Ulcerative Colitis Clinical Trial Monitor — IL-23, JAK, S1P & TL1A Programs

The ulcerative colitis trial landscape in 2026

Ulcerative colitis has become one of the most competitive gastroenterology therapeutic areas, driven by a succession of approved biologics, the arrival of JAK inhibitors, and now a next wave of mechanisms entering late-stage trials. For IBD-focused pharmaceutical and biotech teams, the UC landscape presents both an opportunity (large addressable patient population, willingness to pay, established clinical endpoints) and a challenge (crowded market, escalating trial sizes, increasingly treatment-experienced patient populations).

The UC and Crohn's disease trial ecosystems overlap substantially in mechanism but differ in disease location and some biomarkers. Teams monitoring one should typically monitor the other.

Key therapeutic mechanisms in UC trials

IL-23 inhibitors: selective p19 targeting

The IL-23 class (guselkumab, risankizumab, mirikizumab) has largely displaced IL-12/23 dual inhibitors (ustekinumab) in UC. Active trial programs include:

• Head-to-head IL-23 vs. anti-TNF induction and maintenance (active Phase 3)
• IL-23 in combination with vedolizumab for refractory disease
• Next-generation high-affinity anti-IL-23p19 antibodies with extended dosing intervals
• IL-23 in pediatric UC populations
• Biomarker-driven patient selection: fecal calprotectin, serum IL-23 levels

JAK inhibitors: evolving selectivity and safety profiles

Tofacitinib (pan-JAK) and upadacitinib (JAK1-selective) are approved in UC. The next wave focuses on improved selectivity and safety:

• TYK2 selective inhibitors (deucravacitinib in UC development after psoriasis approval)
• Gut-restricted oral JAK inhibitors: limiting systemic exposure while maintaining mucosal efficacy
• JAK inhibitor combinations with 5-ASA for moderate UC
• JAK inhibitor dosing optimization: lower dose maintenance after high-dose induction

TL1A: the new hot target in IBD

TL1A (TNF-like cytokine 1A) has emerged as a major new target after multiple Phase 2 results showed strong efficacy in both UC and Crohn's disease:

• Tulisokibart (anti-TL1A) Phase 3 enrollment ongoing in UC and Crohn's
• PRA023/MK-7240: anti-TL1A antibody with Phase 3 data emerging
• Competing anti-TL1A programs from multiple sponsors in Phase 1–2
• TL1A combination strategies: anti-TL1A + anti-IL-23 for refractory IBD

S1P receptor modulators: gut-selective approaches

Ozanimod (S1P1/5) is approved in UC. The follow-on S1P modulator landscape includes:

• Etrasimod (S1P1/4/5): approved in UC with cleaner cardiac profile than ozanimod
• Next-generation gut-selective S1P modulators with reduced systemic exposure
• S1P + biologic combinations for refractory patients

Integrin inhibitors: beyond vedolizumab

Vedolizumab (anti-α4β7) remains a mainstay of UC therapy. New integrin-targeting approaches include:

• Subcutaneous vedolizumab optimization and maintenance dosing studies
• Anti-β7 antibodies with different selectivity profiles
• Oral integrin inhibitors under development

Mucosal healing and histological remission as endpoints

The trial endpoint landscape in UC is evolving. Regulatory requirements now emphasize composite endpoints including clinical remission, endoscopic improvement, and histological remission. New trials are increasingly powered on these stricter endpoints, affecting sample sizes and enrollment timelines.

Who monitors ulcerative colitis clinical trials?

• GI-focused pharma and biotech teams with UC or IBD pipeline assets monitoring an increasingly crowded competitive landscape
• Clinical development leaders designing new UC trials who need current competitive intelligence on enrollment and endpoint evolution
• Medical affairs and MSL teams at companies with marketed UC therapies tracking competitor trial activity
• GI healthcare investors following the IBD space, particularly the TL1A story
• Academic gastroenterologists reviewing what Phase 2/3 trials are enrolling for patient referral

Related immunology and GI clinical trial monitors

• Crohn's disease clinical trials — overlapping IBD mechanisms: IL-23, TL1A, JAK, integrin programs
• Rheumatoid arthritis clinical trials — shared JAK inhibitor and biologic platform programs
• Atopic dermatitis clinical trials — overlapping JAK and IL-23/TL1A programs across immunology