Safety and Efficacy of Bimekizumab in Patients With Active Ankylosing Spondylitis: Three-Year Results From a Phase IIb Randomized Controlled Trial and Its Open-Label Extension Study

Objective: To assess the long-term safety, tolerability, and efficacy of bimekizumab in patients with active ankylosing spondylitis (AS). Methods: Patients with active AS who completed the dose-ranging, 48-week BE AGILE randomized controlled trial were eligible to participate in an open-label extension (OLE) study, in which patients received 160 mg of bimekizumab every 4 weeks. We present the safety and efficacy results through 156 weeks. Missing efficacy data were imputed using nonresponder imputation analysis for binary outcomes and multiple imputation for continuous outcomes. Results: From weeks 0–156, 280 of 303 patients (exposure-adjusted incidence rate 141.0 per 100 patient-years) experienced ≥1 treatment-emergent adverse event; the most frequent adverse events were nasopharyngitis (8.1 per 100 patient-years) and upper respiratory tract infection (5.0 per 100 patient-years). Additionally, 67 of 303 patients (9.8 per 100 patient-years) had mild to moderate localized fungal infections (28 of 303 patients had Candida infections [3.7 per 100 patient-years] and 23 of 303 patients had oral candidiasis [3.0 per 100 patient-years]), 10 patients had serious infections (1.3 per 100 patient-years), and no cases of active tuberculosis were reported. Active inflammatory bowel disease (1.1 per 100 patient-years), anterior uveitis (0.7 per 100 patient-years), and adjudicated major adverse cardiovascular events (0.3 per 100 patient-years) were infrequent. The efficacy of bimekizumab treatment demonstrated at week 48 was sustained in the OLE study. At week 156, nonresponder imputation analysis showed that 53.7% of patients (72.6% of observed cases) met the Assessment of SpondyloArthritis international Society criteria for 40% improvement and 28.0% of patients (37.9% of observed cases) achieved partial remission; Ankylosing Spondylitis Disease Activity Scores were reduced from baseline (mean ± SEM 3.9 ± 0.1) to week 48 (2.1 ± 0.1) and week 156 (1.9 ± 0.1) (multiple imputation). Patients showed sustained improvements in pain, fatigue, physical function, and health-related quality of life. Conclusion: The safety profile of bimekizumab was found to be consistent with previously demonstrated findings, and no new safety signals were identified. The efficacy of bimekizumab in patients with AS was sustained through 3 years of treatment.