The effectiveness of adalimumab biosimilars and originator for the treatment of psoriasis: a cohort study from the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR) Duc Binh Phan

Abstract

Adalimumab is an effective but previously expensive biologic for psoriasis. The introduction of biosimilars has reduced the treatment cost since the patent of the originator adalimumab (Humira) expired. However, uncertainties about the real-world effectiveness of adalimumab biosimilars potentially limit their widespread adoption. This cohort study aims to compare the effectiveness of adalimumab biosimilars Amgevita and Imraldi with Humira using data from the British Association of Dermatologists Biologics and Immunomodulators Register (BADBIR). The study outcomes were absolute Psoriasis Area and Severity Index (PASI) of <= 2 and of <= 4 at 12 months after the index date. We compared new users of biosimilar with new users of Humira and compared patients who switched from Humira to biosimilars (switchers) with those who remained on Humira (continuous users). For the new-user analysis, cohort entry dates were the start of treatments. For the switcher analysis, switchers were individuals who transitioned to biosimilars after using Humira consistently for over 2 years and entered the cohort at the time of the switch. Meanwhile, continuous users entered the cohort after 2 years of consistent Humira use and stayed on treatment. We censored follow-up when participants in the Humira cohorts switched to biosimilars, or when users of biosimilars shifted to another adalimumab biosimilar. We used inverse probability of censoring weights and multiple imputations to correct for missing outcomes or censoring. We used logis - tic regression models to adjust for baseline demographics, comorbidities, concomitant conventional systemic treat - ments, and PASI at cohort entry. The new-user analysis included 7124 patients receiving Humira (271 censored), 445 receiving Amgevita, and 374 receiving Imraldi (1 censored). The switcher analysis included 3828 Humira comparators (286 censored), 847 Amgevita switchers, and 615 Imraldi switchers (31 censored). No significant differences were found between new users of Humira and new users of either Amgevita or Imraldi in the probability of achieving PASI <= 2 odds ratio (OR) 0.97, 95% confidence interval (CI) 0.78-1.20, and OR 0.88, 95% CI 0.69-1.12, respectively] and PASI <= 4 (OR 1.06, 95% CI 0.85-1.33, and OR 0.94, 95% CI 0.73-1.22, respectively). Amgevita switchers and Imraldi switchers also had no differences in achieving PASI <= 2 (OR 1.02, 95% CI 0.83-1.26, and OR 0.91, 95% CI 0.71-1.16, respectively) and PASI <= 4 (OR 0.98, 95% CI 0.78-1.23, and OR 0.87, 95% CI 0.65-1.17, respectively) compared with those who continued Humira. In conclusion, our study showed no significant differences in effectiveness between Amgevita, Imraldi and Humira for new users. Switching to Amgevita and Imraldi from Humira did not change treatment effectiveness signifi - cantly.