Abstract 4810: Metabolic reprogramming enhances IL15-GPC3-CAR T cell therapy for hepatocellular carcinoma while mitigating cytokine release syndrome

Abstract Background: This study aims to develop a safer and more effective CAR T cell therapy for hepatocellular carcinoma (HCC). While recent clinical trials have shown promise, IL15-GPC3-CAR T cells demonstrated a 33% partial response rate but were associated with a high incidence of cytokine release syndrome (CRS), occurring in 75% of patients (9/12) compared to 8% (1/12) in GPC3-CAR T cells. Thus, strategies to mitigate CRS while enhancing efficacy are urgently needed. We previously demonstrated that inosine could serve as an alternative energy source for CAR T cells in the glucose-deprived tumor microenvironment (TME) (Nat Metabolism, 2020). More recently, we provided proof of concept that a metabolic reprogramming strategy involving adenosine deaminase 1 (ADA1) enhances T cell survival by converting adenosine to inosine while reducing pro-inflammatory cytokine production (Cell Rep Med, 2024). In this study, we aim to improve IL15-armed GPC3-CAR T cell therapy for HCC by leveraging ADA1 signaling to enhance CAR T cell persistence in the TME while mitigating inflammatory responses, potentially reducing the risk of CRS. Methods: Human PBMCs were transduced with retroviral vectors encoding IL15-GPC3-CAR and ADA1 (designated IL15-GPC3-MRCAR). Antitumor efficacy and toxicity were evaluated in a Huh7 xenograft mouse model. Cytokine levels and mouse survival were measured to assess immune activation and CRS risk. Results: IL15-GPC3-MRCAR T cells demonstrated enhanced proliferation and reduced exhaustion following repeated HCC stimulation in vitro. They also exhibited superior cytotoxic activity compared to IL15-GPC3-CAR or GPC3-MRCAR T cells both in vitro and in vivo. Notably, in the mouse study, IL15-GPC3-CAR T cells resulted in mortality rates comparable to the PBS-treated group, likely due to severe CRS. In contrast, IL15-GPC3-MRCAR T cells significantly extended survival, with outcomes similar to those observed in GPC3-CAR T cells and GPC3-MRCAR T cells groups. Conclusions: IL15-GPC3-MRCAR T cell therapy enhances metabolic fitness and reduces CRS risk, representing a promising advancement in GPC3-targeted therapy for HCC. Further clinical validation is warranted. Citation Format: Kevin Song, Yue Hu, Abhijit Sarkar, Andras Heczey, Xiaotong Song. Metabolic reprogramming enhances IL15-GPC3-CAR T cell therapy for hepatocellular carcinoma while mitigating cytokine release syndrome [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 4810.