PO:03:034 | Inhibition of Radiographic Progression with Bimekizumab Treatment Observed in bDMARD-Naïve Patients with Active Psoriatic Arthritis at 2 Years: Results from a Phase 3 Study and its Open-Label Extension

Laura C Coates¹, M Elaine Husni², Mitsumasa Kishimoto³, Proton Rahman⁴, Philipp Sewerin⁵, Enrique R Soriano⁶, Barbara Ink⁷, Rajan Bajracharya⁷, Jason Coarse⁸, Philip J Mease⁹, Emanuela Mazzola¹⁰, Peter Nash¹¹ | ¹NDORMS, University of Oxford and Oxford Biomedical Research Centre, Oxford University Hospitals NHS Trust Oxford, United Kingdom; ²Department of Rheumatic and Immunologic Diseases, Cleveland Clinic Cleveland, USA; ³Department of Nephrology and Rheumatology, Kyorin University School of Medicine Tokyo, Japan; ⁴Division of Rheumatology, Craig L. Dobbin Genetics Research Centre, Memorial University of Newfoundland St. Johns, Canada; ⁵Rheumazentrum Ruhrgebiet, University Hospital of the Ruhr University Bochum Herne Germany; ⁶Hospital Italiano de Buenos Aires and University Institute Hospital Italiano de Buenos Aires Buenos Aires, Argentina; ⁷UCB Slough, United Kingdom; ⁸UCB Morrisville, USA; ⁹Department of Rheumatology, Providence-Swedish Medical Center and University of Washington Seattle, USA; ¹⁰UCB Milan, Italy; ¹¹School of Medicine, Griffith University, Brisbane, Australia

Purpose of the Work. Minimal changes in radiographic progression have previously been observed in patients (pts) with active psoriatic arthritis (PsA) treated with bimekizumab (BKZ) up to 1-year.[1] Here, we report 2-year radiographic progression with BKZ in biologic disease-modifying antirheumatic drug (bDMARD)-naïve pts with active PsA in BE OPTIMAL and its open-label extension (OLE).

Materials and Methods. BE OPTIMAL (NCT03895203) assessed subcutaneous BKZ 160mg every 4 weeks (wks; Q4W) in PsA pts and was placebo (PBO)-controlled to Wk16, before BKZ switch (PBO/BKZ). BE OPTIMAL included a reference arm (subcutaneous adalimumab [ADA] 40mg Q2W) switching to BKZ at Wk52 (ADA/BKZ) with no washout. Wk52-completers could enter BE VITAL (NCT04009499), an ongoing OLE, receiving BKZ 160mg Q4W. Radiographic progression was assessed on plain hand and feet radiographs using the van der Heijde modified Total Sharp Score (vdHmTSS; score: 0–528), quantifying joint damage based on erosions and joint space narrowing (JSN). Radiographs were read centrally and independently by two readers, blinded to treatment and time of films. 2-year campaign readings were taken at baseline and Wk104. At Wk104, PBO/BKZ, BKZ-randomised and ADA/BKZ pts had received 88, 104 and 52 wks of BKZ, respectively. Data reported for overall radiographic set and a subgroup of pts at higher risk of progression (at-risk set; high-sensitivity C-reactive protein levels [hs-CRP]>=6mg/L and/or >=1 bone erosion at baseline): mean change from baseline (CfB) in vdHmTSS, cumulative probability of vdHmTSS CfB and proportion of pts with no radiographic progression (vdHmTSS CfB <=0.5 and <=0.0) at 2-years of total therapy. Additional outcomes include mean CfB in vdH Erosions and JSN sub-scores. Data reported for pts with radiographs at Wk104 (observed case).

Results. 664/852 pts in overall radiographic set (221[PBO/BKZ], 343[BKZ], 100[ADA/BKZ]) and 566/852 in at-risk set (186[PBO/BKZ], 296[BKZ], 84[ADA/BKZ]) had radiographs at baseline and Wk104. Baseline vdHmTSS scores were similar across arms (Table). Minimal radiographic progression to Wk104 in overall radiographic set (vdHmTSS mean CfB [standard deviation]: 0.08[2.05] PBO/BKZ, 0.07[1.43] BKZ, 0.06[2.01] ADA/BKZ) and at-risk set (0.08[2.23] PBO/BKZ, 0.07[1.53] BKZ, 0.02[2.19] ADA/BKZ; Table). High proportions of pts experienced no radiographic progression (vdHmTSS CfB <=0.5) at Wk104, in overall radiographic set (79.4%[PBO/BKZ], 84.2%[BKZ], 82.8%[ADA/BKZ]) and at-risk set (76.1%[PBO/BKZ], 82.4%[BKZ], 81.9%[ADA/BKZ]; Figure 1A). Most pts had minimal change in vdHmTSS score at 2-years (Figure 1B). Minimal changes in mean vdH Erosions and JSN sub-scores observed at 2-years across arms, in both sets (Table).

Conclusions. Inhibition of radiographic progression was observed at 2-years with BKZ in bDMARD-naïve pts with active PsA. Most pts experienced no radiographic progression, despite original randomisation.