Comparable clinical efficacy of the rituximab (RTX) biosimilar GP2013 and reference RTX has been established in blinded randomized trials. However, when switching from a reference biologic to a biosimilar, potential safety implications are often an important consideration. Therefore, the aim of this study was to evaluate the safety of switching from reference RTX to RTX biosimilar GP2013 compared with treatment continuation with reference RTX in patients with rheumatoid arthritis (RA).
In this multinational, randomized, double-blind, parallel-group safety study, 107 patients with RA who had previously received treatment (of any duration) with reference RTX as part of routine practice and who required continuation of treatment were randomized to receive either GP2013 or to continue treatment with reference RTX. All patients received a stable dosage of methotrexate and folic acid during the study. Study assessments included the incidence of hypersensitivity, infusion-related and anaphylactic reactions, immunogenicity (antidrug antibodies), and general safety.
Regardless of whether patients switched to GP2013 or continued treatment with reference RTX, the incidences of hypersensitivity (9.4% and 11.1%, respectively) and infusion-related reactions (11.3% and 18.5%, respectively) were similarly low. Only 1 patient (in the reference RTX group) developed antidrug antibodies to RTX after starting study treatment. No neutralizing antidrug antibodies were observed. Antidrug antibodies were not associated with adverse events (AEs). No clinically meaningful differences in the rate of AEs were observed between treatment groups.
No safety risks were detected when patients switched from reference RTX to GP2013. The safety profiles of patients in both treatment groups were similar, although the study was not powered for statistical testing of equivalence in safety.