Protagonist Therapeutics Inc. has announced new data from the Phase 2b ANTHEM-UC study of icotrokinra, an investigational oral peptide that selectively blocks the IL-23 receptor, in adults with moderately to severely active ulcerative colitis. The study met its primary endpoint, with all once-daily icotrokinra dose groups achieving clinical response at Week 12. At the highest dose, 36.5% of patients achieved endoscopic improvement and 30.2% achieved clinical remission. Adverse event rates were similar across all icotrokinra and placebo groups. These results were presented at United European Gastroenterology (UEG) Week 2025. Based on these findings, Protagonist Therapeutics plans to initiate a registrational Phase 3 study in ulcerative colitis and a Phase 2b/3 study in Crohn's disease in the fourth quarter of 2025. Icotrokinra is also being evaluated in ongoing Phase 3 studies in plaque psoriasis and psoriatic arthritis, and a New Drug Application was submitted to the U.S. FDA in July 2025 for the treatment of moderate to severe plaque psoriasis in adults and pediatric patients aged 12 years and older.