Primary and secondary efficacy end points (week 12; FAS, NRI/MI)
| Placebo Q4W (n=60) | BKZ 16 mg Q4W (n=61) | BKZ 64 mg Q4W (n=61) | BKZ 160 mg Q4W (n=60) | BKZ 320 mg Q4W (n=61) | |
| ASAS40*, n (%) | |||||
| Week 12 | 8 (13.3) | 18 (29.5) | 26 (42.6) | 28 (46.7) | 28 (45.9) |
| ASAS20*, n (%) | |||||
| Week 12 | 17 (28.3) | 25 (41.0) | 38 (62.3) | 35 (58.3) | 44 (72.1) |
| ASAS5/6*, n (%) | |||||
| Week 12 | 4 (6.7) | 18 (29.5) | 30 (49.2) | 32 (53.3) | 33 (54.1) |
| BASDAI†, mean (SD) | |||||
| Baseline | 6.5 (1.4) | 6.7 (1.4) | 6.7 (1.3) | 6.3 (1.3) | 6.5 (1.6) |
| Week 12 | 5.5 (2.2) | 5.0 (2.1) | 3.9 (2.1) | 3.8 (2.0) | 3.7 (2.1) |
| Change from baseline | −1.0 (1.7) | −1.7 (2.3) | data-fill="true"−2.7 (2.2) | −2.5 (1.8) | −2.9 (2.2) |
| BASFI, mean (SD), | |||||
| Baseline | 5.6 (2.0) | 5.9 (1.7) | 6.0 (1.8) | 5.6 (2.2) | 5.9 (2.0) |
| Week 12 | 5.0 (2.4) | 4.6 (2.4) | 4.1 (2.3) | 3.9 (2.2) | 3.7 (2.5) |
| Change from baseline | −0.6 (1.9) | −1.4 (2.2) | −1.9 (2.4) | −1.7 (1.8) | −2.2 (2.0) |
| ASDAS†, mean (SD), | |||||
| Baseline | 3.8 (0.9) | 3.9 (0.7) | 4.2 (0.8) | 3.9 (0.8) | 3.9 (0.7) |
| Week 12 | 3.5 (1.1) | 3.0 (0.9) | 2.5 (0.9) | 2.5 (1.0) | 2.4 (0.9) |
| Change from baseline | −0.4 (0.7) | −0.9 (1.0) | −1.7 (1.1) | −1.4 (0.9) | −1.5 (0.9) |
*NRI.
†MI.
ASAS, Assessment of SpondyloArthritis international Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BKZ, bimekizumab; FAS, full analysis set; MI, multiple imputation; NRI, non-responder imputation; Q4W, every 4 weeks.