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<!-- DFIN ActiveDisclosure(SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date      : 2021-02-25T19:39:37.4870557+00:00 -->
<!-- Version            : 5.0.1.571 -->
<!-- Package ID         : 17e6df36e8ab42359c646d07fa01ee4b -->
<!-- Copyright (c) 2021 Donnelley Financial Solutions, Inc. All Rights Reserved. -->
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  <xsd:element id="apls_PaymentsForCappedCallTransactionsAndAssociatedCosts" name="PaymentsForCappedCallTransactionsAndAssociatedCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_ProceedsFromIssuanceOfConvertibleNotesNetOfIssuanceCosts" name="ProceedsFromIssuanceOfConvertibleNotesNetOfIssuanceCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_ProceedsFromStockOptionsAndWarrantsExercised" name="ProceedsFromStockOptionsAndWarrantsExercised" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_EquityComponentOfConvertibleNotes" name="EquityComponentOfConvertibleNotes" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_DevelopmentDerivativeLiabilityDisclosureTextBlock" name="DevelopmentDerivativeLiabilityDisclosureTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_AccruedExpensesAndPrepaidAssetsTextBlock" name="AccruedExpensesAndPrepaidAssetsTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_AccruedExpensesAndPrepaidAssetsAbstract" name="AccruedExpensesAndPrepaidAssetsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_LicenseAgreementsTextBlock" name="LicenseAgreementsTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_OfferingCostsPolicyTextBlock" name="OfferingCostsPolicyTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_SummaryOfCommonStockReservedForFutureIssuanceTableTextBlock" name="SummaryOfCommonStockReservedForFutureIssuanceTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_SupplementalCashFlowInformationRelatedToOperatingLeasesTableTextBlock" name="SupplementalCashFlowInformationRelatedToOperatingLeasesTableTextBlock" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_AggregateMilestonePaymentsUponAchievementOfSpecifiedOneTimeRegulatoryAndCommercialMilestoneEvents" name="AggregateMilestonePaymentsUponAchievementOfSpecifiedOneTimeRegulatoryAndCommercialMilestoneEvents" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_DevelopmentCostReimbursement" name="DevelopmentCostReimbursement" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_RoyaltiesEntitledToReceiveAfterFirstCommercialSaleOfApplicableLicensedProductPeriod" name="RoyaltiesEntitledToReceiveAfterFirstCommercialSaleOfApplicableLicensedProductPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_UpfrontPayment" name="UpfrontPayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_NatureOfOrganizationAndOperationsLineItems" name="NatureOfOrganizationAndOperationsLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_NatureOfOrganizationAndOperationsTable" name="NatureOfOrganizationAndOperationsTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_CollaborationAndLicenseAgreementMember" name="CollaborationAndLicenseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_SwedishOrphanBiovitrumABPublMember" name="SwedishOrphanBiovitrumABPublMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_ConvertibleSeniorNotesOneDueTwoThousandTwentySixMember" name="ConvertibleSeniorNotesOneDueTwoThousandTwentySixMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_TwoThousandTwentyConvertibleNotesMember" name="TwoThousandTwentyConvertibleNotesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_TwoThousandNineteenConvertibleNotesMember" name="TwoThousandNineteenConvertibleNotesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_ConvertibleSeniorNotesDueTwoThousandTwentySixMember" name="ConvertibleSeniorNotesDueTwoThousandTwentySixMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_ExchangeAgreementsMember" name="ExchangeAgreementsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_CappedCallTransactionMember" name="CappedCallTransactionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_FollowOnPublicOfferingsMember" name="FollowOnPublicOfferingsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_DebtInstrumentMaturityYear" name="DebtInstrumentMaturityYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_PaymentsToAcquireConvertibleDebt" name="PaymentsToAcquireConvertibleDebt" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_DebtInstrumentNumberOfCounterparties" name="DebtInstrumentNumberOfCounterparties" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_DebtInstrumentConvertibleInitialConversionPrice" name="DebtInstrumentConvertibleInitialConversionPrice" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_CashAndCashEquivalentsAndMarketableSecurities" name="CashAndCashEquivalentsAndMarketableSecurities" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_ScheduleOfSummaryOfSignificantAccountingPoliciesLineItems" name="ScheduleOfSummaryOfSignificantAccountingPoliciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_ScheduleOfSummaryOfSignificantAccountingPoliciesTable" name="ScheduleOfSummaryOfSignificantAccountingPoliciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_AccountingStandardsUpdate202006Member" name="AccountingStandardsUpdate202006Member" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_TwoThousandTenStockIncentivePlanMember" name="TwoThousandTenStockIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_TwoThousandSeventeenStockIncentivePlanMember" name="TwoThousandSeventeenStockIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_TwoThousandSeventeenEmployeeStockPurchasePlanMember" name="TwoThousandSeventeenEmployeeStockPurchasePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_AdditionalFundingAmountUponAchievementOfDevelopmentMilestones" name="AdditionalFundingAmountUponAchievementOfDevelopmentMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_NumberOfMilestonePayments" name="NumberOfMilestonePayments" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_DevelopmentFundingForMinimumPeriodOfOperatingExpense" name="DevelopmentFundingForMinimumPeriodOfOperatingExpense" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_SFJAgreementMember" name="SFJAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_USFoodAndDrugAdministrationAndEuropeanMedicinesAgencyMember" name="USFoodAndDrugAdministrationAndEuropeanMedicinesAgencyMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_IncreaseInAdditionalFundingForDevelopmentCosts" name="IncreaseInAdditionalFundingForDevelopmentCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_NumberOfAdditionalAnnualPayments" name="NumberOfAdditionalAnnualPayments" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_AggregateAmountOfAdditionalAnnualPayments" name="AggregateAmountOfAdditionalAnnualPayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_ProceedsFromCollaboratorsOfAdditionalMilestones" name="ProceedsFromCollaboratorsOfAdditionalMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_DevelopmentDerivativeLiabilitiesGross" name="DevelopmentDerivativeLiabilitiesGross" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_MinimumPaymentOfAdditionalFundingAmount" name="MinimumPaymentOfAdditionalFundingAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_ImpliedCostOfBorrowingDiscountRates" name="ImpliedCostOfBorrowingDiscountRates" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_AccruedResearchAndDevelopmentCurrent" name="AccruedResearchAndDevelopmentCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_AccruedLicenseFeesCurrent" name="AccruedLicenseFeesCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_AccruedPayrollLiabilitiesCurrent" name="AccruedPayrollLiabilitiesCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_PrepaidResearchAndDevelopmentCostCurrent" name="PrepaidResearchAndDevelopmentCostCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_LiabilityComponentMember" name="LiabilityComponentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_EquityComponentMember" name="EquityComponentMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_LoanAndSecurityAgreementMember" name="LoanAndSecurityAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_SiliconValleyBankMember" name="SiliconValleyBankMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_TermLoanFacilityMember" name="TermLoanFacilityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_UnsecuredPromissoryNoteMember" name="UnsecuredPromissoryNoteMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_GoldaDartyPartnersSAMember" name="GoldaDartyPartnersSAMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_PaymentOfConvertibleDebtDiscountsAndCommissions" name="PaymentOfConvertibleDebtDiscountsAndCommissions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_PaymentOfConvertibleDebtOfferingExpenses" name="PaymentOfConvertibleDebtOfferingExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_DebtInstrumentConvertibleCarryingAmountOfLiabilityComponent" name="DebtInstrumentConvertibleCarryingAmountOfLiabilityComponent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_DebtInstrumentConvertibleInitialConversionCapPrice" name="DebtInstrumentConvertibleInitialConversionCapPrice" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_PremiumPaidForCappedCallTransaction" name="PremiumPaidForCappedCallTransaction" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_DebtInstrumentNumberOfEqualMonthlyInstallments" name="DebtInstrumentNumberOfEqualMonthlyInstallments" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_DebtInstrumentPerDiemInterestAmount" name="DebtInstrumentPerDiemInterestAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_FinalPaymentPercentageEqualToOriginalPrincipalAmount" name="FinalPaymentPercentageEqualToOriginalPrincipalAmount" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_ClassOfWarrantOrRightExpirationTerm" name="ClassOfWarrantOrRightExpirationTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_DebtInstrumentAccruedInterestRate" name="DebtInstrumentAccruedInterestRate" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_AdditionalOperatingLeaseRightOfUseAsset" name="AdditionalOperatingLeaseRightOfUseAsset" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_AdditionalOperatingLeaseLiability" name="AdditionalOperatingLeaseLiability" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_LesseeOperatingLeaseMaximumTermOfOptionsToTerminateLease" name="LesseeOperatingLeaseMaximumTermOfOptionsToTerminateLease" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_ConvertibleSeniorNotesNoncurrent" name="ConvertibleSeniorNotesNoncurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_ConvertibleSeniorNotesMember" name="ConvertibleSeniorNotesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_DevelopmentDerivativeLiabilityMember" name="DevelopmentDerivativeLiabilityMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_MarketableSecuritiesMember" name="MarketableSecuritiesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_ChangeInFairValueOfDerivativeLiabilityPercentage" name="ChangeInFairValueOfDerivativeLiabilityPercentage" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_NonRefundableUpfrontPayment" name="NonRefundableUpfrontPayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_ContraResearchAndDevelopmentExpense" name="ContraResearchAndDevelopmentExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_ContraResearchAndDevelopmentCurrent" name="ContraResearchAndDevelopmentCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_ContraResearchAndDevelopmentLongTermAssets" name="ContraResearchAndDevelopmentLongTermAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_AnnualLicenseMaintenanceFees" name="AnnualLicenseMaintenanceFees" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_SalesMilestonePaymentsBasedOnAchievementOfAnnualSalesMilestones" name="SalesMilestonePaymentsBasedOnAchievementOfAnnualSalesMilestones" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_UniversityOfPennsylvaniaMember" name="UniversityOfPennsylvaniaMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_TwoThousandTenLicenseAgreementMember" name="TwoThousandTenLicenseAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_SobiAgreementAndAnotherLicensingTransactionMember" name="SobiAgreementAndAnotherLicensingTransactionMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_NumberOfLicensedProducts" name="NumberOfLicensedProducts" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_RoyaltyExpenseOwed" name="RoyaltyExpenseOwed" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_FutureMilestonePayments" name="FutureMilestonePayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_PercentageOfRoyaltyFeesPayments" name="PercentageOfRoyaltyFeesPayments" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_MilestonePayments" name="MilestonePayments" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_DefinedContributionPlanEligibilityCriteriaMinimumAgeOfFullTimeEmployees" name="DefinedContributionPlanEligibilityCriteriaMinimumAgeOfFullTimeEmployees" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_IncomeTaxesLineItems" name="IncomeTaxesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_IncomeTaxesTable" name="IncomeTaxesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_EffectiveIncomeTaxRateReconciliationIntellectualPropertyTransfer" name="EffectiveIncomeTaxRateReconciliationIntellectualPropertyTransfer" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_EffectiveIncomeTaxRateReconciliationChangeInStateApportionmentTaxReformAndOther" name="EffectiveIncomeTaxRateReconciliationChangeInStateApportionmentTaxReformAndOther" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_EffectiveIncomeTaxRateChangeInPermanentAndOther" name="EffectiveIncomeTaxRateChangeInPermanentAndOther" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_DeferredTaxAssetsDeferredInterestExpense" name="DeferredTaxAssetsDeferredInterestExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_DeferredTaxAssetsContributionCarryforwards" name="DeferredTaxAssetsContributionCarryforwards" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_DeferredTaxAssetsOrphanDrugCredits" name="DeferredTaxAssetsOrphanDrugCredits" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_DeferredTaxLiabilitiesSection481AAdjustment" name="DeferredTaxLiabilitiesSection481AAdjustment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_NetDeferredTaxAssetsBeforeValuationAllowance" name="NetDeferredTaxAssetsBeforeValuationAllowance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_DeferredTaxAssetsTaxCreditCarryforwardsResearchAndDevelopment" name="DeferredTaxAssetsTaxCreditCarryforwardsResearchAndDevelopment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_NetOperatingLossCarryforwardExpirationYear" name="NetOperatingLossCarryforwardExpirationYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_ResearchAndDevelopmentTaxCreditCarryforwardExpirationYear" name="ResearchAndDevelopmentTaxCreditCarryforwardExpirationYear" type="xbrli:gYearItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_NetOperatingLossCarryforwardPeriod" name="NetOperatingLossCarryforwardPeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_OperatingLeaseArea" name="OperatingLeaseArea" type="num:areaItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_MonthlyLeasePayment" name="MonthlyLeasePayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_LeaseCommencementDate" name="LeaseCommencementDate" type="xbrli:dateItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_PercentageIncreaseToExistingPerMonthRentPayment" name="PercentageIncreaseToExistingPerMonthRentPayment" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_OperatingLeaseSquareFeetOfOfficeSpaceLeased" name="OperatingLeaseSquareFeetOfOfficeSpaceLeased" type="num:areaItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_CommitmentsAndContingenciesLineItems" name="CommitmentsAndContingenciesLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_CommitmentsAndContingenciesTable" name="CommitmentsAndContingenciesTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_WalthamMassachusettsMember" name="WalthamMassachusettsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_AmendedWalthamOfficeSpaceLeaseMember" name="AmendedWalthamOfficeSpaceLeaseMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_EstimatedTerminationCostsAndOtherFees" name="EstimatedTerminationCostsAndOtherFees" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceFairValueOfCommonStockPercent" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardExercisePriceFairValueOfCommonStockPercent" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_EquityIncentivePlanTwoThousandAndTenMember" name="EquityIncentivePlanTwoThousandAndTenMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_TwoThousandTwentyInducementStockIncentivePlanMember" name="TwoThousandTwentyInducementStockIncentivePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_TwentySeventeenEmployeeStockPurchasePlanMember" name="TwentySeventeenEmployeeStockPurchasePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_ShareBasedCompensationAwardTrancheFourMember" name="ShareBasedCompensationAwardTrancheFourMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_EmployeeStockPurchasePlanMember" name="EmployeeStockPurchasePlanMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_CommonStockIssuanceDescription" name="CommonStockIssuanceDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsAbstract" name="EmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodWeightedAverageGrantDateFairValue" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeitedInPeriodWeightedAverageGrantDateFairValue" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageGrantDateFairValue" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageGrantDateFairValue" type="num:perShareItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantInPeriodWeightedAverageRemainingContractualTerm" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantInPeriodWeightedAverageRemainingContractualTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodWeightedAverageRemainingContractualTerm" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodWeightedAverageRemainingContractualTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForefeitedInPeriodWeightedAverageRemainingContractualTerm" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForefeitedInPeriodWeightedAverageRemainingContractualTerm" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantInPeriodIntrinsicValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantInPeriodIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeitedInPeriodIntrinsicValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeitedInPeriodIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodAggregateIntrinsicValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedInPeriodAggregateIntrinsicValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit" />
  <xsd:element id="apls_PercentageOfEarningsWithheldToPurchaseSharesOfCommonStock" name="PercentageOfEarningsWithheldToPurchaseSharesOfCommonStock" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_CashReceivedFromIssuanceOfPurchaseRights" name="CashReceivedFromIssuanceOfPurchaseRights" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_SharebasedCompensationArrangementByShareBasedPaymentAwardPercentageOfEarningsWithheldToParticipateInAnOffering" name="SharebasedCompensationArrangementByShareBasedPaymentAwardPercentageOfEarningsWithheldToParticipateInAnOffering" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" />
  <xsd:element id="apls_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAbstract" name="ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_ConvertibleNotesMember" name="ConvertibleNotesMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_CommonStockWarrantsMember" name="CommonStockWarrantsMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_PayableOnExclusiveLicenseOptionThereafter" name="PayableOnExclusiveLicenseOptionThereafter" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_SoftwareDevelopmentServiceCosts" name="SoftwareDevelopmentServiceCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit" />
  <xsd:element id="apls_RevonSystemsIncMember" name="RevonSystemsIncMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
  <xsd:element id="apls_LicenseAgreementAndServicesAgreementMember" name="LicenseAgreementAndServicesAgreementMember" type="nonnum:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true" />
</xsd:schema>
