Windward Bio AG has launched the Phase 2 POLARIS clinical study, a global, randomized, double-blind, placebo-controlled trial evaluating the dosing, safety, and efficacy of HBM9378/WIN378 in patients with asthma. The long-acting monoclonal antibody, developed through a collaboration between Harbour BioMed and Kelun-Biotech, represents a potential breakthrough in asthma treatment with initial data expected in mid-2026.
Novel Anti-TSLP Mechanism Targets Key Inflammatory Pathway
HBM9378/WIN378 is a recombinant fully human monoclonal antibody that potently binds to the thymic stromal lymphopoietin (TSLP) ligand and inhibits TSLP-mediated signaling by blocking the interaction between TSLP and its receptor. TSLP is a well-validated cytokine that plays a key role in the development and progression of immunological conditions, including asthma and chronic obstructive pulmonary disease (COPD), where inhibition has demonstrated benefit across inflammatory phenotypes.
The antibody has been engineered to achieve an extended half-life and effector silencing, administered subcutaneously with the potential for twice-yearly dosing. This extended dosing interval could significantly reduce treatment burden and improve outcomes for patients with advanced respiratory diseases.
Strong Phase 1 Safety and Pharmacokinetic Profile
In Phase 1 trials, HBM9378/WIN378 demonstrated several promising characteristics. The study confirmed the extended half-life necessary for prolonged dosing intervals and showed a low rate of antidrug antibodies. The therapy was safe and well tolerated up to the highest tested dose, with the fully human sequences offering a lower risk of immunogenicity and improved bioavailability compared to other TSLP-targeting therapies.
Addressing Significant Unmet Medical Need
Asthma affects approximately 300 million people worldwide, with prevalence continuing to rise. Despite available treatment options, many patients experience persistent symptoms, frequent exacerbations, and reduced quality of life. Current therapies, mainly inhaled corticosteroids (ICS) and bronchodilators, are inadequate for some patients, underscoring the urgent need for more effective, long-acting treatments that address underlying disease mechanisms.
"We are pleased to see HBM9378/WIN378 advancing rapidly into global clinical development," said Dr. Jingsong Wang, Founder, Chairman and CEO of Harbour BioMed. "This long-acting, fully human anti-TSLP antibody has demonstrated strong potential in previous preclinical and clinical studies. We believe it has the potential to address significant unmet needs for patients with asthma."
Expanding Clinical Program Beyond Asthma
Beyond asthma, HBM9378/WIN378 is being evaluated for COPD treatment. In January 2025, the National Medical Products Administration (NMPA) of China approved an Investigational New Drug (IND) application for HBM9378/WIN378 in COPD. Windward Bio plans to initiate global COPD clinical trials in mid-2026, highlighting the versatility and potential of this innovative therapy across respiratory conditions.
Strategic Partnership Structure
HBM9378/WIN378 originated as a co-development project between Harbour BioMed and Kelun-Biotech, with both parties equally sharing global rights. In January 2025, the companies entered into an exclusive license agreement with Windward Bio, granting the clinical-stage biotechnology company exclusive rights for research, development, manufacturing, and commercialization globally, excluding Greater China and several Southeast and West Asian countries.
Windward Bio, which launched earlier this year with a $200 million Series A funding round led by top-tier investors, describes WIN378 as a potential best-in-disease, long-acting anti-TSLP monoclonal antibody. The company is also building a pipeline of long-acting bispecific antibodies targeting validated biology in respiratory and dermatological conditions.
