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A.J. Bograd

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    ORAL 28 - T Cell Therapy for Lung Cancer (ID 132)

    • Event: WCLC 2015
    • Type: Oral Session
    • Track: Biology, Pathology, and Molecular Testing
    • Presentations: 1
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      ORAL28.02 - Mesothelin-Targeted CAR T-Cell Therapy for the Treatment of Heterogeneous Antigen-Expressing Lung Adenocarcinoma (ID 3172)

      16:45 - 18:15  |  Author(s): A.J. Bograd

      • Abstract
      • Slides

      Adoptive T-cell therapy using chimeric antigen receptors (CAR) is an emerging strategy by redirecting T-cell effector functions against a cancer cell-surface antigen. To target lung adenocarcinoma (ADC) by CAR T-cell therapy, our laboratory has identified mesothelin (MSLN), a cell-surface antigen based on our published observation that MSLN is expressed in 60% of primary and metastatic lung ADC and is associated with tumor aggressiveness. Unlike hematological malignancies where CAR T-cell therapy has been successful targeting CD19, a cell-surface antigen that is uniformly expressed on B cells, MSLN expression intensity and distribution among lung ADC tumors is heterogeneous. The efficacy of CAR T-cell therapy in a heterogeneous antigen microenvironment is unknown. We hypothesized that the MSLN-targeted CAR T cells will be effective against high-antigen expressing lung ADC cells and the presence of even a small proportion of high MSLN expressing cells can enhance CAR T-cell cytotoxicity against low-antigen expressing lung ADC cells.

      Human peripheral blood T cells were retrovirally transduced with a 2[nd] generation of CAR targeting MSLN and bearing CD28 and CD3zeta activation domains. In vitro, we analyzed CAR T-cell cytotoxicity ([51]Cr release assay), effector cytokine secretion (Luminex assay), and proliferation (cell-counting assay) against lung ADC cell lines expressing variable levels of MSLN. In vivo, antitumor efficacy was evaluated by median survival and tumor bioluminescence (BLI) in mice bearing established homogeneous or heterogeneous lung ADC tumors.

      In in vitro assays utilizing lung ADC cells with variable level of MSLN expression [low-antigen expression (EKVX or A549) or high-antigen expression (A549M and H1299M), control lung fibroblast (MRC5) or mesothelial cells (MET5A)], CAR T cells exhibit antigen-specific cytolytic activity, effector cytokine secretion and proliferation in proportion to the MSLN expression on cancer cells. In vivo, a single low dose of CAR T cells eradicates primary and metastatic established tumor expressing high-level of MSLN and prolongs tumor free survival (41 days vs not reached, p<0.0001). We next evaluated CAR T-cell efficacy in heterogeneous antigen microenvironment by mixing low and high antigen-expressing cells (A549 expressing firefly luciferase/A549M) and assessed the A549 tumor burden only by bioluminescence imaging. In the presence of A549M cells, CAR T cells are able to prolong progression-free survival of A549 tumor burden (22 days vs 0 days in absence of A549M cells). Further mechanistic studies demonstrated that CAR T cells lysed an additional 5%-15% A549 or EKVX cells in the presence of H1299M or A549M cells (p<0.05) without off-target cytotoxicity. Antigen-activated CAR T cells were effective against low-antigen expressing lung ADC cells without the need for high-antigen expressing cells in the coculture.

      Our results provide scientific rationale to translate MSLN-targeted CAR T-cell therapy for the treatment of the primary and metastatic lung ADC. A phase I clinical trial (NCT02414269) that includes lung ADC patients is initiated at our center.

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