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A Study Testing Zasocitinib Compared to Placebo in Adults with Nonsegmental Vitiligo to See How Well It Works and How Safe It Is

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What is this trial about?

A plain-language summary of the goals, design and what participants do

This study involves people with nonsegmental vitiligo, a condition where patches of skin lose their color because the cells that produce pigment are damaged or stop working. The treatment being tested is called zasocitinib, also known by its code name TAK-279, which is taken by mouth as a capsule. Some people in the study will receive zasocitinib while others will receive a placebo. The purpose of this study is to find out how well zasocitinib works compared to placebo in treating nonsegmental vitiligo in adults after 24 weeks of treatment.

During the study, participants will take either zasocitinib capsules or placebo capsules for up to 52 weeks. The researchers will measure how much the skin patches improve by looking at changes in the affected areas of skin on the face and the whole body. They will check whether the patches become smaller or regain their color over time. The study will compare different doses of zasocitinib to find out which dose works best and is safe for people with this condition.

The study will track several measures of improvement, including how many people see their facial skin patches improve by at least 75 percent or 50 percent from when they started the study. The researchers will also look at how much the skin patches on the face and the entire body change in size throughout the treatment period. This information will help doctors understand whether zasocitinib could be a helpful treatment option for people living with nonsegmental vitiligo.

The research process

The trial runs in 9 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Initial assessment and baseline measurements

    At the beginning of the trial, your skin condition will be assessed to confirm eligibility. This assessment will measure the extent of vitiligo (a condition where skin loses its color) on your face and entire body.

    The assessment uses two scoring systems: F-VASI (Facial Vitiligo Area Scoring Index) which measures vitiligo on your face, and T-VASI (Total Vitiligo Area Scoring Index) which measures vitiligo across your entire body.

    These baseline measurements will be used to compare changes in your skin condition throughout the trial.

  2. Step 2

    Random assignment to treatment group

    You will be randomly assigned to one of several groups. Some groups will receive zasocitinib (the medication being tested) at different doses, while another group will receive a placebo (a capsule that looks identical but contains no active medication).

    Neither you nor the medical staff will know which treatment you are receiving during this phase. This is called a double-blind design and helps ensure accurate results.

    The trial tests different dose levels of zasocitinib to determine which dose works best.

  3. Step 3

    Daily medication administration

    You will take your assigned medication by mouth in capsule form.

    The medication should be taken orally as directed by the trial instructions.

    You will continue taking the medication daily throughout the treatment period.

  4. Step 4

    Treatment period up to week 24

    The main treatment period lasts for 24 weeks (approximately 6 months).

    During this time, you will attend regular visits where your skin condition will be assessed and monitored.

    The medical team will evaluate how your vitiligo responds to the treatment by measuring changes in the affected areas of your skin.

  5. Step 5

    Primary assessment at week 24

    At week 24, a key assessment will be performed to measure how much your vitiligo has improved.

    The medical team will calculate the percentage of improvement in your facial vitiligo compared to the baseline measurements taken at the start of the trial.

    They will also assess improvement in vitiligo across your entire body.

  6. Step 6

    Safety monitoring throughout the trial

    Throughout the trial, you will be monitored for any side effects or health changes.

    Regular check-ups will be conducted to ensure your safety while taking the medication.

    Any concerns or symptoms should be reported during your scheduled visits.

  7. Step 7

    Birth control requirements during the trial

    If you are able to become pregnant or father a child, you must use highly effective contraception (birth control methods) from the time you agree to participate until the end of the trial.

    This requirement applies throughout the entire duration of your participation.

    For participants in certain regions using hormonal contraception, additional assessments will be performed every 3 months to ensure the birth control method remains appropriate for you.

  8. Step 8

    Use of digital tools and applications

    You will be required to use digital tools and applications as part of the trial procedures.

    These tools may help track your progress, record information, or communicate with the trial team.

    You must be willing and able to use these technologies throughout your participation.

  9. Step 9

    Continued participation beyond week 24

    The trial may continue beyond the 24-week primary assessment period.

    You may be asked to continue taking the medication and attending follow-up visits.

    The total estimated duration of the trial extends until November 2027, though your individual participation timeline will be explained to you.

Who can join the trial?

6 criteria

  • You must have a confirmed diagnosis of non-segmental vitiligo, which is a skin condition where patches of skin lose their color in a pattern that affects both sides of the body. Your vitiligo must meet specific measurements: the F-VASI score, which measures vitiligo on the face, must be at least 0.5, and the T-VASI score, which measures vitiligo on the total body, must be between 5 and 50.
  • You must be between 18 and 75 years old at the time you agree to join the study.
  • If you are able to become pregnant, you must either have reached menopause, which means your periods have permanently stopped and this is confirmed by laboratory tests, or if you are sexually active with someone who can cause pregnancy, you must agree to use a highly effective birth control method from the time you sign the consent form until the end of the study. If you are male and able to father children, you must also use effective birth control. For participants in certain European countries and the United Kingdom who choose to use hormonal birth control, your doctor must assess that the benefits outweigh the risks for you at the start of the study and every 3 months during the study.
  • If you are in certain European countries or the United Kingdom, your doctor must confirm that participating in this study would not put you at increased risk based on safety concerns related to JAK inhibitors, which are a type of medication. These concerns include risks of serious heart problems, cancer, blood clots in veins, serious infections, and increased risk of death.
  • You must be willing and able to understand and follow all study procedures and requirements, including using digital tools and applications, as determined by your doctor.
  • You must provide written agreement to participate in the study and allow use of your health information before any study procedures begin.

Who cannot join the trial?

4 criteria

  • The study does not list specific exclusion criteria, which are reasons why a patient cannot participate in the research.
  • However, this study is designed for adults with non-segmental vitiligo, which is a skin condition where patches of skin lose their color in a pattern that is not limited to one area of the body.
  • Patients who do not have this specific type of vitiligo would not be eligible to participate.
  • Detailed information about who cannot participate should be discussed with the research team conducting the study.
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Investigated drugs

  • Zasocitinib

    is an investigational medication being tested in this clinical trial to treat nonsegmental vitiligo, a skin condition that causes loss of skin color in patches. This medication is being studied to see if it can help restore skin color in adults with this condition.

  • Placebo

    is an inactive substance that looks like the real medication but contains no active treatment. It is used in this study to compare against zasocitinib to help determine if the real medication is working.

What is already known about the treatment

Zasocitinib – Zasocitinib is an investigational medication currently being studied in clinical trials for the treatment of non-segmental vitiligo, a skin condition where patches of skin lose their natural color. This drug is being tested in different doses to determine how well it works and how safe it is for patients with this condition. Zasocitinib belongs to a class of medications that work by blocking specific enzymes in the body's immune system, which may help restore skin pigmentation by reducing the immune response that damages pigment-producing cells. The medication is administered orally, and researchers are comparing its effects against a placebo over a 24-week period to see if it can effectively improve the appearance of affected skin areas.

Investigated diseases

Non-segmental Vitiligo – Non-segmental vitiligo is a skin condition characterized by the loss of skin color in patches that typically appear on both sides of the body in a symmetrical pattern. The condition occurs when melanocytes, the cells responsible for producing skin pigment, are destroyed or stop functioning. White or light-colored patches can develop on various parts of the body, including the face, hands, arms, feet, and other areas. The patches tend to spread over time, though the rate and extent of progression varies greatly between individuals. The condition can affect people of any skin type, but the contrast is often more noticeable in individuals with darker skin tones. Non-segmental vitiligo is the most common form of vitiligo, affecting the majority of people with this condition.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-522309-40-00Protocol codeTAK-279-VT-2001Estimated enrolment200 patientsSponsorTakeda Development Center Americas Inc.

sourced from the EU Clinical Trials Register and site verification

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