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

Abstract

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.

Keywords: adalimumab; biosimilar; paediatric inflammatory bowel disease.

Figure 1

Treatment persistence with Adalimumab (ADA) biosimilar estimated according to the Kaplan-Meier method. [The y-axis has been scaled to the range 0.4–1 for better visualization.].

Figure 2

Clinical remission rates during follow-up.

Figure 3

Boxplot of clinical scores and laboratory data during follow-up (baseline, 6 months, 12 months, 24 months and 36 months). [Bold denotes significant p-value].

Figure 4

Success rate of Adalimumab (ADA) dose escalation in all cohorts and in different groups based on the reason for escalation: low trough levels, disease relapse, and high faecal calprotectin (FC) levels.

Figure 5

ROC curve of Adalimumab (ADA) trough levels at 6 months in predicting ADA biosimilars failure during follow-up.

Figure 6

Kaplan-Meier curves representing different rate of Adalimumab ADA biosimilar failure in patients with ADA trough levels <11.6 μg/mL at 6 months (blue) and those with trough levels ≥ 11.6 μg/mL (red). The assumption of proportional hazard was used for analysis, and no violations were observed.