Effectiveness and Safety of Adalimumab Biosimilar SB5 in IBD: Outcomes in Originator to SB5 Switch, Double Biosimilar Switch and Bio-Naieve SB5 Observational Cohorts

Background and aims Multiple adalimumab (ADA) biosimilars are now approved for use in IBD; however, effectiveness and safety data remain scarce. We aimed to investigate long-term outcomes of the adalimumab (ADA) biosimilar SB5 in IBD patients following a switch from the ADA originator (SB5-switch cohort) or after start of SB5 (SB5-start cohort). Methods We performed an observational cohort study in a tertiary IBD referral centre. All IBD patients treated with Humira® underwent an elective switch to SB5. We identified all these patients in a biologic prescription database that prospectively registered all ADA start and stop dates including brand names. Data on IBD phenotype, CRP, drug persistence, ADA drug and antibody levels, and faecal calprotectin were collected. Results 481 patients were treated with SB5, 256 in the SB5-switch cohort (median follow-up: 13.7 months [8.6-15.2]) and 225 in the SB5-start cohort (median follow-up: 8.3 months [4.2-12.8]). 70.8% of the SB5-switch cohort remained on SB5 beyond one year; 90/256 discontinued SB5, mainly due to adverse events (46/90) or secondary loss of response (37/90). In the SB5-start cohort, 81/225 discontinued SB5 resulting in SB5-drug persistence of 60.3% beyond one year. No differences in clinical remission (p=0.53), CRP (p=0.80), faecal calprotectin (p=0.40) and ADA trough levels (p=0.55) were found between baseline, week 26 and week 52 following switch. Injection site pain was the most frequently reported adverse event. Conclusion Switching from ADA originator to SB5 appeared effective and safe in this study with over 12 months of follow-up.