Abstract 2838: Antigen-independent expansion enhances efficacy of CAR-T cells against solid tumor

Abstract One key hurdle for the CAR-T cell treatment of solid tumors is the limited accessibility of solid tumor antigens outside the tumor microenvironment, which prohibits the expansion of solid tumor-targeting CAR-T cells in patients. Here, we report the characterization of prostatic acid phosphatase (PAP) as a feasible CAR-T target for prostate cancer and a novel approach, named CoupledCAR, to expand solid tumor-targeting CAR-T cells lacking solid tumor antigens based on the observation of non-transduced T cells proliferating together with CD19 CAR-T cells during the treatment of acute lymphocyte leukemia. We demonstrated that CoupledCAR can significantly enhance the expansion and antitumor efficacy of PAP CAR-T cells both in vitro and in vivo. Furthermore, we showed that the expansion of solid tumor-targeting CAR-T cells does not depend on CAR/CD3ζ stimulation through direct antigen binding with CAR but enhances the memory status of CAR-T cells and causes little exhaustion. Since the CoupledCAR system does not rely on solid tumor antigens, we propose that it can be utilized in all CAR-T and T cell therapies for the treatment of solid tumors. Citation Format: Zhiyuan Cao, Chengfei Pu, Xianyang Jiang, Guiting Han, Yuzhe Peng, Wensheng Wang, Wei Ding, Xiaogang Shen, Dongqi chen, Beibei Jia, Xiaoqiang Xu, Zhipeng Huang, Xi Huang, Wenbi Liu, Ruihong Zhu, Lee Tian, Christopher Ballas, Victor.X Lu, Zhao Wu, Lei Xiao. Antigen-independent expansion enhances efficacy of CAR-T cells against solid tumor [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 2838.