Treatment Persistence and Switching Patterns of Adalimumab Biosimilar ABP 501 in European Patients with Rheumatologic Diseases.

INTRODUCTION: ABP 501 was an adalimumab (ADA) biosimilar approved for treating immune-mediated inflammatory diseases (IMIDs) including rheumatoid arthritis (RA), psoriatic arthritis (PsA), and ankylosing spondylitis (AS). In this retrospective study, we aimed to examine the treatment patterns of ABP 501 among patients with these IMIDs using German and French pharmacy claims databases.

METHODS: Patients with RA, PsA, or AS who initiated ABP 501 between October 2018 and March 2020 and were observed continuously for ≥ 365 days both before and after ABP 501 initiation were included. Descriptive analyses of persistence and switch after ABP 501 discontinuation were conducted and reported for each disease cohort by prior use of ADA products (patients naïve to ADA or patients experienced with ADA).

RESULTS: Median (95% confidence interval) persistence on ABP 501 was 9.4 (8.6-10.3), 10.2 (9.0-11.7), and 12.1 (11.0-13.1) months in German patients, and 11.7 (9.9-13.3), 7.1 (5.8-8.4), and 10.8 (9.6-11.9) months in French patients for RA, PsA, and AS, respectively. For patients who switched from ABP 501 to another targeted therapy during the first 12 months of follow-up, switching patterns varied between patients naïve to ADA and patients experienced with ADA in both Germany and France, with patients naïve to ADA switching most frequently to other targeted therapies including non-ADA tumor necrosis factor inhibitor (TNFi), non-TNFi biologic, or Janus Kinase inhibitor (JAKi) and patients experienced with ADA switching most frequently back to ADA reference product (RP).

CONCLUSIONS: Across three rheumatologic diseases, about half of patients persisted on ABP 501 at the end of 12 months after treatment initiation in both Germany and France. Patients experienced with ADA were more likely to switch back to ADA RP, regardless of indication and country, suggesting a possible nocebo effect. Future studies are warranted to understand reasons of discontinuation and switching.