Background/Purpose: The proliferation of similar biotherapeutic products (biosimilars) has helped to reduce the cost burden of biologic therapies for health care systems1. Multiple studies have demonstrated biosimilars to be equally effective based on head-to-head trials of various adalimumab biosimilars in inflammatory autoimmune diseases2. Switching from adalimumab to a biosimilar in patients with stable and controlled diseases generally results in 1-year retention rates of 90% from real world experience outside the U.S.3. Due to the dynamic changes of insurance plans and formularies within the United States healthcare system, there is minimal data on retention rates and persistence of efficacy in real-world U.S. patients. It was our intention to survey the rate of continuation of adalimumab biosimilars in patients switched from adalimumab for inflammatory indications in a single academic medical center.

Methods: All patients 2 years of age and older who had received adalimumab or a biosimilar dispensed by the University of Rochester Specialty Pharmacy between 7/1/2023 and 12/31/2024 were included in the study. Patients were categorized into two cohorts, including those continuing adalimumab exclusively compared to patients who switched to a biosimilar agent(s). Patients were followed until 3/31/2025. The URMC IRB approved the study as exempt with data collected from Epic electronic medical record and Willow Ambulatory Pharmacy dispensing databases.

Results: 1,006 patients were identified and included in the study with an average age of 44 years old (range 2 – 88) and majority (60.2%) female. Rheumatoid arthritis was the most common diagnosis (32.1%) Across the 18-month time period, 97 patients (9.6%) were switched to a biosimilar with adalimumab-adaz and adalimumab-bwwd most common. 15 of 97 (15.5%) did not continue the biosimilar

Conclusion: Real world experience following mandated switch from adalimumab to a biosimilar showed a marginally higher rate of discontinuation than comparable cohorts from outside the United States. The cost of medication saved by switching to biosimilar medications may justify this rate of unanticipated mediation interruption.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/real-world-rate-of-efficacy-of-adalimumab-biosimilars-following-a-mandated-switch-in-an-academic-medical-center/