Yuhan Corporation (CEO Wook-Jae Cho) announced on June 13 that it presented Phase 1b Part 2 results of lesigercept (YH35324) during a poster session at the 2025 European Academy of Allergy and Clinical Immunology (EAACI) Annual Congress held in Glasgow, UK.

Lesigercept is a novel anti-IgE Fc fusion protein designed to alleviate allergic symptoms through a dual mechanism: binding and eliminating both free serum IgE and anti-FcεRIα autoantibodies.

EAACI is one of the world’s largest academic gatherings in allergy and clinical immunology, drawing over 10,000 specialists annually.

Yuhan’s Phase 1b trial, conducted at nine university hospitals in Korea, aimed to establish preliminary proof-of-concept. The conference presentation focused on Part 2 of the study, which evaluated the safety and pharmacodynamics of a single 6 mg/kg subcutaneous dose of lesigercept over 8 weeks. The drug was administered as an add-on to H1-antihistamines in nine patients with chronic spontaneous urticaria (CSU) who remained symptomatic despite prior omalizumab treatment.

Lesigercept was well tolerated and showed strong, sustained suppression of free IgE compared to the control group, aligning with previously published Phase 1 results.

Clinical efficacy was supported by UAS7 (Urticaria Activity Score over 7 days) data. A higher proportion of patients in the lesigercept group achieved complete (UAS7 = 0) or well-controlled disease (UAS7 ≤ 6) at weeks 4 and 8 compared to controls.

In pooled analyses from Parts 1 and 2, both omalizumab-naïve and omalizumab-refractory patients experienced significant reductions in UAS7 scores, suggesting broad efficacy.

Subgroup analysis based on BHRA (Basophil Histamine Release Assay) status also showed consistent symptom improvement across CSU subtypes. These findings suggest that lesigercept could address limitations of omalizumab, particularly in BHRA-positive Type IIb patients.

Dr. Yeol-Hong Kim, Head of R&D at Yuhan, remarked, “What’s notable is the efficacy seen even in patients unresponsive to both H1-antihistamines and omalizumab. We are now finalizing data from repeated-dose cohorts and planning next steps for development.”

Lesigercept was licensed from GI Innovation in July 2020 and is being co-developed by the two companies. Yuhan holds global development and commercialization rights except in Japan, where rights were transferred to Maruho in October 2023.