# Impact of symptom duration on the short- and long-term efficacy of bimekizumab in axial spondyloarthritis: results up to 2 years

## TL;DR

This study shows that bimekizumab is effective for up to two years in treating axial spondyloarthritis, with early treatment potentially offering better long-term outcomes.

## Contribution

The study reveals that symptom duration affects long-term treatment outcomes with bimekizumab in axial spondyloarthritis.

## Key findings

- Bimekizumab improved disease activity and quality of life at 16 weeks regardless of symptom duration.
- Shorter symptom duration subgroups showed better 104-week outcomes compared to longer duration subgroups.
- Treatment effects were sustained over two years in all subgroups.

## Abstract

Bimekizumab, a monoclonal IgG1 antibody that selectively inhibits IL-17F in addition to IL-17A, showed efficacy to 2 years in patients with axial spondyloarthritis (axSpA). In this post hoc analysis, we compare the impact of shorter versus longer symptom duration on the efficacy of bimekizumab to Week 104.

Efficacy outcomes by symptom duration (≤ 2 [ASAS early axSpA definition] versus > 2 years; ≤ 5 versus > 5 years) were assessed across patients from BE MOBILE 1 and 2 (non-radiographic [NCT03928704]/radiographic axSpA [NCT03928743]) and the combined open-label extension (NCT04436640). (Relative) odds ratios and (relative) differences were calculated to compare 16-week bimekizumab versus placebo treatment effect and 104-week outcomes, and infer the significance of differences, between symptom duration subgroups. Analyses were neither powered for these comparisons nor multiplicity adjusted, and should be interpreted accordingly.

Improved disease activity, physical function, fatigue, health-related quality of life and objective signs of inflammation were seen with bimekizumab versus placebo at Week 16 regardless of symptom duration. Outcomes were then sustained or improved with bimekizumab to Week 104 across all subgroups.

16-week bimekizumab versus placebo treatment effect was comparable between subgroups (e.g., ≤ 2-year versus > 2-year symptom duration relative odds ratio [95% CI] for ASDAS < 2.1 in BE MOBILE 1: 0.82 [0.22, 3.08]). Significant differences were observed for some 104-week outcomes between symptom duration subgroups across both studies (e.g., ≤ 5-year versus > 5-year symptom duration odds ratio [95% CI] for ASDAS < 2.1 in BE MOBILE 2: 1.94 [1.02, 3.68]), all favouring the shorter symptom duration subgroups.

Bimekizumab was efficacious to 2 years regardless of symptom duration, with comparable 16-week treatment effect but generally better 104-week outcomes in the shorter versus longer symptom duration subgroups.

Registered on ClinicalTrials.gov; NCT03928704 (BE MOBILE 1; 23rd April 2019), NCT03928743 (BE MOBILE 2; 23rd April 2019), NCT04436640 (BE MOVING; 15th June 2020).

The online version contains supplementary material available at 10.1186/s13075-026-03729-6.