content: <?xml version="1.0" encoding="UTF-8"?><edgarSubmission xmlns="http://www.sec.gov/edgar/ownership" xmlns:com="http://www.sec.gov/edgar/common">
    <!-- Generated by Workiva -->
    <headerData>
      <submissionType>144</submissionType>
      <filerInfo>
        <filer>
          <filerCredentials>
            <cik>0001753224</cik>
            <ccc>XXXXXXXX</ccc>
          </filerCredentials>
        </filer>
        <liveTestFlag>LIVE</liveTestFlag>
  
  
  
      </filerInfo>
    </headerData>
    <formData>
      <issuerInfo>
        <issuerCik>0001722964</issuerCik>
        <issuerName>Y-mAbs Therapeutics, Inc.</issuerName>
        <secFileNumber>001-38650</secFileNumber>
        <issuerAddress>
          <com:street1>230 Park Avenue</com:street1>
          <com:street2>Suite 3350</com:street2>
          <com:city>New York</com:city>
          <com:stateOrCountry>NY</com:stateOrCountry>
          <com:zipCode>10169</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>6468858505</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Thomas Gad</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Officer</relationshipToIssuer>
        </relationshipsToIssuer>
      </issuerInfo>
      <securitiesInformation>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>J.P. Morgan Securities LLC</name>
          <address>
            <com:street1>390 Madison Avenue</com:street1>
            <com:street2>6th Floor</com:street2>
            <com:city>New York</com:city>
            <com:stateOrCountry>NY</com:stateOrCountry>
            <com:zipCode>10017</com:zipCode>
          </address>
        </brokerOrMarketmakerDetails>
        <noOfUnitsSold>70000</noOfUnitsSold>
        <aggregateMarketValue>838600</aggregateMarketValue>
        <noOfUnitsOutstanding>43882638</noOfUnitsOutstanding>
        <approxSaleDate>06/10/2024</approxSaleDate>
        <securitiesExchangeName>Nasdaq</securitiesExchangeName>
      </securitiesInformation>
      <securitiesToBeSold>
        <securitiesClassTitle>Common</securitiesClassTitle>
        <acquiredDate>08/15/2015</acquiredDate>
        <natureOfAcquisitionTransaction>Private Investment</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>Issuer</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>70000</amountOfSecuritiesAcquired>
        <paymentDate>08/15/2015</paymentDate>
        <natureOfPayment>Cash</natureOfPayment>
      </securitiesToBeSold>
      <nothingToReportFlagOnSecuritiesSoldInPast3Months>N</nothingToReportFlagOnSecuritiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Gad Enterprises, LLC</name>
          <address>
            <com:street1>C/O Issuer</com:street1>
            <com:street2>230 Park Avenue, Suite 3350</com:street2>
            <com:city>New York</com:city>
            <com:stateOrCountry>NY</com:stateOrCountry>
            <com:zipCode>10169</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <saleDate>05/21/2024</saleDate>
        <amountOfSecuritiesSold>25000</amountOfSecuritiesSold>
        <grossProceeds>296242</grossProceeds>
      </securitiesSoldInPast3Months>
      <securitiesSoldInPast3Months>
        <sellerDetails>
          <name>Gad Enterprises, LLC</name>
          <address>
            <com:street1>C/O Issuer</com:street1>
            <com:street2>230 Park Avenue, Suite 3350</com:street2>
            <com:city>New York</com:city>
            <com:stateOrCountry>NY</com:stateOrCountry>
            <com:zipCode>10169</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <saleDate>05/23/2024</saleDate>
        <amountOfSecuritiesSold>7351</amountOfSecuritiesSold>
        <grossProceeds>94129</grossProceeds>
      </securitiesSoldInPast3Months>
      <remarks>The shares filed today will be sold by Gad Enterprises, LLC, Thomas Gad, Manager</remarks>
      <noticeSignature>
        <noticeDate>06/10/2024</noticeDate>
        <signature>/s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for Thomas Gad</signature>
      </noticeSignature>
    </formData>
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metadata_documents: [{"type": "144", "sequence": "1", "filename": "primary_doc.xml", "secsgml_size_bytes": 4286}]
text: 144
  0001753224
  XXXXXXXX
  LIVE
  0001722964
  Y-mAbs Therapeutics, Inc.
  001-38650
  230 Park Avenue
  Suite 3350
  New York
  NY
  10169
  6468858505
  Thomas Gad
  Officer
  Common Stock
  J.P. Morgan Securities LLC
  390 Madison Avenue
  6th Floor
  New York
  NY
  10017
  70000
  838600
  43882638
  06/10/2024
  Nasdaq
  Common
  08/15/2015
  Private Investment
  Issuer
  N
  70000
  08/15/2015
  Cash
  N
  Gad Enterprises, LLC
  C/O Issuer
  230 Park Avenue, Suite 3350
  New York
  NY
  10169
  Common Stock
  05/21/2024
  25000
  296242
  Gad Enterprises, LLC
  C/O Issuer
  230 Park Avenue, Suite 3350
  New York
  NY
  10169
  Common Stock
  05/23/2024
  7351
  94129
  The shares filed today will be sold by Gad Enterprises, LLC, Thomas Gad, Manager
  06/10/2024
  /s/ J.P. Morgan Securities LLC as agent and attorney-in-fact for Thomas Gad