{
  "abstract": "Background T Cell Receptor (TCR)-based therapies targeting tumor-associated antigens or cancer neoantigens have shown promising clinical outcomes in recent years. The cancer/testis antigen MAGE-A1 represents one of the popular targets of the MAGE family due to its prevalence in multiple types of cancer and limited expression in normal tissue. TCR-T and soluble TCR-based T cell engagers targeting MAGE-A1 are promising therapeutic approaches for the treatment of multiple cancer indications.Methods TCR discovery targeting the MAGE-A1 96-104:HLA-A*03:01 epitope was performed on PBMCs from melanoma patients using ShennonBio’s proprietary functional profiling platform. Reactive T cells were single-cell sorted and sequenced for their TCR. Identified TCR candidates were expressed in TCR KO Jurkat cells and analyzed for their functional avidity (EC50) by co-culturing with engineered antigen presenting cells pulsed with various concentrations of MAGE-A1 peptide. Lead TCR candidates were then transduced into TCR KO primary T cells of multiple healthy donors and further evaluated for their responses against HLA-A*A03:01+ target cell lines expressing various levels of endogenous MAGE-A1. Engineered TCR-T cells were cocultured with target cells and analyzed for their activation marker expression, cytokine production and target cell lysis. Finally, one of the lead TCRs was tested for its tumor control in a MAGE-A1+ cell line derived xenograft mouse model treated with engineered TCR-T cells.Results The EC 50 values of identified TCRs targeting the MAGE-A196-104:HLA-A*03:01 epitope are within 1 – 500 nM as measured by CD69 upregulation on TCR-transduced Jurkat cells upon peptide stimulation. Engineered TCR-T cells expressing the lead TCRs demonstrated robust upregulation of activation markers (CD137, CD69, and CD25) and cytokine (IFNγ and IL2) secretion after co-culture with HLA-A*03:01+ cell lines of various cancer types expressing endogenous MAGE-A1. No responses were observed against control cell lines that do not express MAGE-A1 or HLA-A*03:01. Engineered TCR-T cells also mediated efficient target cell lysis at low effector : target ratios in cytotoxicity assays. When administered into immunodeficient mice implanted with MAGE-A1-expressing tumor cells, MAGE-A1-specific TCR-T cells were able to control tumor growth and extend animal survival compared to control TCR-T cells.Conclusions Our results demonstrate the successful identification and validation of potent tumor-targeting TCRs using ShennonBio’s proprietary functional profiling platform. The lead TCRs achieved efficient tumor control both in vitro and in vivo without additional affinity optimization, and were therefore advanced as candidates for the development of TCR-based therapies targeting MAGE-A1+ cancers in HLA-A*03:01+patients.Ethics Approval Patient samples and the patient-derived melanoma tumor cell line were collected under IRB # 15781 and IRB # 10958 of University of Virginia. Animal studies were performed following protocols approved by AAALAC and IACUC.",
  "authors": [
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Kaitao Li"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Michael J Malone"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Yih Yang Chen"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Sonali Kanaya"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Kelsy Cotto"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Naomi Ptak"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Paul Shafer"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Bianca Pierrat"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Jonathan DiRusso"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Nathan Ng"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Lauren Hunter"
    },
    {
      "affiliations": [
        "University of Virginia, Charlottesville, VA, USA"
      ],
      "name": "Craig L Slingluff"
    },
    {
      "affiliations": [
        "Shennon Biotechnologies, San Francisco, CA, USA"
      ],
      "name": "Li Sun"
    }
  ],
  "title": "335 Discovery and characterization of MAGE-A1-specific TCR candidates for TCR-based cancer therapy",
  "uid": "9ff6843d-e2fb-5188-9a9c-034d1a487cb5"
}