A Phase 1/1b Study to Evaluate Safety, Tolerability and Pharmacokinetics of ZL-1503 in Healthy Volunteers and Participants With Moderate to Severe Atopic Dermatitis

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 is a phase 1/1b randomized, double blind, placebo-controlled, single dose escalation (SAD) and multiple dose escalation (MAD) study to evaluate the safety, tolerability, and pharmacokinetics (PK) of ZL-1503 in healthy volunteers and participants with moderate to severe atopic dermatitis (AD)

Study Overview

• Status: Recruiting
• Conditions: Atopic Dermatitis (AD)
• Intervention / Treatment: Drug: ZL-1503; Drug: Placebo; Drug: ZL-1503; Drug: Placebo

Detailed Description

The study consists of two parts:

• Part A: single ascending dose in healthy volunteers
• Part B: multiple ascending doses in adult participants with moderate to severe AD

• Study Type: Interventional
• Enrollment (Estimated): 84
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: ZaiLab Medical Director; Phone Number: +86 021-61632588; Email: ZaiLab_1503-001_StudyTeam@zailaboratory.com

Study Locations

• New Zealand
  • Auckland
    • Auckland, Auckland, New Zealand
      • Recruiting
      • ZaiLab Site 18001

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: ZL-1503: Participants will receive single ascending doses of ZL-1503; Part A: Single Ascending Dose (SAD)	Drug: ZL-1503; Healthy volunteers will receive ZL-1503.; Drug: Placebo; Healthy volunteers will receive placebo.; Drug: ZL-1503; Participants with moderate to severe atopic dermatitis will receive ZL-1503.; Drug: Placebo; Participants with moderate to severe atopic dermatitis will receive placebo.
Experimental: ZL-1503: Participants will receive multiple ascending doses of ZL-1503; Part B: Multiple Ascending Dose (MAD)	Drug: ZL-1503; Healthy volunteers will receive ZL-1503.; Drug: Placebo; Healthy volunteers will receive placebo.; Drug: ZL-1503; Participants with moderate to severe atopic dermatitis will receive ZL-1503.; Drug: Placebo; Participants with moderate to severe atopic dermatitis will receive placebo.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Number of participants with adverse events (AEs)	Up to 48 weeks after last intervention
Number of participants with serious adverse events (SAEs)	Up to 48 weeks after last intervention
Number of participants with clinical laboratory abnormalities	Up to 48 weeks after last intervention
Number of participants with vital sign abnormalities	Up to 48 weeks after last intervention
Number of participants with electrocardiogram (ECG) abnormalities	Up to 48 weeks after last intervention

Collaborators and Investigators

• Sponsor: Zai Lab (Shanghai) Co., Ltd.

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2025
• Primary Completion (Estimated): December 28, 2027
• Study Completion (Estimated): December 28, 2027

Study Registration Dates

• First Submitted: November 14, 2025
• First Submitted That Met QC Criteria: November 14, 2025
• First Posted (Estimated): November 19, 2025

Study Record Updates

• Last Update Posted (Actual): December 19, 2025
• Last Update Submitted That Met QC Criteria: December 18, 2025
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Atopic Dermatitis
• Additional Relevant MeSH Terms: Genetic Diseases, Inborn; Immune System Diseases; Hypersensitivity, Immediate; Hypersensitivity; Skin Diseases; Skin Diseases, Genetic; Skin Diseases, Eczematous; Dermatitis; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Skin and Connective Tissue Diseases; Dermatitis, Atopic
• Other Study ID Numbers: ZL-1503-001

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No