A Study to Evaluate the Efficacy and Safety Study of Povorcitinib in Participants With Inadequately Controlled Moderate to Severe Asthma

Inclusion Criteria: * Physician-diagnosed asthma requiring treatment with medium- to high-dose ICS-LABA for at least 12 months prior to screening. * Pre-BD FEV1 \< 80% predicted according to central over read value at Visit 2. * Documented historical post-BD reversibility of FEV1 ≥ 12% and ≥ 200 mL in FEV1. * At least 2 documented asthma exacerbations (requiring treatment with systemic CS, hospitalization, or emergency department visit) within 12 months prior to screening but not within the past 4 weeks prior to screening * ACQ-6 ≥ 1.5 at screening. Exclusion Criteria: * Maintenance use of asthma controllers other than ICS-LABA. * Have undergone bronchial thermoplasty. * Current smokers or participants with a smoking history of ≥ 10 pack-years and participants using vaping products, including electronic cigarettes. * Women who are pregnant (or who are considering pregnancy) or breastfeeding. * Current conditions or history of other diseases, as follows: * Clinically important pulmonary disease other than asthma ,Thrombocytopenia, coagulopathy, or platelet dysfunction. * Venous and arterial thrombosis, deep vein thrombosis, pulmonary embolism, moderate to severe heart failure (NYHA Class III or IV), cerebrovascular accident, myocardial infarction, coronary stenting, or CABG surgery. * Diagnosis of other significant cardiovascular diseases, including but not limited to angina, peripheral arterial disease, or uncontrolled arrhythmias such as atrial fibrillation, supraventricular tachycardia, ventricular tachycardia, and forms of carditis. * Recipient of an organ transplant that requires continued immunosuppression. * Immunocompromised (eg, lymphoma, acquired immunodeficiency syndrome, Wiskott-Aldrich syndrome). * Any malignancies or history of malignancies. * Chronic or recurrent infectious disease. * Receipt of any biologic drugs used for asthma \< 12 weeks or 5 half-lives (if known), whichever is longer, prior to screening