GROWTH OUTCOMES OF IV ANTI-TNF BIOSIMILARS IN PEDIATRIC INFLAMMATORY BOWEL DISEASE

Abstract BACKGROUND Biosimilars are biologic products similar in safety and efficacy to the originator product. Tumor necrosis factor-alpha inhibitors (anti-TNFs) are used in the treatment of inflammatory bowel diseases (IBD). There are limited studies evaluating the long-term outcomes of anti-TNF biosimilars in children with IBD. Growth is an important clinical outcome, especially in childhood-onset IBD. However, no study to date has compared growth outcomes in patients initiated on the IV anti-TNF originator as compared to a biosimilar. METHODS This was a single-center retrospective review of patients with IBD, younger than 16 years old, and initiated on the IV anti-TNF originator or a biosimilar between April 2016 and February 2021 at Nationwide Children’s Hospital. To be eligible for the study and evaluate the primary outcome, patients must remain on the IV anti-TNF therapy for at least 12-months. We used propensity score methodology to identify 37 pairs of matched patients based on baseline characteristics (age of anti-TNF initiation, disease (CD vs UC/IC), behavior, location, perianal type, race). Demographic data, laboratory values, disease activity scores, and growth values (z-scores were recorded for weight, height, and BMI) were collected at baseline (prior to anti-TNF initiation) and 6-months and 12-months post initiation. Linear mixed models with random intercepts accounting for within patient correlation of measurements were fit to test differences in measures over time and between study groups. Hypothesis testing was conducted at an alpha of 0.05 to be used for all statistical analyses. RESULTS There were 113 patients on the originator and 39 patients on a biosimilar who met our eligibility criteria. Nineteen percent of patients on the originator and 16% of patients on a biosimilar were excluded from analysis due to discontinuing the IV anti-TNF agent prior to 12 months. Weight, height, and BMI z-scores increased over time (from baseline to 12-months) for both groups (p