Efficacy outcomes at Week 16 (primary and ranked secondary endpoints) and Week 52
| Baseline | Week 16 | Week 52 | ||||||
| PBO | BKZ 160 mg Q4W | PBO | BKZ 160 mg Q4W | p value* | PBO→BKZ 160 mg Q4W | BKZ 160 mg Q4W | ||
| nr-axSpA (BE MOBILE 1) | n=126 | n=128 | n=126 | n=128 | n=126 | n=128 | ||
| r-axSpA (BE MOBILE 2) | n=111 | n=221 | n=111 | n=221 | n=111 | n=221 | ||
| Clinical response criteria | ||||||||
| ASAS40 (NRI), n (%) | nr-axSpA | – | – | 27 (21.4) | 61 (47.7) | <0.001 | 64 (50.8) | 78 (60.9) |
| r-axSpA | – | – | 25 (22.5) | 99 (44.8) | <0.001 | 76 (68.5) | 129 (58.4) | |
| ASAS20 (NRI), n (%) | nr-axSpA | – | – | 48 (38.1) | 88 (68.8) | <0.001 | 88 (69.8) | 94 (73.4) |
| r-axSpA | – | – | 48 (43.2) | 146 (66.1) | <0.001 | 89 (80.2) | 158 (71.5) | |
| ASAS PR (NRI), n (%) | nr-axSpA | – | – | 9 (7.1) | 33 (25.8) | <0.001 | 38 (30.2) | 38 (29.7) |
| r-axSpA | – | – | 8 (7.2) | 53 (24.0) | <0.001 | 41 (36.9) | 66 (29.9) | |
| ASAS40 in TNFi-naïve patients† (NRI), n (%) | nr-axSpA | – | – | 25 (22.9)‡ | 55 (46.6)§ | <0.001¶ | 58 (53.2)‡ | 73 (61.9)§ |
| r-axSpA | – | – | 22 (23.4)** | 84 (45.7)†† | <0.001 | 67 (71.3)** | 108 (58.7)†† | |
| ASDAS-MI (NRI), n (%) | nr-axSpA | – | – | 9 (7.1) | 35 (27.3) | <0.001 | 37 (29.4) | 47 (36.7) |
| r-axSpA | – | – | 6 (5.4) | 57 (25.8) | <0.001 | 49 (44.1) | 71 (32.1) | |
| Disease activity | ||||||||
| BASDAI CfB (MI), mean (SE) | nr-axSpA | 6.7 (0.1) | 6.9 (0.1) | −1.5 (0.2) | −3.1 (0.2) | <0.001 | −3.5 (0.2) | −3.9 (0.2) |
| r-axSpA | 6.5 (0.1) | 6.5 (0.1) | −1.9 (0.2) | −2.9 (0.1) | <0.001 | −4.0 (0.2) | −3.6 (0.1) | |
| BASDAI50 (NRI), n (%) | nr-axSpA | – | – | 27 (21.4) | 60 (46.9) | <0.001¶ | 62 (49.2) | 69 (53.9) |
| r-axSpA | – | – | 29 (26.1) | 103 (46.6) | <0.001¶ | 69 (62.2) | 119 (53.8) | |
| BASMI CfB† (MI), mean (SE) | nr-axSpA | 3.0 (0.1) | 2.9 (0.1) | −0.1 (0.1) | −0.4 (0.1) | <0.001¶ | −0.4 (0.1) | −0.6 (0.1) |
| r-axSpA | 3.8 (0.2) | 3.9 (0.1) | −0.2 (0.1) | −0.5 (0.1) | 0.006 | −0.7 (0.1) | −0.7 (0.1) | |
| Pain, physical function and quality of life | ||||||||
| Total spinal pain CfB (MI), mean (SE) | nr-axSpA | 7.1 (0.1) | 7.3 (0.1) | −1.7 (0.2) | −3.4 (0.2) | <0.001¶ | −3.9 (0.2) | −4.2 (0.2) |
| r-axSpA | 7.2 (0.1) | 7.1 (0.1) | −1.9 (0.2) | −3.3 (0.2) | <0.001¶ | −4.5 (0.2) | −4.1 (0.2) | |
| Nocturnal spinal pain CfB (MI), mean (SE) | nr-axSpA | 6.7 (0.2) | 6.9 (0.2) | −1.7 (0.2) | −3.6 (0.3) | <0.001 | −4.1 (0.2) | −4.3 (0.3) |
| r-axSpA | 6.8 (0.2) | 6.6 (0.1) | −1.9 (0.2) | −3.3 (0.2) | <0.001 | −4.6 (0.3) | −4.1 (0.2) | |
| BASFI CfB (MI), mean (SE) | nr-axSpA | 5.3 (0.2) | 5.5 (0.2) | −1.0 (0.2) | −2.5 (0.2) | <0.001 | −2.6 (0.2) | −3.0 (0.2) |
| r-axSpA | 5.2 (0.2) | 5.3 (0.2) | −1.1 (0.2) | −2.2 (0.1) | <0.001 | −2.8 (0.2) | −2.8 (0.1) | |
| SF-36 PCS CfB (MI), mean (SE) | nr-axSpA | 33.6 (0.8) | 33.3 (0.7) | 5.5 (0.7) | 9.5 (0.7) | <0.001 | 11.4 (0.9) | 12.2 (0.9) |
| r-axSpA | 34.6 (0.8) | 34.4 (0.6) | 5.9 (0.8) | 9.3 (0.6) | <0.001 | 12.3 (0.9) | 12.0 (0.6) | |
| ASQoL CfB (MI), mean (SE) | nr-axSpA | 9.4 (0.4) | 9.5 (0.4) | −2.5 (0.4) | −5.2 (0.4) | <0.001 | −5.3 (0.4) | −5.9 (0.4) |
| r-axSpA | 8.5 (0.4) | 9.0 (0.3) | −3.2 (0.3) | −5.0 (0.3) | <0.001 | −5.6 (0.4) | −5.7 (0.3) | |
Randomised set. Missing data were imputed using NRI for binary endpoints, RBMI for ranked continuous endpoints at Week 16, and MI for continuous non-ranked and ranked (post Week 16) endpoints at Week 52.
*All tests were performed at a two-sided alpha level of 0.05. For binary endpoints, p values were calculated by logistic regression with treatment, MRI/CRP classification and region (BE MOBILE 1) or treatment, prior TNFi exposure and region (BE MOBILE 2) as factors. For continuous endpoints, p values were obtained by ANCOVA with treatment, MRI/CRP classification and region (BE MOBILE 1) or treatment, prior TNFi exposure and region (BE MOBILE 2) as fixed effects, and baseline values as covariates.
†Ranked secondary endpoint in BE MOBILE 2.
‡n=109.
§n=118.
¶Outcome was not part of the statistical hierarchy, therefore p values are nominal (no multiplicity adjustment) and should not be used as an indicator of statistical significance.
**n=94.
††n=184.
ANCOVA, analysis of covariance; ASAS20/40/PR, Assessment of SpondyloArthritis International Society 20%/40% response/partial remission; ASDAS-MI, Ankylosing Spondylitis Disease Activity Score major improvement; ASQoL, Ankylosing Spondylitis Quality of Life; BASDAI(50), Bath Ankylosing Spondylitis Disease Activity Index (50% response); BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; BKZ, bimekizumab; CfB, change from baseline; CRP, C-reactive protein; MASES, Maastricht Ankylosing Spondylitis Enthesitis Score; MI, multiple imputation; nr-axSpA, non-radiographic axial spondyloarthritis; NRI, non-responder imputation; PBO, placebo; Q4W, every 4 weeks; r-axSpA, radiographic axial spondyloarthritis; RBMI, reference-based multiple imputation; SF-36 PCS, Short-Form 36-Item Health Survey Physical Component Summary; TNFi, tumour necrosis factor inhibitor.