Armoring ROR1 CAR T cells with IL18 improves CAR T cell function and cytotoxicity against pancreatic cancer cell-lines in vitro and in vivo

ROR1 ( R eceptor tyrosine kinase-like O rphan R eceptor 1 ) is a tumor-associated antigen widely expressed in solid tumors and is a promising target for CAR T cell therapy in pancreatic cancer. Cell-based immunotherapy has met with limited success due in part to the immunosuppressive tumor microenvironment (TME). Here we demonstrate that armoring our previously described 1 ROR1 CAR T cell product with interleukin-18 (IL18) enhanced expansion, persistence, and antitumor efficacy against pancreatic cell lines both in vitro and in vivo . ROR-1-specific CAR-T cells were generated in human T cells using lentiviral vectors (LV) expressing a second generation CAR alone, CAR+ constitutive IL-18, or CAR+NFAT-IL18. IL18-ROR1 CAR T cells expanded 1.5 fold more, preserved naïve phenotype, and had reduced LAG3 expression (37% vs 81%) vs CAR. In vitro armored CAR cytotoxicity, determined by xCelligence tumor co-culture assays, was equal to or greater than CAR alone against ROR1(+) tumor cell lines. In an AsPC-1 mouse xenograft model, each CAR construct exhibited anti-tumor efficacy, with IL-18 expressing CARs displaying significantly greater tumor control. The constitutive IL18-CAR completely cleared tumor at day 28 post-T cell infusion and showed increased persistence throughout the study when compared to ROR1 CAR-T lacking IL-18 (Fig.1). CAR+NFAT-IL18 similarly controlled tumor growth compared to UTD. In summary, IL18 armored CAR T cells significantly improved the expansion, persistence, and antitumor efficacy of ROR1 CARs in pancreatic cancer xenograft models. Importantly, NFAT-promoter-based regulation of ROR1 CAR T may offer a viable approach to regulating potential toxicity while retaining boosted IL-18 induced activity. This armoring strategy may offer a promising approach solid tumor indications and warrants further preclinical and translational investigation. A B Fig 1. In vivo demonstration of effective constitutive and inducible IL18 armoring of ROR1 CAR T targeting pancreatic cell-lines. * p<0.05, ** p<0.01, *** p<0.001 Reference: 1. Tran TM et al. J Immunother Cancer 2024;12(4)