Switching Between Reference Adalimumab and Biosimilars in Adult Patients With Inflammatory Bowel Disease: A Systematic Literature Review

Biosimilar adalimumab agents have been introduced as cost-effective alternatives to reference adalimumab for inflammatory bowel disease (IBD); however, uncertainties remain regarding the outcomes of switching between reference and biosimilars in routine practice. Therefore, this systematic review was conducted to assess outcomes following switching between reference adalimumab and biosimilars in adult patients with IBD. A systematic search was undertaken in PubMed/MEDLINE, the Cochrane Library, and Google Scholar to identify relevant studies. Eligible studies included randomized controlled trials, cohort studies, registry-based analyses, and real-world evidence evaluating adult IBD patients (≥18 years) who switched between reference and biosimilar adalimumab. A total of seven studies comprising 5721 patients were included. Among these, three were prospective studies, three were retrospective studies, and one was a cross-sectional study. Follow-up ranged from six months to 26 months. Across studies, remission and response rates after switching were comparable to continuation on reference adalimumab, with most cohorts reporting remission in 74-90% of patients. Biomarkers generally remained stable or improved. Persistence outcomes were heterogeneous, with specialized centers reporting high multi-year persistence (>80%). Safety profiles were similar across products, with injection-site reactions being the most frequent adverse events (AEs) and a common cause of discontinuation. Serious AEs were rare. Immunogenicity data were limited but did not indicate clinically meaningful differences between reference and biosimilars.