Inclusion Criteria:
1. Is male or female, age ≥ 18 and ≤ 75 years
2. Has a documented clinical diagnosis of moderate-to-severe uncontrolled asthma requiring moderate- or high-dose inhaled CS (ICS; ≥ 250 mcg of fluticasone propionate twice daily or equipotent ICS daily dosage to a maximum of 2000 mcg/day of fluticasone propionate or equivalent) and one or more additional controller medications (inhaled LABA or anticholinergic or LTA) for ≥ 3 months, with a stable dose ≥1 month prior to the initial Screening Visit
3. Has a prebronchodilator forced expiratory volume in 1 second (FEV1) ≥ 40% and ≤ 90% of predicted value during the Screening Period, despite use of a moderate- or high-dose ICS and one or more additional controller medications (inhaled LABA or anticholinergic or LTA)
4. Has a history of clinically diagnosed asthma, which could include a history of FEV1 reversibility and/or positive bronchial challenge test
5. Has a history of ≥ 1 clinically significant asthma exacerbation prior to the initial Screening Visit, despite use of a moderate- or high dose ICS and one or more additional controller medications at the time the exacerbation(s) occurred
Exclusion Criteria:
1. Is a current or former smoker with a smoking history of ≥10 pack-years (number of pack-years = number of cigarettes per day/20 × number of years smoked; a former smoker is defined as a subject who stopped smoking ≥ 6 months prior to the Screening Visit)
2. Has a body mass index \> 36 kg/m2
3. Has a documented history or radiological evidence of a clinically important lung condition other than asthma (eg, α1 antitrypsin deficiency, bronchiectasis, cystic fibrosis, primary ciliary dyskinesia, pulmonary fibrosis, allergic bronchopulmonary mycosis, or lung cancer)
4. Has a respiratory tract infection (RTI) within 4 weeks before the initial Screening Visit, or during the Screening Period (these subjects may be re-screened following complete resolution of their RTI)
5. Has an asthma exacerbation within 4 weeks before the initial Screening Visit, or during the Screening Period (these subjects may be re-screened following complete resolution of their exacerbation)
6. Has a diagnosis of currently active malignancy; subjects with a medical history of basal cell carcinoma, localized squamous cell carcinoma of the skin, or in situ carcinoma of the uterine cervix are eligible; subjects with a medical history of other malignancies are eligible if the subject is in remission and curative therapy was completed ≥ 2 years prior to the initial Screening Visit
7. Has a history or presence of clinically concerning cardiac arrythmias, atrial fibrillation, New York Heart Association Class III or IV heart failure, or prolonged QT or corrected QT interval \> 500 milliseconds (ms) at the Screening Visit
8. Has any disorder (including, but not limited to, cardiovascular \[CV\], gastrointestinal \[GI\], hepatic, renal, neurological, musculoskeletal, infectious, endocrine, metabolic, hematological, psychiatric, or major physical impairment) that is not stable in the opinion of the investigator and/or could:
1. Affect the subject's safety
2. Influence the findings of the study or data interpretation
3. Impede the subject's ability to complete the study
9. Has undergone bronchial thermoplasty
10. Has a history of substance abuse (including alcohol) that may, in the investigator's judgment, increase the risk to the subject of participation in the study
11. Has used monoclonal antibody (mAb) therapy for the management of asthma or any other condition within 3 months prior to the initial Screening Visit (these subjects may be re-screened following the 3 month period)
12. Has required an oral corticosteroid burst within 1 month prior to the initial Screening Visit or during the Screening Period (these subjects may be re-screened following the 1 month period); maintenance oral corticosteroids ≤ 10 mg/d prednisone or equivalent is permitted
