Ustekinumab in Paediatric Patients with Moderately to Severely Active Crohn's Disease: UniStar Study Long‐term Extension Results

Objectives To assess the efficacy, safety, immunogenicity, and pharmacokinetics through 240 weeks of ustekinumab treatment in paediatric patients from the long‐term extension (LTE) of the phase 1, double‐blind UniStar trial. Methods Paediatric patients with moderately to severely active Crohn's disease (CD) were randomised 1:1 and stratified by body weight (<40 or ≥40 kg) to low‐ or high‐dose intravenous ustekinumab followed by a subcutaneous maintenance dose at Week 8. At Week 16, patients were eligible to enter the LTE at the discretion of the investigator and continued maintenance dosing every 8 weeks up to Week 240. Results Of the 34 patients who entered the LTE, 25 patients with evaluable data completed Week 48, and 41.2% (14/34) achieved clinical remission at Week 48. Among the 24 patients with Week‐0 C‐reactive protein (CRP) levels ≥3 mg/L, 29.2% (7/24) achieved normalisation of CRP at Week 48, while imputing missing data as failures. Through Week 240, the most common adverse events were infections ( n = 28) and gastrointestinal disorders ( n = 26). The most common serious adverse event was worsening of CD ( n = 6). Only one patient had detectable antibodies to ustekinumab. Median serum ustekinumab concentrations remained consistent through Week 48, were detectable through Week 224, and trended lower in patients <40 kg. Conclusions Efficacy and pharmacokinetics through 1 year and safety and immunogenicity through 4 years of ustekinumab treatment in paediatric patients with CD were generally comparable to those previously reported in adults.