BIMEKIZUMAB MAINTAINED IMPROVEMENTS IN EFFICACY ENDPOINTS AND HAD A CONSISTENT SAFETY PROFILE THROUGH 52 WEEKS IN PATIENTS WITH NON-RADIOGRAPHIC AND RADIOGRAPHIC AXIAL SPONDYLOARTHRITIS: RESULTS FROM TWO PARALLEL PHASE 3 STUDIES

X. Baraliakos, A. Deodhar, D. Van der Heijde, M. Magrey, W. P. Maksymowych, T. Tomita, H. Xu, M. Oortgiesen, U. Massow, C. Fleurinck, A. Ellis, T. Vaux, J. Smith, A. Marten, L. S. GenslerRuhr-Universität Bochum, Rheumazentrum Ruhrgebiet Herne, Bochum, Germany Oregon Health & Science University, Arthritis and Rheumatic Diseases, Portland, United States of America Leiden University Medical Center (LUMC), Department of Rheumatology, Leiden, Netherlands University Hospitals, Case Western Reserve University, Cleveland, United States of America University of Alberta, Department of Medicine, Edmonton, Canada Morinomiya University of Medical Sciences, Graduate School of Health Science, Osaka, Japan Shanghai Changzheng Hospital, Affiliated to Second Military Medical University, Department of Rheumatology and Immunology, Shanghai, China UCB Pharma, N/A, Morrisville, United States of America UCB Pharma, N/A, Monheim am Rhein, Germany UCB Pharma, N/A, Brussels, Belgium UCB Pharma, N/A, Slough, United Kingdom University of California, Department of Medicine, Division of Rheumatology, San Francisco, United States of America  Background Bimekizumab (BKZ), a monoclonal IgG1 antibody that selectively inhibits interleukin (IL)-17F in addition to IL-17A, met all primary/secondary endpoints at Week (Wk) 16 in patients (pts) with active non-radiographic axial spondyloarthritis (nr-axSpA) and radiographic axSpA (r-axSpA; i.e., ankylosing spondylitis), in the parallel phase 3 BE MOBILE 1 and 2 studies, respectively. Objectives To assess efficacy and safety of BKZ in these pts up to Wk 52. Methods BE MOBILE 1 (NCT03928704) and 2 (NCT03928743) both involved a 16-wk placebo (PBO)-controlled and 36-wk maintenance period. Pts were randomised to subcutaneous BKZ 160 mg Q4W (BKZ) or to PBO then BKZ from Wk 16 (PBO/BKZ). Results 220/254 (86.6%) randomised pts with nr-axSpA and 298/332 (89.8%) with r-axSpA completed Wk 52. Efficacy was sustained to Wk 52 in both studies (Table 1). ASAS40 responses in BKZ-randomised pts increased from Wk 16 (nr-axSpA: 47.7%; r-axSpA: 44.8%; non-responder imputation [NRI]) to Wk 52 (60.9%; 58.4%; NRI) with high levels of efficacy across TNFi-naïve and TNFi-IR populations (Table 1). At Wk 52, ASDAS <2.1 was achieved by 61.6% and 57.1%, and ASDAS <1.3 by 25.2% and 23.4%, of BKZ-randomised pts with nr-axSpA and r-axSpA, respectively (Figure 1). Wk 16 reductions from baseline in objective signs of inflammation (MRI, hs-CRP), and improvements in function (BASFI) and ASQoL, were maintained through 52 wks. Efficacy at Wk 52 was similar in PBO/BKZ-treated and BKZ-randomised pts (Table 1). At Wk 52, 75.0% (183/244) of pts with nr-axSpA and 75.5% (249/330) of pts with r-axSpA had ≥1 treatment-emergent adverse event (TEAE) on BKZ; the most frequent (% pts) TEAEs by preferred term (MedDRA v19.0) were nasopharyngitis (nr-axSpa: 12.3%; r-axSpA 9.1%) and upper respiratory tract infection (9.4%; 6.4%); few COVID-19 infections were reported (7.0%; 2.1%). Incidence (pts/100 pt years) of serious TEAEs were low (4.4; 7.1); no major adverse cardiovascular events, active tuberculosis cases, serious COVID-19 infections, or deaths were reported. Most incidences of fungal infection (19.6; 14.9; none serious or systemic) were Candida (12.8; 8.3) and mild to moderate; two pts in both studies discontinued the study due to Candida infections. Incidence of IBD (1.0; 1.0) and uveitis (1.5; 2.4) were low. Conclusion Across the axSpA spectrum, BKZ resulted in sustained efficacy to Wk 52. No new safety signals were observed, consistent with the Wk 24 safety profile. References Deodhar A. Ann Rheum Dis 2022;81:772–3; 2. van der Heijde D. Ann Rheum Dis 2022;81:12–3. Image/graph: Table 1. Efficacy at Wk 52 Mean (SE), unless stated BE MOBILE 1 BE MOBILE 2 PBO→BKZ N=126 BKZ N=128 PBO→BKZ N=111 BKZ N=221 ASAS40 [NRI]n (%) 64 (50.8) 78 (60.9) 76 (68.5) 129 (58.4) ASAS40 in TNFi-naïve [NRI]n (%) 58 (53.2) 73 (61.9) 67 (71.3) 108 (58.7) ASAS40 in TNFi-IR [NRI]n (%) 6 (35.3) 5 (50.0) 9 (52.9) 21 (56.8) ASAS20 [NRI]n (%) 88 (69.8) 94 (73.4) 89 (80.2) 158 (71.5) ASAS PR [NRI]n (%) 38 (30.2) 38 (29.7) 41 (36.9) 66 (29.9) ASAS 5/6 [NRI]n (%) 65 (51.6) 71 (55.5) 74 (66.7) 124 (56.1) BASDAI CfB [MI] –3.5 (0.2) –3.9 (0.2) –4.0 (0.2) –3.6 (0.1) BASFI CfB [MI] –2.6 (0.2) –3.0 (0.2) –2.8 (0.2) –2.8 (0.1) ASDAS-MI [NRI]n (%) 37 (29.4) 47 (36.7) 49 (44.1) 71 (32.1) Nocturnal spinal pain CfB [MI] –4.1 (0.2) –4.3 (0.3) –4.6 (0.3) –4.1 (0.2) ASQoL CfB [MI] –5.3 (0.4) –5.9 (0.4) –5.6 (0.4) –5.7 (0.3) SF-36 PCS CfB [MI] 11.4 (0.9) 12.2 (0.9) 12.3 (0.9) 12.0 (0.6) BASMI CfB [MI] –0.4 (0.1) –0.6 (0.1) –0.7 (0.1) –0.7 (0.1) Total resolution of enthesitis [NRI]n (%) 41 (44.6) 51 (54.3) 31 (46.3) 67 (50.8) ASDAS-CRP CfB [MI] –1.6 (0.1) –1.8 (0.1) –1.9 (0.1) –1.7 (0.1) SPARCC MRI SIJ score CfB [OC]Mean (SD) –6.4 (10.7) –7.6 (10.5) –2.8 (6.1) –4.7 (8.2) Berlin MRI spine score CfB [OC]Mean (SD) –0.4 (2.0) –0.7 (2.5) –2.1 (3.4) –2.4 (3.9) hs-CRP, mg/L [MI]Median 2.2 1.7 2.0 2.3 RS. n: 109, 118, 94, 184; Max 1 TNFi; n: 17, 10, 37; MASES=0 in pts with MASES >0 at BL; n: 92, 67; 132; MRI sub-study; n: 70, 82, 48, 90, 79, 89. Acknowledgements This study was funded by UCB Pharma. Medical writing support was provided by Costello Medical, funded by UCB Pharma. Disclosure of Interests Xenofon Baraliakos Speakers bureau: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer and UCB Pharma, Paid instructor for: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer and UCB Pharma, Consultant of: AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, MSD, Novartis, Pfizer and UCB Pharma, Atul Deodhar Speakers bureau: Janssen, Novartis and Pfizer, Consultant of: AbbVie, Amgen, Aurinia, BMS, Eli Lilly, Janssen, MoonLake, Novartis, Pfizer and UCB Pharma, Grant/research support from: AbbVie, BMS, Celgene, Eli Lilly, MoonLake, Novartis, Pfizer and UCB Pharma, Désirée van der Heijde Consultant of: AbbVie, Bayer, BMS, Cyxone, Eisai, Galapagos, Gilead, GSK, Janssen, Eli Lilly, Novartis, Pfizer and UCB Pharma, Employee of: Director of Imaging Rheumatology BV, Marina Magrey Consultant of: AbbVie, Eli Lilly, Novartis, Pfizer and UCB Pharma, Grant/research support from: AbbVie and UCB Pharma, Walter P Maksymowych Consultant of: AbbVie, BMS, Boehringer-Ingelheim, Celgene, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer and UCB Pharma, Grant/research support from: AbbVie and Pfizer; educational grants from AbbVie, Janssen, Novartis and Pfizer, Employee of: Chief Medical Officer for CARE ARTHRITIS, Tetsuya Tomita Speakers bureau: AbbVie, Astellas, BMS, Eisai, Eli Lilly, Janssen, Kyowa Kirin, Mitsubishi-Tanabe, Novartis and Pfizer, Consultant of: AbbVie, Eli Lilly, Gilead, Novartis and Pfizer, Huji Xu Speakers bureau: AbbVie, Janssen, Novartis, Pfizer and UCB Pharma, Consultant of: AbbVie, Beigene, BioMap, IASO, Pfizer and UCB Pharma, Employee of: Clinical investigator for Peking-Tsinghua Center for Life Sciences, Marga Oortgiesen Shareholder of: UCB Pharma, Employee of: UCB Pharma, Ute Massow Employee of: UCB Pharma, Carmen Fleurinck Employee of: UCB Pharma, Alicia Ellis Employee of: UCB Pharma, Thomas Vaux Employee of: UCB Pharma, julie smith Employee of: UCB Pharma, Alexander Marten Employee of: UCB Pharma, Lianne S. Gensler Consultant of: AbbVie, Acelyrin, Eli Lilly, Fresenius Kabi, Janssen, Novartis, Pfizer and UCB Pharma, Grant/research support from: Novartis and UCB Pharma paid to institution. Keywords: Randomized control trial, Clinical trials, Spondyloarthritis DOI: 10.1136/annrheumdis-2023-eular.1562Citation: , volume 82, supplement 1, year 2023, page 873Session: Spondyloarthritis - treatment (Poster View)