Adoptive immunotherapy based on
chimeric antigen receptor-modified T (CAR-T) cells has been demonstrated as one of the most promising therapeutic strategies in the treatment of
malignancies. However, CAR-T cell therapy has shown limited efficacy for the treatment of solid
tumors. This is, in part, because of
tumor heterogeneity and a hostile tumor microenvironment, which could suppress adoptively transferred T cell activity. In this study, we, respectively, engineered human- or murine-derived-armored
glypican-3 (GPC3)-specific CAR-T cells capable of inducibly expressing
IL-12 (GPC3-28Z-NFAT-IL-12) T cells. The results showed that GPC3-28Z-NFAT-IL-12 T cells could lyse GPC3+
tumor cells specifically and increase
cytokine secretion compared with GPC3-28Z T cells in vitro. In vivo, GPC3-28Z-NFAT-IL-12 T cells augmented the antitumor effect when encountering GPC3+ large
tumor burdens, which could be attributed to
IL-12 increasing IFN-γ production, favoring T cells infiltration and persistence. Furthermore, in immunocompetent hosts, low doses of GPC3-m28Z-mNFAT-mIL-12 T cells exerted superior antitumor efficacy without prior conditioning in comparison with GPC3-m28Z T cells. Also, mIL-12 secretion decreased regulatory T cell infiltration in established
tumors. In conclusion, these findings demonstrated that the inducible expression of
IL-12 could boost CAR-T function with less potential side effects, both in immunodeficient and immunocompetent hosts. The inducibly expressed IL-12-armored GPC3-CAR-T cells could broaden the application of CAR-T-based
immunotherapy to patients intolerant of lymphodepletion
chemotherapy and might provide an alternative therapeutic strategy for patients with GPC3+
cancers.