Bimekizumab Demonstrated Comparable 1-Year Efficacy in Male and Female Patients with Axial Spondyloarthritis: Results from 2 Phase 3 Studies

Objectives To assess bimekizumab (BKZ) efficacy to Week (Wk)52 across the full axial spondyloarthritis (axSpA) disease spectrum, focusing on potential sex-based differences in treatment response. Methods BE MOBILE 1/2 ( NCT03928704 /NCT03928743) included a 16-wk double-blind and 36-wk maintenance period. Patients received BKZ 160mg every 4 wks (Q4W) or placebo (PBO) to Wk16; thereafter, all received BKZ. Sex-stratified outcomes reported to Wk52: ASAS40, ASDAS<2.1, BASDAI, Ankylosing Spondylitis Quality of Life Questionnaire (ASQoL), and objective signs of inflammation (OSI; MRI SPARCC SIJ, MRI Berlin spine, hs-CRP). Wk16 BKZ vs PBO efficacy between males vs females were compared using adjusted relative odds ratios (rOR; logistic regression) and relative differences (RD; ANCOVA). Analyses were post-hoc (no p values). Results 220/254 BE MOBILE 1 (male: 124/138 [89.9%]; female: 96/116 [82.8%]) and 298/332 BE MOBILE 2 patients (male: 215/240 [89.6%]; female: 83/92 [90.2%]) completed Wk52. At baseline, females had longer mean symptom duration (years; non-radiographic [nr]-axSpA: 11.1 vs 7.2; radiographic [r]-axSpA: 15.0 vs 12.9) and lower HLA-B27 positivity (%) (nr-axSpA: 69.0 vs 84.8; r-axSpA: 78.3 vs 88.3) than males; males had lower mean ASQoL scores (nr-axSpA: BKZ: 8.5 vs 10.8, PBO: 8.6 vs 10.2; r-axSpA: BKZ: 8.3 vs 11.1, PBO: 8.4 vs 9.0), and generally higher OSI values than females. Across ASAS40, ASDAS<2.1, and BASDAI, rORs and RDs demonstrated greater Wk16 BKZ vs PBO treatment effect in males vs females (Figure 1). At Wk52, responses were higher in males with nr-axSpA than females, but comparable in r-axSpA. Overall, at Wk52, both sexes responded well in both trials, with >50% of BKZ-randomized patients achieving ASAS40, >40% achieving ASDAS <2.1, and BASDAI score improvements. For ASQoL, both males and females demonstrated substantial improvements with BKZ at Wk16 (nr-axSpA: −5.5 vs −4.8; r-axSpA: −4.8 vs −5.5) compared with PBO (nr-axSpA: −2.1 vs −2.9; r-axSpA: −3.1 vs −3.7). Improvements continued to Wk52 with BKZ (nr-axSpA: BKZ: −5.7 vs −6.2, PBO/BKZ: −5.5 vs −5.1; r-axSpA: BKZ: −5.4 vs −6.5, PBO/BKZ: −5.5 vs −5.8). For change from baseline in OSI outcomes, RDs indicated a higher Wk16 BKZ vs PBO treatment effect in males than females; absolute OSI values were comparable between males/females and maintained or improved to Wk52 with BKZ. Figure 1. ASAS40, ASDAS<2.1 and BASDAI to Wk52 and relative odds ratios and relative differences at Wk16, stratified by sex Conclusion Wk16 BKZ vs PBO treatment effect trended higher among males than females. By Wk52, females showed improvement in longer-term BKZ response, approaching levels comparable to males. Overall BKZ efficacy was demonstrated across clinical, patient-reported, and OSI outcomes in both sexes across the full axSpA disease spectrum.