Bimekizumab maintains long term safety profile in psoriatic arthritis and axial spondyloarthritis, shows study

Axial spondyloarthritis and psoriatic arthritis are chronic inflammatory autoimmune disorders that have a major impact on the quality of life. The management of these diseases has changed by the introduction of biologic agents that target the inflammatory cascade. However, it is important that the safety profile be continuously monitored for these biologic agents since they are used for a prolonged period for chronic management. Bimekizumab is a monoclonal antibody that selectively inhibits the action of interleukin-17A and interleukin-17F. It has shown promising results for the management of inflammatory manifestations in both axSpA and PsA.

The study consisted of a safety analysis from data collected from six phase IIb and phase III clinical trials that tested bimekizumab in patients with axial spondyloarthritis and psoriatic arthritis. The study included all patients who received at least one dose of bimekizumab 160 mg given at four-weekly intervals.

The data cutoff for the phase III trials was in July 2023. The long-term safety results were obtained by allowing the trials to run for several years. The treatment-emergent adverse events were expressed as exposure-adjusted incidence rates per 100 patient-years (EAIR per 100 PY), which allows for a standardized presentation that takes into consideration the varying durations of treatment in the different patients.

Key findings:

• The results of the integrated safety analysis comprised 848 patients with axSpA and 1,409 patients with PsA, representing 2,513.8 patient-years and 3,655.9 patient-years of cumulative exposure, respectively.

• The EAIR for TEAEs was 129.6 per 100 patient-years for axSpA and 126.9 per 100 patient-years for PsA.

• Discontinuation of treatment due to TEAEs was low, with an EAIR of 2.4 per 100 patient-years for axSpA and 2.9 per 100 patient-years for PsA.

• The most common TEAE was COVID-19 infection (EAIR 9.9 per 100 patient-years for both axSpA and PsA).

• The second most common TEAEs were nasopharyngitis (EAIR 8.4 per 100 patient-years for axSpA and 6.8 per 100 patient-years for PsA) and URTI (EAIR 5.0 per 100 patient-years for axSpA and 5.7 per 100 patient-years for PsA).

• The EAIR for oral candidiasis was 3.5 per 100 patient-years for axSpA and 3.8 per 100 patient-years for PsA.

• Serious opportunistic infections were rare (EAIR 0 for axSpA and 0.1 for PsA).

• No active TB cases were observed.

Bimekizumab showed a positive long-term safety profile in patients with axial spondyloarthritis and psoriatic arthritis. There were similar rates of treatment-emergent adverse events in patients with both diseases. There were no new safety concerns identified. This shows the tolerability of bimekizumab therapy over a period of five years. This confirms the role of bimekizumab as a biologic therapy for patients with inflammatory arthritis.

Reference:

Mease PJ, Merola JF, Magrey M, Nash P, Poddubnyy D, Lebwohl M, et al. Bimekizumab longer-term safety profile in adult patients with axial spondyloarthritis or psoriatic arthritis: an updated analysis of six phase IIb/III clinical studies. RMD Open. 2026;12:e006174. https://doi.org/10.1136/rmdopen-2025-006174