Zai Lab Begins First Human Trial of New Eczema Drug Candidate ZL-1503

Zai Lab Limited (NASDAQ:ZLAB, HKEX: 9688))) today announced the dosing of the first participant in a global Phase 1/1b clinical trial evaluating the safety, tolerability, pharmacokinetics, and efficacy of ZL-1503, a potential first-in-class IL-13/IL-31R bispecific antibody for the treatment of atopic dermatitis (AD). ZL-1503, which was identified and advanced internally by Zai Lab's discovery team, targets both IL-13 and IL-31 pathways with an extended serum half-life. The dual targeting potentially provides faster onset of action and superior efficacy.

In preclinical studies, ZL-1503 demonstrated the ability to simultaneously suppress inflammatory and pruritogenic (itch-causing) pathways implicated in AD. These findings, recently presented at the European Academy of Allergy and Clinical Immunology (EAACI) 2025 Congress, highlight ZL-1503's potential as a novel therapeutic option for patients with moderate-to-severe AD.

"The progress of ZL-1503 is another strong example of our global development capabilities, underscoring the speed, scientific rigor and operational excellence of our team," said Rafael G. Amado, M.D., President, Head of Global Research and Development, Zai Lab. "Importantly, ZL-1503 has the potential to provide patients with a novel and much-needed treatment option for managing their disease. We are encouraged by the preclinical data and look forward to evaluating its performance in the clinic."

The Phase 1/1b study of ZL-1503 is a randomized, double-blind, placebo-controlled single-dose and multiple-ascending dose trial designed to evaluate the safety, tolerability, and pharmacokinetics of ZL-1503 in healthy volunteers and participants with moderate to severe AD.