Abstract Background/Aims The Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (PsA; GRAPPA) domainbased treatment recommendations for PsA focus on six domains: peripheral arthritis, axial disease, enthesitis, dactylitis, skin psoriasis, and nail psoriasis, and PsA-related conditions: uveitis and IBD. Bimekizumab (BKZ), a monoclonal IgG1 antibody that selectively inhibits IL17F in addition to IL17A, has superior clinical efficacy vs placebo (PBO) to Week (Wk)16 in phase 3 clinical trials of PsA patients. In patients with psoriasis, superior skin domain efficacy was demonstrated versus secukinumab (IL-17A inhibitor), ustekinumab (IL-12/23 inhibitor), and adalimumab (TNF inhibitor [TNFi]). Methods Included patients received subcutaneous BKZ 160 mg or PBO every 4-wks (Q4W) in BE OPTIMAL (NCT03895203; biologic disease-modifying antirheumatic drugs [bDMARD]naïve patients with PsA), BE COMPLETE (NCT03896581; patients with PsA who were TNFiinadequate responders [TNFiIR]), BE MOBILE 1 (NCT03928704; nonradiographic axial spondyloarthritis [nr-axSpA]) and BE MOBILE 2 (NCT03928743; radiographic [r-]axSpA [i.e. ankylosing spondylitis]). BE OPTIMAL included a reference arm (adalimumab 40 mg Q2W) to Wk52; data not shown. From Wk16, all PBO-randomised patients received BKZ 160 mg Q4W to Wk52 (PBO/BKZ). Wk16 completers from BE COMPLETE entered BE VITAL (NCT04009499; openlabel extension). Outcomes are reported by GRAPPA domain as change from baseline and/or responder rate. Missing data were imputed using non-responder (binary) or multiple (continuous) imputation. Results Wk52 completion was high (BE OPTIMAL: 770/852 [90.4%], BE COMPLETE: 347/400 [86.8%], BE MOBILE 1: 220/254 [86.6%], BE MOBILE 2: 298/332 [89.8%]). Baseline demographics and disease characteristics were previously reported. Across all GRAPPA domains, improvements from Wk16 were sustained at Wk52 in BKZ-treated patients across all studies. Individual domain responses were generally consistent between bDMARD naïve and TNFi-IR patients; results from BE MOBILE 1 and 2 demonstrated BKZ efficacy in patients with axSpA (Table). Responses were generally consistent between BKZ and PBO/BKZ patients at Wk52. To Wk52, there were low rates of adjudicated IBD (2 [0.2%] in BE OPTIMAL) and no instances of uveitis. Conclusion Treatment with BKZ resulted in robust and sustained improvements across GRAPPA domains to Wk52 for both bDMARD naïve and TNFi-IR patients with PsA; results from patients with axSpA support efficacy in the axial domain. Disclosure J.F. Merola: Consultancies; AbbVie, Amgen, Biogen, BMS, Dermavant, Eli Lilly, Janssen, LEO Pharma, Pfizer, Novartis, Regeneron, Sanofi, Sun Pharma, and UCB Pharma. Other; Investigator for AbbVie, Amgen, Biogen, BMS, Dermavant, Eli Lilly, Janssen, LEO Pharma, Pfizer, Novartis, Regeneron, Sanofi, Sun Pharma, and UCB Pharma. P.J. Mease: Consultancies; AbbVie, Acelyrin, Aclaris, Amgen, BMS, Boehringer Ingelheim, Eli Lilly, Galapagos, Gilead, GSK, Janssen, Moonlake Pharma, Novartis, Pfizer, Sun Pharma and UCB Pharma. Member of speakers’ bureau; AbbVie, Amgen, Eli Lilly, Janssen, Novartis, Pfizer and UCB Pharma. Grants/research support; AbbVie, Acelyrin, Amgen, BMS, Eli Lilly, Gilead, Janssen, Novartis, Pfizer, Sun Pharma and UCB Pharma. A. Deodhar: Consultancies; AbbVie, BMS, Eli Lilly, Janssen, MoonLake, Novartis, Pfizer, UCB Pharma. Member of speakers’ bureau; Janssen, Novartis, Pfizer. Grants/research support; AbbVie, BMS, Celgene, Eli Lilly, MoonLake, Novartis, Pfizer, UCB Pharma. B. Ink: Shareholder/stock ownership; AbbVie, GSK, UCB Pharma. Other; Employee of UCB Pharma. C. Fleurinck: Other; Employee of UCB Pharma. R. Bajracharya: Shareholder/stock ownership; UCB Pharma. Other; Employee of UCB Pharma. J. Coarse: Shareholder/stock ownership; UCB Pharma. Other; Employee of UCB Pharma. L.C. Coates: Consultancies; AbbVie, Amgen, BMS, Boehringer Ingelheim, Celgene, Domain, Eli Lilly, Galapagos, Gilead, Janssen, Moonlake Pharma, Novartis, Pfizer, UCB Pharma. Member of speakers’ bureau; AbbVie, Amgen, Biogen, Celgene, Eli Lilly, Galapagos, Gilead, GSK, Janssen, medac, Novartis, Pfizer, UCB Pharma. Grants/research support; AbbVie, Amgen, Celgene, Eli Lilly, Gilead, Janssen, Novartis, Pfizer, UCB Pharma.