Sichuan Kelun-Biotech Biopharmaceutical Co., Ltd. (SKB BIO) and development partner Windward Bio AG have released encouraging interim results from the Phase 2 segment of the global POLARIS-1 trial evaluating SKB378/WIN378 in adults with uncontrolled asthma, and confirmed initiation of the Phase 3 portion of the study.

SKB378/WIN378 is a fully human, ultra-long-acting monoclonal antibody that inhibits thymic stromal lymphopoietin (TSLP) by binding two distinct sites on the cytokine, blocking interaction with both co-receptors. The molecule was engineered for higher potency, an extended half-life and silenced effector function; interim pharmacokinetic modelling indicates a half-life of up to 75 days, supporting twice-yearly dosing.

Phase 2 Study Highlights • Design: 48-week, randomised, double-blind trial comparing three single subcutaneous doses of SKB378/WIN378 with placebo. • Enrolment: 147 patients (target 120); interim analysis based on the first 98 participants. • Efficacy at Week 24 after a single dose: – Forced expiratory volume in one second (FEV1) increased by up to 174 mL, equating to a placebo-adjusted gain of 256 mL (p = 0.033). – Fractional exhaled nitric oxide (FeNO) fell by up to 24 ppb, a 43% reduction (p = 0.006). – Blood eosinophil counts declined by up to 200 cells/µL, a 51% reduction (p < 0.0001). Near-maximal lung-function and biomarker improvements emerged by Week 2 and were sustained through Week 24.

Safety Profile SKB378/WIN378 was well tolerated, with no treatment-related serious adverse events, withdrawals or discontinuations at data cut-off. Adverse-event frequencies were balanced across active and placebo arms; <1% of subjects reported injection-site reactions, and 2% developed anti-drug antibodies without pharmacological impact.

Next-Phase Development Two twice-yearly dosing regimens selected from Phase 2 will advance into the Phase 3 segment of POLARIS-1, which targets annualised asthma exacerbation rate as its primary endpoint in severe asthma. Windward Bio plans to launch a second Phase 3 trial (POLARIS-2) in the first half of 2027. SKB378/WIN378 is also in the Phase 2 SIRIUS study for chronic obstructive pulmonary disease.

Risk Notice The company cautions that SKB378/WIN378 may not ultimately achieve successful development or commercialisation, and investors should exercise prudence when dealing in SKB BIO securities.