The Food and Drug Administration (FDA) has approved Riabni™ (rituximab-arrx), a biosimilar to Rituxan® (rituximab), in combination with methotrexate in adults with moderately to severely active rheumatoid arthritis who have had an inadequate response to 1 or more tumor necrosis factor (TNF) antagonist therapies.

Riabni is a CD20-directed cytolytic antibody. The approval is supported by data from a randomized, double-blind, phase 3 study ( Identifier: NCT02792699) that compared the efficacy, safety, pharmacokinetics and immunogenicity of Riabni to a rituximab reference product in 311 adults with moderate to severe rheumatoid arthritis.

Patients were randomly assigned to receive Riabni, the US rituximab reference product (Rituxan), or the EU rituximab reference product (MabThera). Riabni was found to be clinically equivalent to the rituximab reference products based on the primary endpoint of change in disease activity score 28 using C-reactive protein (DAS28-CRP) at week 24. 

Riabni is also approved for the treatment of adults with Non-Hodgkin lymphoma, chronic lymphocytic leukemia, granulomatosis with polyangiitis, and microscopic polyangiitis.


  1. FDA approves Riabni™ (rituximab-arrx), a biosimilar to Rituxan® (rituximab), for adults with moderate to severe rheumatoid arthritis. News release. Amgen. Accessed June 6, 2022.
  2. Riabni. Package insert. Amgen; 2022. Accessed June 6, 2022.