Armored Inducible Expression of IL-12 Enhances Antitumor Activity of Glypican-3–Targeted Chimeric Antigen Receptor–Engineered T Cells in Hepatocellular Carcinoma

Abstract

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.

Repurposing endogenous immune pathways to tailor and control chimeric antigen receptor T cell functionality

“…We benchmarked our repurposing strategy to the engineering approach developed earlier to reexpress IL-12P70 20,21,46,47 in a tumor cell-dependent manner. To do so, we first assessed the level of IL-12P70 secreted by T cell transduced with increasing amounts of rLV particles encoding NFAT IL-12P70, a construct previously designed to express an IL-12P70 under the control of 6xNFAT promoter 20,21 .…”

Design and Characterization of an “All-in-One” Lentiviral Vector System Combining Constitutive Anti-GD2 CAR Expression and Inducible Cytokines

“…Previously published concepts of CAR T cells that secrete additional effector molecules are mostly based on transduction protocols that involve the delivery of two-vectors [19,38]. Recently, Liu et al described a one-vector system for inducible cytokine expression driven by an NFAT promoter element with six NFAT response elements that is activated following activation of a constitutively expressed Glypican-3 (GP3)-CAR, and they nicely demonstrated the functionality of their one-vector system in in vivo mouse models for hepatocellular carcinoma (HCC) [21]. Similar to the one-vector system by Liu et al, the vector system described here offers a versatile cell modification strategy.…”

“…In this direction, the TRUCK ("T cell redirected for universal cytokine-mediated killing") concept was established, which equips CAR-redirected T cells with an additional NFAT (nuclear factor of activated T cells) inducible cytokine response that results in the restricted locoregional release of a transgenic cytokine upon CAR engagement of cognate target cells. The TRUCK approach can strengthen T cell activation and shape the TME by attracting innate immune cells to provide a more successful attack against tumor cells [17][18][19][20][21]. CAR T cells designed to release transgenic, inducible IL12 had improved cytolytic activity against solid tumors and increased the accumulation of activated macrophages and innate immune cells in the tumor tissue without inducing systemic toxicity in a murine model [19].…”

Recent Advances in Allogeneic CAR-T Cells

“…IL12 released from activated CAR-T is deposited around the target tumor lesion before attracting innate immune cells such as natural killer cell and macrophages that can kill the tumor cells that are invisible to CAR-T cells [31,32]. The fourth generation CAR-T system utilizing an NFAT transcription factor to stimulate IL12 production has been tested on various tumors including solid tumors and showed promising results [33][34][35][36][37].…”