A Study to Assess the Safety and Pharmacokinetics of INCB123667 When Administered Orally to Adult Participants With Moderate or Severe Hepatic Impairment

This study will be conducted to assess the safety and pharmacokinetics of INCB123667 when administered orally to adult participants with moderate or severe hepatic impairment.

Inclusion Criteria: * Ability to comprehend and willingness to sign a written ICF for the study. * Aged 18 to 80 years, inclusive, at the time of signing the ICF. * Moderate or severe hepatic impairment based on CP 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 determinations at screening or check-in (as applicable). Participants with abnormal findings considered not clinically significant by the medical monitor or investigator are eligible. * Body mass index of 18.0 to 43.0 kg/m2 (inclusive). * Willingness to avoid pregnancy or fathering children. Exclusion Criteria: * Participants who have a current, functioning organ transplant or are on the national transplant list and expected to receive a transplant within 3 months. * Tobacco or nicotine-containing product use of \> 10 cigarettes per day within 1 month before screening. * Participants who had a change in disease status within 30 days before screening, as documented by the participant's medical history, that is deemed clinically significant by the investigator. * Participants who have a history of paracentesis within 2 months prior to check-in. * Participants who required new medication or an increase in dose for hepatic encephalopathy within 3 months prior to check-in. * Participants who have a history of unstable diabetes mellitus (as evidenced by hemoglobin A1c ≥ 10.0%). Medications for treatment of diabetes mellitus must be reviewed and approved by the investigator and medical monitor. Participants who have a portal systemic shunt. Up to 3 participants with transjugular intrahepatic portosystemic shunt may be included. * Participants who had esophageal banding within 3 months prior to check-in or required any other treatment for gastrointestinal bleeding within 6 months prior to check-in. Other protocol-defined Inclusion/Exclusion Criteria may apply.