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        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:element id="flks_AccruedExpensesAndOtherCurrentLiabilities" name="AccruedExpensesAndOtherCurrentLiabilities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="flks_AccruedResearchAndDevelopmentExpenseOtherCurrent" name="AccruedResearchAndDevelopmentExpenseOtherCurrent" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="flks_AnnualBonusCost" name="AnnualBonusCost" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="flks_CashRetentionBonusCosts" name="CashRetentionBonusCosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="flks_CashRetentionBonusesPayableUponChangeinControl" name="CashRetentionBonusesPayableUponChangeinControl" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="flks_CommonStockNumberofVotes" name="CommonStockNumberofVotes" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_ConsumerOperationsMember" name="ConsumerOperationsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="flks_ContractwithCustomerRefundPeriod" name="ContractwithCustomerRefundPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_CorporateRestructuringPlanCostStructureReductionMember" name="CorporateRestructuringPlanCostStructureReductionMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_CorporateRestructuringPlanRetentionandSeveranceIncreasesMember" name="CorporateRestructuringPlanRetentionandSeveranceIncreasesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_DocumentAndEntityInformationAbstract" name="DocumentAndEntityInformationAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_DrugDevelopmentMember" name="DrugDevelopmentMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_EquityIncentivePlan2015Member" name="EquityIncentivePlan2015Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_NonemployeeConsultantsandAdvisersMember" name="NonemployeeConsultantsandAdvisersMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="flks_NumberofRetainedEmployees" name="NumberofRetainedEmployees" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_OngoingTerminationBenefitsMember" name="OngoingTerminationBenefitsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="flks_PercentageDecreaseinCompanyWorkforce" name="PercentageDecreaseinCompanyWorkforce" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_RetentionBenefitsMember" name="RetentionBenefitsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="flks_SalesDiscounts" name="SalesDiscounts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="flks_SeveranceBenefitsPayableUponChangeinControlandTerminationWithoutCause" name="SeveranceBenefitsPayableUponChangeinControlandTerminationWithoutCause" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="flks_SharebasedCompensationArrangementbySharebasedPaymentAwardNumberofEmployeesGrantedOptions" name="SharebasedCompensationArrangementbySharebasedPaymentAwardNumberofEmployeesGrantedOptions" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="flks_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsPostTerminationExercisabilityExtendedPeriod" name="SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsPostTerminationExercisabilityExtendedPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="flks_TerminationandRetentionBenefitsMember" name="TerminationandRetentionBenefitsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
</xsd:schema>
