<?xml version="1.0" encoding="utf-8"?>
<!--XBRL document created with Toppan Merrill Bridge  10.9.0.3 -->
<!--Based on XBRL 2.1-->
<!--Created on: 3/3/2025 8:51:04 PM-->
<!--Modified on: 3/3/2025 8:51:04 PM-->
<xsd:schema targetNamespace="http://www.ymabs.com/20241231" attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:us-gaap="http://fasb.org/us-gaap/2024" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:currency="http://xbrl.sec.gov/currency/2024" xmlns:exch="http://xbrl.sec.gov/exch/2024" xmlns:naics="http://xbrl.sec.gov/naics/2024" xmlns:country="http://xbrl.sec.gov/country/2024" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:sic="http://xbrl.sec.gov/sic/2024" xmlns:us-types="http://fasb.org/us-types/2024" xmlns:stpr="http://xbrl.sec.gov/stpr/2024" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:srt-types="http://fasb.org/srt-types/2024" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2022-03-31" xmlns:ymab="http://www.ymabs.com/20241231" xmlns:enum2="http://xbrl.org/2020/extensible-enumerations-2.0" xmlns:us-roles="http://fasb.org/us-roles/2024" xmlns:ref="http://www.xbrl.org/2006/ref" xmlns:xl="http://www.xbrl.org/2003/XLink" xmlns:srt-roles="http://fasb.org/srt-roles/2024" xmlns:utr="http://www.xbrl.org/2009/utr" xmlns:negated="http://www.xbrl.org/2009/role/negated" xmlns:attributeFormDefault="unqualified" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:srt="http://fasb.org/srt/2024" xmlns:deprecated="http://www.xbrl.org/2009/role/deprecated" xmlns:net="http://www.xbrl.org/2009/role/net" xmlns:dei="http://xbrl.sec.gov/dei/2024" xmlns:dtr="http://www.xbrl.org/2009/dtr" xmlns:xbrldi="http://xbrl.org/2006/xbrldi" xmlns:us-gaap-ebp="http://fasb.org/us-gaap-ebp/2024" xmlns:cyd-af-sub="http://xbrl.sec.gov/cyd-af-sub/2024" xmlns:ecd="http://xbrl.sec.gov/ecd/2024" xmlns:ecd-sub="http://xbrl.sec.gov/ecd-sub/2024" xmlns:cyd="http://xbrl.sec.gov/cyd/2024">
  <xsd:annotation>
    <xsd:appinfo>
      <link:roleType roleURI="http://www.ymabs.com/role/DisclosureStandardAndCustomAxisDomainDefaults" id="DisclosureStandardAndCustomAxisDomainDefaults">
        <link:definition>99900 - Disclosure - Standard And Custom Axis Domain Defaults</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.ymabs.com/role/StatementConsolidatedBalanceSheets" id="StatementConsolidatedBalanceSheets">
        <link:definition>995200100 - Statement - Consolidated 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.ymabs.com/role/StatementConsolidatedStatementsOfNetLossAndComprehensiveLoss" id="StatementConsolidatedStatementsOfNetLossAndComprehensiveLoss">
        <link:definition>995200200 - Statement - Consolidated Statements of Net Loss and Comprehensive Loss</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.ymabs.com/role/StatementConsolidatedStatementsOfCashFlows" id="StatementConsolidatedStatementsOfCashFlows">
        <link:definition>995200400 - Statement - Consolidated 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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesSegmentInformationDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesSegmentInformationDetails">
        <link:definition>99940307 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Segment Information (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.ymabs.com/role/DisclosureNetProductRevenueReservesForDiscountsAndAllowancesDetails" id="DisclosureNetProductRevenueReservesForDiscountsAndAllowancesDetails">
        <link:definition>99940404 - Disclosure - NET PRODUCT REVENUE - Reserves for discounts and allowances (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.ymabs.com/role/DisclosureInventoriesDetails" id="DisclosureInventoriesDetails">
        <link:definition>99940601 - Disclosure - INVENTORIES (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.ymabs.com/role/DisclosureInventoriesDetailsCalc2" id="DisclosureInventoriesDetailsCalc2">
        <link:definition>40601 - Disclosure - INVENTORIES (Details) Calc 2</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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsLeaseMaturitiesDetailsCalc2" id="DisclosureLicenseAgreementsAndCommitmentsLeaseMaturitiesDetailsCalc2">
        <link:definition>40608 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - Lease maturities (Details) (calc 2)</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.ymabs.com/role/DisclosureAccruedLiabilitiesDetails" id="DisclosureAccruedLiabilitiesDetails">
        <link:definition>99940801 - Disclosure - ACCRUED LIABILITIES (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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsLeaseMaturitiesDetails" id="DisclosureLicenseAgreementsAndCommitmentsLeaseMaturitiesDetails">
        <link:definition>99940907 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - Lease 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.ymabs.com/role/DisclosureIncomeTaxesCurrentAndDeferredIncomeTaxesDetails" id="DisclosureIncomeTaxesCurrentAndDeferredIncomeTaxesDetails">
        <link:definition>99941202 - Disclosure - INCOME TAXES - Current and deferred 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.ymabs.com/role/DisclosureIncomeTaxesReconciliationOfIncomeTaxesDetails" id="DisclosureIncomeTaxesReconciliationOfIncomeTaxesDetails">
        <link:definition>99941203 - Disclosure - INCOME TAXES - Reconciliation of 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.ymabs.com/role/DisclosureIncomeTaxesDeferredAssetsLiabilitiesDetails" id="DisclosureIncomeTaxesDeferredAssetsLiabilitiesDetails">
        <link:definition>99941204 - Disclosure - INCOME TAXES - Deferred assets (liabilities) (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.ymabs.com/role/StatementConsolidatedStatementsOfChangesInStockholdersEquity" id="StatementConsolidatedStatementsOfChangesInStockholdersEquity">
        <link:definition>995200300 - Statement - Consolidated Statements of Changes in Stockholders' Equity</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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsTables" id="DisclosureLicenseAgreementsAndCommitmentsTables">
        <link:definition>99930903 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS (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.ymabs.com/role/DisclosureStockBasedCompensationTables" id="DisclosureStockBasedCompensationTables">
        <link:definition>99931103 - 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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesConcentrationOfCreditRiskDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesConcentrationOfCreditRiskDetails">
        <link:definition>99940302 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Concentration of Credit Risk (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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesFairValueMeasurementsDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesFairValueMeasurementsDetails">
        <link:definition>99940304 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair Value Measurements (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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesRevenueRecognitionLicenseRevenueDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesRevenueRecognitionLicenseRevenueDetails">
        <link:definition>99940306 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Revenue Recognition - License revenue (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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPropertyAndEquipmentDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesPropertyAndEquipmentDetails">
        <link:definition>99940308 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesProvisionForIncomeTaxesDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesProvisionForIncomeTaxesDetails">
        <link:definition>99940309 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Provision for 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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesStockBasedCompensationDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesStockBasedCompensationDetails">
        <link:definition>99940310 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Stock-Based Compensation (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.ymabs.com/role/DisclosureNetProductRevenueDisaggregationDetails" id="DisclosureNetProductRevenueDisaggregationDetails">
        <link:definition>99940401 - Disclosure - NET PRODUCT REVENUE - Disaggregation (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.ymabs.com/role/DisclosureNetProductRevenueConcentrationsDetails" id="DisclosureNetProductRevenueConcentrationsDetails">
        <link:definition>99940402 - Disclosure - NET PRODUCT REVENUE - Concentrations (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.ymabs.com/role/DisclosureNetProductRevenueReceivablesAllowancesAndAccruedLiabilitiesDetails" id="DisclosureNetProductRevenueReceivablesAllowancesAndAccruedLiabilitiesDetails">
        <link:definition>99940403 - Disclosure - NET PRODUCT REVENUE - Receivables, allowances and accrued liabilities (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.ymabs.com/role/DisclosureNetLossPerShareAntiDilutiveSecuritiesDetails" id="DisclosureNetLossPerShareAntiDilutiveSecuritiesDetails">
        <link:definition>99940502 - Disclosure - NET LOSS PER SHARE - Anti-dilutive securities (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.ymabs.com/role/DisclosureIntangibleAssetsNetDetails" id="DisclosureIntangibleAssetsNetDetails">
        <link:definition>99940701 - Disclosure - INTANGIBLE ASSETS, 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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsMskLicenseAgreementDetails" id="DisclosureLicenseAgreementsAndCommitmentsMskLicenseAgreementDetails">
        <link:definition>99940901 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - MSK License Agreement (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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsSadaLicenseAgreementDetails" id="DisclosureLicenseAgreementsAndCommitmentsSadaLicenseAgreementDetails">
        <link:definition>99940902 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - SADA License Agreement (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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsSummaryOfSignificantAgreementsAndCommitmentsDetails" id="DisclosureLicenseAgreementsAndCommitmentsSummaryOfSignificantAgreementsAndCommitmentsDetails">
        <link:definition>99940903 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - Summary of Significant Agreements and Commitments (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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsContractualAgreementWithFormerChiefFinancialOfficerDetails" id="DisclosureLicenseAgreementsAndCommitmentsContractualAgreementWithFormerChiefFinancialOfficerDetails">
        <link:definition>99940904 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - Contractual Agreement with Former Chief Financial Officer (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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsLeaseAgreementsDetails" id="DisclosureLicenseAgreementsAndCommitmentsLeaseAgreementsDetails">
        <link:definition>99940905 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - Lease agreements (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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsLeaseCostsDetails" id="DisclosureLicenseAgreementsAndCommitmentsLeaseCostsDetails">
        <link:definition>99940906 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - Lease costs (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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsLeaseTermAndDiscountRateDetails" id="DisclosureLicenseAgreementsAndCommitmentsLeaseTermAndDiscountRateDetails">
        <link:definition>99940908 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - Lease term and discount rate (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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitmentsLegalMattersDetails" id="DisclosureLicenseAgreementsAndCommitmentsLegalMattersDetails">
        <link:definition>99940909 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS - Legal matters (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.ymabs.com/role/DisclosureStockBasedCompensation2015PlanDetails" id="DisclosureStockBasedCompensation2015PlanDetails">
        <link:definition>99941101 - Disclosure - STOCK-BASED COMPENSATION - 2015 Plan (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.ymabs.com/role/DisclosureStockBasedCompensation2018PlanDetails" id="DisclosureStockBasedCompensation2018PlanDetails">
        <link:definition>99941102 - Disclosure - STOCK-BASED COMPENSATION - 2018 Plan (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.ymabs.com/role/DisclosureStockBasedCompensationStockBasedCompensationExpenseDetails" id="DisclosureStockBasedCompensationStockBasedCompensationExpenseDetails">
        <link:definition>99941103 - 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.ymabs.com/role/DisclosureStockBasedCompensationUnrecognizedCompensationExpenseDetails" id="DisclosureStockBasedCompensationUnrecognizedCompensationExpenseDetails">
        <link:definition>99941104 - Disclosure - STOCK-BASED COMPENSATION - Unrecognized 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.ymabs.com/role/DisclosureStockBasedCompensationRsusDetails" id="DisclosureStockBasedCompensationRsusDetails">
        <link:definition>99941105 - Disclosure - STOCK-BASED COMPENSATION - RSUs (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.ymabs.com/role/DisclosureStockBasedCompensationPrsusActivityDetails" id="DisclosureStockBasedCompensationPrsusActivityDetails">
        <link:definition>99941106 - Disclosure - STOCK-BASED COMPENSATION - PRSUs Activity (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.ymabs.com/role/DisclosureStockBasedCompensationPrsusAssumptionsDetails" id="DisclosureStockBasedCompensationPrsusAssumptionsDetails">
        <link:definition>99941107 - Disclosure - STOCK-BASED COMPENSATION - PRSUs Assumptions (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.ymabs.com/role/DisclosureStockBasedCompensationStockOptionActivityDetails" id="DisclosureStockBasedCompensationStockOptionActivityDetails">
        <link:definition>99941108 - Disclosure - STOCK-BASED COMPENSATION - Stock option activity (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.ymabs.com/role/DisclosureStockBasedCompensationStockOptionGrantsDetails" id="DisclosureStockBasedCompensationStockOptionGrantsDetails">
        <link:definition>99941109 - Disclosure - STOCK-BASED COMPENSATION - Stock option grants (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.ymabs.com/role/DisclosureStockBasedCompensationStockOptionValuationDetails" id="DisclosureStockBasedCompensationStockOptionValuationDetails">
        <link:definition>99941110 - Disclosure - STOCK-BASED COMPENSATION - Stock option valuation (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.ymabs.com/role/DisclosureIncomeTaxesNetOperatingLossCarryforwardsDetails" id="DisclosureIncomeTaxesNetOperatingLossCarryforwardsDetails">
        <link:definition>99941205 - Disclosure - INCOME TAXES - Net Operating Loss Carryforwards (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.ymabs.com/role/DisclosureOtherBenefitsDetails" id="DisclosureOtherBenefitsDetails">
        <link:definition>99941301 - Disclosure - OTHER BENEFITS (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.ymabs.com/role/DisclosureBusinessRealignmentAndRestructuringChargeDetails" id="DisclosureBusinessRealignmentAndRestructuringChargeDetails">
        <link:definition>99941401 - Disclosure - BUSINESS REALIGNMENT AND RESTRUCTURING CHARGE (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.ymabs.com/role/DocumentDocumentAndEntityInformation" id="DocumentDocumentAndEntityInformation">
        <link:definition>995200090 - 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.ymabs.com/role/StatementConsolidatedBalanceSheetsParenthetical" id="StatementConsolidatedBalanceSheetsParenthetical">
        <link:definition>995200105 - Statement - Consolidated 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.ymabs.com/role/DisclosureOrganizationAndDescriptionOfBusiness" id="DisclosureOrganizationAndDescriptionOfBusiness">
        <link:definition>995210101 - Disclosure - ORGANIZATION AND DESCRIPTION OF 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.ymabs.com/role/DisclosureBasisOfPresentation" id="DisclosureBasisOfPresentation">
        <link:definition>995210201 - Disclosure - BASIS OF PRESENTATION</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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPolicies" id="DisclosureSummaryOfSignificantAccountingPolicies">
        <link:definition>995210301 - 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.ymabs.com/role/DisclosureNetProductRevenue" id="DisclosureNetProductRevenue">
        <link:definition>995210401 - Disclosure - NET PRODUCT REVENUE</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.ymabs.com/role/DisclosureNetLossPerShare" id="DisclosureNetLossPerShare">
        <link:definition>995210501 - Disclosure - NET LOSS PER SHARE</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.ymabs.com/role/DisclosureInventories" id="DisclosureInventories">
        <link:definition>995210601 - Disclosure - INVENTORIES</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.ymabs.com/role/DisclosureIntangibleAssetsNet" id="DisclosureIntangibleAssetsNet">
        <link:definition>995210701 - Disclosure - INTANGIBLE ASSETS, 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.ymabs.com/role/DisclosureAccruedLiabilities" id="DisclosureAccruedLiabilities">
        <link:definition>995210801 - Disclosure - ACCRUED LIABILITIES</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.ymabs.com/role/DisclosureLicenseAgreementsAndCommitments" id="DisclosureLicenseAgreementsAndCommitments">
        <link:definition>995210901 - Disclosure - LICENSE AGREEMENTS AND COMMITMENTS</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.ymabs.com/role/DisclosureStockholdersEquity" id="DisclosureStockholdersEquity">
        <link:definition>995211001 - Disclosure - STOCKHOLDERS' EQUITY</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.ymabs.com/role/DisclosureStockBasedCompensation" id="DisclosureStockBasedCompensation">
        <link:definition>995211101 - 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.ymabs.com/role/DisclosureIncomeTaxes" id="DisclosureIncomeTaxes">
        <link:definition>995211201 - 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.ymabs.com/role/DisclosureOtherBenefits" id="DisclosureOtherBenefits">
        <link:definition>995211301 - Disclosure - OTHER BENEFITS</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.ymabs.com/role/DisclosureBusinessRealignmentAndRestructuringCharge" id="DisclosureBusinessRealignmentAndRestructuringCharge">
        <link:definition>995211401 - Disclosure - BUSINESS REALIGNMENT AND RESTRUCTURING CHARGE</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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies" id="DisclosureSummaryOfSignificantAccountingPoliciesPolicies">
        <link:definition>99920302 - 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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesTables" id="DisclosureSummaryOfSignificantAccountingPoliciesTables">
        <link:definition>99930303 - 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.ymabs.com/role/DisclosureNetProductRevenueTables" id="DisclosureNetProductRevenueTables">
        <link:definition>99930403 - Disclosure - NET PRODUCT REVENUE (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.ymabs.com/role/DisclosureNetLossPerShareTables" id="DisclosureNetLossPerShareTables">
        <link:definition>99930503 - Disclosure - NET LOSS PER SHARE (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.ymabs.com/role/DisclosureInventoriesTables" id="DisclosureInventoriesTables">
        <link:definition>99930603 - Disclosure - INVENTORIES (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.ymabs.com/role/DisclosureIntangibleAssetsNetTables" id="DisclosureIntangibleAssetsNetTables">
        <link:definition>99930703 - Disclosure - INTANGIBLE ASSETS, 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.ymabs.com/role/DisclosureAccruedLiabilitiesTables" id="DisclosureAccruedLiabilitiesTables">
        <link:definition>99930803 - Disclosure - ACCRUED LIABILITIES (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.ymabs.com/role/DisclosureIncomeTaxesTables" id="DisclosureIncomeTaxesTables">
        <link:definition>99931203 - Disclosure - INCOME TAXES (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.ymabs.com/role/DisclosureBasisOfPresentationAccumulatedDeficitDetails" id="DisclosureBasisOfPresentationAccumulatedDeficitDetails">
        <link:definition>99940201 - Disclosure - BASIS OF PRESENTATION - Accumulated deficit (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.ymabs.com/role/DisclosureBasisOfPresentationCashAndCashEquivalentsDetails" id="DisclosureBasisOfPresentationCashAndCashEquivalentsDetails">
        <link:definition>99940202 - Disclosure - BASIS OF PRESENTATION - Cash and cash equivalents (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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesAccountsReceivableNetDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesAccountsReceivableNetDetails">
        <link:definition>99940301 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accounts Receivable, 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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesInventoriesDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesInventoriesDetails">
        <link:definition>99940303 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Inventories (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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesOperatingLeasesDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesOperatingLeasesDetails">
        <link:definition>99940305 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Operating Leases (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.ymabs.com/role/DisclosureSummaryOfSignificantAccountingPoliciesOtherPoliciesDetails" id="DisclosureSummaryOfSignificantAccountingPoliciesOtherPoliciesDetails">
        <link:definition>99940311 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Other policies (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.ymabs.com/role/DisclosureNetLossPerShareBasicAndDilutedDetails" id="DisclosureNetLossPerShareBasicAndDilutedDetails">
        <link:definition>99940501 - Disclosure - NET LOSS PER SHARE - Basic and diluted (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.ymabs.com/role/DisclosureStockholdersEquityAuthorizedCommonAndPreferredStockDetails" id="DisclosureStockholdersEquityAuthorizedCommonAndPreferredStockDetails">
        <link:definition>99941001 - Disclosure - STOCKHOLDERS' EQUITY - Authorized, Common and Preferred Stock (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.ymabs.com/role/DisclosureIncomeTaxesLossBeforeIncomeTaxesDetails" id="DisclosureIncomeTaxesLossBeforeIncomeTaxesDetails">
        <link:definition>99941201 - Disclosure - INCOME TAXES - Loss before 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:linkbaseRef xlink:type="simple" xlink:href="ymab-20241231_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="ymab-20241231_cal.xml" xlink:title="Calculation Links, all" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
      <link:linkbaseRef xlink:type="simple" xlink:href="ymab-20241231_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="ymab-20241231_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" />
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:import namespace="https://xbrl.org/2023/calculation-1.1" schemaLocation="https://www.xbrl.org/2023/calculation-1.1.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/ecd/2024" schemaLocation="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/dei/2024" schemaLocation="https://xbrl.sec.gov/dei/2024/dei-2024.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://www.xbrl.org/dtr/type/2022-03-31" schemaLocation="https://www.xbrl.org/dtr/type/2022-03-31/types.xsd" />
  <xsd:import namespace="http://xbrl.org/2005/xbrldt" schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.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://fasb.org/us-roles/2024" schemaLocation="https://xbrl.fasb.org/us-gaap/2024/elts/us-roles-2024.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/country/2024" schemaLocation="https://xbrl.sec.gov/country/2024/country-2024.xsd" />
  <xsd:import namespace="http://fasb.org/us-gaap/2024" schemaLocation="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd" />
  <xsd:import namespace="http://fasb.org/srt/2024" schemaLocation="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/ecd-sub/2024" schemaLocation="https://xbrl.sec.gov/ecd/2024/ecd-sub-2024.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/cyd/2024" schemaLocation="https://xbrl.sec.gov/cyd/2024/cyd-2024.xsd" />
  <xsd:import namespace="http://xbrl.sec.gov/cyd-af-sub/2024" schemaLocation="https://xbrl.sec.gov/cyd/2024/cyd-af-sub-2024.xsd" />
  <xsd:element name="IncreaseDecreaseInAccruedLiabilitiesAndOther" id="ymab_IncreaseDecreaseInAccruedLiabilitiesAndOther" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element name="NumberOfLicenseAgreements" id="ymab_NumberOfLicenseAgreements" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <xsd:element id="ymab_LeasePayablePerMonth" name="LeasePayablePerMonth" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element name="OrganizationAndDescriptionOfBusinessAbstract" id="ymab_OrganizationAndDescriptionOfBusinessAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="BasisOfPresentationAbstract" id="ymab_BasisOfPresentationAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="AccruedClinicalCostsCurrent" id="ymab_AccruedClinicalCostsCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="AccruedCompensationAndBoardFeesCurrent" id="ymab_AccruedCompensationAndBoardFeesCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="TotalSharesAuthorized" id="ymab_TotalSharesAuthorized" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <xsd:element name="NumberOfVotesPerCommonStock" id="ymab_NumberOfVotesPerCommonStock" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OtherBenefitsDisclosureAbstract" id="ymab_OtherBenefitsDisclosureAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="OtherBenefitsDisclosureTextBlock" id="ymab_OtherBenefitsDisclosureTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="DeferredTaxAssetsAccruedRoyalty" id="ymab_DeferredTaxAssetsAccruedRoyalty" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="ymab_AccruedMilestoneAndRoyaltyPaymentsNoncurrent" name="AccruedMilestoneAndRoyaltyPaymentsNoncurrent" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element name="EquityIncentivePlan2015Member" id="ymab_EquityIncentivePlan2015Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="ShareBasedPaymentArrangementEmployeeAndNonemployeeMember" id="ymab_ShareBasedPaymentArrangementEmployeeAndNonemployeeMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_LeaseArrangementCorporateHeadquartersNewYorkMember" name="LeaseArrangementCorporateHeadquartersNewYorkMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_LeaseArrangementOfficeSpaceDenmarkMember" name="LeaseArrangementOfficeSpaceDenmarkMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="FixedRentPayablePerAnnum" id="ymab_FixedRentPayablePerAnnum" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element name="OwnershipVotingPower" id="ymab_OwnershipVotingPower" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" />
  <xsd:element name="OptionPriceAsPercentageOfFairMarketValueOfCommonStockOnGrantDate" id="ymab_OptionPriceAsPercentageOfFairMarketValueOfCommonStockOnGrantDate" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="EquityIncentivePlan2018Member" id="ymab_EquityIncentivePlan2018Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element name="GranteeOwningMoreThanTenPercentOfVotingPowerMember" id="ymab_GranteeOwningMoreThanTenPercentOfVotingPowerMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" nillable="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_DeferredTaxAssetsNetOfLiabilitiesGross" name="DeferredTaxAssetsNetOfLiabilitiesGross" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" />
  <xsd:element name="AccruedManufacturingCostsCurrent" id="ymab_AccruedManufacturingCostsCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="ymab_LeaseArrangementLaboratoryNewJerseyMember" name="LeaseArrangementLaboratoryNewJerseyMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_LicenseAgreementsAndCommitmentsAbstract" name="LicenseAgreementsAndCommitmentsAbstract" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_ArrangementOtherThanCollaborativeClinicalMilestonePaymentsDue" name="ArrangementOtherThanCollaborativeClinicalMilestonePaymentsDue" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" abstract="false" />
  <xsd:element id="ymab_ArrangementOtherThanCollaborativeRegulatoryMilestonePaymentsDue" name="ArrangementOtherThanCollaborativeRegulatoryMilestonePaymentsDue" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" abstract="false" />
  <xsd:element id="ymab_ArrangementOtherThanCollaborativeSalesBasedMilestonePaymentsDue" name="ArrangementOtherThanCollaborativeSalesBasedMilestonePaymentsDue" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" abstract="false" />
  <xsd:element id="ymab_ArrangementOtherThanCollaborativeAnnualMinimumRoyaltiesPayable" name="ArrangementOtherThanCollaborativeAnnualMinimumRoyaltiesPayable" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="ymab_ArrangementOtherThanCollaborativeAnnualMinimumRoyaltiesPayableFromTenthAnniversary" name="ArrangementOtherThanCollaborativeAnnualMinimumRoyaltiesPayableFromTenthAnniversary" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="ymab_DeferredTaxLiabilitiesRightOfUseAsset" name="DeferredTaxLiabilitiesRightOfUseAsset" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="ymab_DeferredTaxAssetLeaseLiability" name="DeferredTaxAssetLeaseLiability" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="debit" />
  <xsd:element id="ymab_OperatingLossCarryforwardsIndefinite" name="OperatingLossCarryforwardsIndefinite" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="ymab_SadaLicenseAgreementMember" name="SadaLicenseAgreementMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_ArrangementOtherThanCollaborativeAdditionalSalesBasedMilestonePaymentsDueOtherConstructs" name="ArrangementOtherThanCollaborativeAdditionalSalesBasedMilestonePaymentsDueOtherConstructs" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="ymab_CompensationExpenseHealthInsuranceBenefits" name="CompensationExpenseHealthInsuranceBenefits" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="ymab_MskMember" name="MskMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_AccruedLicensingMilestoneAndRoyaltyPaymentsCurrent" name="AccruedLicensingMilestoneAndRoyaltyPaymentsCurrent" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="ymab_ArrangementOtherThanCollaborativeCashPayments" name="ArrangementOtherThanCollaborativeCashPayments" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="ymab_MilestonesAbstract" name="MilestonesAbstract" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_FinancialStatementInformationAbstract" name="FinancialStatementInformationAbstract" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_CostsIncurredAsResultOfGlobalIntangibleLowTaxedIncome" name="CostsIncurredAsResultOfGlobalIntangibleLowTaxedIncome" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="ymab_DevelopmentAndCommercializationArrangementMember" name="DevelopmentAndCommercializationArrangementMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_ScicloneInternationalPharmaceuticalsLtdMember" name="ScicloneInternationalPharmaceuticalsLtdMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_NumberOfCustomers" name="NumberOfCustomers" nillable="true" type="xbrli:integerItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" />
  <xsd:element id="ymab_MckessonMember" name="MckessonMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_CardinalHealthMember" name="CardinalHealthMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_AccruedSalesReservesCurrent" name="AccruedSalesReservesCurrent" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="ymab_AdiumPharmaS.aMember" name="AdiumPharmaS.aMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_ReserveForDiscountsAndAllowancesTableTextBlock" name="ReserveForDiscountsAndAllowancesTableTextBlock" nillable="true" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" />
  <xsd:element id="ymab_ReservesForDiscountsAndAllowancesRollForward" name="ReservesForDiscountsAndAllowancesRollForward" nillable="true" type="xbrli:stringItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_ReserveForDiscountsBalance" name="ReserveForDiscountsBalance" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="ymab_ReserveForDiscountsAdditions" name="ReserveForDiscountsAdditions" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" />
  <xsd:element id="ymab_ReserveForDiscountsReduction" name="ReserveForDiscountsReduction" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="ymab_SalesReturnLiabilityBalance" name="SalesReturnLiabilityBalance" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="ymab_SalesReturnLiabilityAdditions" name="SalesReturnLiabilityAdditions" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" />
  <xsd:element id="ymab_SalesReturnLiabilityReduction" name="SalesReturnLiabilityReduction" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="ymab_ReservesAndAllowancesBalance" name="ReservesAndAllowancesBalance" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" xbrli:balance="credit" />
  <xsd:element id="ymab_ReservesAndAllowancesAdditions" name="ReservesAndAllowancesAdditions" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="credit" />
  <xsd:element id="ymab_ReservesAndAllowancesReductions" name="ReservesAndAllowancesReductions" nillable="true" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" xbrli:balance="debit" />
  <xsd:element id="ymab_FinancialStatementAccruedLiabilitiesMember" name="FinancialStatementAccruedLiabilitiesMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element id="ymab_FinancialStatementAccountsReceivableMember" name="FinancialStatementAccountsReceivableMember" nillable="true" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" abstract="true" xbrli:periodType="duration" />
  <xsd:element name="ThreeCustomersMember" id="ymab_ThreeCustomersMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ContractualAllowanceAndGovernmentRebateLiabilityBalance" id="ymab_ContractualAllowanceAndGovernmentRebateLiabilityBalance" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="ContractualAllowanceAndGovernmentRebateLiabilityAdditions" id="ymab_ContractualAllowanceAndGovernmentRebateLiabilityAdditions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="ContractualAllowanceAndGovernmentRebateLiabilityReduction" id="ymab_ContractualAllowanceAndGovernmentRebateLiabilityReduction" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="TakedaIsraelMember" id="ymab_TakedaIsraelMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="LicenseAndDistributionArrangementMember" id="ymab_LicenseAndDistributionArrangementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="DistributionArrangementMember" id="ymab_DistributionArrangementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="IntangibleAssetsDisclosureAbstract" id="ymab_IntangibleAssetsDisclosureAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RevenueAbstract" id="ymab_RevenueAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="InventoryCurrentAndNoncurrentTable" id="ymab_InventoryCurrentAndNoncurrentTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="InventoryCurrentAndNoncurrentLineItems" id="ymab_InventoryCurrentAndNoncurrentLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ScheduleOfInventoryCurrentAndNoncurrentTableTextBlock" id="ymab_ScheduleOfInventoryCurrentAndNoncurrentTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="InventoryCurrentAndNoncurrent" id="ymab_InventoryCurrentAndNoncurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="AreaOfRealEstatePropertyAdditionalArea" id="ymab_AreaOfRealEstatePropertyAdditionalArea" type="dtr-types:areaItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="FairValueAssetsLevel1ToLevel2TransfersAmount1" id="ymab_FairValueAssetsLevel1ToLevel2TransfersAmount1" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="FairValueAssetsLevel2ToLevel1TransfersAmount1" id="ymab_FairValueAssetsLevel2ToLevel1TransfersAmount1" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="AcquisitionOfTreasurySharesUponRepaymentOfSecuredPromissoryNote" id="ymab_AcquisitionOfTreasurySharesUponRepaymentOfSecuredPromissoryNote" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="ReservesForDiscountsAndAllowancesChangeInEstimate" id="ymab_ReservesForDiscountsAndAllowancesChangeInEstimate" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="ContractualAllowanceAndGovernmentRebateChangeInEstimate" id="ymab_ContractualAllowanceAndGovernmentRebateChangeInEstimate" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="LawsuitFiledByShareholderU.s.DistrictCourtSouthernDistrictOfNewYorkAugust252021Member" id="ymab_LawsuitFiledByShareholderU.s.DistrictCourtSouthernDistrictOfNewYorkAugust252021Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ArrangementOtherThanCollaborativeRegulatoryMilestonePaymentsReceivable" id="ymab_ArrangementOtherThanCollaborativeRegulatoryMilestonePaymentsReceivable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ArrangementOtherThanCollaborativeSalesBasedMilestonePaymentsReceivable" id="ymab_ArrangementOtherThanCollaborativeSalesBasedMilestonePaymentsReceivable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ForeignCurrencyTransactionGainLossBeforeTaxAndOtherTransactions" id="ymab_ForeignCurrencyTransactionGainLossBeforeTaxAndOtherTransactions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="FiniteLivedAndIndefiniteLivedIntangibleAssetsByMajorClassTable" id="ymab_FiniteLivedAndIndefiniteLivedIntangibleAssetsByMajorClassTable" type="xbrli:stringItemType" substitutionGroup="xbrldt:hypercubeItem" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="FiniteLivedAndIndefiniteLivedIntangibleAssetsByMajorClassLineItems" id="ymab_FiniteLivedAndIndefiniteLivedIntangibleAssetsByMajorClassLineItems" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="PriorityReviewVoucherFirstSaleIncomePercentageCounterparty" id="ymab_PriorityReviewVoucherFirstSaleIncomePercentageCounterparty" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="PriorityReviewVoucherSubsequentSaleIncomePercentageCounterparty" id="ymab_PriorityReviewVoucherSubsequentSaleIncomePercentageCounterparty" type="dtr-types:percentItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="LicenseAgreementTermMinimum" id="ymab_LicenseAgreementTermMinimum" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ArrangementOtherThanCollaborativeAnnualMinimumRoyaltiesPayablePatentIssued" id="ymab_ArrangementOtherThanCollaborativeAnnualMinimumRoyaltiesPayablePatentIssued" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="LawsuitFiledByShareholderInCourtOfChanceryOfStateOfDelawareFebruary82023Member" id="ymab_LawsuitFiledByShareholderInCourtOfChanceryOfStateOfDelawareFebruary82023Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="DeferredTaxAssetsCapitalizedResearchAndExperimentation" id="ymab_DeferredTaxAssetsCapitalizedResearchAndExperimentation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="EffectiveIncomeTaxRateReconciliationDeferredAdjustmentsAmount" id="ymab_EffectiveIncomeTaxRateReconciliationDeferredAdjustmentsAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="LicenseAgreementMember" id="ymab_LicenseAgreementMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="MskAndMitMember" id="ymab_MskAndMitMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="WepClinicalLimitedMember" id="ymab_WepClinicalLimitedMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NonExecutiveDirectorsMember" id="ymab_NonExecutiveDirectorsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="InterestIncomeExpenseAndOtherNonoperatingIncomeExpense" id="ymab_InterestIncomeExpenseAndOtherNonoperatingIncomeExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="SwixxBiopharmaAgMember" id="ymab_SwixxBiopharmaAgMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresTwoAbstract" id="ymab_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresTwoAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ContractualAllowanceAndGovernmentRebateChangeInEstimateSalesInPriorYear" id="ymab_ContractualAllowanceAndGovernmentRebateChangeInEstimateSalesInPriorYear" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="LawsuitClassActionU.s.DistrictCourtSouthernDistrictOfNewYorkJanuary182023Member" id="ymab_LawsuitClassActionU.s.DistrictCourtSouthernDistrictOfNewYorkJanuary182023Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="CapitalizedMilestonePaymentsMember" id="ymab_CapitalizedMilestonePaymentsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RestrictedStockUnitsRsusExcludingPerformanceUnitsMember" id="ymab_RestrictedStockUnitsRsusExcludingPerformanceUnitsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RestrictedStockUnitsPerformancePrsusMember" id="ymab_RestrictedStockUnitsPerformancePrsusMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingOnNumberOfAnniversariesOfGrantDate" id="ymab_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingOnNumberOfAnniversariesOfGrantDate" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock" id="ymab_ScheduleOfShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsValuationAssumptionsTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="EmployeesExcludingNonExecutiveDirectorMember" id="ymab_EmployeesExcludingNonExecutiveDirectorMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NonExecutiveDirectorsNewMember" id="ymab_NonExecutiveDirectorsNewMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NonExecutiveDirectorsExcludingNewNonExecutiveDirectorMember" id="ymab_NonExecutiveDirectorsExcludingNewNonExecutiveDirectorMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="NonUsOtherMember" id="ymab_NonUsOtherMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="WesternEuropeMember" id="ymab_WesternEuropeMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="EasternAsiaMember" id="ymab_EasternAsiaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ChiefFinancialOfficerFormerMember" id="ymab_ChiefFinancialOfficerFormerMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="LossContingencyShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsCancellationsInPeriod" id="ymab_LossContingencyShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsCancellationsInPeriod" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="LitigationSettlementPlaintiffAndCounselFeeExpense" id="ymab_LitigationSettlementPlaintiffAndCounselFeeExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ConsultingServicesPayment" id="ymab_ConsultingServicesPayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="StrategicRestructuringPlan2023Member" id="ymab_StrategicRestructuringPlan2023Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="LeaseArrangementCorporateHeadquartersNewJerseyMember" id="ymab_LeaseArrangementCorporateHeadquartersNewJerseyMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="FixedRentPayablePerAnnumYearOneFollowingRentFreePeriod" id="ymab_FixedRentPayablePerAnnumYearOneFollowingRentFreePeriod" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="credit" />
  <xsd:element name="DirectorNonEmployeeMember" id="ymab_DirectorNonEmployeeMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="LossContingencyShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsCancellations" id="ymab_LossContingencyShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsCancellations" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="CencoraMember" id="ymab_CencoraMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="LesseeOperatingLeaseOptionToExtendNumber" id="ymab_LesseeOperatingLeaseOptionToExtendNumber" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" />
  <xsd:element name="LesseeOperatingLeaseRentFreePeriod" id="ymab_LesseeOperatingLeaseRentFreePeriod" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ArrangementOtherThanCollaborativeProductAndCommercialMilestonePaymentsReceivable" id="ymab_ArrangementOtherThanCollaborativeProductAndCommercialMilestonePaymentsReceivable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="NobelpharmaCo.Ltd.Member" id="ymab_NobelpharmaCo.Ltd.Member" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="WesternAsiaMember" id="ymab_WesternAsiaMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ArrangementOtherThanCollaborativeMilestonePaymentsReceivable" id="ymab_ArrangementOtherThanCollaborativeMilestonePaymentsReceivable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="BusinessRealignmentPlanMember" id="ymab_BusinessRealignmentPlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="RestructuringAndRelatedActivitiesNumberOfBusinessUnitsRealigned" id="ymab_RestructuringAndRelatedActivitiesNumberOfBusinessUnitsRealigned" type="xbrli:integerItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="InpharmusMember" id="ymab_InpharmusMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="DistributionArrangementAmendmentMember" id="ymab_DistributionArrangementAmendmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodPrecedingVestingDateForDeterminingAverageStockPrice" id="ymab_ShareBasedCompensationArrangementByShareBasedPaymentAwardPeriodPrecedingVestingDateForDeterminingAverageStockPrice" type="xbrli:durationItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" />
  <xsd:element name="ArrangementOtherThanCollaborativeIncreaseDecreaseInPotentialMilestonePaymentsPayable" id="ymab_ArrangementOtherThanCollaborativeIncreaseDecreaseInPotentialMilestonePaymentsPayable" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="LicenseAgreementAmendmentMember" id="ymab_LicenseAgreementAmendmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="IncreaseDecreaseInInventoriesCurrent" id="ymab_IncreaseDecreaseInInventoriesCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="IncreaseDecreaseInInventoriesNoncurrent" id="ymab_IncreaseDecreaseInInventoriesNoncurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="credit" />
  <xsd:element name="ResearchAndDevelopmentExpenseOutsourcedManufacturing" id="ymab_ResearchAndDevelopmentExpenseOutsourcedManufacturing" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ResearchAndDevelopmentExpenseClinicalTrials" id="ymab_ResearchAndDevelopmentExpenseClinicalTrials" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ResearchAndDevelopmentExpenseOutsourcedResearchAndSupplies" id="ymab_ResearchAndDevelopmentExpenseOutsourcedResearchAndSupplies" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ResearchAndDevelopmentExpensePersonnelCosts" id="ymab_ResearchAndDevelopmentExpensePersonnelCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ResearchAndDevelopmentExpenseProfessionalAndConsultingFees" id="ymab_ResearchAndDevelopmentExpenseProfessionalAndConsultingFees" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ResearchAndDevelopmentExpenseStockBasedCompensation" id="ymab_ResearchAndDevelopmentExpenseStockBasedCompensation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ResearchAndDevelopmentExpenseInformationTechnologyExpenses" id="ymab_ResearchAndDevelopmentExpenseInformationTechnologyExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ResearchAndDevelopmentExpenseOther" id="ymab_ResearchAndDevelopmentExpenseOther" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ResearchAndDevelopmentExpenseMilestonesAndLicenseAcquisitionCosts" id="ymab_ResearchAndDevelopmentExpenseMilestonesAndLicenseAcquisitionCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="SingleReportableSegmentMember" id="ymab_SingleReportableSegmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="true" />
  <xsd:element name="EffectiveIncomeTaxRateReconciliationReturnToProvisionAmount" id="ymab_EffectiveIncomeTaxRateReconciliationReturnToProvisionAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="DeferredTaxAssetsUnicap" id="ymab_DeferredTaxAssetsUnicap" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="instant" abstract="false" xbrli:balance="debit" />
  <xsd:element name="ArrangementOtherThanCollaborativeNonRefundableAmountReceived" id="ymab_ArrangementOtherThanCollaborativeNonRefundableAmountReceived" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
  <xsd:element name="AccruedMilestoneAndRoyaltyPaymentsNoncurrentReversal" id="ymab_AccruedMilestoneAndRoyaltyPaymentsNoncurrentReversal" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" nillable="true" xbrli:periodType="duration" abstract="false" xbrli:balance="debit" />
</xsd:schema>
