• Willing and able to give informed consent prior to any study specific procedure being performed;

• Male and non-pregnant, non-lactating female subjects, including women of child bearing potential (WOCBP), between 15-70 years of age at the time of informed consent;

• Diagnosis of large-duct PSC based on cholangiogram (at MRCP, ERCP, PTC) according to the most recent published guidelines (EASL);

• Baseline ALP ≥1.5 times upper limit normal at screening;

• Absence of biliary obstruction and/or malignancy within 6-12 months of entry into the study;

• If a patient is on ursodeoxycholic acid (UDCA) or 5-aminosalicylic acid he or she is expected to remain on the same daily dose during the study period;

• Patients who received antibiotics or probiotics may participate if they had a washout period of at least 3-month prior to study entry;

• If a patient has been on obeticholic acid or other experimental therapies (e.g. cilofexor and norUDCA) for PSC, they must complete a 3-month washout period before study entry;

• PSC with or without IBD. IBD diagnosis should be documented and with a minimum disease duration of 6 months, as determined by endoscopic and histopathology assessment. IBD should be in clinical remission or mildly active according to CDAI and partial Mayo score for CD and UC, respectively (i.e. patients with CDAI score \< 220 and pMayo score \<5). Patients without documented IBD need a colonoscopy with segmental biopsies within 12 months prior to baseline visit;

⁃ Female subjects of childbearing potential must test negative for pregnancy at screening, baseline and follow-up visits and if engage in sexual intercourse must agree to use specific methods of contraception.

⁃ Male subjects with female partners of childbearing potential must use condoms during treatment and until the end of relevant systemic exposure.