Clinical Research Directory

Inclusion Criteria: * 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.