New IL-13/IL-31R Bispecific Antibody Data Presented at EAACI

A new IL-13/IL-31R bispecific antibody demonstrated ability to simultaneously suppress the inflammatory and pruritogenic pathways in atopic dermatitis (AD), according to preclinical study data presented at the European Academy of Allergy and Clinical Immunology (EAACI) Congress 2025 in Glasgow, Scotland.

The antibody, ZL-1503, is a potential novel treatment option for moderate-to-severe AD, manufacturer Zai Lab Limited said in a press release.

“Medications that inhibit IL-4/IL-13 signaling have markedly improved the therapeutic landscape for AD,” the company said in the release. “Certain AD symptoms are mediated by IL-31; however, they are only partially alleviated by IL-4/IL-13 inhibition. As a result, many patients experience slow and modest clinical responses to currently available medications.”

ZL-1503 was evaluated in a pilot preclinical study in non-human primates to assess its long-term effects on IL-31-mediated scratching and IL-13-induced signaling (pSTAT6). An intravenous single dose of ZL-1503 (10 mg/kg, iv) completely inhibited IL-13-mediated pSTAT6 and IL-31-induced scratching for at least 76 days in all preclinical subjects. Two out of three subjects exhibited prolonged IL-13-mediated pSTAT6 inhibition for over 118 days, and one out of three subjects sustained IL-31-induced scratching inhibition for over 133 days. Pharmacokinetic (PK) analysis of serum samples collected during the study revealed that ZL-1503 exhibited slow clearance, correlating closely pharmacodynamic (PD) responses, demonstrating strong PK/PD relationships in blocking IL-13 and IL-31 pathways in the preclinical model. ZL-1503 was well tolerated following weekly IV dosing up to 150 mg/kg.

Additionally, in vitro studies showed that binding to one target did not affect ZL-1503’s blocking effects on the other target.