(009) Drug survival and safety of biosimilars compared with originator adalimumab for Psoriasis: a multinational cohort study

Background: The introduction of adalimumab biosimilars following the patent expiration of the originator adalimumab – Humira® offers the opportunity to reduce treatment costs. However, concerns about the effectiveness and safety of biosimilars limit widespread adoption for psoriasis treatment.

Objectives: This study aims to compare the drug survival and safety of adalimumab biosimilars to Humira® for the treatment of psoriasis.

Methods: We conducted a prevalent new user cohort study using data from the French Système National des Données de Santé (SNDS) in France, the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR) in the UK and the Republic of Ireland, and the Spanish Registry of Systemic Therapy in Psoriasis (Biobadaderm) in Spain. We compared adalimumab naïve patients initiating adalimumab biosimilars (new users) with Humira® new users, and patients who switched from Humira® to biosimilars with those who stayed on Humira® treatment, matching 1:1 patients on previous adalimumab exposure time to create equal-sized cohorts of biosimilar and Humira® users. The co-primary outcomes were drug discontinuation and serious adverse events (SAE). Cox proportional hazard models were fitted to calculate the hazard ratios (HR) of the outcomes. Meta-analyses using random effect models were used to combine the results from 3 databases.

Results: 7387 biosimilar new users and 3654 switchers were matched and compared with Humira® users. There were no significant differences between biosimilar new users and Humira® new users for all-cause discontinuation (fully adjusted HR: 0.99, 95% CI: 0.94 – 1.04). Switchers had a significantly higher all-cause discontinuation rate compared to patients who stayed on Humira® (HR: 1.35, 95% CI: 1.19 – 1.52). Similar results were recorded for discontinuation due to ineffectiveness or due to adverse events. No significant differences were recorded in the risks of SAEs between biosimilar new users and Humira® new users (Incidence rate ratio IRR: 0.91 95% CI: 0.80 – 1.05) and between switchers and Humira® continuous users (IRR: 0.92 95% CI: 0.83 – 1.01).

Conclusions: The drug survival and safety of adalimumab biosimilars were similar to that of Humira® in people with psoriasis who were new users. Switching from Humira® to biosimilar did not affect the rates of serious adverse events. However, patients who switched to biosimilars were more likely to discontinue their treatments compared to those who stayed on Humira® treatment.