Abstract B22: A chimeric antigen receptor (CARs) based upon a killer immunoglobulin-like receptor (KIR) triggers robust cytotoxic activity in solid tumors

Abstract

Abstract Chimeric antigen receptors (CARs) based upon a single chimeric molecule bearing an antigen binding domain linked in cis to the cytoplasmic domains of CD3ζ and costimulatory receptors CD28 or 4-1BB provide a potent method for engineering T cell cytotoxicity towards tumors. We describe a simple chimeric multichain receptor based upon a killer immunoglobulin-like receptors (KIRs) normally expressed by natural killer (NK) cells and T cells. Constructed by fusing a single chain variable fragment (scFv) to the transmembrane and cytoplasmic domain of a KIR, we show that a KIR-based CAR targeting mesothelin (SS1-KIR) triggers antigen-specific cytotoxic activity and cytokine production that is comparable to CD3ζ-based CARs with antigen-induced proliferation that is independent of additional costimulation. Using a xenograft model of mesothelioma resistant to T cell immunotherapy, we further demonstrate that a KIR-based CAR targeting mesothelin exhibits more potent anti-tumor activity compared with T cells bearing mesothelin-specific CD3ζ-based CARs with costimulation despite in vivo persistence of the latter CAR-modified T cells. Evaluation of tumor infiltrating lymphocytes demonstrate that KIR-based CAR+ T cells show resistance to acquired hypofunction within the tumor microenivornment compared with CD3ζ-based CARs with costimulatory receptor domains. The ability of a KIR-based CAR to induce regression of a tumor in which second generation CD3ζ-based CARs show limited activity supports the future clinical evaluation of a KIR-based CAR in mesothelioma and other tumors. Citation Format: Enxiu Wang, Liang-Chuan Wang, Ching-Yi Tsai, Vijay Bhoj, Steven Albelda, Edmund Moon, Michael C. Milone. A chimeric antigen receptor (CARs) based upon a killer immunoglobulin-like receptor (KIR) triggers robust cytotoxic activity in solid tumors. [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy: A New Chapter; December 1-4, 2014; Orlando, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2015;3(10 Suppl):Abstract nr B22.