On December 17, the U.S. Food and Drug Administration (FDA) approved rituximab-arrx (Riabni), a biosimilar to rituximab (Rituxan), for the treatment of adult patients with non-Hodgkin lymphoma, chronic lymphocytic leukemia, granulomatosis with polyangiitis (Wegener's granulomatosis), and microscopic polyangiitis. The biosimilar will be made available in the United States in January 2021.
Rituximab-arrx is a biosimilar to rituximab, an anti-CD20 monoclonal antibody. The active ingredient of rituximab-arrx is a monoclonal antibody that has the same amino acid sequence as rituximab. Rituximab-arrx also has the same strength as rituximab, and the dosage form and route of administration are identical to the intravenous formulation of the reference product.
Rituximab-arrx, a CD20-directed cytolytic antibody, was proven to be highly similar to rituximab based on a totality of evidence, which included comparative analytical, nonclinical, and clinical data, with no clinically meaningful differences in safety or effectiveness. The data package was composed of, in part, results from a pharmacokinetic similarity study and a comparative clinical study.
The randomized, double-blind, comparative clinical study evaluated the efficacy, pharmacokinetics, pharmacodynamics, safety, tolerability, and immunogenicity of rituximab-arrx compared to rituximab in subjects with grade 1, 2, or 3a follicular B-cell non-Hodgkin lymphoma and low tumor burden. There were 256 patients enrolled and randomly assigned 1:1 to receive a 375 mg/m2 intravenous infusion of either rituximab-arrx or rituximab once weekly for 4 weeks followed by dosing at weeks 12 and 20. The primary endpoint, an assessment of overall response rate by week 28, was within the prespecified margin for rituximab-arrx compared to rituximab, showing clinical equivalence. Pharmacokinetics, pharmacodynamics, safety, and immunogenicity of rituximab-arrx were similar to rituximab.
The wholesale acquisition cost of rituximab-arrx in the United States will be 23.7% lower than the reference product rituximab. At launch, rituximab-arrx will be priced 16.7% below the current rituximab average selling price.