P38 Safety of biosimilars compared with originator adalimumab for psoriasis: a multinational cohort study

Abstract Adalimumab is a widely used biologic treatment for moderate-to-severe psoriasis. With the expiration of Humira®—the originator adalimumab—patent, adalimumab biosimilars have become available, offering the potential to reduce treatment costs. However, concerns about the safety of biosimilars in clinical practice remain a significant barrier to their widespread adoption for psoriasis treatment. This study aims to compare the safety of adalimumab biosimilars to Humira® for psoriasis in real-world practice. We conducted a prevalent-new user cohort study using data from the French National Health Data System (SNDS), the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR), and the Spanish Registry of Systemic Therapy in Psoriasis (BIOBADADERM). The study compared adalimumab-naive patients (new users) initiating biosimilars with those initiating Humira, and patients who switched from Humira to biosimilars (switchers) with those who continued on Humira. Patients were matched 1:1 based on previous adalimumab exposure time to create equal-sized cohorts of biosimilar and originator users. The primary outcome was serious adverse events (SAEs), defined as any medical events during the use of the study drugs resulting in death or hospitalization. In the result, a total of 7387 biosimilar new users and 3654 switchers were matched and compared respectively with Humira new users and continuous users. The incidence rates of SAEs per patient-year were similar between biosimilar and Humira new users [incidence rate ratio (IRR): 0.91, 95% confidence interval (CI): 0.80–1.05] and between switchers and continuous Humira® users (IRR: 0.92, 95% CI: 0.83–1.01). The time to the first SAE occurrence was significantly lower among biosimilar new users compared with Humira® new users [hazard ratio (HR), 0.83; 95% CI: 0.72–0.96]. However, this difference was observed only in registries where most Humira users were recruited before biosimilars were available, suggesting potential residual confounding from changes over time in practices and prescription trends. The time to the first SAE occurrence was similar between switchers and continuous Humira users (HR: 0.94, 95% CI: 0.85–1.05). In conclusion, adalimumab biosimilars demonstrated a comparable safety profile to Humira for both new users and patients who switched from Humira to biosimilars.