Safety, Tolerability, and Pharmacokinetics of Nebulized GB05-Human IFNα1b Inhalation Solution: A Randomized, Placebo-Controlled, Dose-Escalation Phase I Study in Healthy Chinese Adult Volunteers.

Introduction: Human respiratory syncytial virus (RSV) is the leading cause of lower respiratory tract infection, especially in children and older people. However, no effective treatment is currently available. Type I interferons (IFNs) are a group of cytokines that help regulate the activity of the immune system. GB05, human IFNα1b inhalation solution, was developed under US Food and Drug Administration (FDA) standard guidelines to combat RSV infection. This randomized, double-blind, placebo-controlled, dose-escalation phase I trial evaluated the safety, tolerability, and pharmacokinetics of nebulized GB05.

Methods: A total of 35 eligible healthy Chinese adult volunteers were enrolled in this study. In the single ascending dose (SAD) study, volunteers were randomized into 0.2, 0.6, 1.2, and 1.8 million IU of GB05 or placebo. In the multiple ascending dose (MAD) study, volunteers received 1.2 or 1.8 million IU of GB05 or placebo for four consecutive days. Safety, tolerability, immunogenicity, and plasma pharmacokinetics were assessed for all groups.

Results: All adverse events were mild or moderate and resolved spontaneously. The most common adverse event was decreased white blood cell count (8.6% in SAD and 10% in MAD). No serious adverse events, deaths, or adverse events that reached the termination criteria occurred during the study. In SAD, the maximum concentration and area under the curve increased across the dose range of 1.2-1.8 million IU in a non-linear relationship. The maximum plasma concentration after GB05 nebulization (1.06 IU/ml in the 1.8 million IU group) reflected a low concentration in the blood, suggesting a better lung uptake of GB05 and reduced incidence or risks of adverse events. In MAD, a steady state was reached after continuous administrations of twice daily for 3 days.

Conclusions: Overall, nebulized GB05 exhibited satisfactory safety, tolerability, and favorable pharmacokinetic (PK) profiles in healthy adult volunteers, supporting further clinical investigation in patients infected with respiratory syncytial virus.

Clinical Trial Registration: ClinicalTrials.gov Identifier NCT06277167.