Sex differences with bimekizumab in axSpA: earlier gain in men, convergence by Week 52
Post-hoc sex analysis of bimekizumab (BKZ; dual IL-17A/F inhibitor) in the phase 3 BE MOBILE trials: BE MOBILE 1 (nr-axSpA, NCT03928704) and BE MOBILE 2 (r-axSpA, NCT03928743), through Week 52.
Population. Sex balance differed by phenotype: nr-axSpA was roughly balanced (54.3% male); r-axSpA was male-predominant (72.3% male). At baseline, males generally had higher objective inflammation (MRI, hs-CRP), while females tended to report worse health-related quality of life (e.g. higher ASQoL).
Week 16 (BKZ vs placebo). Treatment effect versus placebo was typically larger in men than in women on composite and patient-reported outcomes: ASAS40, ASDAS <2.1, BASDAI, BASFI, pain, fatigue, and HRQoL. That pattern held across both nr- and r-axSpA.
Week 52 (BKZ-randomised patients). Responses were sustained or continued to improve in both sexes. Women showed clear longer-term gains, narrowing the early gap, though absolute rates often remained numerically higher in menโespecially in nr-axSpA.
Conference-reported Week 52 rates in BKZ-randomised patients (male vs female):
โข ASAS40: nr-axSpA 64.4% vs 56.4%; r-axSpA 59.4% vs 55.7%
โข ASDAS <2.1: nr-axSpA 72.0% vs 47.4%; r-axSpA 57.7% vs 55.8%
โข Mean BASDAI change: nr-axSpA โ4.0 vs โ3.6; r-axSpA โ3.6 vs โ3.4
ASQoL also improved substantially in both sexes by Week 16 and further by Week 52 (in some arms the Week 52 ASQoL gain was larger in women).
Objective inflammation. Despite higher baseline MRI inflammation and hs-CRP in men, both sexes reached similarly low levels by Week 16, maintained through Week 52. Absolute MRI and hs-CRP values converged even when the Week 16 placebo-controlled difference favoured men.
Takeaway. Men tended to respond earlier on clinical and patient-reported measures. Women caught up over the year, with substantial longer-term improvement. Suppression of objective inflammation was robust and comparable in both sexes by Week 16 and 52. Efficacy was shown across the full axSpA spectrum in both sexes.
*Rudwaleit M, Ramiro S, Poddubnyy D, et al. Bimekizumab efficacy in male and female patients with axial spondyloarthritis: 52-week results from the phase 3 BE MOBILE trials. Rheumatology (Oxford). Published online August 14, 2026.
๐
doi.org/10.1093/rheumatologyโฆ