Adalimumab Biosimilars Demonstrate Long-Term Durability and Cost-Effectiveness in Paediatric Inflammatory Bowel Disease: A Real-World Two-Centre European Cohort Study.

PURPOSE: Adalimumab biosimilars are increasingly used in paediatric Inflammatory Bowel Disease (PIBD), but data remain limited. This study assessed their durability, efficacy, safety and cost implications in PIBD.

PATIENTS AND

METHODS

Consecutive PIBD patients who started adalimumab biosimilars between October 2018 and December 2023 at two centres in Scotland and Italy, with at least 6 months follow-up, were included. Demographic, disease, treatment, and adverse event data were collected. Disease activity was assessed at baseline, 6, 12, 24, 36 months, and at last follow-up. Durability was evaluated using Kaplan-Meier analysis.

RESULTS

In total 130 patients (81 males; median age 12.3 years) were included (115 Crohn's Disease, 7 Ulcerative Colitis, 8 IBD unclassified). The biosimilars were ABP 501 (85%), GP2017 (14%), SB5 (1%); 41 (32%) patients switched from originator. After a median follow-up of 26 months, 87/130 (67%) patients remained on biosimilars, while 43 discontinued at a median of 14 months. Durability probabilities were 93%, 86%, 75%, 62%, and 57% at 6, 12, 24, 36, and 54 months, respectively. Patients previously exposed to ADA originator had a lower risk of biosimilar failure (hazard ratio, adjusted for age at diagnosis: 0.51 [95% confidence interval: 0.26-0.99], p=0.047). Trough levels ≥11.6 μg/mL at 6 months were associated with greater durability (AUC=0.68, p=0.007). Adverse events occurred in 46/130 patients, mainly psoriasis and injection site reactions (13% each), with one lymphoma. Estimated cost savings were 5,030€ per patient/year.

CONCLUSION

This real-life study demonstrated high durability and remission rates for adalimumab biosimilars in PIBD, confirming their clinical, cost-effectiveness and safety profile in children.