ISM012-042 (ISM5411), A PHD1/2 INHIBITOR, PREVENTATIVELY AND THERAPEUTICALLY MITIGATES T CELL TRANSFER-INDUCED COLITIS IN MICE

Abstract INTRODUCTION Inflammatory Bowel Disease (IBD) is driven by dysregulated mucosal immune responses, involving innate (e.g., macrophages, neutrophils, dendritic cells) and adaptive immune components, like Th17 and Th1 cells, which secrete pro-inflammatory cytokines. Current treatments, such as corticosteroids, 5-aminosalicylates, and anti-TNF-α antibodies, are limited by frequent relapses and side effects, including opportunistic infections. Previously, we demonstrated that ISM012-042, an orally administered gut-restricted small molecule, significantly alleviated symptoms in TNBS- and Oxazolone-induced acute colitis mouse models [1]. Here, we investigate the efficacy of ISM012-042 in a chronic T cell transfer-induced colitis model, informing safer and more effective IBD therapies. METHODS Female CB17 mice (8 weeks old) were randomized into one control group receiving Balb/c mouse-derived 5 × 105 CD4+CD45RBlow T cells IP and six groups receiving 5 × 105 CD4+CD45RBhigh T cells IP to induce colitis. Mice were treated with vehicle, ISM012-042 (10 or 30 mpk, PO, QD), anti-TNF-α (25 mpk, IP, Q3D), or combinations, administered either preventively (days 0–42) or therapeutically (days 21–42). Disease severity was monitored via body weight, Disease Activity Index (DAI) scores, and colon length, weight, and density. Cytokines (IL-6, IFN-γ, TNF-α, IL-17A) in intestinal mucosa at day 42 were quantified using CBA, and Swiss-rolled colon histopathology was evaluated with H&E and Masson staining. T cell subsets in mesenteric lymph nodes were quantified by flow cytometry. RESULTS Groups receiving preventative ISM012-042 or anti-TNF-α showed significantly reduced body weight loss, lower DAI scores, increased colon length, reduced colon weight, reduced local expression of inflammatory cytokines (IFN-γ, TNF-α, and IL-6), and decreased GATA3+, T-bet+, and IL-17A+ T cell subsets. Histological analysis also revealed less intestinal mucosa crypt damage, inflammatory cell infiltration, and fibrosis. Therapeutic dosing of ISM012-042, administered post-colitis induction, and its combination with anti-TNF-α reduced DAI scores, colon density, and cytokines (IL-6, IFN-γ, TNF-α, IL-17A). CONCLUSION ISM012-042, administered preventively or therapeutically, alone or with anti-TNF-α, effectively mitigated chronic T cell transfer-induced colitis by preserving colon integrity, and suppressing pro-inflammatory T cell subsets and cytokines, suggesting its potential as a versatile IBD therapy. References 1. Fu, Y., Ding, X., Zhang, M. et al. Intestinal mucosal barrier repair and immune regulation with an AI-developed gut-restricted PHD inhibitor. Nat Biotechnol (2024).