RT Journal Article
SR Electronic
T1 Shed antigen-induced blocking effect on CAR-T cells targeting Glypican-3 in Hepatocellular Carcinoma
JF Journal for ImmunoTherapy of Cancer
JO J Immunother Cancer
FD BMJ Publishing Group Ltd
SP e001875
DO 10.1136/jitc-2020-001875
VO 9
IS 4
A1 Luan Sun
A1 Fang Gao
A1 Zhanhui Gao
A1 Lei Ao
A1 Na Li
A1 Sujuan Ma
A1 Meng Jia
A1 Nan Li
A1 Peihua Lu
A1 Beicheng Sun
A1 Mitchell Ho
A1 Shaochang Jia
A1 Tong Ding
A1 Wei Gao
YR 2021
UL http://jitc.bmj.com/content/9/4/e001875.abstract
AB Background Glypican-3 (GPC3), a cell surface glycoprotein that is pathologically highly expressed in hepatocellular carcinoma (HCC), is an attractive target for immunotherapies, including chimeric antigen receptor (CAR) T cells. The serum GPC3 is frequently elevated in HCC patients due to the shedding effect of cell surface GPC3. The shed GPC3 (sGPC3) is reported to block the function of cell-surface GPC3 as a negative regulator. Therefore, it would be worth investigating the potential influence of antigen shedding in anti-GPC3 CAR-T therapy for HCC.Methods In this study, we constructed two types of CAR-T cells targeting distinct epitopes of GPC3 to examine how sGPC3 influences the activation and cytotoxicity of CAR-T cells in vitro and in vivo by introducing sGPC3 positive patient serum or recombinant sGPC3 proteins into HCC cells or by using sGPC3-overexpressing HCC cell lines.Results Both humanized YP7 CAR-T cells and 32A9 CAR-T cells showed GPC3-specific antitumor functions in vitro and in vivo. The existence of sGPC3 significantly inhibited the release of cytokines and the cytotoxicity of anti-GPC3 CAR-T cells in vitro. In animal models, mice carrying Hep3B xenograft tumors expressing sGPC3 exhibited a worse response to the treatment with CAR-T cells under both a low and high tumor burden. sGPC3 bound to CAR-T cells but failed to induce the effective activation of CAR-T cells. Therefore, sGPC3 acted as dominant negative regulators when competed with cell surface GPC3 to bind anti-GPC3 CAR-T cells, leading to an inhibitory effect on CAR-T cells in HCC.Conclusions We provide a proof-of-concept study demonstrating that GPC3 shedding might cause worse response to CAR-T cell treatment by competing with cell surface GPC3 for CAR-T cell binding, which revealed a new mechanism of tumor immune escape in HCC, providing a novel biomarker for patient enrolment in future clinical trials and/or treatments with GPC3-targeted CAR-T cells.All data relevant to the study are included in the article or uploaded as online supplemental information.