OBJECTIVES: Previous network meta-analysis established higher relative efficacy for ASAS outcomes at Week (Wk)16 with subcutaneous bimekizumab 160mg every four weeks (Q4W), a selective inhibitor of IL-17F in addition to IL‑17A, versus subcutaneous secukinumab 150mg Q4W, an IL-17A-only inhibitor, in patients with radiographic axSpA (r-axSpA; i.e. ankylosing spondylitis). This matching-adjusted indirect comparison (MAIC) assessed relative efficacy at Wk52 of bimekizumab versus secukinumab 150mg and the secukinumab 300mg dose escalation approved for inadequate responders.

METHODS: Individual patient data from BE MOBILE 2 (Bimekizumab 160mg; NCT03928743; n=220) were matched to MEASURE 1/2/3/4 pooled summary data (secukinumab 150mg: NCT01358175; NCT01649375; NCT02008916; NCT02159053; n=504) and MEASURE 3 (secukinumab 300mg: n=76). Adjusting for cross-trial differences, BE MOBILE 2 patients were reweighted to match baseline characteristics in the secukinumab trials. Propensity score weights were based on age, sex, ethnicity, TNFi exposure, weight/BMI, time-from-diagnosis and baseline BASDAI. These were selected by expert clinician consensus and literature review, but limited to characteristics reported by the MEASURE trials. 52‑wk outcomes were recalculated for ASAS20/40 and BASDAI change from baseline. Odds ratios (OR) or mean difference (MD) for unanchored comparisons are reported with 95% CI.

RESULTS: With bimekizumab, patients had higher likelihood of achieving ASAS20 (OR [95% CI]: 1.44 [0.99, 2.09]; effective sample size [ESS]=176), significantly higher likelihood of achieving ASAS40 (1.49 [1.05, 2.11]; ESS=176) and significantly higher likelihood of achieving greater reductions from baseline in BASDAI (MD [95% CI]: –0.43 [–0.83, – 0.03]; ESS=182) than with secukinumab 150mg at Wk52. Dose escalation with secukinumab 300mg showed similar likelihood of achieving ASAS20/40 to bimekizumab (ESS=112), however unlicensed intravenous loading in MEASURE 3 may overestimate efficacy of licensed subcutaneous 300mg dosing.

CONCLUSIONS: Patients with r-axSpA treated with bimekizumab 160mg Q4W had significantly higher likelihood of long-term ASAS40 and BASDAI responses versus secukinumab 150mg, and similar likelihood of achieving ASAS20/40 versus secukinumab 300mg (escalated dose).