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  <xsd:element name="StockOptionExercisedOneMember" id="epix_StockOptionExercisedOneMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="StockOptionExercisedTwoMember" id="epix_StockOptionExercisedTwoMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="DocumentFinancialStatementErrorCorrectionFlag" id="epix_DocumentFinancialStatementErrorCorrectionFlag" type="xbrli:booleanItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="AmountOfMilestonePaymentsAtStartOfThirdPhaseClinicalTrial" id="epix_AmountOfMilestonePaymentsAtStartOfThirdPhaseClinicalTrial" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="LegacyOptionPlanAndRsuPlanMember" id="epix_LegacyOptionPlanAndRsuPlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
</xsd:schema>
