Comparing immunogenicity and safety following transition from reference rituximab to biosimilar rituximab (DRL_RI) in patients with rheumatoid arthritis: a randomized, double-blind, phase 3 study.

Objectives: To assess immunogenicity and safety in patients with active rheumatoid arthritis (RA) transitioning from rituximab [US-licensed rituximab: Reference Product (RP); EU-approved rituximab: Reference Medicinal Product (RMP)] to DRL_RI (proposed rituximab biosimilar), in comparison to those continuing on RP/RMP.

Methods: This double-blind, randomized, Phase 3 study included 140 RA patients having prior exposure to RP/RMP; transitioned to DRL_RI (n = 70) or continued with RP/RMP (n = 70) for two 1000 mg infusions on Days 1 and 15. Assessments included Time-matched Rituximab Concentration (TMRC), anti-drug antibodies (ADAs), neutralizing antibodies (NAbs) and ADA titre over 12 weeks, and safety follow-up till 26 weeks.