Safety and Efficacy Study of Fluticasone Furoate/Vilanterol (FF/VI) Fixed Dose Combination (FDC) Compared to FF Alone in Subjects With Asthma

Inclusion Criteria

• For all subjects: Between 5 and 17 years of age inclusive, at the time of signing the informed consent.
• A history of symptoms consistent with a diagnosis of asthma for at least 6 months.
• Pre-bronchodilator FEV1 >50 percent to =12 percent in FEV1 within 10 to 40 minutes following 2 to 4 inhalations of salbutamol inhalation aerosol (or 1 nebulized treatment with albuterol/salbutamol solution). Use of a spacer is permitted.
• Uncontrolled asthma, with a childhood asthma control test (cACT)/ACT score 50 percent to =1 on the day-time or night-time asthma symptom scores) and/or daily albuterol/salbutamol on at least 3 of the last 7 consecutive days of the run-in period (not including the date of randomization).
• Compliance with run-in medication: compliance is defined as use of run-in medication on at least 4 of the last 7 consecutive days of the run-in period (not including the date of randomization) recorded in the electronic subject diary.
• Compliance with completion of the daily diary reporting: defined as completion of all questions on 4 out of the last 7 days during the run-in period (not including the date of randomization).

Exclusion Criteria

• For all subjects: History of life threatening asthma defined as an asthma episode that required intubation and/or was associated with hypercapnea, respiratory arrest or hypoxic seizures.
• Any asthma exacerbation requiring the use of oral steroids within 6 weeks of Visit 1, systemic or depot corticosteroids within 12 weeks of Visit 1, or ER attendance within 3 months of Visit 1 or hospitalization within 6 months of Visit 1.
• A culture documented or suspected bacterial or viral infection of the upper or lower respiratory tract, sinus or middle ear that has not resolved within 4 weeks of Visit 1 and which led to a change in asthma management or, in the opinion of the investigator, is expected to affect the subject's asthma status or the subject's ability to participate in the study.
• Clinical visual evidence of oropharyngeal candidiasis.
• Fasting blood glucose at screening >100 milligrams/deciliter (mg/dL) (5.6 moles per liter [mol/L]).
• Obesity (Body Mass Index [BMI] above the 97th centile based on the centers for disease control and prevention [CDC] charts).
• Any significant abnormality or medical condition identified at the screening medical assessment (including serious psychological disorder) that in the investigator's opinion, preclude entry into the study due to risk to the subject or that may interfere with the conduct and/or outcome of the study.
• QTc >450 milliseconds (msec) or QTc >480 msec in subjects with bundle branch block or any other clinically significant abnormality in the screening 12-lead ECG.
• Use of any prohibited medications.
• Present use of any tobacco products.
• Drug allergies: any adverse reaction including immediate or delayed hypersensitivity to any beta 2-agonists, sympathomimetic drug or any intranasal, inhaled, or systemic corticosteroid therapy. Known or suspected sensitivity to the constituents of the ELLIPTA Inhaler (i.e. lactose or magnesium stearate).
• Milk Protein Allergy: history of severe milk protein allergy.
• Participated in a clinical trial and has received an investigational product within the following time period prior to the first dosing day in the current study: 30 days, five half-lives or twice the duration of the biological effect of the study treatment (whichever is longer).
• Exposure to more than 4 investigational medicinal products within 12 months prior to the first dosing day.
• An affiliation with the investigator site: the parents/guardians or child is an immediate family member of the participating investigator, sub-investigator, study coordinator, or employee of the participating investigator.
• The parent or guardian has a history of psychiatric disease, intellectual deficiency, substance abuse or other condition (example, inability to read, comprehend or write) which may affect: vali