{
  "abstract": "Background Metastatic castration-resistant prostate cancer (mCRPC) remains a disease with low long-term survival, and while new modalities are showing progress, there is still an unmet need for durable responses in advanced mCRPC patients. While CAR T cells have shown remarkable success in hematological cancers, activity in solid tumors is limited by off-tumor toxicity, antigen heterogeneity, poor persistence, and functional suppression resulting from the tumor microenvironment (TME). To address these challenges, we have developed AB-3028, an autologous logic-gated CAR T cell product for the potential treatment of mCRPC. The AB-3028 DNA cassette that is introduced by non-viral engineering includes three functional modules: a sequential ‘AND’ logic gate designed to limit off-tumor toxicity through dual antigen recognition; an improved shRNA-miR module targeting FAS and TGFβR2 designed to resist TME suppression; and a synthetic pathway activator (SPA) designed to potentiate long-term functional persistence of T cells.Methods The expression of tumor antigens was evaluated by IHC on tumor samples from mCRPC patients and tumor cell lines. The dual-antigen specificity of AB-3028 was evaluated in vitro using single antigen- and dual antigen-expressing target cells, and in vivo using single antigen- and dual antigen-positive tumors established on contralateral flanks. In vitro repetitive tumor challenge assay was performed with dual antigen-positive tumor cells to assess the functional contributions of the SPA and TGFβR2 shRNA modules. In addition, AB-3028 anti-tumor activity and the capability to overcome TME-mediated suppression were also assessed in vivo using a PC3 mCRPC xenograft model. A constitutive CAR incorporating a dominant-negative TGF-β receptor (dnTGFβRII) was used as a reference control.Results Tumor lines with physiological levels of the target antigens were validated. In both in vitro co-cultures and the dual-flank in vivo xenograft model, AB-3028 demonstrated anti-tumor responses against cells co-expressing the antigens, while showing minimal activity against tumors expressing one of the antigens alone. AB-3028 maintained long-term killing during an in vitro repetitive stimulation assay, which was dependent on SPA and TGFβR2 shRNA modules. AB-3028 exhibited anti-tumor efficacy in the PC3 indication specific xenograft model and provided a survival benefit at doses 4-fold lower compared to a constitutive CAR including a dominant-negative TGF-β receptor (dnTGFβRII).Conclusions Preclinical data demonstrate that AB-3028 has selectivity for tumors, as well as multiple engineered features that enhance T cell fate and function in the tumor microenvironment. These results support the evaluation of AB-3028 in the clinic for the treatment of mCRPC.",
  "authors": [
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Suchismita Mohanty"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Hongruo Yun"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Alma Gomez"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Jeremy Chen"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Xinyan Tang"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Vince Thomas"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Nickolas Attanasio"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Amanda Fearon"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Neroli Xie"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Stanley Zhou"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Stephen Santoro"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Alba Gonzalez"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Jun Feng"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Christopher L Murriel"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "Aaron Cooper"
    },
    {
      "affiliations": [
        "ArsenaBio, South San Francisco, CA, USA"
      ],
      "name": "W Nicholas Haining"
    }
  ],
  "title": "256 Preclinical development of AB-3028, a logic-gated engineered CAR T cell product intended for the treatment of metastatic castration-resistant prostate cancer (mCRPC)",
  "uid": "75da5a8c-c557-527e-9e76-d3b20bf069be"
}