Abstract 4105: Improvement of CD133-specific chimeric antigen receptor T cells by secreting anti-PD-L1 single-chain variable fragment against cholangiocarcinoma

Abstract

Abstract Cholangiocarcinoma (CCA) is rare but hard-to-treat solid cancer affecting people worldwide. Cancer stem cells (CSCs) in CCA contribute to tumor heterogeneity and resistance to conventional therapies. Thus, CSCs are notable targets for cancer immunotherapy. CD133 is a potential CSC surface marker overexpressed in various cancers. T cell-based immunotherapy, namely chimeric antigen receptor (CAR) T-cell targeting CD133 has shown potential in eradication of some solid tumors including CCA. Nevertheless, anti-tumor function of CAR T cell could be decreased under immunosuppressive tumor microenvironment (TME). Thus, to improve its function under TME, the next-generation of CD133-specific CAR T-cell is required. We therefore constructed two lentiviral vectors containing: (i) anti-CD133 single-chain variable fragment (scFv), 4-1BB costimulatory molecule, and CD3ζ (133CAR), and (ii) anti-CD133 scFv, 4-1BB, and CD3ζ in tandem with anti-PD-L1 scFv (133CARsL). The lentiviruses were transduced to generate CD133-specific CAR T cells expressing the second-generation (133CART) or anti-CD133 CAR with self-secreting anti-PD-L1 scFv (133CARTsL). The latter was able to simultaneously target CD133 and PD-L1 molecules on CCA cells. CCA cells endogenously expressing CD133 and PD-L1 were cocultured with either 133CART or 133CARTsL. In short-term coculture, the antitumor effects of 133CARTsL were not different from that of 133CART. However, in long-term coculture and after tumor re-challenge, 133CARTsL showed lower expression of programmed cell death protein (PD-1) and better cytotoxic function against high CD133 and PD-L1 CCA cells. The higher potential of 133CARTsL with reduced exhaustion profile would offer great promise for application of CD133-targeting CAR T cells in solid tumors. Citation Format: Thanich Sangsuwannukul, Kamonlapat Supimon, Thaweesak Chieochansin, Kornkan Choomee, Jatuporn Sujjitjoon, Mutita Junking, Pa-thai Yenchitsomanus. Improvement of CD133-specific chimeric antigen receptor T cells by secreting anti-PD-L1 single-chain variable fragment against cholangiocarcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4105.