For people with Palmoplantar Pustulosis (PPP), every day can be challenging.

The purpose of the RIST4721-202 PPP research study is to evaluate if RIST4721, the investigational medication, is a safe and effective treatment for Palmoplantar Pustulosis.

During this research study, medical professionals will provide study-related care and monitoring of your Palmoplantar Pustulosis (PPP).

About the RIST4721-202 PPP study

Doctors at research centers are looking for volunteers for the RIST4721-202 PPP study.

This research study is evaluating an investigational medication (RIST4721) taken by mouth for the treatment of PPP.

People who are qualified and choose to take part will receive study-related care at no cost. Your overall health will be monitored by a team of doctors and their staff throughout the study.

Who can participate in the study?

To qualify* for this study, you must:

Be between the ages of 18 and 74 years old

Have had PPP for at least 6 months

Have moderate to severe PPP confirmed by evaluation by the study doctor and their staff

*Please note that there are other eligibility criteria that you must meet to participate in the study.

Short Study Summary

Medical condition

Palmoplantar Pustulosis (moderate to severe)

Study duration

Part A: 12 weeks / Part B: 72 weeks



Subjects will receive RIST4721 or placebo for 12 weeks. The placebo will look like RIST4721, but it will not contain active medication. You will be randomly assigned to RIST4721 or placebo. This is called the Part A study treatment period.

After 12 weeks, eligible subjects will be invited to participate in an optional extension period that lasts for up to 72 weeks. All eligible subjects will be assigned to receive RIST4721 during Part B. This is called the Part B study treatment period.

What happens if I Participate?

The first step is to see if you
pre-qualify. If you do, and want to learn more, your information will be sent to the research center that you select.

Research center staff will contact you to talk about the study and get more information about your health history. You may be invited to the research center to take some tests.

If you qualify for the study the research staff will talk to you about the potential benefits and possible risks of participation and what will happen during the study. After you understand and have asked all of your questions you will sign a consent form.

During the study the research staff will talk to you about each visit and ask you how you are feeling.

You can leave
the study at any time and for any reason.

Step 1: Screening

This is the time when the study doctor and staff determine if you are eligible, and you decide if you want to participate. This step will take place up to 4 weeks prior to the start of the Part A study treatment period.

Step 2: Treatment (Part A & Part B)

If you are eligible, you will take the Part A study treatment as directed by the study doctor and visit the research center for appointments. You will receive either a lower dose of RIST 4721, a higher dose of RIST4721, or placebo.

If you complete 12 weeks of the study and are eligible to continue into part B, you may elect to continue into Part B. If you decide to continue, you will take the higher dose of RIST4721 as directed by the study doctor and visit the research center for appointments.

Step 3: Follow Up

You will visit the research center for the last time 4 weeks after you have had your last dose of study treatment.

What is Palmoplantar Pustulosis (PPP)?

Palmoplantar Pustulosis is a rare inflammatory skin condition. It is different from psoriasis but as many as a quarter of people with PPP also have psoriasis. PPP presents itself as small to large blisters on the palms of hands and soles of feet. The blisters are filled with non-infectious, sterile fluid (pustules). These are often painful and cause a burning sensation.

Over time the blisters turn brown, peel off, and can form a crust with redness and burning in the hands and feet. Once developed, PPP is a chronic disease that may persist for decades. PPP is not contagious and cannot be spread from person to person.

The disease is also referred to as Chronic palmoplantar pustular psoriasis, Pustulosis palmaris et plantaris, or Persistent palmoplantar pustulosis.

Frequently Asked Questions

Who does it affect and why?
PPP is more commonly diagnosed in females than males. It is more common in people who are currently smokers or have previously been smokers. It can be triggered by infections, trauma, stress, and various therapeutic agents, but the initial cause of the disease remains poorly understood.
About research studies
Clinical research participation is an important part of developing new treatments. In order to assess the safety and effectiveness of new medications, research requires people like you to take the first step. Participation in a clinical study is not a guarantee of treatment.