An Efficacy and Safety Study of Fluticasone Furoate/Vilanterol 100/25 Microgram (mcg) Inhalation Powder, Fluticasone Propionate/Salmeterol 250/50 mcg Inhalation Powder, and Fluticasone Propionate 250 mcg Inhalation Powder in Adults and Adolescents With Persistent Asthma

This study is a randomized, double-blind, double-dummy, parallel group, multicenter, non-inferiority study. The study will enroll adult and adolescent asthmatic subjects who are currently receiving mid dose inhaled corticosteroids (ICS) plus long-acting beta2-agonist (LABA) (equivalent to fluticasone propionate \[FP\]/salmeterol 250/50 microgram \[mcg\]twice daily \[BD\]), either via a fixed dose combination product or through separate inhalers. The study consists of a LABA washout period of 5 days and a run-in period of 4 weeks, followed by a treatment period of 24 weeks, and a follow up contact period of one week. The total duration of the study is 30 weeks. Approximately 1461 subjects will be randomized to one of the following three treatments (487 per treatment): fluticasone furoate (FF)/vilanterol (VI) 100/25 mcg once daily (OD) in the evening (PM) via ELLIPTA™ inhaler plus placebo BD via ACCUHALER™/DISKUS™; FP/salmeterol 250/50 mcg BD via ACCUHALER/DISKUS inhaler plus placebo OD (PM) via ELLIPTA inhaler; FP 250 mcg BD via ACCUHALER/DISKUS inhaler plus placebo OD (PM) via ELLIPTA inhaler. In addition, all subjects will be supplied with albuterol/salbutamol inhalation aerosol to use as needed to treat acute asthma symptoms. This study will determine if FF/VI 100/25 mcg OD via ELLIPTA inhaler is non-inferior to FP/salmeterol 250/50 mcg BD via ACCUHALER/DISKUS inhaler in adult and adolescent asthmatic subjects already adequately controlled on a twice-daily ICS/LABA. SERETIDE, ELLIPTA, ACCUHALER, RELVAR, and DISKUS are trademarks of the GlaxoSmithKline Group of Companies.