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Efficacy and Safety of Rezpegaldesleukin (NKTR-358) in Patients Aged ≥12 Years 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 red, itchy, and inflamed patches, often affecting people with moderate‑to‑severe symptoms. The investigational medicine being tested is called Rezpegaldesleukin (also known by the code name NKTR‑358) and it is given as a subcutaneous injection, which means the medicine is delivered just under the skin. Participants may receive the active drug or a matching placebo that contains only saline solution.

The purpose of the trial is to compare how well the study medicine works against the placebo in improving the signs and symptoms of the disease. Participants will receive a series of injections over a period of about six months, with regular clinic visits to check the skin, ask about itching or pain, and record any side effects. The study does not involve any additional procedures beyond these scheduled visits.

To assess improvement, researchers use simple tools such as the EASI score, which rates the extent and severity of eczema on the body, and the IGA rating, a quick overall assessment of disease severity. Patients also rate their itch or skin pain using a numeric rating scale (NRS), where 0 means no symptom and 10 means the worst imaginable. These measures help determine whether the treatment leads to meaningful relief compared with the placebo.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment Visit

    You attend the first study visit after agreeing to join the trial.

    During this visit, the study staff confirms that you meet the eligibility criteria for moderate-to-severe atopic dermatitis and records your medical history.

  2. Step 2

    Baseline Assessments

    You undergo a series of examinations that establish the starting point for the study, including skin evaluations and symptom questionnaires.

    These baseline measurements will be used later to determine how the treatment affects your condition.

  3. Step 3

    Randomization

    You are assigned, by chance, to receive either the active study drug or a placebo.

    The assignment is kept unknown to you and the study team to ensure unbiased results.

  4. Step 4

    First Injection

    You receive a subcutaneous injection (injection under the skin).

    If you are assigned to the active group, the injection contains rezpegaldesleukin (NKTR-358) at a dose of 0 µg (micrograms) in a solution for injection.

    If you are assigned to the placebo group, the injection contains sodium chloride 0.9% solution.

    The injection is administered by qualified study personnel according to the study protocol.

  5. Step 5

    Scheduled Follow‑Up Visits

    You return to the study site for regular visits as defined by the study schedule.

    At each visit you receive the next injection of either rezpegaldesleukin or placebo, following the same dose and route as the first injection.

    During these visits you also complete symptom questionnaires and undergo skin assessments to monitor progress.

  6. Step 6

    Week 24 Evaluation

    At the 24‑week mark you undergo a comprehensive evaluation.

    The primary goals are to determine whether your skin condition has improved enough to achieve an IGA 0/1 response (clear or almost clear skin) and an EASI‑75 response (at least 75 % reduction in the eczema severity score).

    Secondary goals include assessing higher levels of improvement (EASI‑90), itch reduction, skin pain reduction, and changes in other quality‑of‑life scores.

  7. Step 7

    End‑of‑Study Visit

    After the final assessments, the study concludes for you.

    You receive a summary of the study procedures you completed and any final instructions from the study team.

Who can join the trial?

5 criteria

  • Be at least 12 years old on the day you sign the consent form and weigh at least 40 kg (about 88 lb) before randomization.
  • Have chronic atopic dermatitis (eczema that has been present for 12 months or more) as confirmed by the doctor.
  • Meet the severity requirements for moderate‑to‑severe eczema: an Investigator’s Global Assessment (IGA) score of 3 or higher (scale 0‑4), involvement of at least 10 % of body surface area (BSA), and an Eczema Area and Severity Index (EASI) score of 16 or higher.
  • Be a candidate for systemic therapy (treatment that works throughout the whole body) because you have not responded well enough to topical medications (creams or ointments applied to the skin) in the past 6 months, or you cannot tolerate those skin‑applied treatments.
  • Provide written informed consent (a signed form showing you understand the study and agree to take part) and agree to follow all study procedures, including using a highly effective method of birth control if needed.

Who cannot join the trial?

6 criteria

  • Having other skin problems besides atopic dermatitis (AD), or a skin infection in the area affected by AD that needs treatment with medicines that kill germs (antimicrobial therapy).
  • Having an AD that has been changing quickly or unpredictably (unstable course) now or in the past.
  • Having ever had long‑lasting hives that appear without a known cause (chronic idiopathic urticaria) or having any type of hives within 4 weeks before the study starts.
  • Having used strong steroid creams (topical corticosteroids, TCS) in a way that could lead to a sudden flare‑up when stopping them (withdrawal).
  • Having taken any of these medicines before the screening visit: aldesleukin (a type of immune‑system drug), an experimental drug similar to a protein called IL‑2 (IL‑2 analog), a drug that works throughout the whole body to modify the immune system (systemic biologic), an oral pill that blocks certain immune signals (oral JAK inhibitor, JAKi), or any other experimental drug for AD.
  • Having a current or recent sudden and active infection (acute, active infection).
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Investigated drugs

NKTR-358 is an experimental medicine that is given as a small injection under the skin. It contains a protein called rezpegaldesleukin, which is designed to help balance the immune system. In this study, researchers are testing whether NKTR-358 can reduce the redness, itching, and swelling that people with moderate-to-severe atopic dermatitis (eczema) experience. The medication is being evaluated to see if it improves skin symptoms and overall quality of life compared with a placebo.

What is already known about the treatment

  • Rezpegaldesleukin (NKTR-358)

    This investigational drug is given as a subcutaneous injection in a sterile solution for injection. It is currently in Phase 3 clinical trials and not yet approved for general medical use. The medication is being studied to treat moderate‑to‑severe atopic dermatitis by selectively expanding regulatory T‑cells, which helps calm the immune response and reduce skin inflammation. It belongs to the class of immunomodulatory cytokine therapies, specifically a selective interleukin‑2 (IL‑2) agonist.

  • Sodium Chloride 0.9% Solution

    This product is an isotonic saline solution that can be administered by injection or infusion. It is an approved, widely used medication for many years and is listed in standard medical references. The solution is used to replace lost fluids, provide electrolytes, and clean wounds or surgical sites. It is classified as an electrolyte solution and a sterile isotonic saline preparation.

Investigated diseases

Atopic Dermatitis - Atopic dermatitis is a chronic inflammatory skin condition characterized by itchy, red, and scaly patches. It often begins in childhood and can persist or reappear later in life. The rash typically appears on the face, neck, and flexural areas, and may spread to other parts of the body. Symptoms can flare up periodically, with periods of relative calm between episodes. Over time, the skin may become thicker and more lichenified due to repeated scratching. The condition can be associated with other allergic diseases such as asthma or hay fever.
Trial detailsLast updated 5 Nov 2026
Age18+ yearsPhasePhase IIITrial ID2025-524925-42-00Protocol code25-358-09Estimated enrolment363 patientsSponsorNektar Therapeutics

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