The CLI-05993AB6-03 Study is an interventional study designed to investigate the safety and efficacy of a new low global warming potential propellant (HFA-152a) compared to the currently approved one (HFA-134a) in the medication (CHF5993) in patients with moderate to severe asthma

Outpatients attending the hospital clinics/study centers will be recruited. Moderate to severe controlled asthma adult subjects will be recruited. A total of 513 subjects will be randomised. The whole study will last approximately 16 weeks for each subject.

Inclusion Criteria:

• Subject's written informed consent obtained prior to any study related procedure;
• Male and female adults aged ≥ 18 and ≤ 75;
• Body mass index (BMI) within the range of 18.0 to 35.0 kg/m2 inclusive;
• Non-smokers or ex-smokers who smoked < 10 pack-years (pack-years = the number of cigarette packs per day x the number of years) and stopped smoking > 1 year (6 months for e-cigarettes) prior to screening;
• Diagnosis of asthma: physician-diagnosed asthma for at least
• 6 months and with diagnosis before the age of 50 years;
• Stable asthma therapy: a stable treatment with medium/high doses of inhaled corticosteroids (ICS) + long-acting β-agonist (LABA) + long-acting muscarinic antagonist (LAMA) (fixed or free combination) or medium/high doses of ICS+LABA (fixed or free combination) for at least 4 weeks before screening (medium and high-dose ICS defined as BDP non-extrafine > 500-1000 μg and > 1000 μg respectively, or estimated clinical comparable dose).
• Subjects must have a cooperative attitude and the ability to be trained to use correctly the pMDI inhalers and e-Diary, to be able to read/write, to be able to perform the required outcomes measurements (e.g., technically acceptable spirometry, e-Diary completion) and the ability to understand the risks involved.

Exclusion Criteria:

• History of near fatal asthma, hospitalisation for asthma in intensive care unit which in the judgement of the Investigator may place the subject at undue risk, emergency room access for asthma in the previous 6 months before enrolment;
• Asthma exacerbation requiring systemic corticosteroids (SCS) or emergency room admission or hospitalisation within 4 weeks prior to study entry and/or during the run-in period (to be checked again prior to randomisation);
• Non-permanent asthma: exercise-induced, seasonal asthma (as the only asthma-related diagnosis) not requiring daily asthma control medecine

Double-blind multicentre, randomised, active-controlled, 2-arm, parallel-group