Abstract 2311: Analysis of glypican 3-targeted chimeric antigen receptor T cells in hepatocellular carcinoma cell and mouse models

Abstract

Abstract Background: Glypican-3 (GPC3) is a cell surface protein that is highly expressed in hepatocellular carcinoma (HCC). Methods and Results: In this report, we analyzed two chimeric antigen receptors (CARs) targeting GPC3, CAR (HN3) recognizes the N-lobe of GPC3 while CAR (hYP7) targets the C-lobe that is close to the cell surface. In a real-time cell cytolytic assay, we found that CAR (hYP7) T cells showed higher cytolytic activity than CAR(HN3) T cells at an E:T ratio of 2:1 when co-cultured with HepG2 cells for up to 140 hours. The Luminex analysis showed that CAR (hYP7) T cells produced significantly more Th1/Th2 cytokines and chemokines than CAR (HN3) T cells following exposure to Hep3B and HepG2 cells. In the Hep3B peritoneal dissemination xenograft mouse model, a single intraperitoneal infusion of CAR (hYP7) cells exhibited sustainable antitumor efficacy, and all of the mice survived without recurrence 10 weeks post treatment. Strikingly, we demonstrated that single injection of CAR (hYP7) T cells derived from either healthy donor or HCC patient significantly regressed tumor growth in the orthotopic HCC mouse model. Using a highly sensitive droplet digital PCR (ddPCR), we detected high frequencies of CAR T cells in the spleen and tumor microenvironment of mice in the CAR (hYP7) group. By contrast, CD19 CAR T cells showed no sign of gene integration in either tissue. More importantly, we found that CD8+ CAR (hYP7) T cells recovered from mouse spleens exhibited much higher lytic activity against HCC cells than CD4+ CAR (hYP7) T cells. Finally, we found that the GPC3-targeted CAR T cells downregulated the Wnt signaling in HCC cells. Conclusion: The hYP7 antibody-derived GPC3-specific CAR is a promising therapeutic that could be tested for the treatment of advanced stage liver cancer. Citation Format: Dan Li, Nan Li, Yifan Zhang, Haiying Fu, Zhijian Duan, Alissa Hummer, Hongjia Yang, Madeline B. Torres, Xiaoling Luo, Ling Su, Hu Zhu, Josh Kramer, Jinqiu Chen, Xiaolin Wu, Matthew Hall, Qun Wang, Stephen Hewitt, Tim Greten, Mitchell Ho. Analysis of glypican 3-targeted chimeric antigen receptor T cells in hepatocellular carcinoma cell and mouse models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2311.