PiggyBac-engineered T cells expressing a glypican-3-specific chimeric antigen receptor show potent activities against hepatocellular carcinoma

Abstract

Glypican-3 (GPC3) is an attractive target for chimeric antigen receptor (CAR)-T cell therapy, as it is overexpressed in most hepatocellular carcinoma (HCC) tissues but shows restricted expression in healthy adult tissues. Herein, we generated GPC3-specific CAR-T cells for HCC therapy by electroporation with plasmid DNA encoding the piggyBac (PB) transposon and the hyperactive piggyBac transposase simultaneously instead of by commonly-used viral vectors. Our results demonstrated that GPC3CAR gene was efficiently integrated into the genome of T cells utilizing the PB transposon system. Upon stimulation with GPC3 antigen, GPC3CAR-T cells could be effectively activated, proliferate strongly and secrete high levels of cytokines. It also was demonstrated that GPC3CAR-T cells displayed potent cytotoxicity against GPC3-positive HCC cell lines in vitro by using real-time cell analyser (RTCA) system and the JuLI™ Stage Cell History Recorder. More importantly, in a Huh-7 xenograft mouse model, GPC3CAR-T cells significantly reduced the tumour burden companied with the secretion of high levels of IFN-γ. Moreover, T cells in mice treated with GPC3CAR-T cells could infiltrate into tumour tissues and persist as effector memory T cells (TEM). Overall, our study suggests that the use of PB system-based GPC3CAR-T cell therapy could be a promising clinical strategy for patients with HCC.

Keywords: Chimeric antigen receptor; Glypican-3; Hepatocellular carcinoma; piggyBac transposon.