To Determine the Effects of Seladelpar on Normalization of Alkaline Phosphatase Levels in Subjects with Primary Biliary Cholangitis (PBC) and an Incomplete Response or Intolerance to Ursodeoxycholic Acid (UDCA).

The primary objective is to evaluate the effect of seladelpar treatment at Week 52 compared to placebo based on normalization of alkaline phosphatase (ALP) defined by a composite endpoint of ALP ≤ 1.0× upper limit of normal (ULN) and ≥ 15% decrease from baseline in PBC participants with an ALP value greater than ULN but less than 1.67× ULN.

Key Inclusion Criteria:

Individuals must meet the following criteria to be eligible for study participation:

1. Male or female with a diagnosis of primary biliary cholangitis (PBC) based on history.
2. Ursodeoxycholic acid (UDCA) for the 12 months prior to screening (with stable dose for > 3 months prior to screening) OR intolerant to UDCA (last dose of UDCA > 3 months prior to screening).
3. ALP > 1× ULN and < 1.67× ULN.
4. Females of reproductive potential must use at least 1 barrier contraceptive and a second effective birth control method during the study and for at least 90 days after the last dose. Male participants who are sexually active with female partners of reproductive potential must use barrier contraception, and their female partners must use a second effective birth control method during the study and for at least 90 days after the last dose.

Key Exclusion Criteria:

1. Previous exposure to seladelpar (MBX-8025).
2. A medical condition other than PBC that, in the Investigator's opinion, would preclude full participation in the study (eg, cancer) or confound its results.
3. Advanced PBC as defined by the Rotterdam criteria.
4. Laboratory parameters measured by the Central Laboratory at screening.
5. Clinically important hepatic decompensation.
6. Other chronic liver diseases.
7. Known history of human immunodeficiency virus (HIV) or positive antibody test at screening.
8. Clinically important alcohol consumption, defined as more than 2 drink units per day in women and 3 drink units per day in men, or inability to quantify alcohol intake reliably.
9. History of malignancy diagnosed or treated, active or within 2 years, or ongoing evaluation for malignancy; localized treatment of squamous or noninvasive basal cell skin cancers and cervical carcinoma in situ is allowed if appropriately treated prior to screening.
10. History of drug abuse that would compromise the quality of the clinical study.
11. Treatment with obeticholic acid or fibrates 6 weeks prior to screening.
12. Treatment with colchicine, methotrexate, azathioprine, or long-term systemic corticosteroids within 2 months prior to screening.
13. Initiation or dose adjustment of anti-pruritic drugs indicated for the treatment of pruritus within 1 month prior to screening.
14. Immunosuppressant therapies within 6 months prior to screening.
15. Other medications that affect liver or gastrointestinal functions, as well as the roux-en-y gastric bypass procedure, may be prohibited and should be discussed with the medical monitor on a case by-case basis.
16. Treatment with any other investigational therapy or device within 30 days or within halflives, whichever is longer, prior to screening.
17. Pregnancy or plans to become pregnant, or breastfeeding.
18. Any other condition(s) that would compromise the safety of the individual or compromise the quality of the clinical study, as judged by the investigator.

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