Ustekinumab in pediatric ulcerative colitis: Phase 3 UNIFI Jr efficacy and safety results

touchIMMUNOLOGY coverage of DDW 2026

What was the rationale for investigating ustekinumab in pediatric UC?

At present, the advanced therapies that are approved by the FDA for the treatment of pediatric ulcerative colitis are all anti-TNF medications. While often effective, primary non-response and loss of response are still common. So, additional therapies are needed. In contrast to pediatrics, there are a dozen other therapies with alternative mechanisms of action available for adults.

What were the aims and design of the phase 3 UNIFI Jr study?

UNIFI 2 meant to examine the safety and efficacy of ustekinumab in moderately to severely ill children, aged 2-17 years, with ulcerative colitis. The trial closely mirrored the pivotal adult studies that led to regulatory approval. Dosing of the medication was either weight based (≥40 kg) or body surface area based (<40 kg), depending on weight. Ustekinumab was administered subcutaneously either every 8 weeks or 12 weeks during maintenance after a single dose IV induction.

What were the key endpoints at Week 8 and Week 52?

The critical endpoints were clinical remission at Week 8, after the single IV induction dose, and then clinical remission at Week 52 in those who were Week 8 responders. The Mayo score was used to categorize clinical activity.

What were the findings, and how did remission rates compare across subgroups such as prior biologic exposure, weight, and dosing interval?

Response (67%) and remission (25%) at Week 8 were very similar to that seen in the adult trial (58%, 19%). Those patients who were dosed every 8 weeks during maintenance did better than those who were dosed every 12 weeks. The response (80%) and remission (49%) rates at Week 52, in those who were Week 8 responders, was also similar to that seen in the adult study (70%, 44%). Those subjects who were anti-TNF naïve prior to ustekinumab did numerically better, but the individual treatment groups were small. Those subjects < 40kg, whose dose was body surface area based, did numerically better at Week 8 than those who weighed 40 kg or more.

What was the safety profile of ustekinumab in the study?

The safety profile was excellent and again mirrored that seen in adult studies. Remember, though, the patient population studied was only a little over 100 patients. The take home message is that ustekinumab can be a useful therapy for children with ulcerative colitis, whether patients are anti-TNF naïve or previously treated with anti-TNF.