Effectiveness and safety of rituximab-pvvr versus originator rituximab for rheumatoid arthritis in the veterans health administration.

OBJECTIVE: Real-world comparisons of rituximab biosimilars with originator rituximab have largely focused on oncology, with limited evidence in rheumatoid arthritis (RA). This gap is particularly pertinent to the Veterans Health Administration (VHA), where patients with RA are older and have greater comorbidity. We evaluated the effectiveness and safety of rituximab-pvvr versus originator rituximab in Veterans with RA by (1) describing treatment patterns, (2) assessing effectiveness, (3) evaluating adverse events, and (4) identifying reasons for switching back to the originator after initiating the biosimilar. METHODS: We conducted a retrospective cohort study using VHA Pharmacy Benefits Management data among Veterans aged ≥18 years who received originator rituximab or rituximab-pvvr for RA between March 1, 2020 and August 31, 2023. Effectiveness outcomes (e.g., prednisone use) and safety outcomes (e.g., infection) were assessed using regression analyses within entropy-balanced subgroups of incident originator and biosimilar users. RESULTS: A total of 1,717 Veterans with RA received originator rituximab or rituximab-pvvr during the study period. Among 1,074 incident users, there were no significant differences between originator and biosimilar groups in effectiveness (e.g., discontinued prednisone use: Risk Difference (RD) = 0.05; 95% Confidence Interval (CI), -0.04 to 0.14) or safety (e.g., infection-related hospitalizations or emergency department visits: RD = -0.02; 95% CI, -0.08 to 0.05). CONCLUSIONS: We found no clinically meaningful differences in the effectiveness or safety of rituximab-pvvr compared with originator rituximab among incident users with RA. These real-world findings support the clinical use of rituximab-pvvr and may improve clinician and patient confidence in biosimilar adoption.