Cambridge, Massachusetts, USA / Rotterdam, Netherlands / Shanghai, China | March 22, 2026
Harbour BioMed has announced the online publication of Phase I clinical trial results for HBM9378 (SKB378/WIN378), a novel TSLP-targeting monoclonal antibody, highlighting a favorable safety profile, extended half-life, and promising pharmacokinetic characteristics in healthy subjects. The randomized, double-blind, placebo-controlled study represents a significant milestone in the development of next-generation biologics targeting immunological diseases, supporting further clinical evaluation in conditions such as severe asthma and chronic obstructive pulmonary disease (COPD).
Phase I Study Confirms Safety and Tolerability Profile
The first-in-human Phase I trial enrolled 50 healthy adult participants across multiple dose cohorts ranging from 20 mg to 900 mg, designed to evaluate safety, tolerability, pharmacokinetics (PK), and immunogenicity of HBM9378. The results demonstrated that the incidence of treatment-emergent adverse events (TEAEs) was comparable between the treatment and placebo groups, with no dose-dependent increase in safety risks, confirming a favorable safety and tolerability profile.
Importantly, the study reported no injection site reactions across all dose levels, further supporting the drug’s acceptable safety characteristics for subcutaneous administration. The low incidence of anti-drug antibodies (ADA) at only 5%, with no impact on drug exposure or clinical outcomes, indicates minimal immunogenicity risk, a critical factor in biologic drug development.
Extended Half-Life Supports Improved Dosing Strategy
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A key highlight of the study was the extended half-life (T1/2) of 55.0 to 65.8 days, significantly longer than many existing biologics in the same class. This extended half-life, combined with a dose-proportional increase in drug exposure (Cmax and AUC), suggests that HBM9378 could enable less frequent dosing schedules, potentially improving patient adherence and long-term treatment outcomes.
The median time to maximum concentration (Tmax) ranged from 4.05 to 14.1 days, indicating a predictable pharmacokinetic profile. These findings are particularly important for chronic diseases such as asthma and COPD, where long-term therapy adherence is critical for disease control.
Targeting TSLP for Immunological Disease Management
HBM9378 is a fully human monoclonal antibody targeting thymic stromal lymphopoietin (TSLP), a key cytokine involved in the pathogenesis of multiple inflammatory and respiratory diseases. By inhibiting TSLP signaling, the therapy aims to modulate upstream immune pathways, offering a broad therapeutic impact across various immunological conditions.
The molecule has been engineered with half-life extension and silenced effector function, enhancing its bioavailability and safety profile while reducing potential immune-related adverse effects. Its fully human structure further minimizes immunogenicity risks, positioning it as a potential best-in-class biologic therapy.
The development of HBM9378 is supported by a global collaboration framework, with ongoing and planned clinical studies, including a Phase II POLARIS trial in asthma, and regulatory approvals such as IND clearance in China for COPD, reflecting strong momentum in its clinical development program.
The Phase I results for HBM9378 demonstrate strong safety, favorable pharmacokinetics, and extended half-life, supporting its advancement into later-stage clinical trials. With its innovative mechanism targeting TSLP and potential for reduced dosing frequency, HBM9378 represents a promising therapeutic candidate in the treatment of chronic immunological and respiratory diseases. These findings underscore Harbour BioMed’s commitment to advancing next-generation antibody therapies addressing significant unmet medical needs.
Source: Harbour BioMed press release
