Deep-Dive Webinar of IL13/IL31 Bispecific For Atopic Dermatitis

Research evidence excerpt

Deep-Dive Webinar of IL13/IL31 Bispecific For Atopic Dermatitis

July 8, 2026

and manufacturing processes designed to minimize aggregation and

glycosylation. Based on the SAD data generated thus far, management

has not observed concerning ADA trends, although repeated-dose

MAD data will provide the more definitive assessment.

2. Ph1 trial is progressing rapidly with data readouts by YE&early 2027

●Two-part Ph1 design: SAD in healthy volunteers, then MAD in AD

patients. Part A is a single ascending dose (SAD) study in healthy

volunteers; Part B is a multiple ascending dose (MAD) study in AD

patients and has two dosing cohorts.

●SAD cohorts are complete. This part of the study consists of 6 dose

cohorts between 50mg - 1,000mg, each cohort with ~6 treated and 2

placebo healthy volunteers dosed IV. Data readout this year will include

safety, PK, PD biomarkers (TARC, pSTAT6) and ADA. The PK data in

combination with a subcutaneous bioequivalent study (just added to

clinicaltrials.gov) will be used to determine Ph2b dose.

●MAD cohorts are enrolling now. This part of the trial consists of 2

cohorts: Cohort A 250mg and Cohort B 500mg enrolling AD patients.

Across both cohorts we expect ~27 patients on ZL-1503 and ~10

placebo. ZL-1503 is given Q2W for 4 weeks, followed by 12 weeks.

●Subcutaneous bioequivalent study in place: In parallel, Zai has

completed development of a subcutaneous formulation. Following

FDA feedback, the company plans to conduct a bridging study in ~40

healthy volunteers before advancing into Ph2.

●AD data might be presented by YE/early 2027: Management indicated

that data from the first MAD cohort could be available by year-end

2026 in-house. It's TBD whether it will be released this year or early

next year with the second cohort at a scientific meeting.

3.