BACKGROUND: Dual neutralization of both interleukin 17A and 17F with the monoclonal antibody bimekizumab may have greater efficacy in psoriasis than neutralization of interleukin 17A alone. OBJECTIVE: To provide longer-term efficacy and safety data for bimekizumab from a phase 2b extension study in patients with moderate to severe psoriasis (BE ABLE 2). METHODS: After the 12-week initial study (BE ABLE 1), patients who had a 90% improvement in Psoriasis Area and Severity Index (PASI 90) at week 12 received bimekizumab 64, 160, or 320 mg for an additional 48 weeks (60 weeks in total). The primary objective was safety. RESULTS: Across all dose groups (N = 217), initial PASI 90 responders generally maintained high levels of efficacy through week 60: PASI 90, 80% to 100%; 100% improvement in PASI, 69% to 83%; Investigator's Global Assessment score 0 or 1, 78% to 100% (all nonresponder imputation). Incidence of serious treatment-emergent adverse events was 15/217 (6.9%). No cases of inflammatory bowel disease, major adverse cardiovascular events, or suicidal ideation or behavior were reported. LIMITATIONS: Low numbers in the bimekizumab 64 mg group (n = 15). The majority of 60-week data reported here are primarily for the week 12 PASI 90 responders only. CONCLUSION: Bimekizumab response rates were maintained through week 60. A substantial proportion of patients achieved complete skin clearance. Bimekizumab was generally well tolerated.