRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="pths_PIPEProceedsAllocatedToDebtPayable" abstract="false" name="PIPEProceedsAllocatedToDebtPayable" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_PIPEProceedsAllocatedToFeesAccountsPayable" abstract="false" name="PIPEProceedsAllocatedToFeesAccountsPayable" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_ProceedsFromPIPENet" abstract="false" name="ProceedsFromPIPENet" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_VentureLoanAndSecurityAgreementTermLoansMember" abstract="true" name="VentureLoanAndSecurityAgreementTermLoansMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ThreeCustomersMember" abstract="true" name="ThreeCustomersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_CustomerOneMember" abstract="true" name="CustomerOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_CustomerTwoMember" abstract="true" name="CustomerTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_CustomerThreeMember" abstract="true" name="CustomerThreeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_WorkingCapital" abstract="false" name="WorkingCapital" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_NumberOfAgreementsRelatedToAnOutLicenseToThirdParty" abstract="false" name="NumberOfAgreementsRelatedToAnOutLicenseToThirdParty" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_ManufacturingAndLaboratoryEquipmentMember" abstract="true" name="ManufacturingAndLaboratoryEquipmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_SatoLicenseMember" abstract="true" name="SatoLicenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ReedyCreekMember" abstract="true" name="ReedyCreekMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxLiability" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxLiability" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_BusinessCombinationConsiderationTransferredEquityInterestPricePerShare" abstract="false" name="BusinessCombinationConsiderationTransferredEquityInterestPricePerShare" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:perShareItemType"/>
  <xs:element id="pths_BusinessCombinationRecognizedAssetsAcquiredOperatingLeaseRightOfUseAssets" abstract="false" name="BusinessCombinationRecognizedAssetsAcquiredOperatingLeaseRightOfUseAssets" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_BusinessCombinationRecognizedLiabilityAssumedAccruedLiabilitiesCurrent" abstract="false" name="BusinessCombinationRecognizedLiabilityAssumedAccruedLiabilitiesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_BusinessCombinationRecognizedLiabilityAssumedOperatingLeaseLiabilitiesCurrent" abstract="false" name="BusinessCombinationRecognizedLiabilityAssumedOperatingLeaseLiabilitiesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_BusinessCombinationRecognizedLiabilityAssumedDeferredRevenueLongTermPortion" abstract="false" name="BusinessCombinationRecognizedLiabilityAssumedDeferredRevenueLongTermPortion" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_BusinessCombinationRecognizedLiabilityAssumedOperatingLeaseLiabilitiesNoncurrent" abstract="false" name="BusinessCombinationRecognizedLiabilityAssumedOperatingLeaseLiabilitiesNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_PrepaidPrescriptionDrugUserFeeActFeesCurrent" abstract="false" name="PrepaidPrescriptionDrugUserFeeActFeesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_CommercialDataPlatformsCurrent" abstract="false" name="CommercialDataPlatformsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_PatientAssistancePlatformsCurrent" abstract="false" name="PatientAssistancePlatformsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_FinancialReportingPlatformsCurrent" abstract="false" name="FinancialReportingPlatformsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_OtherPrepaidExpensesAndOtherCurrentAssetsCurrent" abstract="false" name="OtherPrepaidExpensesAndOtherCurrentAssetsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_SatoLicenseNetOfImpairmentMember" abstract="true" name="SatoLicenseNetOfImpairmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_XepiTransactionIntangibleAssetMember" abstract="true" name="XepiTransactionIntangibleAssetMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_XeglyzeTransactionIntangibleAssetMember" abstract="true" name="XeglyzeTransactionIntangibleAssetMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_WebsiteDevelopmentMember" abstract="true" name="WebsiteDevelopmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_DrugProductManufacturingSubcontractorCurrent" abstract="false" name="DrugProductManufacturingSubcontractorCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_PDUFAFeeCurrent" abstract="false" name="PDUFAFeeCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_AccruedGrossToNetAdjustmentsCurrent" abstract="false" name="AccruedGrossToNetAdjustmentsCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_ReedyCreekLicenseMember" abstract="true" name="ReedyCreekLicenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ZELSUVMILicenseMember" abstract="true" name="ZELSUVMILicenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_XepiLicenseMember" abstract="true" name="XepiLicenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ContractualObligationCurrent" abstract="false" name="ContractualObligationCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_ContractualObligationNoncurrent" abstract="false" name="ContractualObligationNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_InterestPayableNoncurrent" abstract="false" name="InterestPayableNoncurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_BiofronteraInc.Member" abstract="true" name="BiofronteraInc.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_XEPITransactionMember" abstract="true" name="XEPITransactionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_XEGLYZEAssetPurchaseAgreementMember" abstract="true" name="XEGLYZEAssetPurchaseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_AssetAcquisitionContingentConsiderationTypeAxis" abstract="true" name="AssetAcquisitionContingentConsiderationTypeAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="pths_AssetAcquisitionContingentConsiderationTypeDomain" abstract="true" name="AssetAcquisitionContingentConsiderationTypeDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ContingentConsiderationAchievementOfCommercialQuantitiesMember" abstract="true" name="ContingentConsiderationAchievementOfCommercialQuantitiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ContingentConsiderationAchievementOfSalesBasedMilestonesMember" abstract="true" name="ContingentConsiderationAchievementOfSalesBasedMilestonesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ContingentConsiderationAcceptanceOfInitialAPIPurchaseMember" abstract="true" name="ContingentConsiderationAcceptanceOfInitialAPIPurchaseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_FerrerInternacionalS.A.AndInterquimS.A.U.Member" abstract="true" name="FerrerInternacionalS.A.AndInterquimS.A.U.Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_FerrerMember" abstract="true" name="FerrerMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_FerrerLicenseAgreementMember" abstract="true" name="FerrerLicenseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_AssetAcquisitionConsiderationTypeAxis" abstract="true" name="AssetAcquisitionConsiderationTypeAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="pths_AssetAcquisitionConsiderationTypeDomain" abstract="true" name="AssetAcquisitionConsiderationTypeDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_AssetAcquisitionContractualAmountMember" abstract="true" name="AssetAcquisitionContractualAmountMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_AssetAcquisitionNumberOfContingentMilestones" abstract="false" name="AssetAcquisitionNumberOfContingentMilestones" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_AssetAcquisitionContingentConsiderationNumberOfNetSalesAchievements" abstract="false" name="AssetAcquisitionContingentConsiderationNumberOfNetSalesAchievements" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_LicenseAndSupplyAgreementPurchaseObligationForecastPeriod" abstract="false" name="LicenseAndSupplyAgreementPurchaseObligationForecastPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_LicenseAndSupplyAgreementPurchaseObligationBindingForecastPeriod" abstract="false" name="LicenseAndSupplyAgreementPurchaseObligationBindingForecastPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_LicenseAndSupplyAgreementPurchaseRequirementPercentage" abstract="false" name="LicenseAndSupplyAgreementPurchaseRequirementPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_LicenseAndSupplyAgreementInitialTerm" abstract="false" name="LicenseAndSupplyAgreementInitialTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_LicenseAndSupplyAgreementRenewalTerm" abstract="false" name="LicenseAndSupplyAgreementRenewalTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_LicenseAndSupplyAgreementNoticeOfTerminationMinimumPeriodBeforeEndOfTerm" abstract="false" name="LicenseAndSupplyAgreementNoticeOfTerminationMinimumPeriodBeforeEndOfTerm" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_LicenseAndSupplyAgreementUpfrontPaymentPayable" abstract="false" name="LicenseAndSupplyAgreementUpfrontPaymentPayable" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_LicenseAndSupplyAgreementRoyaltyBasedOnNetSalesPercent" abstract="false" name="LicenseAndSupplyAgreementRoyaltyBasedOnNetSalesPercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_LicenseAndSupplyAgreementInitialSupplyAmount" abstract="false" name="LicenseAndSupplyAgreementInitialSupplyAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_AssetAcquisitionAllocatedPurchasePriceMember" abstract="true" name="AssetAcquisitionAllocatedPurchasePriceMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_VariousMember" abstract="true" name="VariousMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_AssetAcquisitionRoyaltyPaymentOnNetSalesPercent" abstract="false" name="AssetAcquisitionRoyaltyPaymentOnNetSalesPercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_IntangibleAssetsGrossIncludingGoodwill" abstract="false" name="IntangibleAssetsGrossIncludingGoodwill" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_DevelopedTechnologyMember" abstract="true" name="DevelopedTechnologyMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" abstract="false" name="FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_SatoMember" abstract="true" name="SatoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_RevenueFromContractWithCustomerRenewalPeriod" abstract="false" name="RevenueFromContractWithCustomerRenewalPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_RevenueFromContractWithCustomerContractTerminationWithoutCauseAdvanceWrittenNoticePeriod" abstract="false" name="RevenueFromContractWithCustomerContractTerminationWithoutCauseAdvanceWrittenNoticePeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_RevenueFromContractWithCustomerContractTerminationMaterialBreachAdvanceWrittenNoticePeriod" abstract="false" name="RevenueFromContractWithCustomerContractTerminationMaterialBreachAdvanceWrittenNoticePeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_ConvertibleNotesMember" abstract="true" name="ConvertibleNotesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_AssetBasedLoanFacilityMember" abstract="true" name="AssetBasedLoanFacilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ConvertibleInvestorsMember" abstract="true" name="ConvertibleInvestorsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_XEPIMember" abstract="true" name="XEPIMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ZELSUVMIMember" abstract="true" name="ZELSUVMIMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_HorizonWarrantsMember" abstract="true" name="HorizonWarrantsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_DebtInstrumentRepaymentPeriodAxis" abstract="true" name="DebtInstrumentRepaymentPeriodAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="pths_DebtInstrumentRepaymentPeriodDomain" abstract="true" name="DebtInstrumentRepaymentPeriodDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_DebtInstrumentRepaymentPeriodOneMember" abstract="true" name="DebtInstrumentRepaymentPeriodOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_DebtInstrumentRepaymentPeriodTwoMember" abstract="true" name="DebtInstrumentRepaymentPeriodTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_DebtInstrumentRepaymentPeriodThreeMember" abstract="true" name="DebtInstrumentRepaymentPeriodThreeMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_NumberOfProductsAcquired" abstract="false" name="NumberOfProductsAcquired" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_DebtInstrumentVariableRateFloor" abstract="false" name="DebtInstrumentVariableRateFloor" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentNumberOfMonthlyPayments" abstract="false" name="DebtInstrumentNumberOfMonthlyPayments" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_DebtInstrumentMilestoneTrailing12MonthNetRevenueMinimum" abstract="false" name="DebtInstrumentMilestoneTrailing12MonthNetRevenueMinimum" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_LineOfCreditFacilityCommitmentFeePercentageFinalPayment" abstract="false" name="LineOfCreditFacilityCommitmentFeePercentageFinalPayment" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentPrepaymentPremiumPercent" abstract="false" name="DebtInstrumentPrepaymentPremiumPercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_ClassOfWarrantOrRightWarrantsIssuablePercentOfDebtDividedByExercisePrice" abstract="false" name="ClassOfWarrantOrRightWarrantsIssuablePercentOfDebtDividedByExercisePrice" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentEventOfDefaultPotentialIncreaseInInterestRate" abstract="false" name="DebtInstrumentEventOfDefaultPotentialIncreaseInInterestRate" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentSeniorRankIndebtednessMaximum" abstract="false" name="DebtInstrumentSeniorRankIndebtednessMaximum" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_DebtInstrumentInterestRateDefault" abstract="false" name="DebtInstrumentInterestRateDefault" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentConvertiblePercentOfSharesOwnedAfterConversionMaximum" abstract="false" name="DebtInstrumentConvertiblePercentOfSharesOwnedAfterConversionMaximum" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentConvertiblePercentOfSharesOwnedModificationNoticePeriod" abstract="false" name="DebtInstrumentConvertiblePercentOfSharesOwnedModificationNoticePeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_DebtInstrumentConsiderationToInvestorsPercentRoyaltyOnNetSales" abstract="false" name="DebtInstrumentConsiderationToInvestorsPercentRoyaltyOnNetSales" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentPercentageOfMilestonePaymentRetainedByCompany" abstract="false" name="DebtInstrumentPercentageOfMilestonePaymentRetainedByCompany" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentConvertibleDaysPriorToConsummationOfChangeOfControl" abstract="false" name="DebtInstrumentConvertibleDaysPriorToConsummationOfChangeOfControl" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_DebtInstrumentRepaymentProhibitionLiftedPeriodFollowingRepaymentOfOtherDebt" abstract="false" name="DebtInstrumentRepaymentProhibitionLiftedPeriodFollowingRepaymentOfOtherDebt" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_PledgeAgreementPercentageOfAggregateNetSalesOfEndProduct" abstract="false" name="PledgeAgreementPercentageOfAggregateNetSalesOfEndProduct" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_PledgeAgreementAccruedLiabilitiesForPaymentsMaximum" abstract="false" name="PledgeAgreementAccruedLiabilitiesForPaymentsMaximum" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_WarrantLiability" abstract="false" name="WarrantLiability" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_DebtInstrumentsAndWarrantsFairValueDisclosure" abstract="false" name="DebtInstrumentsAndWarrantsFairValueDisclosure" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_LongTermDebtFairValueAllocationPercent" abstract="false" name="LongTermDebtFairValueAllocationPercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_WarrantLiabilityFairValueAllocationPercent" abstract="false" name="WarrantLiabilityFairValueAllocationPercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentsAndWarrantsFairValueAllocationPercent" abstract="false" name="DebtInstrumentsAndWarrantsFairValueAllocationPercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_LongTermDebtFairValueAllocationAmount" abstract="false" name="LongTermDebtFairValueAllocationAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_WarrantLiabilityFairValueAllocationAmount" abstract="false" name="WarrantLiabilityFairValueAllocationAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_DebtInstrumentsAndWarrantsFairValueAllocationAmount" abstract="false" name="DebtInstrumentsAndWarrantsFairValueAllocationAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_DebtInstrumentThirdPartyFeeAmount" abstract="false" name="DebtInstrumentThirdPartyFeeAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_LongTermDebtFairValueAllocationNet" abstract="false" name="LongTermDebtFairValueAllocationNet" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_WarrantLiabilityFairValueAllocationNet" abstract="false" name="WarrantLiabilityFairValueAllocationNet" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_DebtInstrumentsAndWarrantsFairValueAllocationNet" abstract="false" name="DebtInstrumentsAndWarrantsFairValueAllocationNet" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_MeasurementInputPaidInKindPeriodMember" abstract="true" name="MeasurementInputPaidInKindPeriodMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_MeasurementInputWeightedAverageFairValuePerOptionMember" abstract="true" name="MeasurementInputWeightedAverageFairValuePerOptionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_DebtInstrumentSubordinationPremiumPercent" abstract="false" name="DebtInstrumentSubordinationPremiumPercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentCompanySpecificRiskPremiumPercent" abstract="false" name="DebtInstrumentCompanySpecificRiskPremiumPercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentBloombergBYieldCurvePercent" abstract="false" name="DebtInstrumentBloombergBYieldCurvePercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_DebtInstrumentDiscountRatePercent" abstract="false" name="DebtInstrumentDiscountRatePercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_VentureLoanAndSecurityAgreementTermLoansFinalPaymentMember" abstract="true" name="VentureLoanAndSecurityAgreementTermLoansFinalPaymentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_VentureLoanAndSecurityAgreementMember" abstract="true" name="VentureLoanAndSecurityAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_LongTermDebtMaturityYearFiveAndThereafter" abstract="false" name="LongTermDebtMaturityYearFiveAndThereafter" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPaymentInKind" abstract="false" name="FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisLiabilityPaymentInKind" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_ReedyCreekPurchaseAgreementMember" abstract="true" name="ReedyCreekPurchaseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_NovanMember" abstract="true" name="NovanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ResearchAndDevelopmentArrangementFundingReceived" abstract="false" name="ResearchAndDevelopmentArrangementFundingReceived" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_ResearchAndDevelopmentArrangementOngoingQuarterlyPaymentPercentage" abstract="false" name="ResearchAndDevelopmentArrangementOngoingQuarterlyPaymentPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_ResearchAndDevelopmentArrangementOngoingQuarterlyPaymentFeesOrMilestonePaymentsPercentage" abstract="false" name="ResearchAndDevelopmentArrangementOngoingQuarterlyPaymentFeesOrMilestonePaymentsPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_UNCLicenseAgreementU.S.PatentsMember" abstract="true" name="UNCLicenseAgreementU.S.PatentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_OriginalUNCLicenseAgreementU.S.PatentsMember" abstract="true" name="OriginalUNCLicenseAgreementU.S.PatentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_U.S.PatentsCoveringZELSUVMIMember" abstract="true" name="U.S.PatentsCoveringZELSUVMIMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_UNCLicenseMember" abstract="true" name="UNCLicenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ChannelCoveredProductsLicenseMember" abstract="true" name="ChannelCoveredProductsLicenseMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_UNCMember" abstract="true" name="UNCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_NomisRoyaltyVestLCMember" abstract="true" name="NomisRoyaltyVestLCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_NRVLigandMadisonMember" abstract="true" name="NRVLigandMadisonMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_MaidsonMember" abstract="true" name="MaidsonMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_LigandAssignmentAgreementAmendmentMember" abstract="true" name="LigandAssignmentAgreementAmendmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_LigandRoyaltyAgreementMember" abstract="true" name="LigandRoyaltyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_UNCLicenseAgreementMember" abstract="true" name="UNCLicenseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ZELSUVMIRoyaltyAgreementMember" abstract="true" name="ZELSUVMIRoyaltyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ChannelProductsRoyaltyAgreementMember" abstract="true" name="ChannelProductsRoyaltyAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_RoyaltyEventAxis" abstract="true" name="RoyaltyEventAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="pths_RoyaltyEventDomain" abstract="true" name="RoyaltyEventDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_PriorToTheExpirationOfInitialRoyaltyTermMember" abstract="true" name="PriorToTheExpirationOfInitialRoyaltyTermMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_AfterTheExpirationOfInitialRoyaltyTermMember" abstract="true" name="AfterTheExpirationOfInitialRoyaltyTermMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_FirstCommercialSaleMember" abstract="true" name="FirstCommercialSaleMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_OccurrenceOfObtaining35000ThresholdInNetSalesForFourConsecutiveQuartersMember" abstract="true" name="OccurrenceOfObtaining35000ThresholdInNetSalesForFourConsecutiveQuartersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_NumberOfPatentsObtained" abstract="false" name="NumberOfPatentsObtained" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_FiniteLivedIntangibleAssetsTermExtension" abstract="false" name="FiniteLivedIntangibleAssetsTermExtension" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_AssignmentAgreementPercentageOfMilestonePaymentsPayable" abstract="false" name="AssignmentAgreementPercentageOfMilestonePaymentsPayable" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_AssignmentAgreementPercentageOfOtherAmountsReceivedPayable" abstract="false" name="AssignmentAgreementPercentageOfOtherAmountsReceivedPayable" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_RoyaltyAgreementVariableConsiderationPercentOfNetSales" abstract="false" name="RoyaltyAgreementVariableConsiderationPercentOfNetSales" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_RevenueRemainingPerformanceObligationVariableConsiderationAmount" abstract="false" name="RevenueRemainingPerformanceObligationVariableConsiderationAmount" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_RevenueRemainingPerformanceObligationVariableConsiderationNetSalesThreshold" abstract="false" name="RevenueRemainingPerformanceObligationVariableConsiderationNetSalesThreshold" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_RevenueRemainingPerformanceObligationVariableConsiderationPercentOfNonRoyaltySublicenseIncome" abstract="false" name="RevenueRemainingPerformanceObligationVariableConsiderationPercentOfNonRoyaltySublicenseIncome" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_RoyaltyAgreementTerminationNoticePeriod" abstract="false" name="RoyaltyAgreementTerminationNoticePeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_RoyaltyAgreementDevelopmentRightsPeriod" abstract="false" name="RoyaltyAgreementDevelopmentRightsPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_LicenseAgreementRequiredRegulatoryAndCommercialMilestonePaymentsMaximum" abstract="false" name="LicenseAgreementRequiredRegulatoryAndCommercialMilestonePaymentsMaximum" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_LicenseAgreementMaterialBreachUncuredPeriod" abstract="false" name="LicenseAgreementMaterialBreachUncuredPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_LicenseAgreementWrittenNoticeForBankruptcyOrInsolvencyEventsPeriod" abstract="false" name="LicenseAgreementWrittenNoticeForBankruptcyOrInsolvencyEventsPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_RoyaltyAgreementPurchasePrice" abstract="false" name="RoyaltyAgreementPurchasePrice" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_RoyaltyAgreementVariableConsiderationPercentOfNonRoyaltySublicensingPayments" abstract="false" name="RoyaltyAgreementVariableConsiderationPercentOfNonRoyaltySublicensingPayments" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_MeasurementInputProbabilityOfSuccessMember" abstract="true" name="MeasurementInputProbabilityOfSuccessMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ContractualObligationMeasurementInput" abstract="false" name="ContractualObligationMeasurementInput" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="pths_ContractualObligationRollForward" abstract="true" name="ContractualObligationRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="pths_ContractualObligationLiabilityInterestAccretion" abstract="false" name="ContractualObligationLiabilityInterestAccretion" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_ContractualObligationLiabilityPaymentsAccrued" abstract="false" name="ContractualObligationLiabilityPaymentsAccrued" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_ContractualObligationLiabilityConvertibleFeesAllocatedToRoyalty" abstract="false" name="ContractualObligationLiabilityConvertibleFeesAllocatedToRoyalty" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_ContractualObligationLiabilityEffectiveAnnualDiscountRate" abstract="false" name="ContractualObligationLiabilityEffectiveAnnualDiscountRate" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_LeasePeriodAxis" abstract="true" name="LeasePeriodAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="pths_LeasePeriodDomain" abstract="true" name="LeasePeriodDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_Months110Member" abstract="true" name="Months110Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_Months1112Member" abstract="true" name="Months1112Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_LesseeOperatingLeaseLeasedArea" abstract="false" name="LesseeOperatingLeaseLeasedArea" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:areaItemType"/>
  <xs:element id="pths_LesseeOperatingLeaseAdditionalLeasedArea" abstract="false" name="LesseeOperatingLeaseAdditionalLeasedArea" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:areaItemType"/>
  <xs:element id="pths_LesseeOperatingLeaseExpirationPeriodAfterRentCommencementDate" abstract="false" name="LesseeOperatingLeaseExpirationPeriodAfterRentCommencementDate" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_LesseeOperatingLeaseNumberOfRenewalOptions" abstract="false" name="LesseeOperatingLeaseNumberOfRenewalOptions" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="pths_LesseeOperatingLeaseMonthlyBaseRent" abstract="false" name="LesseeOperatingLeaseMonthlyBaseRent" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_LesseeOperatingLeaseMonthlyBaseRentIncreasePercent" abstract="false" name="LesseeOperatingLeaseMonthlyBaseRentIncreasePercent" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_LesseeOperatingLeaseRentAbatementPeriodFollowingRentCommencementDate" abstract="false" name="LesseeOperatingLeaseRentAbatementPeriodFollowingRentCommencementDate" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_LesseeOperatingLeaseCollateral" abstract="false" name="LesseeOperatingLeaseCollateral" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" abstract="false" name="LesseeOperatingLeaseLiabilityToBePaidAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_CEFPurchaseAgreementMember" abstract="true" name="CEFPurchaseAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_WarrantsToPurchaseCommonSharesIssuedMember" abstract="true" name="WarrantsToPurchaseCommonSharesIssuedMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_TwoThousandTwentyThreePlanMember" abstract="true" name="TwoThousandTwentyThreePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_CommonStockIncreaseDecreaseInCapitalSharesReservedForFutureIssuance" abstract="false" name="CommonStockIncreaseDecreaseInCapitalSharesReservedForFutureIssuance" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="pths_SaleOfStockAuthorizedAmount" abstract="false" name="SaleOfStockAuthorizedAmount" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="pths_ClassOfWarrantOrRightPeriodFollowingCommencementDateExercisable" abstract="false" name="ClassOfWarrantOrRightPeriodFollowingCommencementDateExercisable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="pths_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueRollForward" abstract="true" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueRollForward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="pths_EstimatedAnnualEffectiveIncomeTaxRatePercent" abstract="false" name="EstimatedAnnualEffectiveIncomeTaxRatePercent" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="pths_NumberOfReportableSegmentsNotDisclosedFlag" abstract="false" name="NumberOfReportableSegmentsNotDisclosedFlag" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="pths_CommercialOperationsSegmentMember" abstract="true" name="CommercialOperationsSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_ResearchAndDevelopmentOperationsSegmentMember" abstract="true" name="ResearchAndDevelopmentOperationsSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="pths_LineOfCreditFacilityAccordionFeatureIncreaseLimit" abstract="false" name="LineOfCreditFacilityAccordionFeatureIncreaseLimit" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
