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A Study of KT-621 Tablets Taken by Mouth for Adults with Moderate to Severe Atopic Dermatitis

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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 atopic dermatitis, which is a long-term skin condition that causes red, itchy, and inflamed skin. The study focuses on those with moderate to severe forms of this condition, meaning their symptoms are more serious and affect a larger portion of their body. The treatment being tested is KT-621, which is an experimental medication given as a tablet by mouth. Some people in the study will receive KT-621 while others will receive placebo.

The purpose of this study is to find out how well different doses of KT-621 work compared to placebo in treating moderate to severe atopic dermatitis. The study will also look at how safe the medication is and what side effects it may cause. Researchers want to understand if this new treatment can help reduce the symptoms of atopic dermatitis, including the extent of skin involvement, the severity of the rash, and the itching that people experience.

The study has two main parts. In the first part, which lasts 16 weeks, people are randomly assigned to receive either KT-621 at different dose levels or placebo. Neither the people in the study nor the doctors know who is receiving the actual medication or placebo during this time. After the first 16 weeks, there is a second part where everyone receives KT-621 in an open manner, meaning both the people in the study and the doctors know what is being given. This second part continues up to week 68. Throughout the study, doctors will measure changes in the skin condition, the amount of itching, and any side effects that occur.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Baseline visit and treatment assignment

    At the baseline visit, your condition will be assessed using several measurements. Your skin will be evaluated for the extent and severity of atopic dermatitis.

    The severity of your skin condition will be measured using the EASI score (a scale that assesses redness, thickness, scratching, and the area of skin affected) and the vIGA-AD score (a 5-point scale where doctors rate the overall severity of your atopic dermatitis).

    Your itch level will be recorded using the Peak Pruritus NRS, which is a scale where you rate your worst itch over the past 24 hours from 0 to 10.

    You will be randomly assigned to receive either KT-621 tablets or a placebo (a tablet that looks identical but contains no active medication). Neither you nor your doctor will know which treatment you are receiving during this phase.

  2. Step 2

    Double-blind, placebo-controlled treatment period

    This period lasts for 16 weeks.

    You will take KT-621 tablets or placebo tablets by mouth. The exact dose will be determined by the treatment group you are assigned to.

    During this time, you will continue to apply moisturizer to your skin at least twice daily.

    You will attend regular visits where your skin condition and itch levels will be assessed.

    Any side effects or health changes will be monitored and recorded throughout this period.

  3. Step 3

    Week 16 assessment

    At week 16, a comprehensive evaluation of your condition will be performed.

    Your EASI score will be measured to determine the percentage change from the beginning of the study.

    Your doctor will assess whether your vIGA-AD score has improved to 0 or 1 with at least a 2-point reduction from baseline.

    Your itch improvement will be evaluated to see if there has been at least a 4-point improvement in your Peak Pruritus NRS score.

    The response of your skin will be categorized as EASI-50 (50% improvement), EASI-75 (75% improvement), or EASI-90 (90% improvement) from baseline.

  4. Step 4

    Open-label treatment period

    After week 16, you will enter an open-label period that continues until week 68.

    During this phase, all participants will receive KT-621 tablets by mouth. Both you and your doctor will know that you are receiving the active medication.

    The dose of KT-621 will be determined based on the study protocol.

    You will continue to apply moisturizer to your skin at least twice daily.

    Regular monitoring visits will continue throughout this period.

  5. Step 5

    Ongoing monitoring through week 68

    Throughout the entire study period up to week 68, your safety will be monitored continuously.

    Any side effects or adverse health events will be recorded and assessed.

    Blood samples may be collected at specified times to measure the levels of KT-621 in your blood. This helps determine how your body processes the medication.

    Your skin condition and itch levels will continue to be evaluated at regular intervals.

  6. Step 6

    Study completion

    The study concludes at week 68.

    A final assessment of your skin condition, itch levels, and overall health will be performed.

    All side effects and health changes throughout the study will be reviewed.

Who can join the trial?

8 criteria

  • You must be between 18 and 75 years old at the time you sign the consent form to join the study
  • You must have long-lasting atopic dermatitis, which is a skin condition that causes red, itchy, and inflamed skin, and this condition must have been present for at least 3 years before your first visit
  • Your EASI score must be 16 or higher at both the first visit and the start of the study. The EASI score is a measurement that doctors use to assess how severe your skin condition is by looking at redness, thickness, scratching, and how much of your body is affected
  • Your vIGA-AD score must be 3 or higher on a scale from 0 to 4 at both the first visit and the start of the study. This score is used by doctors to rate the overall severity of your atopic dermatitis
  • At least 10% of your body surface area must be affected by atopic dermatitis at both the first visit and the start of the study
  • Your average peak itching score during the week before the study starts must be 4 or higher on a scale where you rate your worst itching. This is called the Peak Pruritus NRS, where pruritus means itching
  • Within the 6 months before starting the study, you must have medical records showing that skin creams or ointments used to treat atopic dermatitis either did not work well enough for you, or you were not able to use them for medical reasons
  • You must have been applying a moisturizer at least twice daily for at least 7 days in a row right before the study starts, using the same amount each time

Who cannot join the trial?

4 criteria

  • The study information does not list specific reasons why patients cannot participate in this clinical trial
  • If you are interested in participating, a doctor conducting the study will review your complete medical history to determine if you are eligible
  • General exclusion reasons in clinical trials may include having other serious medical conditions, taking certain medications, being pregnant or breastfeeding (feeding a baby with breast milk), or having had recent treatments that might affect the study results
  • Each clinical trial has its own specific requirements, and the research team will carefully evaluate whether the study is safe and appropriate for you
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Investigated drugs

  • KT-621

    is an investigational medication being tested in this clinical trial. It is taken by mouth and is being studied to see if it can help people with moderate to severe atopic dermatitis, which is a skin condition that causes red, itchy, and inflamed skin. The study will test different amounts of this medication to find out which dose works best and is safe for patients.

  • 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 KT-621 to help researchers understand if the actual medication is working better than no treatment at all.

What is already known about the treatment

KT-621 – KT-621 is an experimental oral medication currently being studied in Phase 2b clinical trials for the treatment of moderate to severe atopic dermatitis, a chronic inflammatory skin condition that causes itchy and inflamed patches of skin. The medication is taken by mouth and is being tested at different dose levels to determine the most effective and safe amount for patients. This study aims to compare how well KT-621 works against a placebo (inactive treatment) in reducing the symptoms of atopic dermatitis, though the specific mechanism of how the drug works at the molecular level has not been disclosed in the available trial information.

Investigated diseases

Atopic Dermatitis – Atopic dermatitis is a chronic inflammatory skin condition that causes the skin to become red, itchy, and dry. The disease typically appears in childhood but can occur at any age, often running in families with a history of allergies or asthma. It progresses through periods of flare-ups when symptoms worsen and periods of remission when the skin improves. During flare-ups, the affected skin may develop patches that are extremely itchy, leading to scratching that can cause the skin to thicken, crack, or weep. The condition commonly affects areas such as the face, hands, feet, and the insides of elbows and knees. In moderate to severe cases, the symptoms significantly impact daily activities and quality of life due to intense itching and widespread skin involvement.
Trial detailsLast updated 2 Oct 2026
Age18+ yearsPhasePhase IITrial ID2025-522370-36-00Protocol codeKT621-AD-201Estimated enrolment200 patientsSponsorKymera Therapeutics Inc.

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