Infliximab Biosimilar Utilization in a Large Pediatric Learning Health System

<b>Background/Objectives</b>: Infliximab biosimilars entered the United States (US) market in November 2016. Uptake of infliximab biosimilars has been slow in adult studies. We aimed to assess variation in the initiation of infliximab biosimilars in a large pediatric cohort. <b>Methods</b>: We performed a retrospective cohort study using data from 2016 to 2023 prospectively collected by the ImproveCareNow (ICN) Network, a multicenter pediatric inflammatory bowel disease (IBD) quality improvement collaborative. Pediatric patients with IBD who started any infliximab therapy were included. Descriptive statistics were used to summarize patient characteristics and changes in the use of infliximab agents. Chi-square or Fisher's exact tests were used to evaluate differences in infliximab biosimilar initiation over time by race, age, ethnicity, and region. <b>Results</b>: In total, 4602 patients from 73 ICN centers started an infliximab agent. Infliximab biosimilar initiation rose steadily from 1% in 2018 to nearly 42% in 2023, with 88% of centers using biosimilars in 2023. Overall, from 2016 to 2023, the total percentage of patients who were started on an infliximab biosimilar was 17.3%. There were no differences in infliximab biosimilar initiation by age, race, or ethnicity, except in 2020 for age and race. The Midwest, West, and Southwest regions had higher initiation rates of infliximab biosimilars than the rest of the US. <b>Conclusions</b>: The percentage of patients with IBD initiating an infliximab biosimilar rose slowly to nearly 42% by 2023, and eight (12%) centers never recorded prescribing an infliximab biosimilar in the ICN Network. There were no differences in biosimilar initiation based on race or ethnicity.