W172 - GNTI-932: Gut-specific CAR-Treg cells exhibit enhanced localization and therapeutic efficacy in pre-clinical models of colitis.

Abstract Text: Polyclonal Treg cells have demonstrated safety and tolerability in trials for refractory inflammatory bowel disease (IBD). However, limited efficacy has been observed, likely due to challenges in Treg persistence and target specificity. To overcome this shortcoming, we have developed an engineering strategy to generate Treg cells (EngTreg) from human bulk CD4 T cells that constitutively express FOXP3 for stability; contain a rapamycin-activated chemically induced IL-2 signaling complex (CISC) for persistence; and express a chimeric antigen receptor (CAR) specific to a gut antigen for localization, called GNTI-932. Here we evaluated the biological utility of our gut-specific CAR to support EngTreg gut localization and boost antigen-specific suppressive activity for the treatment of IBD. Murine CAR-EngTreg (CAR-mEngTreg) surrogates were generated and top candidates determined by an in vitro activation and suppression assay. Target specific CAR-mEngTregs rapidly homed to the gut over non-target tissue sites and were more proliferative, compared to non-target-CAR controls in naïve mice. Intravascular staining revealed reduced levels of circulating target specific CAR-mEngTregs in the vasculature of off-target tissues, particularly the lung. Preferential gut-localization and proliferation was also observed in an inflammatory model of acute colitis (Dextran-sodium-sulfate). Consequently, target specific CAR-mEngTreg cells significantly accelerated resolution of pathology in a CD45RBhi colitis model, characterized by reduced accumulation of inflammatory immune cells, biomarkers (lipocalin-2) of gut inflammation and histopathological scores. These data demonstrate our CAR-EngTreg strategy recognizing a gut specific target endows superior localization and efficacy profiles in preclinical models of colitis to enhance Treg therapies for IBD.