Yuhan’s allergy drug shows promise for patients unresponsive to Xolair

(Yuhan Corp.)

Yuhan Corp.’s investigational allergy treatment has demonstrated significant efficacy in patients who did not respond to Xolair, the standard anti-IgE therapy, according to clinical trial results that were presented on Sunday at a major European immunology conference.

The Korean pharmaceutical company announced results from Part 2 of its Phase 1b trial for lesigercept (YH35324) at the European Academy of Allergy and Clinical Immunology (EAACI) 2025, held in Glasgow. The data were shared in poster format.

Lesigercept is a next-generation anti-IgE Fc fusion protein designed to bind and eliminate both free immunoglobulin E (IgE) and autoantibodies targeting the Fc epsilon RI receptor. This dual mechanism suppresses allergic reactions more effectively than conventional therapies.

The trial enrolled nine patients in South Korea with chronic spontaneous urticaria who had not achieved symptom control with Xolair despite concurrent H1 antihistamine use. Participants received a single subcutaneous dose of lesigercept at 6 mg/kg, with outcomes monitored over eight weeks and compared against a control group.

Results showed a strong and sustained reduction in serum IgE levels, as well as marked improvements in urticaria symptoms as measured by the Urticaria Activity Score over 7 days (UAS7). Several patients achieved complete remission (UAS7 score of 0) or well-controlled status (6 or below), with response rates notably higher than in the control group.

A combined analysis of Part 1 and Part 2 of the Phase 1b trial showed statistically significant reductions in UAS7 scores both in patients with no prior Xolair exposure and those who had not responded to it.

Lesigercept also produced consistent treatment effects across subtypes based on basophil histamine release assay (BHRA) results, suggesting broad applicability beyond specific allergic phenotypes.

Kim Yeol-hong, Head of R&D at Yuhan, said the key finding is that the drug produced meaningful symptom improvement in patients who failed to respond to both antihistamines and omalizumab (Xolair). He added that the company is currently evaluating the drug’s safety, pharmacokinetics, and pharmacodynamics with repeated dosing and is planning the next phase of clinical development.

Yuhan licensed lesigercept from GI Innovation in July 2020 and holds global rights excluding Japan, with the Japanese rights transferred to Maruho in October 2023.