Zai Lab Limited (NASDAQ:ZLAB) reported preliminary results from the first-in-human portion of its global Phase 1/1b clinical trial evaluating ZL-1503, an investigational bispecific antibody for moderate-to-severe atopic dermatitis.
Strong Biomarker Inhibition And Extended Half-Life
Data from 48 healthy volunteers showed that ZL-1503 rapidly and sustainably blocked the IL-13 pathway.
A single dose of 200 mg or higher inhibited phosphorylated STAT6, a key atopic dermatitis signaling biomarker, by at least 90% through Week 12.
The treatment also lowered circulating type 2 inflammatory biomarkers, including TARC, CCL26, and IgE.
Investigators evaluated doses ranging from 50 mg to 1,000 mg against a placebo in the randomized, double-blind study.
Pharmacokinetic assessments revealed dose-proportional exposure and an extended half-life of roughly 40 to 50 days.
This duration nearly doubles the half-life of several approved anti-IL-13 and anti-IL-31 biologics, supporting future maintenance dosing once every 12 weeks.
Favorable Safety Profile And Mechanism Of Action
Participants tolerated ZL-1503 well across every tested dose level. Researchers reported no serious adverse events, dose-limiting toxicities, or detectable anti-drug antibodies as of the data cutoff.
Most treatment-emergent adverse events remained mild and stemmed from study procedures or unrelated illnesses, causing zero study drug interruptions.
Zai Lab internally designed ZL-1503 with serum half-life extension technology to target both IL-13 and IL-31 receptor alpha. While IL-13 drives type 2 inflammation and tissue remodeling, IL-31 triggers itch and amplifies local immune responses.
Earlier this year, preclinical studies showed that ZL-1503 delivered rapid itch relief and significantly reduced inflammation in animal models.
Upcoming Clinical Milestones For ZL-1503
Zai Lab continues evaluating multiple ascending doses of ZL-1503 in adults with moderate-to-severe atopic dermatitis and expects Part B cohort data in the first half of 2027.
The company also finished enrolling participants in an intravenous-to-subcutaneous bioavailability bridging study, with initial Phase 1 results due in 2027.
ZLAB Price Action: Zai Lab shares were down 6.84% at $24.26 at the time of publication on Friday, according to Benzinga Pro data.
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