Patient demographics and baseline characteristics
| BE MOBILE 1 (nr-axSpA) | BE MOBILE 2 (r-axSpA) | |||
| PBO n=126 | BKZ 160 mg Q4W n=128 | PBO n=111 | BKZ 160 mg Q4W n=221 | |
| Sex, male, n (%) | 65 (51.6) | 73 (57.0) | 80 (72.1) | 160 (72.4) |
| Age, years, mean (SD) | 39.4 (11.8) | 39.5 (11.1) | 39.2 (12.6) | 41.0 (12.1) |
| HLA-B27 positive, n (%) | 94 (74.6) | 103 (80.5) | 93 (83.8) | 191 (86.4) |
| Geographical region,* n (%) | ||||
| Asia† | 13 (10.3) | 15 (11.7) | 21 (18.9) | 40 (18.1) |
| Eastern Europe‡ | 71 (56.3) | 73 (57.0) | 55 (49.5) | 108 (48.9) |
| Western Europe§ | 33 (26.2) | 31 (24.2) | 32 (28.8) | 67 (30.3) |
| North America¶ | 9 (7.1) | 9 (7.0) | 3 (2.7) | 6 (2.7) |
| BMI, kg/m2, mean (SD) | 27.7 (5.5) | 27.2 (6.0) | 27.1 (5.8) | 26.8 (5.7) |
| Time since first symptoms of axSpA, years, mean (SD) | 9.0 (9.0) | 9.1 (8.7) | 11.9 (8.6) | 14.2 (11.0) |
| Time since first diagnosis of axSpA, years, mean (SD) | 3.6 (5.4) | 3.7 (6.2) | 5.7 (6.9) | 6.7 (8.3) |
| ASDAS, mean (SD) | 3.7 (0.7) | 3.7 (0.8) | 3.7 (0.8) | 3.7 (0.8)** |
| hs-CRP, mg/L, geometric mean (geometric CV, %) | 5.0 (230.5) | 4.6 (297.7) | 6.7 (197.4) | 6.5 (275.0) |
| hs-CRP>ULN,†† n () | 71 (56.3) | 70 (54.7) | 67 (60.4) | 137 (62.0) |
| BASDAI, mean (SD) | 6.7 (1.3) | 6.9 (1.2) | 6.5 (1.3) | 6.5 (1.3) |
| PtGADA,‡‡ mean (SD) | 6.9 (1.9) | 7.1 (1.9) | 6.7 (1.8) | 6.6 (2.0)** |
| Total spinal pain,‡‡ mean (SD) | 7.1 (1.6) | 7.3 (1.5) | 7.2 (1.2) | 7.1 (1.6) |
| Nocturnal spinal pain, mean (SD) | 6.7 (2.1) | 6.9 (2.0) | 6.8 (1.8) | 6.6 (1.9) |
| Morning stiffness (mean of BASDAI Q5&6),‡‡ mean (SD) | 6.9 (1.6) | 7.0 (1.8) | 6.8 (1.6) | 6.7 (1.9) |
| BASFI,‡‡ mean (SD) | 5.3 (2.3) | 5.5 (2.2) | 5.2 (2.0) | 5.3 (2.2) |
| BASMI, mean (SD) | 3.0 (1.2) | 2.9 (1.3) | 3.8 (1.6) | 3.9 (1.6) |
| ASQoL, mean (SD) | 9.4 (4.4) | 9.5 (4.6) | 8.5 (4.3) | 9.0 (4.7) |
| SF-36 PCS, mean (SD) | 33.6 (8.7) | 33.3 (8.3) | 34.6 (8.7) | 34.3 (8.4)** |
| MRI Berlin spine score,§§ mean (SD) | 1.6 (2.9)¶¶ | 1.6 (2.6)*** | 3.2 (4.1)††† | 3.3 (4.5)‡‡‡ |
| MRI SPARCC SIJ score,§§ mean (SD) | 9.8 (12.6)§§§ | 8.0 (9.9)¶¶¶ | 3.8 (6.1)††† | 5.4 (8.4)**** |
| Current enthesitis (MASES>0), n (%) | 92 (73.0) | 94 (73.4) | 67 (60.4) | 132 (59.7) |
| MASES,†††† mean (SE) | 4.9 (0.4) | 4.8 (0.3) | 4.4 (0.3) | 4.2 (0.3) |
| Current peripheral arthritis (SJC>0), n (%) | 43 (34.1) | 45 (35.2) | 22 (19.8) | 44 (19.9) |
| History of IBD,‡‡‡‡ n (%) | 1 (0.8) | 3 (2.3) | 1 (0.9) | 3 (1.4) |
| History of uveitis,‡‡‡‡ n (%) | 21 (16.7) | 19 (14.8) | 24 (21.6) | 33 (14.9) |
| History of psoriasis,‡‡‡‡ n (%) | 7 (5.6) | 9 (7.0) | 10 (9.0) | 16 (7.2) |
| Prior TNFi exposure (TNFi-IR patients),§§§§ n (%) | 17 (13.5) | 10 (7.8) | 17 (15.3) | 37 (16.7) |
| Concomitant medication use at baseline, n (%) | ||||
| NSAIDs | 93 (73.8) | 96 (75.0) | 85 (76.6) | 181 (81.9) |
| Oral glucocorticoids | 14 (11.1) | 7 (5.5) | 8 (7.2) | 15 (6.8) |
| csDMARDs¶¶¶¶ | 32 (25.4) | 29 (22.7) | 19 (17.1) | 47 (21.3) |
Randomised set. Patients in BE MOBILE 1 met ASAS criteria and patients in BE MOBILE 2 met mNY and ASAS criteria.
*Patients categorised by the stratum to which they were randomised.
†Includes Turkey, Japan and China.
‡Includes Bulgaria, Czech Republic, Hungary and Poland.
§Includes Belgium, France, Germany, The Netherlands, Spain and the UK.
¶Includes the USA only.
**n=220.
††ULN value for hs-CRP is 5 mg/L.
‡‡Part of the primary outcome measure.
§§In patients in the MRI substudy.
¶¶n=67.
***n=79.
†††n=48.
‡‡‡n=89.
§§§n=70.
¶¶¶n=82.
****n=90.
††††In patients with MASES >0 at baseline.
‡‡‡‡Based on extra-articular assessments at screening or baseline.
§§§§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.
¶¶¶¶Methotrexate in 21 patients with nr-axSpA and 12 patients with r-axSpA, sulfasalazine in 33 patients with nr-axSpA and 52 patients with r-axSpA.
ASAS, Assessment of SpondyloArthritis International Society; ASDAS, Ankylosing Spondylitis Disease Activity Score; ASQoL, Ankylosing Spondylitis Quality of Life; axSpA, axial spondyloarthritis; 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; CRP, C-reactive protein; csDMARD, conventional synthetic disease-modifying antirheumatic drug; CV, coefficient of variation; HLA-B27, human leukocyte antigen-B27; hs-CRP, high-sensitivity C-reactive protein; IBD, inflammatory bowel disease; IR, inadequate response; MASES, Maastricht Ankylosing Spondylitis Enthesitis Score; mNY, modified New York; nr-axSpA, non-radiographic axial spondyloarthritis; NSAID, non-steroidal anti-inflammatory drug; PBO, placebo; PtGADA, Patient’s Global Assessment of Disease Activity; Q, question; Q4W, every four weeks; 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.