{
  "abstract": "Background Mesothelin (MSLN) is an attractive target for CAR T cell therapy in solid tumors due to its over-expression in tumors compared with normal tissues. A previous trial using second-generation MSLN CAR T (SS1-41BBz) demonstrated safety but limited clinical durability. 1 Two subsequent trials using CD3-based MSLN-targeted CAR T using different Ab binders reported serious on-target off-tumor toxicities in SAE.2 3 This highlights the need for safer and more effective CAR T therapies for solid tumors. We previously developed SynKIR-110, a multi-chain CAR T targeting MSLN using the SS1 binder fused to NK cell-signaling and activation molecules.4 This novel split-signal KIR-CAR design aims to prevent CD3-based T cell exhaustion and anti-tumor durability.Methods T cell phenotype and function of SynKIR-110 versus SS1-41BBz CAR T were evaluated in vitro in co-cultures with repeated exposure to MSLN- or MSLN+ target cell lines. Target cell killing was assessed using Incucyte assays, while T cell activation and exhaustion markers were analyzed by flow cytometry. For in vivo analysis, NSG mice were implanted subcutaneously with MSLN+ EM-meso tumors. After 6d, mice received low or high doses of SynKIR-110, SS1-41BBζ or non-transduced T cells via tail vein injection. Tumor size was measured over time via calipers, and histopathology was performed at an early (d11) and late (d32) timepoints post-infusion.Results In vitro SynKIR-110 showed sustained killing of MSLN+ targets with minimal activation or cytokine production against MSLN- cells, whereas SS1-41BBz CAR T exhibited increased off-target toxicity, progressive exhaustion, and loss of specificity. In vivo, SynKIR-110 induced robust tumor regression at both primary and metastatic sites, outperforming SS1-41BBz CAR T cells, which showed delayed tumor infiltration and limited efficacy. Moreover, SS1-41BBz CAR T cells accumulated in lungs and other normal tissues, while SynKIR-110 preferentially trafficked to tumors and avoided normal tissues infiltration. SynKIR-110 cell products also showed reduced activation and exhaustion markers expression at baseline.Conclusions SynKIR-110 T cells demonstrate superior anti-tumor activity and reduced non-specific activation and exhaustion compared to conventional 41BB-CD3z CAR T cells, both in vitro and in vivo. These results findings support SynKIR-110 as a promising candidate with improved safety and efficacy for targeting MSLN + tumors.References Haas, et al. Mol Ther. 2019 Nov 6;27(11):1919-1929.Atara Biotherapeutics, Inc. (2022, Feb 18. Atara Biotherapeutics Provides Update on ATA2271 Autologous CAR T Trial [Press Release]. https://www.businesswire.com/news/home/20220217006012/en/Atara-Biotherapeutics-Provides-Update-on-ATA2271-Autologous-CAR-T-TrialHaas, et al. Mol Ther. 2023 Aug 2;31(8):2309-2325.Wang, et al. Cancer Immunol Res. 2015 Jul;3(7):815-26.",
  "authors": [
    {
      "affiliations": [
        "Verismo Therapeutics, Philadelphia, PA, USA"
      ],
      "name": "Nora Yucel"
    },
    {
      "affiliations": [
        "Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA",
        "Center for Cellular Immunotherapies, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA"
      ],
      "name": "Selene Nunez-Cruz"
    },
    {
      "affiliations": [
        "Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA",
        "Center for Cellular Immunotherapies, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA"
      ],
      "name": "John Leferovich"
    },
    {
      "affiliations": [
        "Verismo Therapeutics, Philadelphia, PA, USA"
      ],
      "name": "Tony Truong"
    },
    {
      "affiliations": [
        "Verismo Therapeutics, Philadelphia, PA, USA"
      ],
      "name": "Megan Blair"
    },
    {
      "affiliations": [
        "Verismo Therapeutics, Philadelphia, PA, USA"
      ],
      "name": "Jun Xu"
    },
    {
      "affiliations": [
        "Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA",
        "Center for Cellular Immunotherapies, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA"
      ],
      "name": "Michael C Milone"
    },
    {
      "affiliations": [
        "Verismo Therapeutics, Philadelphia, PA, USA"
      ],
      "name": "Laura A Johnson"
    }
  ],
  "title": "298 A novel NK-cell based split-signaling killer immunoglobulin receptor (KIR)-based CAR T targeting mesothelin, SynKIR-110, shows increased safety profile and increased efficacy in vitro and in vivo",
  "uid": "7b9e1354-3bb1-5385-883f-e995ac4ec434"
}