Patient demographics and baseline characteristics
| BE MOBILE 1 (nr-axSpA) | BE MOBILE 2 (r-axSpA) | |||
| BKZ 160 mg Q4W n=128 | PBO n=126 | BKZ 160 mg Q4W n=221 | PBO n=111 | |
| Sex, male, n (%) | 73 (57.0) | 65 (51.6) | 160 (72.4) | 80 (72.1) |
| Age, years, mean (SD) | 39.5 (11.1) | 39.4 (11.8) | 41.0 (12.1) | 39.2 (12.6) |
| Geographical region, n (%) | ||||
| Asia* | 15 (11.7) | 13 (10.3) | 40 (18.1) | 21 (18.9) |
| Eastern Europe† | 73 (57.0) | 71 (56.3) | 108 (48.9) | 55 (49.5) |
| Western Europe‡ | 31 (24.2) | 33 (26.2) | 67 (30.3) | 32 (28.8) |
| North America§ | 9 (7.0) | 9 (7.1) | 6 (2.7) | 3 (2.7) |
| BMI, kg/m2, mean (SD) | 27.2 (6.0) | 27.7 (5.5) | 26.8 (5.7) | 27.1 (5.8) |
| HLA-B27 positive, n (%) | 103 (80.5) | 94 (74.6) | 191 (86.4) | 93 (83.8) |
| Prior TNFi exposure (TNFi-IR patients),¶ n (%) | 10 (7.8) | 17 (13.5) | 37 (16.7) | 17 (15.3) |
| Time since first symptoms of axSpA, years, mean (SD) | 9.1 (8.7) | 9.0 (9.0) | 14.2 (11.0) | 11.9 (8.6) |
| Time since first diagnosis of axSpA, years, mean (SD) | 3.7 (6.2) | 3.6 (5.4) | 6.7 (8.3) | 5.7 (6.9) |
| hs-CRP, mg/L, geometric mean (geometric CV, %) | 4.6 (297.7) | 5.0 (230.5) | 6.5 (275.0) | 6.7 (197.4) |
| hs-CRP>ULN,** n (%) | 70 (54.7) | 71 (56.3) | 137 (62.0) | 67 (60.4) |
| ASDAS-CRP, mean (SD) | 3.7 (0.8) | 3.7 (0.7) | 3.7 (0.8)†† | 3.7 (0.8) |
| BASDAI, mean (SD) | 6.9 (1.2) | 6.7 (1.3) | 6.5 (1.3) | 6.5 (1.3) |
| Morning stiffness (mean of BASDAI Q5&6),‡‡ mean (SD) | 7.0 (1.8) | 6.9 (1.6) | 6.7 (1.9) | 6.8 (1.6) |
| Total spinal pain,‡‡ mean (SD) | 7.3 (1.5) | 7.1 (1.6) | 7.1 (1.6) | 7.2 (1.2) |
| Nocturnal spinal pain, mean (SD) | 6.9 (2.0) | 6.7 (2.1) | 6.6 (1.9) | 6.8 (1.8) |
| BASMI, mean (SD) | 2.9 (1.3) | 3.0 (1.2) | 4.0 (1.6)†† | 3.8 (1.6)§§ |
| BASFI,‡‡ mean (SD) | 5.5 (2.2) | 5.3 (2.3) | 5.3 (2.2) | 5.2 (2.0) |
| ASQoL, mean (SD) | 9.5 (4.6) | 9.4 (4.4) | 9.0 (4.7) | 8.5 (4.3) |
| SF-36 PCS, mean (SD) | 33.3 (8.3) | 33.6 (8.7) | 34.3 (8.4)†† | 34.6 (8.7) |
| PtGADA,‡‡ mean (SD) | 7.1 (1.9) | 6.9 (1.9) | 6.6 (2.0)†† | 6.7 (1.8) |
| MRI Berlin spine score,¶¶ mean (SD) | 1.6 (2.9)*** | 1.9 (3.2)††† | 3.8 (5.3)‡‡‡ | 3.3 (4.9)§§§ |
| MRI SPARCC SIJ inflammation score,¶¶ mean (SD) | 8.5 (10.3)¶¶¶ | 10.5 (13.8)**** | 7.4 (10.7)†††† | 5.8 (7.7)§§§ |
| Current enthesitis (MASES>0), n (%) | 94 (73.4) | 92 (73.0) | 132 (59.7) | 67 (60.4) |
| MASES,‡‡‡‡ mean (SE) | 4.8 (0.3) | 4.9 (0.4) | 4.2 (0.3) | 4.4 (0.3) |
| Current peripheral arthritis (SJC>0), n (%) | 45 (35.2) | 43 (34.1) | 44 (19.9) | 22 (19.8) |
| History of peripheral arthritis,§§§§ n (%) | 51 (39.8) | 53 (42.1) | 84 (38.0) | 38 (34.2) |
| History of IBD,§§§§ n (%) | 3 (2.3) | 1 (0.8) | 3 (1.4) | 1 (0.9) |
| History of uveitis,§§§§ n (%) | 19 (14.8) | 21 (16.7) | 33 (14.9) | 24 (21.6) |
| History of psoriasis,§§§§ n (%) | 9 (7.0) | 7 (5.6) | 16 (7.2) | 10 (9.0) |
| Concomitant medication use at baseline, n (%) | ||||
| NSAIDs | 97 (75.8) | 93 (73.8) | 180 (81.4) | 85 (76.6) |
| Oral glucocorticoids | 7 (5.5) | 14 (11.1) | 15 (6.8) | 8 (7.2) |
| csDMARDs¶¶¶¶ | 30 (23.4) | 32 (25.4) | 47 (21.3) | 19 (17.1) |
Randomised set.
*Includes Turkey, Japan and China.
†Includes Bulgaria, Czech Republic, Hungary and Poland.
‡Includes Belgium, France, Germany, Netherlands, Spain and UK.
§Includes USA only.
¶Defined as patients who were intolerant or experienced an inadequate response to previous TNFi treatment given at an approved dose for at least 12 weeks.
**ULN value for hs-CRP is 5 mg/L.
††n=220.
‡‡Part of the primary outcome measure.
§§n=108.
¶¶In patients in MRI substudy.
***n=75.
†††n=65.
‡‡‡n=82.
§§§n=45.
¶¶¶n=79.
****n=68.
††††n=83.
‡‡‡‡In patients with MASES>0 at baseline.
§§§§Based on extramusculoskeletal assessments at screening or baseline.
¶¶¶¶Methotrexate in 21 patients with nr-axSpA and 12 patients with r-axSpA, sulfasalazine in 34 patients with nr-axSpA and 52 patients with r-axSpA.
ASDAS, Ankylosing Spondylitis Disease Activity Score; ASQoL, Ankylosing Spondylitis Quality of Life; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; BASMI, Bath Ankylosing Spondylitis Metrology Index; BKZ, bimekizumab; BMI, body mass index; csDMARD, conventional synthetic disease-modifying antirheumatic drug; CV, coefficient of variation; HLA-B27, human leucocyte antigen-B27; hs-CRP, high-sensitivity C-reactive protein; IBD, inflammatory bowel disease; IR, inadequate response; MASES, Maastricht Ankylosing Spondylitis Enthesitis Score; n, number of patients with the characteristic; nr-axSpA, non-radiographic axial spondyloarthritis; NSAID, non-steroidal anti-inflammatory drug; PBO, placebo; PtGADA, Patient’s Global Assessment of Disease Activity; Q, question; r-axSpA, radiographic axial spondyloarthritis; SF-36 PCS, Short-Form 36-item Health Survey Physical Component Summary; SIJ, sacroiliac joint; SJC, swollen joint count; SPARCC, Spondyloarthritis Research Consortium of Canada; TNFi, tumour necrosis factor inhibitor; ULN, upper limit of normal.