CHENGDU, China – June 9, 2026
Kelun-Biotech has announced that its partner Windward Bio has successfully dosed the first patients in the Phase 2 SIRIUS clinical study evaluating SKB378/WIN378 for the treatment of chronic obstructive pulmonary disease (COPD), marking a significant milestone in the development of a potential first-in-class ultra long-acting anti-TSLP therapy. The initiation of the SIRIUS trial expands the clinical development of SKB378/WIN378 beyond asthma and into a second major respiratory disease area with substantial unmet medical need. The candidate is already being evaluated in the ongoing Phase 2/3 POLARIS asthma study, with initial Phase 2 data expected in the second half of 2026 and Phase 3 asthma development anticipated to begin later this year. As one of the most promising next-generation respiratory biologics currently in development, SKB378/WIN378 has the potential to become the first-to-market, twice-yearly anti-TSLP monoclonal antibody for both asthma and COPD, offering a differentiated treatment option for millions of patients worldwide.
Phase 2 SIRIUS Trial Targets High-Risk COPD Patients
The newly initiated SIRIUS study is a global, randomized, double-blind, placebo-controlled Phase 2 clinical trial designed to evaluate the safety, tolerability, pharmacokinetics, and pharmacodynamics of SKB378/WIN378 in patients with moderate-to-severe COPD. Chronic obstructive pulmonary disease remains one of the most serious respiratory disorders globally and is currently the third leading cause of death worldwide. Characterized by progressive airflow limitation, chronic inflammation, and recurrent exacerbations, COPD continues to impose a significant clinical and economic burden despite the availability of inhaled maintenance therapies.
More than three million patients with moderate-to-severe COPD remain at high risk of recurrent exacerbations, highlighting the urgent need for innovative treatment approaches capable of providing improved disease control. By targeting thymic stromal lymphopoietin (TSLP), a key upstream driver of airway inflammation, SKB378/WIN378 aims to address fundamental disease mechanisms and potentially reduce the frequency and severity of exacerbations that often lead to hospitalization, declining lung function, and increased mortality.
Ultra Long-Acting Anti-TSLP Therapy Shows Strong Potential
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SKB378/WIN378 is a fully human monoclonal antibody engineered to potently inhibit TSLP, a clinically validated target involved in the initiation and progression of multiple inflammatory and respiratory diseases. The therapy has been specifically designed with half-life extension technology and silenced effector function, enabling prolonged biological activity and supporting the possibility of twice-yearly dosing. Early clinical evaluation in a Phase 1 study demonstrated an extended half-life, a low incidence of anti-drug antibodies, and a favorable safety and tolerability profile across all tested dose levels.
The prospect of a biologic treatment requiring only two administrations per year could represent a major advancement for patients and healthcare systems by improving treatment adherence and reducing administration burden. The drug is administered subcutaneously and has generated considerable interest due to its potential to deliver long-lasting control of airway inflammation across multiple respiratory conditions. Industry experts view ultra long-acting biologics as a critical area of innovation capable of transforming chronic disease management.
Expanding Global Respiratory Development Strategy
The launch of the SIRIUS COPD study strengthens the broader development strategy for SKB378/WIN378 and reinforces the growing collaboration between Kelun-Biotech, Harbour BioMed, and Windward Bio. Originally developed as a co-development program between Kelun-Biotech and Harbour BioMed, the therapy was later licensed to Windward Bio for global development rights outside Greater China and selected international territories. Beyond COPD, the candidate is advancing rapidly in asthma through the ongoing POLARIS Phase 2/3 study, where initial data are expected later this year. If clinical results continue to demonstrate strong efficacy and safety, the first Phase 3 asthma trial is anticipated to begin in the fourth quarter of 2026.
With increasing demand for targeted biologics capable of addressing severe respiratory diseases, SKB378/WIN378 has emerged as a promising candidate with the potential to reshape treatment paradigms in both asthma and COPD. The first patient dosing in SIRIUS represents an important step toward achieving that goal and underscores the growing momentum behind innovative anti-TSLP therapies in respiratory medicine.
Source: Kelun-Biotech press release
