- Design
- MRI and radiographic substudies of phase 3 RCTs with open-label extension
- Population
- Patients with non-radiographic and radiographic axial spondyloarthritis
- Primary outcome
- MRI inflammation and structural lesions; radiographic progression at 104 weeks
- Effect
- SPARCC SIJ -7.6 (nr-axSpA), -5.1 (r-axSpA) at week 52; mSASSS change 0.3 at week 104
BE MOBILE 1 (non-radiographic) and BE MOBILE 2 (radiographic axial spondyloarthritis) tested bimekizumab, which blocks both IL-17A and IL-17F, against placebo for 16 weeks and then open-label. MRI substudies scored inflammation and structural lesions, and radiographs were taken at 104 weeks.
At 52 weeks, sacroiliac inflammation fell (SPARCC change -7.6 non-radiographic, -5.1 radiographic) and spinal inflammation fell (Berlin -0.5 and -2.5). Sacroiliac erosion scores decreased (-1.8 in both), backfill and fat lesions increased, and ankylosis barely changed. Radiographic progression to week 104 was minimal (mNY change 0.03; mSASSS change 0.3).
Falling erosion with rising backfill is the pattern expected when inflammation settles and repair begins. Without a long-term control group, the radiographic data cannot show that bimekizumab slows structural progression more than other biologics.
- Bimekizumab reduced MRI inflammation in both radiographic and non-radiographic axial spondyloarthritis
- Backfill and fat lesions rising as erosions fall suggest repair after inflammation
- Structural data are uncontrolled beyond week 16
- Its availability and cost in India are not established here
Why it matters
It adds imaging evidence that dual IL-17 blockade calms inflammation in the axial skeleton.
Don't overread it
Observed-case open-label data without a control group cannot show disease modification.
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