Outcomes in Adult Inflammatory Bowel Disease Clinical Trials: Assessment of Similarity Among Participants with Adolescent-onset and Adult-onset Disease.

Background and aims: Most paediatric inflammatory bowel disease [IBD] studies are performed after medications are approved in adults, and the majority of participants in these studies are adolescents. We hypothesised that adolescent-onset IBD is not fundamentally different from adult-onset IBD. If this is correct, the value of delaying access to novel drugs in adolescents becomes questioned.

Methods: Data from 11 randomised, double-blind, placebo-controlled, adult Phases 2 and 3 trials of four biologics were analysed. Participants were categorised as having adolescent- or adult-onset disease [diagnosed 12 to <18, or ≥18 years]. Multivariable modelling explored the association between age at diagnosis and response to treatment, after adjustment for disease duration, extent, and severity at baseline. Data from dose arms were pooled to evaluate similarity of therapeutic response between adolescent- and adult-onset IBD within the same trial [not between doses or across trials]. Ratios of odds ratios [ORs] between the two groups were evaluated.

Results: Data from 6283 study participants (2575 with Crohn's disease [CD], 3708 with ulcerative colitis [UC]) were evaluated. Of 2575 study participants with CD, 325 were 12-<18 years old at diagnosis; 836 participants [32.4%] received placebo. Of 3708 participants with UC, 221 were 12-<18 years old at diagnosis; 1212 [33%] were receiving placebo. The majority of the ratios of ORs were within 2-fold, suggesting that responses in adolescent- and adult-onset participants are generally similar.

Conclusion: Data presented lend support for extrapolating efficacy of biologics from adults to adolescents with IBD, which would facilitate earlier labelling and patient access.