Abstract Background Pediatric inflammatory bowel disease (PIBD) is characterized by a more aggressive disease course and frequent inadequate response to first-line therapies (1). Ustekinumab, an IL-12/23 inhibitor approved for adult IBD, is increasingly used in children, yet evidence on its effectiveness, especially regarding optimization strategies such as intravenous reinduction (IR), remains limited (2-3). This study reports a single-center real-world experience on clinical response (CR) to ustekinumab at 8 and 52 weeks and on outcomes following IR in selected patients. Methods We permormed a retrospective, monocentric, observational study including PIBD patients treated with ustekinumab between January 2020 and April 2025. Demographic, clinical, laboratory, and endoscopic data were collected at baseline, week 8, and week 52. CR was defined as PCDAI ≤12.5 for Crohn’s disease (CD) and PUCAI ≤10 for ulcerative colitis (UC). IR consisted of an additional intravenous dose using the standard induction regimen. Comparative analyses between responders and non-responders were performed. The authors used ChatGPT (OpenAI) for linguistic review only; data analysis and all scientific content were performed independently by the authors. Results Twenty-nine patients (82% CD, 18% UC) were included. Median age at diagnosis 11.7 years (IQR: 10.6– 14.9), with a median follow-up of 54 months. CR was achieved by 72% at week 8 and 48% at week 52; among early responders, 57% sustained response at one year. At week 8, elevated CRP (p = 0.01), lower hemoglobin (p = 0.06), and growth delay (p = 0.07) were associated with lack of response; high CRP reduced CR likelihood by 73%. At week 52, B2 behavior disease in CD (p = 0.03) and lower hemoglobin (p = 0.05) were associated with non-response, with B2 behavior decreasing the probability of CR by 92%. Six patients (20.7%), all with CD, underwent IR due to insufficient response after standard induction. IR was performed at a median of 26.1 weeks (IQR 18.5–33.7) from treatment start. By week 52, 4/6 (66%) achieved CR and one achieved combined clinical and endoscopic remission. Conclusion Ustekinumab is an effective therapeutic option for PIBD, with meaningful early and sustained response rates. Intravenous reinduction may further improve outcomes in selected CD patients with inadequate response to standard induction. Larger prospective studies are warranted to better define predictors of response and to optimize therapeutic strategies in pediatric IBD. References: 1. Levine A, Koletzko S, Turner D, et al. ESPGHAN revised porto criteria for the diagnosis of inflammatory bowel disease in children and adolescents. J Pediatr Gastroenterol Nutr. 2014;58(6):795-806. doi:10.1097/MPG.0000000000000239 2. Sandborn WJ, Rebuck R, Wang Y, et al. Five-Year Efficacy and Safety of Ustekinumab Treatment in Crohn’s Disease: The IM-UNITI Trial. Clinical Gastroenterology and Hepatology. 2022;20(3):578-590.e4. doi:10.1016/j.cgh.2021.02.025 3. Sands BE, Sandborn WJ, Panaccione R, et al. Ustekinumab as Induction and Maintenance Therapy for Ulcerative Colitis. New England Journal of Medicine. 2019;381(13):1201-1214. doi:10.1056/nejmoa1900750 Conflict of interest: Mr. Mondi’, Filippo: No conflict of interest Milo, Francesco: No conflict of interest Giudice, Antonella: No conflict of interest Ricci, Alessandra Maria: No conflict of interest Imondi, Chiara: No conflict of interest Angelino, Giulia: No conflict of interest Balassone, Valerio: No conflict of interest Benvenuto, Francesca: No conflict of interest Bracci, Fiammetta: No conflict of interest Cardile, Sabrina: No conflict of interest Chiarazzo, Giulia: No conflict of interest Contini, Anna Chiara iolanda: No conflict of interest Esposito, Emanuele: No conflict of interest Faraci, Simona: No conflict of interest Logrieco, Giuseppe: No conflict of interest Malamisura, Monica: No conflict of interest Rea, Francesca: No conflict of interest Romeo, Erminia Francesca: No conflict of interest Tambucci, Renato: No conflict of interest Torroni, Filippo: No conflict of interest Caldaro, Tamara: No conflict of interest Diamanti, Antonella: No conflict of interest De Angelis, Paola: No conflict of interest Knafelz, Daniela: No conflict of interest
Mondì et al. (Thu,) studied this question.