A Study of PALI-2108 in Healthy Volunteers, Patients With Ulcerative Colitis, and Patients With Fibrostenosing Crohn's Disease

This is a Phase 1b, open-label, exploratory study designed to evaluate the pharmacodynamic effects of PALI-2108, a phosphodiesterase-4 (PDE4) inhibitor, in patients with fibrostenotic Crohn's disease (FSCD). The study will assess molecular, cellular, and histologic changes in intestinal tissue and peripheral blood following short-term oral administration of PALI-2108. Eligible participants with FSCD will undergo paired ileal pinch biopsies and peripheral blood collection at baseline and after 14 days of PALI-2108 treatment. The primary objective is to elucidate the mechanism of action of PALI-2108 in modulating inflammatory and fibrotic pathways relevant to FSCD pathobiology. Analyses will include single-nucleus RNA sequencing (snRNA-seq) of intestinal biopsies and single-cell RNA sequencing (scRNA-seq) of PBMCs to profile treatment-induced transcriptomic changes across immune and stromal cell populations. The FSCD cohort is part of a larger, multi-part study that also includes a completed Phase 1a first-in-human portion in healthy volunteers and an ulcerative colitis (UC) cohort evaluating clinical and biomarker responses to PALI-2108 treatment.