A Study to Assess the Potential for Airway Sensitivity Reactions With Propellants HFA-152a (Test) and HFA-134a (Reference) Administered Via Pressurized Inhalers in Adults With Mild Asthma

Inclusion Criteria:

Participants are eligible to be included in the study if all the following criteria apply:

• Male or female; females may be of childbearing potential, of nonchildbearingpotential, or postmenopausal.

• Participant must be 18 to 45 years of age inclusive, at the time of screening.

• Confirmed diagnosis of asthma: documented, established diagnosis of asthma for atleast 6 months.

• Receiving 1 of the following asthma treatments, at a stable dose, for at least 12weeks prior to the screening visit and is anticipated to remain stable for theduration of the study:

• As needed short-acting beta-agonists (SABA) only

• As needed SABA plus low-dose Inhaled corticosteroids (ICS) (defined as 100-250 µg/day fluticasone propionate or equivalent taken whenever SABA is taken).

• Daily maintenance low-dose ICS, plus as needed SABA or ICS-SABA single inhalercombination therapy

• Low dose combination single inhaler ICS-formoterol or single inhaler ICS-SABAas needed for symptom relief (and if needed, before exercise)

• Leukotriene receptor antagonist (LTRAs) in combination with any of the abovetherapies

• Asthma Control Questionnaire (ACQ)-6 score <1.5 at screening and Day -1.

• No severe asthma exacerbations within 6 months prior to screening and ≤1 severeexacerbation during the 12 months prior to screening.

• Lung function: subjects with a pre-bronchodilator FEV1 ≥60% predicted at Screeningand Day-1.

• A female participant is eligible to participate if she is not pregnant orbreastfeeding, and one of the following conditions applies:

• Is a Woman of non-childbearing potential (WONCBP) OR

• Is a Woman of childbearing potential (WOCBP) and using a contraceptive methodthat is highly effective, with a failure rate of <1%.

• Female participants must have a negative highly sensitive pregnancy test (urine orserum as required by local regulations) within 28 days before the first dose ofstudy intervention.

• For male participants, no contraceptive measures are required.

• Non-smokers, or previous smokers who have not used any tobacco containing-productsor vaping products within 12 months prior to study start, and with a total pack yearhistory of ≤10 pack years.

• The use of marijuana, even with a valid prescription, is prohibited within 12 monthsprior to study start.

• Capable of giving signed informed consent which includes compliance with therequirements and restrictions listed in the ICF and protocol.

Exclusion Criteria:

Participants are excluded from the study if any of the following criteria apply:

• A history of life-threatening asthma or asthma that is unstable in the opinion ofthe investigator.

• Asthma treatment requiring use of biologic agents (e.g. mepolizumab or dupilumab),chronic systemic corticosteroids, or oral controller agents other than LTRAs.

• Respiratory disorders other than asthma; A history of respiratory diseases toinclude (but not limited to): pneumothorax, pulmonary fibrotic disease,bronchopulmonary dysplasia, chronic bronchitis, cystic fibrosis, bronchiectasis,interstitial lung disease, emphysema, chronic obstructive pulmonary disease,tuberculosis and other respiratory abnormalities other than asthma that, in theopinion of the investigator, would put the participant at risk through studyparticipation, or would affect the study analyses if the disease exacerbates and/orrequires additional therapy during the study. This includes history of lung cancerand previous thoracic surgery such as lung resection.

• Asthma Exacerbation: Any severe asthma exacerbation within 6 months prior toscreening. (Severe asthma exacerbation defined as a deterioration of asthmarequiring the use of systemic corticosteroids (tablets, suspension, or injection)for at least 3 days, or a single depo injection or an in-patient hospitalization orearly discontinuation (ED) visit due to asthma that required systemiccorticosteroids).

• Biologic/immunosuppressive therapies that can be used for the treatment ofrespiratory diseases during the 6 months, or 5 half-lives whichever is longer-priorto start of the study.

• Participants undergoing de-sensitization therapy.

• Administration of systemic, oral, or depot corticosteroids for asthma treatmentwithin 12 weeks of Visit 1. Intranasal corticosteroids are permitted if at a stabledose for at least 3 months prior to screening.

• Stable doses (3 months or longer) of the following are permitted:

• Intranasal corticosteroids

• Oral anti-histamines