A Study to Compare the Efficacy, Safety and Tolerability of FF/UMEC/VI With FF/VI in 12-17-year-olds With Asthma

The primary purpose of this study is to evaluate the effects of Fluticasone Furoate (FF)/ Umeclidinium (UMEC)/ Vilanterol (VI) on lung function compared with FF/VI after 24 weeks of treatment.

Inclusion Criteria: * Participant must be 12 to 17 years of age (inclusive), at the time of signing the informed consent/assent. * Participants who have a diagnosis of asthma as defined by the National Institutes of Health \[NIH, 2020\] at least 1 year prior to Visit 0. * Participants who have required daily Inhaled corticosteroids (ICS)/ Long-Acting Beta2-Agonist (LABA) treatment for at least 12 weeks prior to Visit 0 with no changes to maintenance asthma medications during the 6 weeks immediately prior to Visit 0 (including no changes to a stable total ICS dose of \>250 to \<=500 microgram (mcg)/day fluticasone propionate, or equivalent). * In the 1 year prior to Visit 1: A documented healthcare contact for acute asthma symptoms; OR A documented temporary change in asthma therapy for acute asthma symptoms, according to a prespecified asthma action plan (or equivalent). * Participants with inadequately controlled asthma (ACQ-6 score ≥1.5) at Visit 1, despite ICS/LABA maintenance therapy. * A best pre-bronchodilator FEV1 \>40% to \<=90% of the predicted normal value and a ≥12% increase in FEV1 with albuterol/salbutamol at Visit 1. Predicted values will be based on the European Respiratory Society (ERS) Global Lung Function Initiative. Exclusion Criteria: * Chest X-ray documented pneumonia in the 6 weeks prior to Visit 1. * Any asthma exacerbation requiring a change in maintenance asthma therapy and/or the use of systemic corticosteroids for at least 3 days in the 6 weeks prior to Visit 1. (Participants requiring a temporary change in asthma therapy (e.g., oral corticosteroids or increased dose of ICS) to treat an exacerbation in the 6 weeks prior to Visit 1 are not explicitly excluded at Visit 1 provided that, at the Investigator's discretion, the participant's condition is stable after they have resumed their pre-exacerbation maintenance asthma therapy (without modification), returned to their baseline asthma status and they are considered appropriate for enrollment into this study of up to 6 months duration) * History of Life-threatening Asthma * Participants with current evidence of active pulmonary diseases or abnormalities other than asthma (e.g., pneumonia, active tuberculosis, significant bronchiectasis, etc.). * Current smokers and users of other inhaled products for recreation with or without nicotine (defined as participants who use cigarettes, e-cigarettes, other/vaping-related devices, cigars or pipe tobacco\]) within 12 months prior to Visit 1.