Amgen and Allergan Announce Positive Topline Results for ABP 798

Amgen and Allergan today announced positive topline results of a combined phase 1 and phase 3 study evaluating ABP 798, a proposed biosimilar rituximab, in comparison with the reference Rituxan in patients with rheumatoid arthritis (RA).

The study enrolled 311 patients with RA to receive either ABP 798 (n = 104), US-sourced reference rituximab (n = 103), or EU-sourced reference rituximab (n = 104). The study’s duration was 48 weeks, and included a single transition for patients receiving the US-licensed reference to the proposed biosimilar.

The study’s primary endpoint was pharmacokinetic (PK) similarity between the reference and the proposed biosimilar. The PK endpoints evaluated were the area under the serum concentration—time curve and maximum serum concentration, and the drug makers state that both fell within the prespecified equivalence margin.

Equivalence in efficacy was measured by the change from baseline in Disease Activity Score in a count of 28 joints, measured with C-reactive protein, at week 24. According to Amgen and Allergan, “equivalent efficacy was established.” Furthermore, safety and immunogenicity were both similar among the 3 arms of the study.

“Results from this study show pharmacokinetic and clinical equivalence between ABP 798 and rituximab, further demonstrating Amgen's commitment to providing patients with access to high-quality, biological therapies,” said David M. Reese, MD, executive vice president of research and development at Amgen, in a statement. "We look forward to continuing to leverage our experience and expertise in biotechnology to bring more biosimilars to patients."

The companies noted that they are also currently undertaking another study intended to support regulatory applications; the second study is being conducted in patients with non-Hodgkin lymphoma.

If eventually approved, the biosimilar could compete not only with reference rituximab but also with Celltrion and Teva’s biosimilar, Truxima, which is now approved in both the United States and European Union (where it is also approved under the names Rituzena, Ritemvia, and Blitzima), and Sandoz’s biosimilar, approved in the European Union under the names Riximyo and Rixathon.

While it is not yet clear which indications Amgen and Allergan will seek for the biosimilar, if approved in inflammatory disease indications, ABP 798 could provide an option for US patients with inflammatory diseases who are not served by Truxima; when the biosimilar was approved in late 2018, it was only granted indications in oncology. According to a representative from Celltrion, the “skinny label” was a response to challenges in the patent landscape.