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<!-- Creation Date      : 2020-08-05T23:35:54.5525293+00:00 -->
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  <xsd:element id="phat_LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestRemainderOfFiscalYear" name="LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestRemainderOfFiscalYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="phat_LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestDueNextTwelveMonths" name="LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestDueNextTwelveMonths" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="phat_LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestInYearTwo" name="LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestInYearTwo" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="phat_LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestInYearThree" name="LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestInYearThree" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="phat_LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestInYearFour" name="LongTermDebtMaturitiesRepaymentsOfPrincipalAndInterestInYearFour" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="phat_LongTermDebtAndInterest" name="LongTermDebtAndInterest" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="phat_DebtInstrumentInterestAndFinalPaymentFee" name="DebtInstrumentInterestAndFinalPaymentFee" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="phat_FoundersMember" name="FoundersMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="phat_EmployeesMember" name="EmployeesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="phat_TwoThousandNineteenEquityIncentivePlanMember" name="TwoThousandNineteenEquityIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="phat_TwoThousandNineteenIncentiveAwardPlanMember" name="TwoThousandNineteenIncentiveAwardPlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="phat_EmployeeStockPurchasePlanMember" name="EmployeeStockPurchasePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="phat_ShareBasedPaymentArrangementEmployeeAndNonemployeeMember" name="ShareBasedPaymentArrangementEmployeeAndNonemployeeMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="phat_StockRepurchaseProgramNumberOfSharesRightLapse" name="StockRepurchaseProgramNumberOfSharesRightLapse" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="phat_RepurchaseRightLapseRate" name="RepurchaseRightLapseRate" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="phat_RepurchaseRightLapseShares" name="RepurchaseRightLapseShares" type="xbrli:decimalItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="phat_SharesAggregateRepurchasePrice" name="SharesAggregateRepurchasePrice" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="phat_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantAnnualIncrease" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantAnnualIncrease" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="phat_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareVesting" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareVesting" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="phat_CommonStockWarrantMember" name="CommonStockWarrantMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="phat_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockOptionsExercisedAndSharesVested" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardStockOptionsExercisedAndSharesVested" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="phat_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesAndSharesVestedInPeriodWeightedAverageExercisePrice" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesAndSharesVestedInPeriodWeightedAverageExercisePrice" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
</xsd:schema>
