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ZL-1503

Phase 1

Atopic Dermatitis (AD) | Small molecule | Dermatology |Zai Lab Limited|Last Updated: Aug 20, 2026

Target and mechanism

Molecular targetIL-13 and IL-31R
Target classBispecific Antibody
ModalitySmall molecule

Success Probability

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Market & Valuation

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Trial Design

RandomizedDouble-BlindCONTROLLED
Total Trials1
Total Enrollment84

FDA Designations

No designations recorded

Clinical trial landscape

ZL-1503 · 2 trials · 2 indications

Phase 1 2
NCT07658482A Phase 1 Study to Evaluate Pharmacokinetics, Safety and Tolerability of ZL-1503 in Healthy VolunteersHealthy Volunteers
NOT YET_RECRUITING36 Analytics
NCT07235384A Phase 1/1b Study to Evaluate Safety, Tolerability and Pharmacokinetics of ZL-1503 in Healthy Volunteers and Participants With Moderate to Severe Atopic DermatitisAtopic Dermatitis (AD)
RECRUITING84 Analytics
PHASE1NOT YET_RECRUITING
A Phase 1 Study to Evaluate Pharmacokinetics, Safety and Tolerability of ZL-1503 in Healthy Volunteers
Healthy VolunteersUnlock trial analytics
PHASE1RECRUITING
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
Atopic Dermatitis (AD)Unlock trial analytics

Study Endpoints

Primary Endpoints

Maximum plasma concentration (Cmax)
From Predose to Day 337
Time to maximum concentration (Tmax)
From Predose to Day 337
Area under the plasma concentration-time curve from time 0 to last quantifiable concentration (AUClast)
From Predose to Day 337
Area under the plasma concentration-time curve from time zero to infinity (AUCinf)
From Predose to Day 337
Apparent terminal elimination half-life (t1/2)
From Predose to Day 337
Apparent total body clearance (CL/F)
From Predose to Day 337
Apparent volume of distribution (Vz/F)
From Predose to Day 337
Steady State Volume of distribution (Vss IV)
From Predose to Day 337
Total Body Clearance (CL IV)
From Predose to Day 337
Absolute bioavailability (F)
From Predose to Day 337
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
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Study Design & Arms

AllocationRANDOMIZED
MaskingNONE
ModelPARALLEL
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
ZL-1503 (Intravenous Administration)EXPERIMENTAL -
ZL-1503 (Subcutaneous Dose 1)EXPERIMENTAL -
ZL-1503 (Subcutaneous Dose2)EXPERIMENTAL -
ZL-1503: Participants will receive single ascending doses of ZL-1503EXPERIMENTALPart A: Single Ascending Dose (SAD)
ZL-1503: Participants will receive multiple ascending doses of ZL-1503EXPERIMENTALPart B: Multiple Ascending Dose (MAD)

Interventions

NameTypeDescription
ZL-1503DRUGHealthy volunteers will receive a single intravenous dose of ZL-1503.
PlaceboDRUGHealthy volunteers will receive placebo.
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Eligibility Criteria

Age Range18 Years to 65 Years
SexALL
Healthy VolunteersYes
Study Sites1

Inclusion Criteria: * Healthy male and female volunteers, 18-65 years of age * Body mass index (BMI) between ≥ 18.5 and \< 32.5 kg/m2 * Negative pregnancy tests for women of childbearing potential. Exclusion Criteria: * Significant health issues, such as positive tests for human immunodeficiency ...

Countries:New ZealandAustraliaChina
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Recent Changes (Last 90 Days)

LOWAug 20, 2026NCT07658482lastUpdatePostDate: changed
LOWAug 20, 2026NCT07658482lastUpdatePostDate: changed
LOWAug 7, 2026NCT07235384lastUpdatePostDate: changed
LOWAug 7, 2026NCT07235384lastUpdatePostDate: changed
LOWJun 22, 2026NCT07658482NEW_TRIAL: changed
LOWJun 22, 2026NCT07658482NEW_TRIAL: changed

Frequently asked questions about ZL-1503

What is ZL-1503 used for?

ZL-1503 is an investigational small molecule being developed for moderate to severe atopic dermatitis (AD). It is also being studied in healthy volunteers to evaluate its safety, tolerability, and pharmacokinetics. The drug is currently in Phase 1 clinical development and is not yet approved by regulatory authorities.

What does ZL-1503 target?

ZL-1503 targets IL-13 and IL-31R, making it a bispecific antibody. By targeting these pathways, the drug is designed to modulate immune responses involved in atopic dermatitis. This dual-targeting approach is being investigated for its potential to treat moderate to severe AD.

Who makes ZL-1503?

ZL-1503 is being developed by Zai Lab Limited, a biopharmaceutical company listed on the NASDAQ under the ticker symbol ZLAB. The company is conducting clinical trials for this drug in multiple countries, including Australia, China, and New Zealand.

What phase is ZL-1503 in?

ZL-1503 is in Phase 1 clinical development. It is currently being evaluated in two Phase 1 trials: one recruiting study in healthy volunteers and participants with moderate to severe atopic dermatitis, and another not yet recruiting study in healthy volunteers. The drug remains investigational and has not been approved.

What clinical trials is ZL-1503 in?

ZL-1503 is being studied in two clinical trials. NCT07235384 is a Phase 1/1b study in healthy volunteers and participants with moderate to severe atopic dermatitis, currently recruiting in Australia, China, and New Zealand. NCT07658482 is a Phase 1 study in healthy volunteers in New Zealand, not yet recruiting.

Is ZL-1503 the same as any other drug?

ZL-1503 is a unique investigational drug candidate developed by Zai Lab Limited. It is a bispecific antibody targeting IL-13 and IL-31R. No alternative names for this drug have been disclosed in the available clinical trial information.