The approval of the Amgen product marks the third biosimilar approval in the United States since the beginning of 2020.
The FDA has approved Amgen's rituximab biosimilar Riabni, which references Rituxan and is indicated for the treatment of adult patients with non-Hodgkin lymphoma (NHL), chronic lymphocytic leukemia, granulomatosis with polyangiitis, and microscopic polyangiitis. Amgen said the product would be commercialized in the United States starting in January 2021.
The approval milestone follows recent US biosimilar launches for Amgen including a trastuzumab (Kanjinti, 2019) and bevacizumab (Mvasi, 2019). The company has 10 biosimilars in total, 5 approved in the United States and 3 available in the European Union.
Riabni is a CD20-directed cytolytic antibody that has demonstrated biosimilarity to the reference product via comparative analytical, nonclinical, and clinical data. The totality of evidence included a pharmacokinetic similarity study and comparative clinical study, Amgen said.
Efficacy, pharmacokinetics (PK), pharmacodynamics (PD), safety, tolerability and immunogenicity were evaluated in patients with grade 1, 2, or 3a follicular B-cell NHL and low tumor burden. Investigators enrolled 256 patients and randomized them 1:1 to receive 375 mg/m2 intravenously of either the biosimilar or reference product, once weekly for 4 weeks, followed by dosing at weeks 12 and 20.
Amgen said the primary end point was overall response rate by week 28, which was within the prespecified margin for equivalence to Rituxan. PK, PD, safety, and immunogenicity also were equivalent, and no meaningful differences in safety or effectiveness were detected.
The pharmaceutical company said Riabni will be marketed at a discount to the reference product of 23.7% below wholesale acquisition cost (WAC), or a WAC of $716.80 per 100 mg and $3584 per 500 mg single-dose vial. These costs are 15.2% less than the WAC for the biosimilar rituximab Truxima, Amgen said.
The company added that Riabni's average sales price will be 16.7% below the current average for Rituxan.