Harbour BioMed's TSLP-Targeting Antibody HBM9378 Shows Favorable Safety Profile in Phase I Trial
Key Insights
Harbour BioMed (search) published positive Phase I results for HBM9378, a novel TSLP (search)-targeting monoclonal antibody, demonstrating favorable safety and extended half-life in 50 healthy subjects.
The randomized, placebo-controlled study showed treatment-emergent adverse events comparable to placebo across dose ranges from 20-900 mg, with mean half-life ranging from 55.0 to 65.8 days.
HBM9378 exhibited dose-proportional exposure and low immunogenicity (5% anti-drug antibody incidence), supporting advancement to Phase II trials for severe asthma and COPD treatment.
Harbour BioMed (search) announced the publication of positive Phase I results for HBM9378, a novel thymic stromal lymphopoietin (TSLP (search))-targeting monoclonal antibody, in the peer-reviewed journal Drug Design, Development and Therapy. The first-in-human trial demonstrated a favorable safety profile and extended half-life that support further clinical development for severe immunological disorders.
Phase I Trial Design and Results
The randomized, double-blind, placebo-controlled, single-ascending-dose study enrolled 50 healthy adult subjects to evaluate the safety, tolerability, pharmacokinetics, and immunogenicity of HBM9378. The dose-escalation study included five cohorts (20 mg, 60 mg, 200 mg, 600 mg, and 900 mg), with eight subjects receiving HBM9378 and two receiving placebo at each dose level.
The trial, led by Dr. Min Xu at Chengdu Fifth People's Hospital, showed that treatment-emergent adverse events were comparable between HBM9378 dose groups and placebo, with no trend for increasing safety risks with dose escalation. The median time to maximum concentration ranged from 4.05 to 14.1 days, while the mean half-life ranged from 55.0 to 65.8 days across all dose levels.
Pharmacokinetic Profile and Safety
HBM9378 demonstrated dose-proportional exposure, with maximum concentration (Cmax) and area under the curve (AUC) increasing proportionally across the 20 to 900 mg dose range. The incidence of anti-drug antibodies was low at 5% (2/40 subjects) during the study period, with no clinical correlate or impact on drug exposure. Notably, no injection site reactions were observed in any dose group.
"This Phase I clinical trial demonstrates that HBM9378 is well-tolerated and exhibits a favorable pharmacokinetic profile in healthy subjects," said Dr. Min Xu, the study's principal investigator. "The extended half-life of HBM9378 may reduce dosing frequency in clinical practice, potentially enhancing patient adherence and improving outcomes."
Therapeutic Target and Development Strategy
HBM9378 is a half-life extended, fully human monoclonal antibody targeting TSLP (search), a well-validated cytokine that plays a key role in the development and progression of immunological diseases, including asthma and chronic obstructive pulmonary disease (COPD). The molecule features fully human sequences, offering lower immunogenicity risk and improved bioavailability, with engineered half-life extension and silenced effector function for subcutaneous administration.
The antibody was jointly developed by Harbour BioMed (search) and Kelun-Biotech (search) as a co-development project with equally shared global rights. In January 2025, both companies entered into a strategic partnership with Windward Bio (search), granting Windward Bio exclusive global licensing rights excluding Greater China and several Southeast and West Asian countries.
Clinical Development Pipeline
Harbour BioMed (search) has completed a Phase I clinical trial in China under an Investigational New Drug application for moderate-to-severe asthma treatment. Windward Bio (search) initiated a global Phase II POLARIS trial for asthma in July 2025. Additionally, China's National Medical Products Administration has approved the IND application for HBM9378 in COPD treatment.
"The positive Phase I results for HBM9378 mark a significant milestone in our mission to develop innovative therapies for immunological diseases," said Dr. Jingsong Wang, Founder, Chairman, and CEO of Harbour BioMed (search). "The favorable safety profile and extended half-life observed reinforce our confidence in HBM9378's potential to address unmet medical needs in conditions like severe asthma and chronic obstructive pulmonary disease."
The favorable Phase I results support continued clinical development of HBM9378 as a potential best-in-class treatment for patients with severe immunological disorders, with its extended half-life potentially offering improved dosing convenience and patient adherence compared to existing therapies.