A Study to Evaluate the Pharmacokinetics and Safety of INCB161734 in Participants With Hepatic Impairment

• Ability to comprehend and willingness to sign a written ICF for the study.
• Age 18 to 80 years (inclusive) at the time of signing the ICF.
• Moderate or severe hepatic impairment based on Child-Pugh score.
• Medical findings consistent with the degree of hepatic dysfunction, determined by medical history, physical examination, vital sign measurements, 12-lead ECGs, and clinical laboratory examinations at screening and check-in.
• BMI of 18.0 to 44.0 kg/m2 (inclusive) at screening.
• Ability to swallow and retain oral tablets.
• Willingness to avoid pregnancy or fathering children.

Exclusion Criteria:

• In the opinion of the investigator, history of uncontrolled or unstable cardiovascular, respiratory, renal, GI, endocrine, hematopoietic, psychiatric, and/or neurological disease within 6 months before screening or evidence of rapidly deteriorating hepatic function.
• History or current diagnosis of uncontrolled or significant cardiac disease indicating significant risk of safety for participation in the study.
• Current, functioning organ transplant or on the national transplant list and expected to receive a transplant within 3 months.
• History of an autoimmune disease diagnosis (eg, myasthenia gravis).
• History of malignancy within 5 years before screening, with the exception of cured basal cell carcinoma, squamous cell carcinoma of the skin, ductal carcinoma in situ, or Gleason 6 prostate cancer.
• History of clinically significant GI disease or surgery (cholecystectomy and appendectomy are allowed) that could impact the absorption of study drug.
• Severe ascites (ascites requiring paracentesis more than twice every 4 weeks) or encephalopathy ≥ Grade 2 (precludes them from understanding and signing an ICF).
• Any major surgery within 4 weeks before screening.
• Donation of blood within 4 weeks before screening (within 2 weeks for plasma only).
• Blood transfusion within 4 weeks before check-in (Day -1).
• Current or recent history (within 30 days before screening) of a clinically significant bacterial, fungal, parasitic, or mycobacterial infection, or currently receiving systemic antibiotics or current clinically significant viral infection at screening or check-in (Day -1).
• History of alcoholism within 3 months before screening.
• Positive breath, urine, or blood test for ethanol or positive serum or urine screen for drugs of abuse that is not otherwise explained by permitted concomitant medications.
• Current treatment or treatment within 30 days or 5 half-lives (whichever is longer) before study drug administration with another investigational medication or current enrollment in another investigational drug study.
• Current treatment or treatment within 15 days or 5 half-lives (whichever is longer) before study drug administration with an inducer or inhibitor of CYP3A4, P-gp, or BCRP.

• Use of prescription drugs (including hormonal contraceptives) within 14 days before study drug administration or nonprescription medications/products (including megadose vitamins, minerals, and phytotherapeutic, herbal, or plant-derived preparations as well as pre/probiotics) within 7 days before study drug administration.

  • Note 1: Occasional acetaminophen, standard-dose ibuprofen, and standard-dose vitamins are permitted.
  • Note 2: Established therapy for hepatic disease, or the treatment of associated disorders, that has been stable for at least 7 days prior to study drug administration is allowed if approved by the medical monitor and investigator.
• Consumption of alcohol within 1 month before screening.
• Consumption of caffeine-containing foods and beverages within 3 days before check-in (Day -1).
• Consumption of Seville oranges, grapefruits, pomelos, exotic citrus fruits, grapefruit hybrids, or fruit juices within 7 days before the first dose of study drug.
• Current use of prohibited medication.
• Receipt of live (including attenuated) vaccines or anticipation of need for such a vaccine during the study. (Note: Non-live or inactivated vaccines allowed up to 2 weeks before study drug administration.).
• Known hypersensitivity or severe reaction to INCB161734 or excipients of INCB161734.
• History of any significant drug allergy (such as anaphylaxis or hepatotoxicity) deemed clinically relevant by the investigator.
• Inability to undergo venipuncture or tolerate venous access.
• Any condition that would, in the investigator's judgment, interfere with full participation in the study, including administration of study drug and attending required study visits; pose a significant risk to the participant; or interfere with interpretation of the study data.
• Currently smoke > 10 cigarettes per day, or equivalent use of other tobacco- or nicotine-containing products, and are unwilling to refrain from tobacco or nicotine use on treatment days and abide by CRU restrictions.
• Women who are pregnant or breastfeeding.
• New medication requirement or an increase in dose for hepatic encephalopathy within 3 months prior to check-in.
• Current portal systemic shunt.
• Esophageal banding within 3 months prior to check-in or required any other treatment for GI bleeding within 6 months prior to check-in. Hemorrhoidal banding is permitted.

Other protocol-defined Inclusion/Exclusion Criteria may apply.