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          <com:street1>830 WINTER ST</com:street1>
          <com:city>WALTHAM</com:city>
          <com:stateOrCountry>MA</com:stateOrCountry>
          <com:zipCode>02451</com:zipCode>
        </issuerAddress>
        <issuerContactPhone>(781)895-0600</issuerContactPhone>
        <nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>Lentini Renee</nameOfPersonForWhoseAccountTheSecuritiesAreToBeSold>
        <relationshipsToIssuer>
          <relationshipToIssuer>Officer</relationshipToIssuer>
        </relationshipsToIssuer>
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      <securitiesInformation>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <brokerOrMarketmakerDetails>
          <name>Merrill Lynch</name>
          <address>
            <com:street1>225 Liberty St</com:street1>
            <com:street2>Floor 37</com:street2>
            <com:city>New York</com:city>
            <com:stateOrCountry>NY</com:stateOrCountry>
            <com:zipCode>10281</com:zipCode>
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        <aggregateMarketValue>77075.15</aggregateMarketValue>
        <noOfUnitsOutstanding>266264274</noOfUnitsOutstanding>
        <approxSaleDate>02/05/2024</approxSaleDate>
        <securitiesExchangeName>NASDAQ</securitiesExchangeName>
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        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <acquiredDate>02/03/2024</acquiredDate>
        <natureOfAcquisitionTransaction>Vesting of restricted stock unit award</natureOfAcquisitionTransaction>
        <nameOfPersonfromWhomAcquired>ImmunoGen, Inc.</nameOfPersonfromWhomAcquired>
        <isGiftTransaction>N</isGiftTransaction>
        <amountOfSecuritiesAcquired>2631</amountOfSecuritiesAcquired>
        <paymentDate>02/03/2024</paymentDate>
        <natureOfPayment>Granted as part of issuer equity compensation plan</natureOfPayment>
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          <name>Renee Lentini</name>
          <address>
            <com:street1>830 WINTER ST</com:street1>
            <com:city>WALTHAM</com:city>
            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>02451</com:zipCode>
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        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <saleDate>11/06/2023</saleDate>
        <amountOfSecuritiesSold>219545</amountOfSecuritiesSold>
        <grossProceeds>3356795.85</grossProceeds>
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          <name>Renee Lentini</name>
          <address>
            <com:street1>830 WINTER ST</com:street1>
            <com:city>WALTHAM</com:city>
            <com:stateOrCountry>MA</com:stateOrCountry>
            <com:zipCode>02451</com:zipCode>
          </address>
        </sellerDetails>
        <securitiesClassTitle>Common Stock</securitiesClassTitle>
        <saleDate>12/26/2023</saleDate>
        <amountOfSecuritiesSold>6548</amountOfSecuritiesSold>
        <grossProceeds>194760.72</grossProceeds>
      </securitiesSoldInPast3Months>
      <noticeSignature>
        <noticeDate>02/05/2024</noticeDate>
        <planAdoptionDates>
          <planAdoptionDate>06/06/2023</planAdoptionDate>
        </planAdoptionDates>
        <signature>Renee Lentini</signature>
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text: 144
  0001838777
  XXXXXXXX
  LIVE
  0000855654
  ImmunoGen, Inc.
  000-17999
  830 WINTER ST
  WALTHAM
  MA
  02451
  (781)895-0600
  Lentini Renee
  Officer
  Common Stock
  Merrill Lynch
  225 Liberty St
  Floor 37
  New York
  NY
  10281
  2631
  77075.15
  266264274
  02/05/2024
  NASDAQ
  Common Stock
  02/03/2024
  Vesting of restricted stock unit award
  ImmunoGen, Inc.
  N
  2631
  02/03/2024
  Granted as part of issuer equity compensation plan
  N
  Renee Lentini
  830 WINTER ST
  WALTHAM
  MA
  02451
  Common Stock
  11/06/2023
  219545
  3356795.85
  Renee Lentini
  830 WINTER ST
  WALTHAM
  MA
  02451
  Common Stock
  12/26/2023
  6548
  194760.72
  02/05/2024
  06/06/2023
  Renee Lentini