

<!--XBRL document created with Toppan Merrill Bridge  9.3.0.107 -->
<!--Based on XBRL 2.1-->
<!--Created on: 8/12/2019 2:50:47 PM-->
<!--Modified on: 8/12/2019 2:50:47 PM-->
<xsd:schema targetNamespace="http://www.nextcure.com/20190630" attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:invest="http://xbrl.sec.gov/invest/2013-01-31" xmlns:ref="http://www.xbrl.org/2006/ref" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:nonnum="http://www.xbrl.org/dtr/type/non-numeric" xmlns:xl="http://www.xbrl.org/2003/XLink" xmlns:us-gaap-att="http://xbrl.us/us-gaap/attributes" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:net="http://www.xbrl.org/2009/role/net" xmlns:num="http://www.xbrl.org/dtr/type/numeric" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:attributeFormDefault="unqualified" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:country="http://xbrl.sec.gov/country/2017-01-31" xmlns:currency="http://xbrl.sec.gov/currency/2017-01-31" xmlns:us-gaap="http://fasb.org/us-gaap/2018-01-31" xmlns:us-types="http://fasb.org/us-types/2018-01-31" xmlns:dei="http://xbrl.sec.gov/dei/2018-01-31" xmlns:stpr="http://xbrl.sec.gov/stpr/2018-01-31" xmlns:us-roles="http://fasb.org/us-roles/2018-01-31" xmlns:negated="http://www.xbrl.org/2009/role/negated" xmlns:nxtc="http://www.nextcure.com/20190630">
  <xsd:annotation>
    <xsd:appinfo>
      <link:roleType roleURI="http://www.nextcure.com/role/StatementCondensedBalanceSheets" id="StatementCondensedBalanceSheets">
        <link:definition>00100 - Statement - CONDENSED BALANCE SHEETS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/StatementCondensedStatementsOfOperations" id="StatementCondensedStatementsOfOperations">
        <link:definition>00200 - Statement - CONDENSED STATEMENTS OF OPERATIONS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/StatementCondensedStatementsOfCashFlows" id="StatementCondensedStatementsOfCashFlows">
        <link:definition>00400 - Statement - CONDENSED STATEMENTS OF CASH FLOWS</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureSummaryOfSignificantAccountingPoliciesRestrictedCashDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesRestrictedCashDetails">
        <link:definition>40201 - Disclosure - Summary of Significant Accounting Policies - Restricted Cash (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosurePropertyAndEquipmentNetDetails" id="DisclosurePropertyAndEquipmentNetDetails">
        <link:definition>40401 - Disclosure - Property and Equipment, Net - (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureAgreementWithEliLillyAndCompanyDeferredRevenueIncludedInBalanceSheetsDetails" id="DisclosureAgreementWithEliLillyAndCompanyDeferredRevenueIncludedInBalanceSheetsDetails">
        <link:definition>40502 - Disclosure - Agreement with Eli Lilly and Company - Deferred revenue included in balance sheets (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureCommitmentsAndContingenciesFutureMinimumPaymentsDetails" id="DisclosureCommitmentsAndContingenciesFutureMinimumPaymentsDetails">
        <link:definition>40602 - Disclosure - Commitments and Contingencies - Future Minimum Payments (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureTermLoanMaturitiesDetails" id="DisclosureTermLoanMaturitiesDetails">
        <link:definition>40702 - Disclosure - Term Loan - Maturities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureTermLoanMaturitiesDetailscalc2" id="DisclosureTermLoanMaturitiesDetailscalc2">
        <link:definition>40802 - Disclosure - Term Loan - Maturities (Details)_Calc2</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DocumentDocumentAndEntityInformation" id="DocumentDocumentAndEntityInformation">
        <link:definition>00090 - Document - Document and Entity Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/StatementCondensedBalanceSheetsParenthetical" id="StatementCondensedBalanceSheetsParenthetical">
        <link:definition>00105 - Statement - CONDENSED BALANCE SHEETS - (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/StatementCondensedStatementsOfPreferredStockAndStockholdersDeficit" id="StatementCondensedStatementsOfPreferredStockAndStockholdersDeficit">
        <link:definition>00300 - Statement - CONDENSED STATEMENTS OF PREFERRED STOCK AND STOCKHOLDERS&#x2019; DEFICIT</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/StatementCondensedStatementsOfPreferredStockAndStockholdersDeficitParenthetical" id="StatementCondensedStatementsOfPreferredStockAndStockholdersDeficitParenthetical">
        <link:definition>00305 - Statement - CONDENSED STATEMENTS OF PREFERRED STOCK AND STOCKHOLDERS&#x2019; DEFICIT (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureTermLoan" id="DisclosureTermLoan">
        <link:definition>10701 - Disclosure - Term Loan</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureStockBasedCompensation" id="DisclosureStockBasedCompensation">
        <link:definition>10801 - Disclosure - Stock-Based Compensation</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureIncomeTaxes" id="DisclosureIncomeTaxes">
        <link:definition>10901 - Disclosure - Income Taxes</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureSubsequentEvents" id="DisclosureSubsequentEvents">
        <link:definition>11001 - Disclosure - Subsequent Events</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureTermLoanTables" id="DisclosureTermLoanTables">
        <link:definition>30703 - Disclosure - Term Loan (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureStockBasedCompensationTables" id="DisclosureStockBasedCompensationTables">
        <link:definition>30803 - Disclosure - Stock-Based Compensation (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureNatureOfBusinessDetails" id="DisclosureNatureOfBusinessDetails">
        <link:definition>40101 - Disclosure - Nature of the Business - (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureFairValueOfFinancialInstrumentsDetails" id="DisclosureFairValueOfFinancialInstrumentsDetails">
        <link:definition>40301 - Disclosure - Fair Value of Financial Instruments - (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureAgreementWithEliLillyAndCompanyOtherDetails" id="DisclosureAgreementWithEliLillyAndCompanyOtherDetails">
        <link:definition>40501 - Disclosure - Agreement with Eli Lilly and Company - Other (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureTermLoanOtherDetails" id="DisclosureTermLoanOtherDetails">
        <link:definition>40701 - Disclosure - Term Loan - Other (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureStockBasedCompensationStockOptionsDetails" id="DisclosureStockBasedCompensationStockOptionsDetails">
        <link:definition>40801 - Disclosure - Stock-Based Compensation - Stock options (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureStockBasedCompensationStockBasedCompensationExpenseDetails" id="DisclosureStockBasedCompensationStockBasedCompensationExpenseDetails">
        <link:definition>40802 - Disclosure - Stock-Based Compensation - Stock based compensation expense (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureIncomeTaxesDetails" id="DisclosureIncomeTaxesDetails">
        <link:definition>409101 - Disclosure - Income Taxes - (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureSubsequentEventsDetails" id="DisclosureSubsequentEventsDetails">
        <link:definition>41001 - Disclosure - Subsequent Events - (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureNatureOfBusiness" id="DisclosureNatureOfBusiness">
        <link:definition>10101 - Disclosure - Nature of the Business</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureSummaryOfSignificantAccountingPolicies" id="DisclosureSummaryOfSignificantAccountingPolicies">
        <link:definition>10201 - Disclosure - Summary of Significant Accounting Policies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureFairValueOfFinancialInstruments" id="DisclosureFairValueOfFinancialInstruments">
        <link:definition>10301 - Disclosure - Fair Value of Financial Instruments</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosurePropertyAndEquipmentNet" id="DisclosurePropertyAndEquipmentNet">
        <link:definition>10401 - Disclosure - Property and Equipment, Net</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureAgreementWithEliLillyAndCompany" id="DisclosureAgreementWithEliLillyAndCompany">
        <link:definition>10501 - Disclosure - Agreement with Eli Lilly and Company</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureCommitmentsAndContingencies" id="DisclosureCommitmentsAndContingencies">
        <link:definition>10601 - Disclosure - Commitments and Contingencies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies" id="DisclosureSummaryOfSignificantAccountingPoliciesPolicies">
        <link:definition>20202 - Disclosure - Summary of Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables" id="DisclosureSummaryOfSignificantAccountingPoliciesTables">
        <link:definition>30203 - Disclosure - Summary of Significant Accounting Policies (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureFairValueOfFinancialInstrumentsTables" id="DisclosureFairValueOfFinancialInstrumentsTables">
        <link:definition>30303 - Disclosure - Fair Value of Financial Instruments (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosurePropertyAndEquipmentNetTables" id="DisclosurePropertyAndEquipmentNetTables">
        <link:definition>30403 - Disclosure - Property and Equipment, Net (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureAgreementWithEliLillyAndCompanyTables" id="DisclosureAgreementWithEliLillyAndCompanyTables">
        <link:definition>30503 - Disclosure - Agreement with Eli Lilly and Company (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureCommitmentsAndContingenciesTables" id="DisclosureCommitmentsAndContingenciesTables">
        <link:definition>30603 - Disclosure - Commitments and Contingencies (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.nextcure.com/role/DisclosureCommitmentsAndContingenciesOtherDetails" id="DisclosureCommitmentsAndContingenciesOtherDetails">
        <link:definition>40601 - Disclosure - Commitments and Contingencies - Other (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:linkbaseRef xlink:type="simple" xlink:href="nxtc-20190630_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="nxtc-20190630_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="nxtc-20190630_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="nxtc-20190630_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:title="Calculation Links, all" />
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:import namespace="http://xbrl.sec.gov/dei/2018-01-31" schemaLocation="https://xbrl.sec.gov/dei/2018/dei-2018-01-31.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2009/role/negated" schemaLocation="http://www.xbrl.org/lrr/role/negated-2009-12-16.xsd" />
  <xsd:import namespace="http://www.xbrl.org/dtr/type/numeric" schemaLocation="http://www.xbrl.org/dtr/type/numeric-2009-12-16.xsd" />
  <xsd:import namespace="http://www.xbrl.org/dtr/type/non-numeric" schemaLocation="http://www.xbrl.org/dtr/type/nonNumeric-2009-12-16.xsd" />
  <xsd:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" />
  <xsd:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" />
  <import namespace="http://fasb.org/us-gaap/2018-01-31" schemaLocation="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd" xmlns="http://www.w3.org/2001/XMLSchema" />
  <import namespace="http://fasb.org/srt/2018-01-31" schemaLocation="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_DocumentAndEntityInformationAbstract" name="DocumentAndEntityInformationAbstract" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RelatedPartyTransactionsDeferredRevenueCurrent" name="RelatedPartyTransactionsDeferredRevenueCurrent" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RelatedPartyTransactionsDeferredRevenueNoncurrent" name="RelatedPartyTransactionsDeferredRevenueNoncurrent" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_Series3PreferredStockMember" name="Series3PreferredStockMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_IncreaseDecreaseInDeferredRevenueFromRelatedParty" name="IncreaseDecreaseInDeferredRevenueFromRelatedParty" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_DescriptionOfNewAccountingPronouncementsNotYetAdoptedPolicyTextBlock" name="DescriptionOfNewAccountingPronouncementsNotYetAdoptedPolicyTextBlock" nillable="true" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_ResearchEquipmentMember" name="ResearchEquipmentMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_CollaborativeArrangementDisclosureAbstract" name="CollaborativeArrangementDisclosureAbstract" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_ResearchAndDevelopmentCollaborativeAgreementMember" name="ResearchAndDevelopmentCollaborativeAgreementMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_EliLillyAndCompanyMember" name="EliLillyAndCompanyMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_CollaborativeArrangementPeriodOfExpiryFromDateOfAgreement" name="CollaborativeArrangementPeriodOfExpiryFromDateOfAgreement" nillable="true" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_CollaborativeArrangementUpfrontNonRefundablePaymentReceived" name="CollaborativeArrangementUpfrontNonRefundablePaymentReceived" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_A2015OmnibusIncentivePlanMember" name="A2015OmnibusIncentivePlanMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_DebtInstrumentMonthlyPaymentsNumber" name="DebtInstrumentMonthlyPaymentsNumber" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_PeriodForWhichBaseRentIsAbated" name="PeriodForWhichBaseRentIsAbated" nillable="true" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_AnnualBaseRentPerMonthAfterAbatement" name="AnnualBaseRentPerMonthAfterAbatement" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_PercentageOfAnnualIncreaseInLeaseRent" name="PercentageOfAnnualIncreaseInLeaseRent" nillable="true" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_CollaborativeArrangementMaximumDevelopmentRegulatoryAndSalesMilestoneReceivable" name="CollaborativeArrangementMaximumDevelopmentRegulatoryAndSalesMilestoneReceivable" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_CollaborativeArrangementMaximumDevelopmentRegulatoryAndSalesMilestonePayableUponOptionExercise" name="CollaborativeArrangementMaximumDevelopmentRegulatoryAndSalesMilestonePayableUponOptionExercise" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageRemainingContractualTerm" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageRemainingContractualTerm" nillable="true" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_PaymentsOfUnderwritingDiscountsAndCommissions" name="PaymentsOfUnderwritingDiscountsAndCommissions" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_CollaborationAgreementTransactionPrice" name="CollaborationAgreementTransactionPrice" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RelatedPartyTransactionsDeferredRevenue" name="RelatedPartyTransactionsDeferredRevenue" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RelatedPartyTransactionsDeferredRevenueUpFrontPayment" name="RelatedPartyTransactionsDeferredRevenueUpFrontPayment" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RelatedPartyTransactionsDeferredRevenueAttributedPremiumOnProceedsFromInvestment" name="RelatedPartyTransactionsDeferredRevenueAttributedPremiumOnProceedsFromInvestment" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RelatedPartyTransactionsDeferredRevenueResearchAndDevelopmentSupportPayment" name="RelatedPartyTransactionsDeferredRevenueResearchAndDevelopmentSupportPayment" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RelatedPartyTransactionsDeferredRevenueCollaborationRevenueRecognized" name="RelatedPartyTransactionsDeferredRevenueCollaborationRevenueRecognized" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_ScheduleOfDeferredRevenueFromRelatedPartyTableTextBlock" name="ScheduleOfDeferredRevenueFromRelatedPartyTableTextBlock" nillable="true" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedWeightedAverageRemainingContractualTerm" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisedWeightedAverageRemainingContractualTerm" nillable="true" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_LetterOfCredit" name="LetterOfCredit" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RevenueRecognitionNumberOfPerformanceObligations" name="RevenueRecognitionNumberOfPerformanceObligations" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_OmnibusIncentive2019PlanMember" name="OmnibusIncentive2019PlanMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_EmployeeStockPurchase2019PlanMember" name="EmployeeStockPurchase2019PlanMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_ShareBasedCompensationArrangementIncreaseInSharesForIssuanceAsPercentageOfNumberOfCommonStockOutstanding" name="ShareBasedCompensationArrangementIncreaseInSharesForIssuanceAsPercentageOfNumberOfCommonStockOutstanding" nillable="true" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_ShareBasedCompensationArrangementThresholdNumberOfCommonStockForIssuanceUnderPlan" name="ShareBasedCompensationArrangementThresholdNumberOfCommonStockForIssuanceUnderPlan" nillable="true" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_NoncashOrPartNoncashConversionOfConvertiblePreferredStockIntoCommonStock" name="NoncashOrPartNoncashConversionOfConvertiblePreferredStockIntoCommonStock" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_StockIssuedDuringPeriodValueInitialPublicOffering" name="StockIssuedDuringPeriodValueInitialPublicOffering" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_StockIssuedDuringPeriodSharesInitialPublicOffering" name="StockIssuedDuringPeriodSharesInitialPublicOffering" nillable="true" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RequiredReserveRestrictedCashCurrent" name="RequiredReserveRestrictedCashCurrent" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_PreferredStockAbstract" name="PreferredStockAbstract" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_SharePriceOfCommonStockOnDateOfGrantAsPercentOfFairMarketValueOfCompanyStock" name="SharePriceOfCommonStockOnDateOfGrantAsPercentOfFairMarketValueOfCompanyStock" nillable="true" type="num:percentItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingContractualTerm" name="SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingContractualTerm" nillable="true" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationPeriod" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardExpirationPeriod" nillable="true" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_OmnibusIncentive2015PlanAndEmployeeStockPurchase2019PlanMember" name="OmnibusIncentive2015PlanAndEmployeeStockPurchase2019PlanMember" nillable="true" type="nonnum:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" xmlns="http://www.w3.org/2001/XMLSchema" />
  <element id="nxtc_RestrictedCashAndOtherAssetsCurrent" name="RestrictedCashAndOtherAssetsCurrent" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" xmlns="http://www.w3.org/2001/XMLSchema" />
</xsd:schema>