Long-term safety, immunogenicity and efficacy comparing FKB327 with the adalimumab reference product in patients with active rheumatoid arthritis: data from randomised double-blind and open-label extension studies.

Background/objective: FKB327 is a biosimilar of the antitumour necrosis factor adalimumab reference product (RP). A randomised, double-blind (DB) phase 3 study compared the efficacy of FKB327 with the RP in patients with active rheumatoid arthritis (RA) inadequately controlled with methotrexate (MTX). A subsequent randomised open-label extension (OLE) study with treatment switching assessed long-term safety, efficacy, pharmacokinetics and immunogenicity of FKB327 compared with the RP.

Methods: Patients with moderate-to-severe, active RA on a stable dose of MTX were randomised 1:1 to receive FKB327 or the RP (40 mg subcutaneously every other week) for 24 weeks. Patients who completed the DB study were enrolled in the OLE and rerandomised 2:1 to receive FKB327 or the RP; two-thirds continued on the same treatment and one-third switched for 30 weeks. All patients received FKB327 through Week 76. Long-term efficacy, safety and immunogenicity were assessed.

Results: Of 728 patients in the DB study, 645 were enrolled in the FKB327-OLE study. The American College of Rheumatology (ACR)20 response rates for all treatment groups at Week 30 in the OLE ranged from 83.2% to 85.9%. ACR20 response rates remained stable for all patients regardless of single- or double-switching treatment and were similar for all treatment sequences through Week 76. The safety profile and incidence of antidrug antibodies were comparable across sequences.

Conclusion: Efficacy, safety and immunogenicity were similar among patients with RA treated with FKB327 or the RP for up to 2 years, and were not affected by single- or double-switching treatment.