POS0939 BIMEKIZUMAB IN PATIENTS WITH ACTIVE NON-RADIOGRAPHIC AXIAL SPONDYLOARTHRITIS: 24-WEEK EFFICACY & SAFETY FROM BE MOBILE 1, A PHASE 3, MULTICENTRE, RANDOMISED, PLACEBO‑CONTROLLED STUDY

Abstract

Background: Bimekizumab (BKZ) is a monoclonal IgG1 antibody that selectively inhibits IL‐17F in addition to IL‐17A. BKZ has shown rapid and sustained efficacy and was well tolerated up to 156 weeks (wks) in a phase 2b study in patients (pts) with active ankylosing spondylitis.1,2 Objectives: To assess efficacy and safety of BKZ vs placebo (PBO) in pts with active non‐radiographic axial spondyloarthritis (nr‐axSpA) up to Wk 24 in the ongoing pivotal phase 3 study, BE MOBILE 1. Methods: BE MOBILE 1 (NCT03928704) comprises a 16‐wk double‐blind, PBO‐controlled period and 36‐wk maintenance period. Pts were aged ≥18 yrs, had BASDAI ≥4 and spinal pain ≥4 at BL, and sacroiliitis on MRI and/or elevated CRP at screening. Pts were randomised 1:1, BKZ 160 mg Q4W:PBO. From Wk 16, all pts received BKZ 160 mg Q4W. Primary and secondary efficacy endpoints were assessed at Wk 16. Results: Of 254 randomised pts (BKZ: 128; PBO: 126), 244 (96.1%) completed Wk 16, 240 (94.5%) Wk 24. BL characteristics were comparable between groups: mean age 39.4 yrs, symptom duration 9.0 yrs; 54.3% pts male, 77.6% HLA‐B27+, 10.6% TNFi‐experienced. At Wk 16, the primary (ASAS40: 47.7% BKZ vs 21.4% PBO; p<0.001) and all ranked secondary endpoints were met (Table 1). Responses were rapid with BKZ, including in PBO pts who switched to BKZ at Wk 16, and increased to Wk 24 (Figure 1; Table 1). Substantial reductions of hs‐CRP by Wk 2 and MRI SIJ infammation by Wk 16 were achieved with BKZ vs PBO (Table 1). At Wk 24, >50% of pts initially randomised to BKZ had achieved ASDAS <2.1 (Figure 1). Over 16 wks, 80/128 (62.5%) pts had ≥1 TEAE on BKZ vs 71/126 (56.3%) on PBO; most frequent were nasopharyngitis (BKZ: 9.4%; PBO: 4.8%), upper respiratory tract infection (BKZ: 7.0%; PBO: 7.1%) and oral candidiasis (BKZ: 3.1%; PBO: 0%). No systemic candidiasis was observed. Up to 16 wks, incidence of SAEs was low (BKZ: 0.0%; PBO: 0.8%); no MACE or deaths were reported; 0 IBD cases occurred in pts on BKZ vs 1 (0.8%) in a pt on PBO. Conclusion: Dual inhibition of IL‐17A and IL‐17F with BKZ in pts with active nr‐axSpA resulted in rapid, clinically relevant improvements in efficacy outcomes vs PBO. No new safety signals were observed.