AVANT was a Phase 3, 24-week, randomized, parallel-group, double-blind, double-dummy, placebo-controlled study to assess the efficacy and safety of aclidinium/formoterol 400 μg/12 μg combination vs monotherapies and aclidinium vs placebo (1:1:1:1) in Asian patients (∼70% of whom were Chinese) with moderate-to-severe stable chronic obstructive pulmonary disease. Endpoints were analyzed hierarchically to incorporate type I error control. At Week 24, aclidinium/formoterol demonstrated improvements from baseline in 1-h morning post-dose forced expiratory volume in 1 s (FEV₁) vs aclidinium (least squares [LS] mean 92 mL; 95% confidence interval [CI] 60, 124 mL; p < 0.001), and in trough FEV₁ vs formoterol (LS mean 85 mL; 95% CI 53, 117 mL; p < 0.001). Furthermore, aclidinium provided improvements in trough FEV₁ vs placebo (LS mean 134 mL; 95% CI 103, 166 mL; p < 0.001). There was an improvement in transition dyspnea index focal score at Week 24 for aclidinium/formoterol vs placebo (LS mean 0.8; 95% CI 0.2, 1.3; p = 0.005) but not for aclidinium vs placebo (LS mean 0.4; 95% CI −0.1, 1.0; p = 0.132). Improvements in St George's Respiratory Questionnaire total scores occurred for aclidinium/formoterol vs placebo (LS mean −4.0; 95% CI −6.7, −1.4; p = 0.003) and aclidinium vs placebo (LS mean −2.9; 95% CI −5.5, −0.3; p = 0.031). Aclidinium/formoterol and aclidinium were well tolerated and safety findings were consistent with known profiles; rates of treatment-emergent adverse events (AEs) (aclidinium/formoterol: 54.8%; aclidinium: 47.4%; placebo: 53.9%), serious AEs (7.2, 7.9, and 7.8%, respectively), and AEs leading to discontinuation of study medication (2.3, 1.5, and 2.2%, respectively) were similar between groups.