Single- and multiple-dose testing of ZL-1503 in adults with moderate to severe atopic dermatitis and healthy volunteers

A Phase 1/1b Randomized, Double Blind, Placebo-controlled, Single and Multiple Dose Escalation Study to Evaluate the Safety, Tolerability, and Pharmacokinetics of ZL-1503 in Healthy Volunteers and Participants With Moderate to Severe Atopic Dermatitis (AD)

This study will test whether single and repeated doses of the investigational drug ZL-1503 are safe and how the body processes them in healthy adults and adults with moderate to severe atopic dermatitis.

Quick facts

• Phase: Phase 1
• Study type: Interventional
• Enrollment: 84 (estimated)
• Ages: 18 Years to 65 Years
• Sex: All
• Sponsor: Zai Lab (Hong Kong), Ltd. (Industry-sponsored)
• Locations: 1 site (Auckland, Auckland)
• Trial ID: NCT07235384 on ClinicalTrials.gov

What this trial studies

This randomized, double-blind, placebo-controlled Phase 1/1b trial uses single ascending dose (SAD) and multiple ascending dose (MAD) cohorts to measure safety, tolerability, and pharmacokinetics of ZL-1503. Part A enrolls healthy volunteers for single ascending doses, while Part B enrolls adults with moderate-to-severe atopic dermatitis for multiple ascending doses. Participants are randomized to receive ZL-1503 or placebo and undergo clinical exams, laboratory monitoring, and scheduled PK sampling with dose-escalation guided by safety data. Results will inform dosing and go/no-go decisions for later-stage studies.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18–65 with moderate-to-severe atopic dermatitis (EASI ≥16, BSA ≥10%, vIGA-AD ≥3) who have had AD for at least 12 months, an average peak pruritus score ≥4, and an inadequate response to topical treatments; healthy adults meeting Part A criteria may enroll in the single-dose cohorts.

Not a fit: People with mild AD, those under 18 or over 65, pregnant women, individuals with significant comorbidities or positive HIV/HBV/HCV tests, or those outside the permitted BMI ranges are unlikely to benefit or be eligible for participation.

Why it matters

Potential benefit: If ZL-1503 is safe and has favorable pharmacokinetics, it could become a new systemic treatment option for people with moderate to severe atopic dermatitis.

How similar studies have performed: While other systemic therapies for AD (such as biologics and JAK inhibitors) have proven effective, ZL-1503 is a novel investigational compound and its safety and efficacy in patients have not yet been established.

Eligibility criteria

Inclusion Criteria:

* Part A:

  1. Healthy male and female volunteers, 18-65 years of age
  2. Body mass index (BMI) between ≥ 18.5 and \< 32.5 kg/m2
  3. Negative pregnancy tests for women of childbearing potential.
* Part B:

  1. 18-65 years of age;
  2. BMI between ≥18.5 and \<40.0 kg/m2
  3. Have a diagnosis of AD at least 12 months prior to Day 1;
  4. Moderate-to-severe AD at Screening and Baseline visit, defined as:

     1. Eczema Area and Severity Index (EASI) score ≥ 16;
     2. Affected Body Surface Area (BSA)≥ 10%;
     3. vIGA-AD™ score ≥ 3
  5. History of an inadequate response to treatment with topical medications
  6. Average peak pruritus numeric rating scale (PP-NRS) score ≥4 in the 7 days before randomization.
  7. Negative pregnancy tests for women of childbearing potential.

Exclusion Criteria:

* Part A and B:

  1. Significant health issues, such as positive tests for human immunodeficiency virus (HIV), hepatitis C virus (HCV), hepatitis B surface antigen (HBsAg), active tuberculosis, immunodeficiencies or autoimmune diseases.
  2. History of major metabolic, liver, kidney, hematologic or other significant disorders.
  3. Abnormal Electrocardiogram (ECG) findings
  4. Clinically relevant abnormal lab results, including low blood counts, or abnormal liver and kidney function.
  5. History of drug abuse or addiction within 6 months prior to screening
  6. Current smoker or use of any nicotine or tobacco containing products within the last 6 months prior to dosing.
  7. Donated \>500mL blood within 2 months of dosing.
* For Part B only:

  1. Presence of dermatologic conditions and/or comorbidities that might confound the diagnosis of AD and/or might interfere with study assessments.
  2. Uncontrolled chronic disease that might require bursts of oral corticosteroids.
  3. Any other sound medical, psychiatric, and/or social reason as determined by the investigator.

Where this trial is running

Auckland, Auckland

• ZaiLab Site 18001 — Auckland, Auckland, New Zealand (Recruiting)

Study contacts

• Study coordinator: ZaiLab Medical Director

Conditions Atopic Dermatitis