A rituximab biosimilar provided rheumatoid arthritis (RA) patients similar safety and efficacy outcomes compared to the reference drug in a study. According to the study authors, “ABP 798 is a proposed biosimilar to the originator biologic rituximab, an anti-CD20 monoclonal antibody.”
The study included adult RA patients with moderate-to-severe disease with an inadequate response or intolerance to other disease-modifying antirheumatic drugs, including at least one tumor necrosis factor inhibitor. Patients received either ABP 798 or U.S.- or EU-sourced rituximab 1,000 two weeks apart. After 24 weeks, the ABP 798 and EU-sourced rituximab patients received a second dose of the same treatment, and the U.S.-sourced rituximab group was given ABP 798. The primary outcome was 24-week change in Disease Activity Score 28-joint C-reactive protein (DAS28-CRP); additional outcomes included DAS28-CRP changes at other timepoints; American College of Rheumatology (ACR) core set improvements of at least 20% (ACR20), 50% (ACR50), and 70% (ACR70) compared to baseline at weeks eight, 12, 24, 40, and 48; and hybrid ACR at the same timepoints.
The study enrolled 311 patients (282 completed the full study). The mean decrease in DAS28-CRP from baseline between the ABP 798 and pooled rituximab groups (−2.197 vs. −2.125, respectively) achieved clinical equivalence; all three groups achieved similar mean decreases up to 48 weeks. The proportion of patients in each group who achieved ACR20, ACR50, and ACR70 through week 48 was also similar, and mean hybrid ACR scores were similar among the groups.
The study was published in Clinical Rheumatology.
“This double-blind, randomized comparative study confirmed clinical equivalence in terms of efficacy between ABP 798 and rituximab RP [reference product] in patients with active moderate-to-severe RA. The overall safety and immunogenicity were similar between ABP 798 and rituximab RP over the entire study period and were not affected by the single transition. Together with the report of [pharmacokinetics] equivalence between ABP 798 and rituximab RP, the current results confirm clinical similarity between the 2 agents. Along with the demonstration of analytical similarity between ABP 798 and the rituximab RP, the results of this comparative clinical study contribute towards the totality of evidence that is required for demonstrating biosimilarity between a proposed biosimilar and the RP,” the researchers concluded.