Abstract 571: Inclusion of a Dap10 costimulatory domain decreases cytokine release syndrome in chimeric antigen-expressing gamma delta T cells

Abstract

Abstract Adoptive transfer of T cells is a promising anti-tumor therapy for many cancers. To enhance tumor recognition by T cells, chimeric antigen receptors (CAR) consisting of signaling domains fused to receptors that recognize tumor antigens can be expressed in T cells. While CAR T cells can successfully treat hematopoietic malignancies, CAR T cells have not shown success in treating solid tumors. There are many factors that may enhance CAR T cell efficacy and safety for solid tumor treatment, including addition of costimulatory domains to increase T cell functions and switching the T cell type used from alpha beta to gamma delta T cells. We developed a novel CAR (chimeric PD-1, chPD1) that targets the programmed death 1 receptor (PD-1) ligands expressed on many types of solid tumors. The aim of this study was to compare anti-tumor efficacy and safety of chPD1-expressing gamma delta and alpha beta T cells in murine breast and ovarian cancer models. Inclusion of different costimulatory domains, CD28, 4-1BB, and Dap-10, in the chPD1 receptor was also compared. There were no differences in T cell viability and proliferation when comparing costimulatory domains or T cell type. Additionally, there were no significant differences in killing of murine breast and ovarian cancer cell lines. ChPD1-CD28 T cells had increased secretion of proinflammatory and cytokine release syndrome (CRS)-inducing cytokines, including IFN-gamma, IL-2, IL-6, GM-CSF, and nitric oxide, compared to chPD1-41BB and chPD1-Dap10 receptors. Additionally, alpha beta chPD1 T cells had increased cytokine secretion of inflammatory cytokines compared to chPD1 gamma delta T cells. Furthermore, while gamma delta and alpha beta T cells expressing chPD1 receptors with a Dap10 domain had similar anti-tumor efficacy in vivo, chPD1-Dap10 gamma delta T cells had the lowest serum levels of inflammatory cytokines IFN-gamma, IL-6, and GM-CSF. Therefore, inclusion of Dap10 domains in gamma delta T cells may be a safer and more efficacious option for CAR T cell therapy of solid tumors. Citation Format: Amorette E. Barber. Inclusion of a Dap10 costimulatory domain decreases cytokine release syndrome in chimeric antigen-expressing gamma delta T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 571.