A Study to Evaluate Efficacy and Safety of an Investigational Drug Named Volixibat in Patients With Itching Caused by Primary Sclerosing Cholangitis (PSC)

Inclusion Criteria: 1. Provide freely signed informed consent and assent (as applicable) and be willing to comply with all study visits and requirements through end of study, including the follow-up period. 2. Subjects aged ≥12 years for eligible regions; otherwise ≥18 years 3. Confirmed diagnosis of large duct or small duct PSC based on American Association for the Study of Liver Disease (AASLD) guidelines. 4. Pruritus associated with PSC as assessed by Adult ItchRO. 5. Ursodeoxycholic acid (UDCA) and anti-pruritic medication use will be allowed if meeting additional criteria. 6. Concomitant Inflammatory Bowel Disease (IBD) is allowed if meeting additional criteria. Exclusion Criteria: 1. Pruritus associated with an etiology other than PSC 2. Evidence or clinical suspicion of decompensated cirrhosis, or a history of decompensation events 3. History of ileostomy or small bowel surgery/resection or other surgeries that may have disrupted the enterohepatic circulation 4. Evidence, history, or suspicion of other liver disease; PSC patients with AIH are not excluded. 5. Bile duct stent or percutaneous bile duct drain placement, or balloon dilatation procedure of a stricture within 12 weeks of Screening 6. Exceeding pre-defined biochemical values for alanine aminotransferase/aspartate aminotransferase (ALT/AST), estimated glomerular filtration rate (eGFR),serum creatinine (sCr), platelet count, international normalized ratio (INR) and total bilirubin 7. History of liver transplantation