GlaxoSmithKline (GSK) said that its respiratory drug Nucala (mepolizumab) has succeeded in reducing flares in patients with hypereosinophilic syndrome (HES) in a phase 3 study.
The late-stage study evaluated subcutaneously administered mepolizumab 300mg (3x100mg) every four weeks against placebo in 108 adolescent and adult patients with severe HES.
The HES trial met its primary endpoint of delivering a statistically significant result with 50% fewer patients experiencing a HES flare in the mepolizumab arm, compared to placebo. The GSK drug was evaluated for its efficacy and safety in combination with standard of care treatment over the 32-week study period.
The company said that secondary endpoints of the late-stage trial were also significant statistically, while supporting the primary endpoint.
GSK chief scientific officer and R&D president Hal Barron said: “Mepolizumab has the potential to change the treatment landscape for patients with HES which is a complex and debilitating disease with limited therapeutic options today.”
Patients having HES have a persistent and notable overproduction of eosinophils. When these white blood cells infiltrate certain tissues, the result could be inflammation and organ damage.
University of Utah allergist, immunologist and HES expert Gerald Gleich said: “Mepolizumab is thought to work by reducing blood eosinophil levels and evidence suggests it has potential as a targeted treatment option for a range of inflammatory diseases driven by raised eosinophils.
“These data are very promising and should provide hope for patients affected by this rare, life-threatening condition caused by eosinophilic inflammation.”
The GSK respiratory drug had secured both fast track and orphan drug designations from the US Food and Drug Administration (FDA) for HES. The drug also has orphan drug designation from the European Medicines Agency (EMA) for the same indication.
Mepolizumab, which is a monoclonal antibody that targets IL-5, was first approved in 2015 in the US for severe eosinophilic asthma. In 2017, the GSK drug was approved in the US for Eosinophilic Granulomatosis with Polyangiitis (EGPA).
Overall, the GSK respiratory drug has been approved in the US, Europe and in more than 20 other markets, as an add-on maintenance treatment for patients having severe eosinophilic asthma (SEA).
The drug is believed to stop IL-5 from binding to its receptor on the surface of eosinophils, thereby lowering blood eosinophils without depleting them completely.