This is a study comparing CHF 5993 pMDI HFA-152a with CHF 1535 pMDI HFA-134a in Chinese patients with asthma uncontrolled on medium doses of ICS+LABA.

The study will be conducted at sites in China. The study will be composed of a run-in period with CHF 1535 pMDI HFA-134a (reference product) followed by a 24-week randomised treatment period when CHF 5993 pMDI HFA-152a (test product) or the reference product will be administered. Total study duration is 27 weeks. AEs and SAEs will be monitored from the informed consent signature until the subject's study participation ends, including AEs of particular interest such as cough. Serial spirometry will be performed both for subjects under study treatment as well as for subjects that discontinued the study treatments but continued the study using a different medication

Inclusion Criteria:

• Subjects must meet all of the following inclusion criteria to be eligible for enrolment into the study:

  1. Subjects must provide written informed consent prior to any study-related procedures;

  2. Subjects must be male or female Chinese aged ≥18 and

     ≤75 years;

  3. Subjects must have a documented history of asthma for at least 1 year and asthma must have been diagnosed before the subject's age of 40;

  4. Subjects must have uncontrolled asthma, receiving double therapy only on medium doses of ICS in combination with LABA at a stable dose for at least 4 weeks prior to screening;

  5. Subjects must have a pre-bronchodilator FEV1 <80% of their predicted normal value, after appropriate wash out from bronchodilators at the screening visit.

  6. Subjects must have a positive response to a reversibility test at screening.

  7. Subjects must have uncontrolled asthma evidenced by a score at the ACQ-7 ≥1.5 (this criterion must be met at screening and at randomisation).

     Exclusion Criteria:

• Subjects meeting any of the following criteria will be excluded from study enrolment:

  1. Subjects who have a history of near fatal asthma or of a past hospitalisation for status asthmaticus or severe asthma exacerbation which, in the judgement of the Investigator, may place the subject at undue risk;
  2. Subjects who have undergone hospitalisation, emergency room visit or use of systemic corticosteroids for an asthma exacerbation in the 4 weeks prior to the screening visit or during the run-in period;
  3. Subjects with any asthma exacerbation or respiratory tract infection in the 4 weeks prior to the screening visit or during run-in period;
  4. Subjects with any change in dose, schedule or formulation of the combination ICS+LABA in the 4 weeks prior to the screening visit;
  5. Subjects who have used systemic corticosteroid medication in the 4 weeks prior to screening or slow-release corticosteroids in the 12 weeks prior to screening;
  6. Subjects who have a history of a diagnosis of chronic obstructive pulmonary disease (COPD) (according to the Global Initiative for Chronic Obstructive Lung Disease [GOLD] document), cystic fibrosis, bronchiectasis or alpha- 1 antitrypsin deficiency or any other significant lung disease which may interfere with study evaluations;
  7. Subjects who are current smokers; ex-smokers with total cumulative exposure ≥10 pack-years; having stopped smoking 1 year or less prior to the screening visit;
  8. Subjects who are treated with monoclonal antibodies (e.g., anti-immunoglobulin (Ig)E or anti-IgG antibodies) or biological drugs;
  9. Subjects who have received an investigational drug within 2 months or six half-lives (whichever is greater) prior to the screening visit, or have been previously randomised in this study, or are currently participating in another clinical study.