Bimekizumab Responses Sustained Through 3 Years in Psoriatic Arthritis

Improvements with bimekizumab were sustained through 3 years in 5 of the 6 psoriatic arthritis (PsA) domains in the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) framework, according to a pooled post hoc analysis published in Rheumatology.

GRAPPA recommends a domain-based treatment approach targeting the lowest possible disease activity across peripheral arthritis, axial disease, enthesitis, dactylitis, skin psoriasis, and nail psoriasis. Bimekizumab is a humanized monoclonal IgG1 antibody that inhibits interleukin (IL)-17F in addition to IL-17A.

Investigators pooled data from 1,112 patients in the UCB-sponsored phase 3 BE OPTIMAL (biologic-naive) and BE COMPLETE (prior inadequate response or intolerance to tumor necrosis factor inhibitors) trials and their open-label extension, BE VITAL. Patients received subcutaneous bimekizumab 160mg every 4 weeks; those randomized to placebo switched to bimekizumab at week 16. At year 3 (week 148), 59.2% had a swollen joint count of 0, 34.6% had a tender joint count of 0, and 54.8% achieved at least 50% improvement in American College of Rheumatology response criteria.

Among patients with baseline involvement, complete resolution at year 3 occurred in 56.6% for enthesitis (Leeds Enthesitis Index), 68.6% for dactylitis, 64.6% for skin psoriasis (100% improvement in Psoriasis Area and Severity Index among those with ≥3% body surface area affected), and 68.0% for nail psoriasis. Over 3 years, 6 of 1,090 treated patients reported an inflammatory bowel disease event (5 new-onset) and 4 reported uveitis (2 new-onset). High-sensitivity C-reactive protein normalized in 63.2% of patients at year 3, and mean blood pressure remained stable.

The authors noted that axial involvement was not prospectively characterized and that Bath Ankylosing Spondylitis Disease Activity Index improvements in an exploratory subgroup do not constitute evidence of axial efficacy. They also cautioned that the inflammatory biomarker results do not demonstrate cardiovascular benefit. Additional limitations included the lack of a placebo arm during the extension and reliance on imputation.

Source: Deodhar A, Gottlieb AB, Merola JF, et al. Bimekizumab efficacy across GRAPPA domains to 3 years in patients with psoriatic arthritis: a post hoc analysis of two phase 3 studies. Rheumatology (Oxford). Published online 2026. doi:10.1093/rheumatology/keag557