The purpose of this study is to evaluate the drug interaction between povorcitinib and the oral contraceptive levonorgestrel/ethinyl estradiol in healthy adult females.

Inclusion Criteria:

• Ability to comprehend and willingness to sign a written ICF for the study.
• Females aged 18 to 60 years, inclusive, at the time of signing the ICF.
• Body mass index between 18.0 and 30.5 kg/m2, inclusive.
• No clinically significant findings in screening evaluations (eg, clinical, laboratory, and ECG evaluations).
• Ability to swallow and retain oral medication.

Exclusion Criteria:

• History of uncontrolled or unstable cardiovascular, respiratory, renal, gastrointestinal, endocrine, hematopoietic, psychiatric, and/or neurological disease within 6 months before screening.
• Presence or history of a malabsorption syndrome (eg, Crohn's disease or chronic pancreatitis) that could affect drug absorption.
• Current or recent (within 3 months before screening) clinically significant gastrointestinal disease (eg, gallbladder disease) or surgery (including cholecystectomy; excluding appendectomy) that could affect the absorption of study treatment.
• History of cardiovascular, cerebrovascular, peripheral vascular, or thrombotic disease (eg, deep vein thrombosis), pulmonary embolism, or uncontrolled hypertension (ie, blood pressure > 140/90 mmHg at screening, confirmed by repeat testing).
• Positive test for HBV, HCV, or HIV. Participants whose results are compatible with prior immunization for or immunity due to infection with HBV may be included at the discretion of the investigator.
• History of tobacco- or nicotine-containing product-use within 1 month before screening.
• Pregnant, breastfeeding, or planning to conceive during the study.

Other protocol-defined Inclusion/Exclusion Criteria may apply.