Efficacy and Safety of Switching from Innovator Rituximab to Biosimilar CT-P10 Compared with Continued Treatment with CT-P10: Results of a 56-Week Open-Label Study in Patients with Rheumatoid Arthritis

Abstract

BACKGROUND: CT-P10 is a biosimilar candidate of innovator rituximab (RTX) that demonstrated a comparable clinical profile to RTX in a phase I randomized controlled trial (RCT) in rheumatoid arthritis (RA) (ClinicalTrials.gov identifier: NCT01534884). OBJECTIVE: This open-label extension (OLE) study (NCT01873443) compared the efficacy and safety of CT-P10 in patients with RA who received CT-P10 from the outset (i.e., from the start of the RCT and also in the OLE: 'maintenance group') with those who received RTX during the RCT and switched to CT-P10 during the OLE ('switch group'). METHODS: Patients who completed the RCT were recruited. Based on the Disease Activity Score using 28 joints (DAS28) and predefined safety criteria, patients could receive up to two courses of CT-P10 during the OLE. Efficacy [DAS28 and European League Against Rheumatism (EULAR) response], safety and immunogenicity were assessed. RESULTS: Eighty-seven patients were enrolled: 58 and 29 had previously received CT-P10 or RTX, respectively, in the RCT. Of these, 38 (65.5%) and 20 (69.0%) were treated with CT-P10 in the OLE and therefore comprised the maintenance and switch groups, respectively. The mean change in DAS28-erythrocyte sedimentation rate (ESR) from baseline (week 0 of RCT) at week 24 of the first OLE treatment course in the maintenance and switch groups was -2.7 and -2.4, respectively. The proportion of patients with good/moderate EULAR responses was also comparable between groups. Antidrug antibodies were detected in 13.2 and 15.0% of patients in the maintenance and switch groups, respectively, at week 24 of the first OLE course. CT-P10 treatment was well-tolerated when administered for up to 2 years or after switching from RTX. CONCLUSION: In this study population, comparable efficacy and safety profiles were observed in patients who switched from RTX to CT-P10 and those maintained on CT-P10 throughout treatment.