Impact of biologic induction dose and concomitant drugs on anti-drug antibody formation in a pediatric IBD cohort with high Hispanic representation.

Objectives: The use of biologic therapy is increasing in pediatric patients with inflammatory bowel disease (IBD). However, efficacy may be compromised by increased drug clearance and anti-drug antibodies (ADAs). Historically, concomitant immunomodulator therapy (CIT) has been used to prevent ADA formation. Pediatric studies evaluating CIT have focused largely on white, non-Hispanic patients and have demonstrated variable benefits. This study evaluated the utility of CIT in preventing ADAs in a pediatric IBD population with high Hispanic representation. Methods: We reviewed the charts of patients undergoing biologic induction at the Miller Children's Pediatric IBD Center between 2013 and 2023. Patients with missing therapeutic drug monitoring data or incomplete follow-up were excluded. Categorical variables were compared using chi-square or Fisher's exact tests, and continuous variables were analyzed using t tests. Multivariate logistic regression identified independent predictors of ADA formation. Results: Of 163 pediatric patients, 75 had Crohn's disease (CD) and 80 had ulcerative colitis (UC). High-dose infliximab (IFX) was protective against ADA formation (p < 0.001), as were corticosteroids (p = 0.029). UC patients were more likely to receive corticosteroids at induction (CD: 27/75, UC: 45/80; p = 0.011). Among UC patients, CIT reduced ADA formation (odds ratio: 0.18; 95% confidence interval: 0.04-0.73; p = 0.031). Hispanic patients were more likely to have UC (CD: 18/73, UC: 46/80; p < 0.001). Hispanic UC patients had shorter times to biologic initiation (p = 0.025) and were more likely to receive both high-dose IFX and corticosteroids at the time of biologic induction (p = 0.044). Conclusions: High-dose IFX may obviate the need for CIT in ADA prevention in pediatric IBD. UC patients may benefit more from CIT than CD patients. Disparities in treatment timing and medication use among Hispanic UC patients highlight the need for further investigation.