Clinical and radiological outcomes of ustekinumab in pediatric perianal Crohn's disease: a multicenter retrospective study from the Pediatric IBD Porto Group of ESPGHAN.

Background
Perianal Crohn's disease (pCD) is a severe pediatric phenotype with high morbidity. Although antitumor necrosis factor (TNF) agents are first-line therapy, remission is not achieved in a subset of patients. We aimed to evaluate clinical and radiological outcomes of ustekinumab (UST) in pediatric patients with pCD.Methods
This is a multicenter retrospective study including pediatric patients with pCD treated with UST between 2016 and 2023. Primary outcomes were clinical and radiological remission at predefined time points. Clinical remission was defined as absence of fistula drainage without antibiotics or unplanned perianal interventions. Radiological remission was defined as a Pediatric MRI-Based perianal Crohn's Disease (PEMPAC) score of <10 on pelvic MRI.Results
Fifty patients were included, of whom 2 were anti-TNF-naive. The median age at UST initiation was 15 years (IQR 12.4-16.2). Clinical remission was observed in 46% (23/50; P = .006 vs baseline), 48% (23/48; P = .036 vs baseline), and 42% (19/45; P = .13 vs baseline) at weeks 26, 52, and 104, respectively. Radiological remission was 29% (10/34) and 30% (13/43) at weeks 52 and 104, respectively (both P < .01 vs baseline). In multivariable analysis, higher baseline PEMPAC scores were independently associated with lower odds of both clinical (P < .01; OR 0.88, 95% CI 0.68-0.95) and radiological remission (P < .01; OR 0.81, 95% CI 0.62-0.94).Conclusions
UST was associated with perianal clinical remission in a substantial proportion of pediatric patients, approaching 50% at 1 year, and radiological healing in about one-third at 2 years, supporting its potential role in pediatric pCD.Ustekinumab was associated with clinical remission in approximately half and radiological healing in over one-third of pediatric patients with anti-TNF exposed perianal Crohn’s disease over one year, supporting its use as a viable therapeutic option in this challenging population.