P39 Outcomes after switching back to the originator adalimumab in psoriasis patients who previously switched to biosimilars

Abstract Adalimumab is widely used for moderate-to-severe psoriasis, with many patients transitioning from the originator—Humira® to biosimilars. Limited evidence exists on outcomes for those switching back to Humira or other biologics after discontinuing biosimilars. This study aims to compare the risk of discontinuation, treatment effectiveness, and safety between patients switching back to Humira and those switching to other biologics after discontinuing biosimilars. Using data from the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR), we conducted a cohort study including psoriasis patients who switched from Humira to biosimilars and then either back to Humira or to other biologics. Outcomes included the risk of discontinuation, psoriasis area and severity index (PASI) at 1 year, and the risk of serious adverse events (SAEs). We used fine stratification weights based on propensity score to balance patient characteristics. Patients were stratified as having less or more than 2 years of Humira® treatment before switching to biosimilars. In the result, the study included 187 patients who switched back to Humira and 177 patients who switched to other biologics. For patients who had <2 years of Humira treatment before transitioning to biosimilars, switching back to Humira resulted in a similar discontinuation rate [hazard ratio (HR): 1.21, 95% confidence interval (CI): 0.55–2.68] and comparable PASI at 1 year [3.0 (standard deviation, SD 5.8) vs. 3.3 (SD 4.6)] compared with switching to other biologics. Patients who had over 2 years of Humira® treatment before switching to biosimilars were less likely to discontinue treatment (HR: 0.52, 95% CI: 0.31–0.89), and had lower PASI at 1 year [2.4 (SD 4.7) vs. 3.6 (SD 6.3)] if they switched back to Humira® compared with those who switched to other biologics. SAEs were recorded in 12 out of 187 patients who switched back to Humira and in 12 out of 177 patients who switched to other biologics. In conclusion, among patients who switched back to Humira, those with <2 years of prior Humira treatment had similar outcomes compared with those who switched to other biologics. However, patients with over 2 years of prior Humira® treatment experienced better outcomes when switching back to Humira compared with switching to other biologics. Due to the limited data available in this study, further research with larger sample sizes is required to confirm these results.