P180 Minimal spinal radiographic progression in patients with radiographic axial spondyloarthritis over 2 years of bimekizumab treatment: results from a phase 3 open-label extension study

The effect of dual inhibition of interleukin (IL)17F in addition to IL-17A with bimekizumab (BKZ) on structural radiographic progression in the spine has not yet been reported in radiographic axial spondyloarthritis (r-axSpA) patients. Here, we report the impact of BKZ on 2-year spinal radiographic progression and new syndesmophyte formation in r-axSpA patients in the open-label extension (OLE) of the phase 3 BE MOBILE 2 study.

BE MOBILE 2 (NCT03928743) study design has been reported previously.¹ At Week (Wk)52, eligible patients with r-axSpA could enroll in an ongoing OLE (NCT04436640). Baseline (BL) and Wk104 spinal radiographs were assessed using modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) by 2 central readers; change scores differing by ≥ 5 points were adjudicated. All readers were blinded to timepoint. The average score change across readers was determined for each radiograph; if 3 readers used, the average of the 2 closest change scores was calculated. Syndesmophytes were recorded if identified by 2 reviewers at a given anatomical site. New syndesmophytes were defined as syndesmophytes present at Wk104 but not at BL at the same site. For patients with mSASSS available at BL and Wk104, we report mean and cumulative probability of change from baseline (CfB) in mSASSS at Wk104, and the proportion of nonprogressors, using definitions mSASSS CfB ≤0.5 and mSASSS CfB <2. We also report patient proportions with new syndesmophytes at Wk104 in those with/without BL syndesmophytes. Potential predictive factors for spinal radiographic progression (mSASSS CfB ≥2) at Wk104 were assessed using logistic regression models.

Of 332 randomised patients, 286 (86.1%) entered the OLE; 267 (80.4%) completed Wk104. Of Wk104 completers, 71.2% (190/267) had an mSASSS available at BL and Wk104. Mean (SD) BL mSASSS was 7.3 (13.8), with a CfB of 0.3 (1.9) at Wk104. Most patients (157/190; 82.6%) had no spinal radiographic progression at Wk104 (mSASSS CfB ≤0). The proportion of nonprogressors at Wk104 (mSASSS CfB ≤0.5) was 85.3% (162/190). When defined as mSASSS CfB <2, 92.1% (175/190) were non-progressors, including 83.1% (69/83) with existing BL structural damage (mSASSS ≥2). BL syndesmophytes were present in 57/190 patients (30.0%). At Wk104, only 12/57 patients (21.1%) with BL syndesmophytes and 2/133 patients (1.5%) without BL syndesmophytes had developed new syndesmophytes. Of the potential predictive factors assessed using the univariable models, presence of BL syndesmophytes, non-White ethnicity and positive HLA-B27 were found to significantly increase likelihood of spinal radiographic progression (mSASSS CfB ≥2) at Wk104.

Minimal spinal radiographic progression was demonstrated at 2 years of BKZ treatment in r-axSpA patients. A high proportion of patients were non-progressors, including in those with BL spinal damage. A minor fraction of patients developed new syndesmophytes at 2 years, including almost 1/5 with existing BL syndesmophytes.

X. Baraliakos: Consultancies; Consultant of AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, Novartis, Pfizer and UCB. Member of speakers’ bureau; Speakers bureau from AbbVie, BMS, Chugai, Eli Lilly, Galapagos, MSD, Novartis, Pfizer, and UCB. Grants/research support; Grant/research support from: Novartis and UCB. Other; Paid instructor for AbbVie, BMS, Chugai, Eli Lilly, Galapagos, MSD, Novartis, Pfizer and UCB. S. Ramiro: Consultancies; Consultancy fees from AbbVie, Eli Lilly, Galapagos, Johnson & Johnson Innovative Medicine, Novartis, Pfizer, Sanofi and UCB. Grants/research support; Grants from AbbVie, Galapagos, MSD, Novartis, Pfizer and UCB. W.P. Maksymowych: Honoraria; Honoraria/consulting fees from AbbVie, BMS, Boehringer-Ingelheim, Celgene, Eli Lilly, Galapagos, Johnson & Johnson Innovative Medicine, Novartis, Pfizer and UCB. Grants/research support; Research grants from AbbVie, Galapagos, Pfizer and UCB; educational grants from AbbVie, Johnson & Johnson Innovative Medicine, Novartis and Pfizer. Other; Chief Medical Officer for CARE ARTHRITIS. M. Østergaard: Consultancies; Consulting fees from Abbott, Pfizer, Merck, Roche and UCB. Member of speakers’ bureau; Speakers’ bureaus for Abbott, BMS, Merck, Mundipharma, Pfizer and UCB. Grants/research support; Research grants from Abbott, Pfizer and Centocor. U. Massow: Corporate appointments; Employee of UCB. T. Vaux: Shareholder/stock ownership; Employee and shareholder of UCB. C. Prajapati: Corporate appointments; Contractor for UCB and employee of Veramed. A. Marten: Corporate appointments; Employee of UCB. N. de Peyrecave: Corporate appointments; Employee of UCB. D. Poddubnyy: Consultancies; Consultant for AbbVie, Biocad, Eli Lilly, Gilead, GSK, MSD, MoonLake Immunotherapeutics, Novartis, Pfizer, Samsung Bioepis and UCB. Member of speakers’ bureau; Speaker for AbbVie, BMS, Eli Lilly, MSD, Novartis, Pfizer and UCB. Grants/research support; Grant/research support from: AbbVie, Lilly, MSD, Novartis and Pfizer.