Long-Term Safety and Durability of Selective IL-23 p19 Inhibition: GALAXI 1 Trial

Article Impact Level: HIGH
Data Quality: STRONG
Summary of  Inflammatory Bowel Diseases  https://doi.org/10.1093/ibd/izag055
Dr. Anita Afzali  et al.

Points

Researchers evaluated the long-term safety and efficacy of the selective IL-23 p19 subunit inhibitor guselkumab through a five-year analysis of the Phase 2 GALAXI 1 extension trial.
Crohn’s disease affects approximately 780,000 Americans and carries a high lifetime risk of surgical intervention, making long-term therapeutic durability an essential priority for clinical gastroenterologists.
At the five-year milestone, 97.7 percent of patients remaining on the biologic therapy achieved clinical remission, with all matching participants maintaining a completely corticosteroid-free status.
Objective markers of structural mucosal healing were highly favorable, as more than 71 percent achieved endoscopic response and more than 51 percent reached complete endoscopic remission.
The observed clinical benefits occurred independently of prior biologic failures, while the overall safety profile revealed no new adverse safety signals during the extended follow-up.

Summary

Long-term efficacy, durability, and safety profile of guselkumab, a selective, dual-acting interleukin-23 p19 subunit inhibitor, in patients presenting with moderately to severely active Crohn’s disease. Crohn’s disease is a progressive, chronic inflammatory condition affecting approximately 780,000 Americans, presenting high lifetime surgery risks and considerable systemic morbidity. Because long-term remission remains a defining clinical challenge due to high secondary loss of response to traditional treatments, this five-year analysis of the randomized Phase 2 GALAXI 1 long-term extension study sought to determine if targeted IL-23 inhibition could alter disease progression and sustain objective mucosal healing in an often treatment-refractory patient cohort.

The long-term extension data demonstrated exceptional clinical and anatomical response rates among individuals remaining on the biologic protocol over the five-year monitoring period. Specifically, 97.7% of the longitudinal patient cohort achieved complete clinical remission, with 100% of those in remission successfully achieving corticosteroid-free status. Objective markers of deep mucosal healing were highly pronounced, as more than 71% of participants demonstrated a robust endoscopic response, and more than 51% achieved full endoscopic remission. Crucially, these high clinical and endoscopic therapeutic benefits were observed uniformly across the cohort, showing equal effectiveness in patients with prior inadequate responses to conventional drugs and those with extensive prior biologic exposure.

Safety evaluations performed over the five-year extension phase revealed a highly favorable profile, with no new or unexpected safety signals identified. Reported side effects were entirely consistent with historical safety databases established during earlier induction and maintenance clinical trials. By inducing high rates of corticosteroid-free clinical remission alongside profound structural tissue healing, these findings underscore that precise, mechanism-based IL-23 p19 targeting operates as a highly durable, disease-modifying therapeutic approach. While Phase 3 clinical frameworks will continue to establish comprehensive hazard ratios for surgical avoidance, these baseline data validate the clinical utility of guselkumab for long-term management of complex, refractory Crohn’s disease.

Link to the article: https://academic.oup.com/ibdjournal/advance-article/doi/10.1093/ibd/izag055/8666252?login=false

References

Afzali, A., Danese, S., Panaccione, R., Rubin, D. T., Sands, B. E., Reinisch, W., Panés, J., Van Rampelbergh, R., Terry, N. A., Salese, L., Vetter, M. L., Yee, J., Corbett, C., Van Duijnhoven, W., Hisamatsu, T., Andrews, J. M., D’Haens, G. R., the GALAXI 1 investigators, Oliinyk, O., … Ritter, T. (2026). Five-year efficacy and safety of guselkumab for moderately to severely active Crohn’s disease: Results from the phase 2 GALAXI 1 trial. Inflammatory Bowel Diseases, izag055. https://doi.org/10.1093/ibd/izag055