• Incidence of treatment-emergent adverse events (TEAEs), as well as biochemistry, hematology, and urinalysis [ Time Frame: Up to 24 weeks ]
• Incidence and severity of PSC-related symptoms or procedures [ Time Frame: Up to 24 weeks ]
• Incidence of Hepatic disease progression events, defined by the occurrence of liver transplantation, MELD score, hepatic decompensation events, and/or hepatocellular carcinoma [ Time Frame: Up to 24 weeks ]

• Drug: Seladelpar
  Capsule(s) administered orally once daily
  Other Name: MBX-8025
• Drug: Placebo to match Seladelpar
  Capsule(s) administered orally once daily

• Placebo Comparator: Placebo (N=25)
  Placebo for the remainder of the study
  Intervention: Drug: Placebo to match Seladelpar
• Experimental: Seladelpar 5 mg (N=25)
  5 mg seladelpar daily for the remainder of the study
  Intervention: Drug: Seladelpar
• Experimental: Seladelpar 10 mg (N=25)
  10 mg seladelpar for the remainder of the study
  Intervention: Drug: Seladelpar
• Experimental: Seladepar 25 mg (N=25)
  25 mg seladelpar for the remainder of the study
  Intervention: Drug: Seladelpar

Key Inclusion Criteria:

1. Confirmed diagnosis of PSC based on any two of the following three criteria:

   • Historical evidence of an elevated AP > ULN from any prior laboratory result
   • Liver biopsy consistent with PSC
   • Abnormal cholangiography consistent with PSC as measured by MRCP, ERCP, or percutaneous transhepatic cholangiography (PTC)

2. Subjects must have the following specific additional laboratory parameters measured by the Central Laboratory at Screening:

   • AP ≥ 1.5 × ULN and < 8 × ULN
   • Total bilirubin ≤ 2 × ULN
   • ALT and AST ≤ 5 × ULN
   • eGFR > 60 mL/min/1.73 m^2
   • Platelets ≥ 140 × 10^3/µL
   • International Normalized Ratio (INR) ≤ 1.3 (in the absence of warfarin or other anticoagulant therapy)
   • Albumin ≥ 3.5 g/dL

3. Patients taking UDCA will be allowed to enroll if meeting the following criteria:

   • Total daily dose of ≤ 20 mg/kg/day
   • A minimum of 6 months of stable treatment
   • Minimum of 12 weeks off treatment prior to Screening if UDCA is recently discontinued

Key Exclusion Criteria:

1. Clinically significant acute or chronic liver disease of an etiology other than PSC
2. Patients with a diagnosis of overlapping autoimmune hepatitis (AIH) and PSC
3. Secondary or IgG4 related sclerosing cholangitis
4. Small duct PSC
5. Presence of a cholangiocarcinoma on cholangiography or MRI at Screening as determined by the central radiologist and the principal investigator (PI) or medical monitor
6. Bile duct stent or percutaneous bile duct drain placement, or balloon dilatation procedure of a stricture within 12 weeks of Screening
7. History, evidence, or high suspicion of cholangiocarcinoma or other hepatobiliary malignancy based on imaging, screening laboratory values, and/or clinical symptoms
8. Presumptive or diagnosed acute cholangitis within 12 weeks of Screening and through Day 1

9. Evidence of compensated or decompensated cirrhosis based on histology, relevant medical complications, or laboratory parameters:

   • Historical liver biopsy demonstrating cirrhosis (eg, Ludwig Stage 4 or Ishak Stage 5)
   • Current or prior history of decompensated liver disease, including ascites, hepatic encephalopathy, variceal bleeding or other clinical conditions consistent with cirrhosis and/or portal hypertension,
   • Liver stiffness > 14.4 kPa by FibroScan, or

   • Combined low platelet count (< 140 × 10^3/µL ) with one of the following:

     • Serum albumin < 3.5 g/dL,
     • INR > 1.3 (not due to antithrombotic agent use), or
     • Total bilirubin > ULN
10. Prior or actively listed for liver transplantation
11. Prior exposure to seladelpar

Note: Other protocol defined Inclusion/Exclusion criteria may apply.