• Male, non-pregnant and non-lactating female subjects (20-65 years of age, inclusive).

• A clinical diagnosis of mild asthma with historical documentation of the asthma diagnosis according to either: (1) the National Asthma Education and Prevention Program (NAEPP) guidelines (2007) or (2) the Global Initiative for Asthma (GINA) Global Strategy for Asthma Management and Prevention (2020).

• Stable mild asthma receiving the following required inhaled medications for at least 1 month prior to screening: Low doses of ICS alone, or in combination with SABA, used regularly with a stable regimen.

• Forced Expiratory Volume in 1 second (FEV1) ≥ 80% of the local predicted normal value after withholding SABA ≥ 8 hours.

• Airway responsiveness to methacholine demonstrated by a pre-albuterol-dose (baseline) PC20 ≤ 8 mg/mL.

• Nonsmoker for at least 6 months prior to the study and a maximum smoking history of 5 pack-years (the equivalent of one pack per day for 5 years).

• Provision of written informed consent.

• Other than asthma, in general good health.

• Body mass index (BMI) between 17 and 35 kg/m2 (inclusive).

⁃ Able to correctly use MDI inhalers.

⁃ Able to perform valid and reproducible pulmonary function tests including no evidence of spirometry effort-induced bronchoconstriction.

⁃ If the subject or subject's partner is of child-bearing potential, a medically acceptable form of contraception will be used for the duration of the study. Medically acceptable contraceptives include: (1) surgical sterilization, (2) Health Authority approved female hormonal contraceptives, (3) an intrauterine device (IUD), (4) condoms with spermicide, or (5) diaphragm with spermicide.