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Efficacy and Safety of Rezpegaldesleukin (NKTR-358) in Patients Aged 12 Years and Older 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

The study focuses on Atopic Dermatitis, a chronic skin condition that causes dry, itchy, and inflamed patches. Participants who are 12 years of age or older and have moderate‑to‑severe disease will receive either the investigational drug Rezpegaldesleukin (NKTR-358) or a placebo. The drug is administered as a subcutaneous injection, which means it is given just under the skin using a small needle.

The purpose of the study is to determine whether the medication provides greater improvement in the signs and symptoms of the skin condition than the placebo. After a screening visit, participants will receive the assigned injection at regular intervals over several months and will attend clinic visits to check their skin, report any side effects, and undergo routine safety tests. The study will end after the final follow‑up visit, at which point the overall results will be analyzed.

The research process

The trial runs in 5 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Screening and Baseline Assessments

    After joining the study, you will undergo screening procedures to confirm eligibility and to record the initial severity of your atopic dermatitis.

    Baseline measurements will include clinical scores and questionnaires that evaluate skin condition, itch intensity, and overall quality of life.

  2. Step 2

    Randomization to Study Medication

    Based on a computer‑generated schedule, you will be assigned to receive either NKTR-358 (the active drug, also called rezpegaldesleukin) or a placebo (sodium chloride 0.9% solution).

    The assignment is double‑blind, meaning neither you nor the study staff will know which product you receive.

  3. Step 3

    First Dose Administration

    You will receive the first dose of the assigned product by subcutaneous injection, which is an injection into the fatty tissue just under the skin.

    The dose of NKTR-358 is 0 µg per kilogram of body weight, prepared as a solution for injection.

    If you are assigned to the placebo, you will receive a matching injection of sodium chloride 0.9% solution.

  4. Step 4

    Ongoing Treatment Visits

    You will attend scheduled clinic visits throughout the 24‑week treatment period to receive additional injections as directed by the study team.

    During each visit, your skin condition and any side effects will be evaluated, and you may be asked to complete the same questionnaires used at baseline.

  5. Step 5

    Final Assessment at Week 24

    At the end of the 24‑week period, a comprehensive assessment will be performed to determine the effectiveness of the study medication.

    The primary outcomes include the Investigator Global Assessment (IGA) score of 0 or 1 and a 75 % reduction in the Eczema Area and Severity Index (EASI‑75).

    Secondary outcomes evaluate higher levels of improvement, changes in itch and skin pain scores, and other quality‑of‑life measures.

Who can join the trial?

8 criteria

  • Be a male or female who is at least 12 years old on the day you sign the consent form and weighs at least 40 kg before the study starts.
  • Have chronic atopic dermatitis (AD), meaning you have had the skin rash and symptoms for at least 12 months before the screening visit, as confirmed by the doctor.
  • Be a candidate for systemic therapy (treatment that works throughout the whole body) and have a documented history of either:
    • not responding well enough to all topical (applied to the skin) medicines in the past 6 months, or
    • being unable to use a topical medicine because of side effects (intolerance).
    • Give written, informed consent to join the study and agree to follow all study procedures, including using a highly effective birth control method if required.
    • Meet the study’s severity requirements for AD:
      • A GA score of 3 or higher on a scale of 0 to 4 (the GA score measures how bad the rash looks).
      • At least 10 % of your body surface area (BSA) affected by the rash.
      • An EASI score of 16 or higher (the EASI score combines redness, thickness, scratching, and area of the rash to rate severity).

Who cannot join the trial?

6 criteria

  • Having any other skin problems besides atopic dermatitis, including a skin infection that needs treatment with antibiotics (antimicrobial therapy).
  • Having an unstable course of atopic dermatitis, meaning the rash and itching flare up and improve unpredictably.
  • Having ever had chronic idiopathic urticaria (long‑lasting hives with no known cause) at any time, or having had hives from any cause within 4 weeks before the first study visit.
  • Having a history of using strong skin creams (topical corticosteroids) in a way that suggests a high chance of withdrawal symptoms when stopping them (topical corticosteroid withdrawal).
  • Having taken any of the following medicines before screening: aldesleukin; an experimental drug similar to the immune protein IL‑2 (investigational IL‑2 analog); a medicine that works throughout the body to modify the immune system (systemic biologic); a pill that blocks certain immune signals (oral JAK inhibitor); or any other experimental drug for atopic dermatitis.
  • Having a current or recent serious infection that is active (acute infection).
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Investigated drugs

NKTR-358 is an experimental medication being tested as a single treatment for people aged 12 years and older who have moderate‑to‑severe atopic dermatitis (eczema). It is given by a subcutaneous injection, meaning it is injected just under the skin in a liquid solution. The drug is designed to work on the immune system to reduce the skin inflammation and itching that cause the symptoms of atopic dermatitis. In this trial, participants receive NKTR-358 and are compared to those who receive a placebo to see how well the medication improves the signs and symptoms of the disease.

What is already known about the treatment

  • Rezpegaldesleukin (NKTR-358)

    This medication is supplied as a sterile solution for injection and is given by subcutaneous (under the skin) injection. It is currently being studied in Phase 3 clinical trials and is not yet approved for general medical use. The drug is being tested for the treatment of moderate‑to‑severe atopic dermatitis. It works by a specially designed form of interleukin‑2 that mainly activates regulatory T‑cells, helping to calm the immune system and reduce skin inflammation. It is classified as an immunomodulatory cytokine therapy.

  • Sodium Chloride 0.9% Solution

    This product is a sterile isotonic saline solution that can be injected under the skin, often used as a placebo in studies. It is an approved medical product that is widely used for fluid replacement and as a harmless carrier for other drugs. In this trial it has no therapeutic effect on atopic dermatitis and simply provides a neutral vehicle for the test drug. Its action is purely physical, supplying sodium and chloride ions without any specific drug activity, and it is classified as an electrolyte solution.

Investigated diseases

Atopic Dermatitis - Atopic dermatitis is a long‑lasting skin condition that causes itchy, red, and dry patches. It usually begins in childhood but can appear at any age. The rash often comes and goes, with periods of worsening called flares. Over time the skin barrier becomes weaker, making the skin more prone to irritation and dryness. Lesions can spread to larger areas of the body and become more persistent as the disease progresses.
Trial detailsLast updated 5 Nov 2026
Age18+ yearsPhasePhase IIITrial ID2025-525129-11-00Protocol code25-358-10Estimated enrolment305 patientsSponsorNektar Therapeutics

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