The VISTAS Study is seeking adults with PSC to learn if volixibat, an investigational medication, might be a safe and effective treatment option for cholestatic itch, and whether volixibat may improve markers associated with PSC disease progression.

You or a loved one may qualify to participate if you:

  • Are 18 years of age or older
  • Have a confirmed diagnosis of large duct or small duct PSC
  • Are currently affected by cholestatic itch caused by PSC

Eligible participants in the VISTAS Study:

Help advance PSC research! The VISTAS Study is designed to give medical professionals the information they need to potentially help you and other PSC patients suffering from cholestatic itch.

Receive standard medical care for PSC from an experienced medical team paid by the study sponsor.

About PSC

Primary Sclerosing Cholangitis (PSC)


PSC is a rare liver disease that causes damage to the bile ducts inside and outside the liver. It is frequently associated with chronic infections, inflammatory bowel disease (IBD), Type 1 diabetes, celiac disease, thyroid disease, and an abnormal immune system.


A common complication from PSC is intense itching which can lead to fatigue, social isolation, and an overall lower quality of life. Currently, there are no approved or effective medications to treat PSC or PSC-associated itch, and some patients ultimately require liver transplantation. Sometimes the intense PSC-associated itch itself can lead to liver transplantation.

About the VISTAS Study

The VISTAS Study will evaluate the safety and effectiveness of an investigational medication named volixibat. Information about volixibat’s effects on PSC-associated itch and on markers associated with PSC disease progression will be obtained in the VISTAS Study.

What will happen during this study?

The study consists of a screening period, a treatment period, and a follow-up period. The total duration of the study is at least 32 weeks with the potential option to participate in an open-label extension study (OLE), during which participants are to receive volixibat for an additional 2 years, approximately.


First, you must be evaluated to determine if you meet the criteria for entry into the study. During the screening period of 4 weeks, study staff will assess your itch and your health and determine if you are eligible for the VISTAS Study. Upon entering the screening period, you need to complete an eDiary once each day for the duration of your participation in the study.


If you qualify for the study, you will enter the study treatment period of 28 weeks. During this time, you will take study treatment as instructed and will have appointments where the study team will perform study-related tests and procedures and ask questions about your health. During the study treatment period, you need to complete an eDiary once each day.


Whether you are treated with the investigational medicine will be determined randomly. You will receive standard medical care for PSC from an experienced medical team, plus oral, twice-daily dosing with the investigational medicine (volixibat) or placebo.


After successful completion of the core study treatment period, you will be able to continue participation, if eligible, in an extension period called the Open-Label Extension (OLE) study, where you will receive volixibat and continue to be closely monitored by your doctor for up to two years. If you choose not to participate in the OLE study, you will have a follow-up visit four weeks after completing the core study treatment period to close out your participation in the VISTAS Study. If you are a part of the OLE study, your follow-up will be four weeks after the completion of the OLE study treatment period.

Am I Eligible?

To participate in this clinical research study, you must meet a set of eligibility criteria. Some are listed here. A study representative will be able to give you more information to see if you or your loved one qualifies.

You or a loved one may qualify if you:

Are 18 years of age or older

Have a confirmed diagnosis of large duct or small duct PSC

Are currently affected by cholestatic itch caused by PSC

Additional study requirements and exclusions may apply. A study representative will discuss these with you during the screening period.

Clinical Research

Clinical research studies aim to advance treatment options for patients.

Through clinical research, scientists and doctors determine whether a new medical strategy, drug, or device is safe and effective for people. New treatments are only approved through clinical research studies, which rely on potential study participants, like you, to evaluate their safety and efficacy. Participation in clinical research studies is voluntary. If you take part, you may withdraw from the study at any time.

What is investigational medication?

Investigational medications are not yet approved by any government health authority such as the FDA. A clinical research study is used to test the safety and efficacy (or effectiveness) of an investigational medication.

What are the stages of development for a new medication?

Clinical trials are important to help determine if new medications are both safe and effective. Typically, investigational medications must pass through three phases of development in clinical trials, called Phase 1, Phase 2, and Phase 3 for approval. Results from each phase must be properly assessed before medications can be approved for use in the public. Volixibat has already been studied in more than 400 patients in earlier Phase 1 and Phase 2 studies in patients with conditions other than PSC. The VISTAS Study is a Phase 2 study.

Frequently Asked Questions

Why is this clinical research study being conducted?

The VISTAS Study is seeking adults with PSC to learn if volixibat might be a safe and effective treatment option for cholestatic itch, and whether volixibat may improve markers associated with PSC disease progression.

Will compensation be provided?

No, unless otherwise specified by your study site. However, you may be reimbursed for study-related expenses, such as travel for study participants. All study-related treatments, medications, office visits, procedures and examinations are provided at no cost to participants.

Is study participation voluntary?

Yes! While it is important to remain in a clinical research study after enrollment, you have the right to cease your participation at any time for any reason. If you do decide to leave the study, speak with the study doctor first to discuss how leaving the clinical research study may affect your health, along with other treatment options.

How long is the study and how many study center visits are required?

The duration of the VISTAS Study is at least 32 weeks. There will be 10 planned study visits that occur over this time. All study participants who successfully complete the core study treatment period and meet eligibility criteria may participate in an Open Label Extension study.

What can I expect on my first visit to the study center?

This initial appointment is an opportunity for you to:


  • Learn more about the VISTAS Study. You will be speaking with the study team at the study center to learn more about participation in the core study and the optional long-term extension study and to see if you qualify.
  • Ask any important questions. These can be any questions you may have about the VISTAS Study or clinical research in general.
  • Determine if the VISTAS Study may be right for you. If you agree to be considered for the study, the center will ask you to review and sign an informed consent form. After you speak with the study team and learn details about the study, they will review some additional study criteria to determine if you are eligible to participate in the study.

Who is conducting the VISTAS Study?

Mirum Pharmaceuticals, Inc., based in Foster City, California, is a biopharmaceutical company focused on the development and commercialization of therapies to treat debilitating liver diseases. Mirum is developing two apical sodium bile transporter (ASBT) inhibitors for the treatment of cholestatic liver diseases, including maralixibat for pediatric liver diseases, and volixibat for adult liver diseases.


In addition to PSC, volixibat is being evaluated in intrahepatic cholestasis of pregnancy (ICP) and primary biliary cholangitis (PBC).


Maralixibat is an investigational oral drug in development for Alagille syndrome (ALGS), progressive familial intrahepatic cholestasis (PFIC), and biliary atresia (BA).


Mirum works closely with advocates and the patient communities to understand and address the most critical aspects affecting patients and families living with rare liver diseases.


For more information about Mirum, please visit

How can I learn more?

To learn more, please talk to your doctor for more information. You can also visit using the study ID: VLX-301.

Study Locations

For more information on study center locations, please visit the VISTAS Study page on

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