Abstract 6094: Enhanced GPC3-chimeric antigen receptor T cells with secreted bi-specific CD39-PD-L1 antibody for improved liver cancer therapy

Abstract Glypican-3 (GPC3)-targeted chimeric antigen receptor (CAR) T cell therapy shows promise for treating liver cancer. However, the immunosuppressive tumor microenvironment (TME), characterized by elevated levels of adenosine and PD-L1 expression, significantly hinders CAR T cell efficacy. We previously demonstrated that a bi-specific antibody, OriA631-B, which targets CD39—an enzyme crucial for converting extracellular ATP into adenosine—and PD-L1, yields significant antitumor effects. Our findings indicate that GPC3 CAR T cells upregulate CD39 upon activation by liver cancer cells, which also express PD-L1.To enhance antitumor efficacy, we engineered GPC3 CAR T cells to secrete a fragment of OriA631-B that targets both CD39 and PD-L1 (termed GPC3 CAR-T-CD39-VHH-PD-L1-ScFv). In a mouse model of liver cancer, GPC3 CAR-T-CD39-VHH-PD-L1-ScFv exhibited superior antitumor activity compared to GPC3 CAR T cells alone. Specifically, while GPC3 CAR T cells inhibited tumor growth, the GPC3 CAR-T-CD39-VHH-PD-L1-ScFv nearly eliminated tumors by day 20, whereas tumors in the GPC3 CAR T group measured around 200 mm3.This enhanced efficacy is attributed to the localized delivery of the bi-specific antibody fragment, which effectively inhibits adenosine signaling and PD-L1-mediated immune checkpoint blockade. Our findings suggest that GPC3 CAR-T-CD39-VHH-PD-L1-ScFv represents a novel therapeutic strategy for liver cancer, offering improved efficacy and potentially reduced side effects associated with systemic antibody administration. Citation Format: Zhongliang Li Bing Liu Huajing Wang Ke He Xiaopei Li, Dingjie Liu, Ligong Lu, Xu He, Xiaowen He, Ze Yang, Meixiao Zhan. Enhanced GPC3-chimeric antigen receptor T cells with secreted bi-specific CD39-PD-L1 antibody for improved liver cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6094.