Inflammatory bowel disease and peptides — what the literature actually supports

Why this dossier exists

Inflammatory bowel disease — Crohn's disease and ulcerative colitis taken together — is a chronic, immune-mediated inflammatory condition of the gastrointestinal tract affecting an estimated 2.39 million adults in the United States (Lewis JD, Parlett LE, Jonsson Funk ML et al., Gastroenterology 2023, 165:1197–1205.e2) and roughly 6–7 million worldwide. The standard-of-care therapeutic ladder — 5-aminosalicylates for mild ulcerative colitis, corticosteroids for induction, immunomodulators (azathioprine, methotrexate) for maintenance, anti-TNF biologics (infliximab, adalimumab), anti-integrin (vedolizumab), anti-IL-12/23 (ustekinumab), IL-23 selective agents, and JAK inhibitors (tofacitinib, upadacitinib) — is one of the better-evidenced therapeutic landscapes in modern gastroenterology, with large multicenter randomized trials supporting each major class in moderate-to-severe disease.

Into the gap between that regimen and unmet patient need a recognisable peptide conversation has developed. The cluster the practitioner community has converged on is BPC-157 — the molecule originally characterised from human gastric juice, and the single peptide whose pharmaceutical development program for ulcerative colitis (PL 14736) reached Phase II — paired with KPV on a PepT1-transport and NF-κB-suppression mechanism documented across two independent 2008 mouse-colitis papers. Three further peptides circle the conversation at lower prevalence: Thymosin α-1 on immunomodulation case-series footing, ARA-290 / cibinetide on innate-repair-receptor anti-inflammatory mechanism, and the GLP-1 class (Semaglutide and tirzepatide) on a substantial 2024–2025 retrospective-cohort literature in IBD outcomes. Two non-stack comparators anchor the framing: teduglutide (Gattex / Revestive), the GLP-2 analog FDA-approved in 2012 for short bowel syndrome and the closest thing the field has to proof-of-concept that a GI peptide can carry rigorous development to a marketed indication; and larazotide acetate, the zonulin-antagonist octapeptide whose Phase III in celiac disease was discontinued for futility in 2022 and offers the most informative recent failure mode.

The honest read is uncomfortable for the practitioner framing. No published Phase II or III randomized controlled trial supports BPC-157 or KPV for induction or maintenance of remission in Crohn's disease or ulcerative colitis. The mechanistic literature is real, the rodent models are reproducible across independent laboratories, and the development programs that would have produced pivotal-trial data either did not publish results (PL 14736) or failed at the pivotal stage (larazotide for celiac). What the corpus does have is a teduglutide regulatory record that is not an IBD indication, and a rapidly expanding retrospective-cohort literature on GLP-1 receptor agonists in IBD where the signal is favourable but the trial design that would establish causality has not yet read out. Any peptide consideration in IBD is overlay on top of the standard medical regimen, not a substitute for it.