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.
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.
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.
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.