UK-based pharmaceutical firm GlaxoSmithKline (GSK) has unveiled positive results from the study of Nucala (mepolizumab) for treating patients with Hypereosinophilic Syndrome (HES).

The phase 3 study is a randomised, double-blind, placebo-controlled study that enrolled 108 patients to investigate the efficacy and safety of subcutaneous mepolizumab 300mg administered every four weeks compared with placebo in adolescent and adult patients with severe HES.

GSK said that the phase 3 study has shown statistically significant results by reducing HES flare, a worsening condition requiring an escalation in therapy, by 50% in patients treated with mepolizumab.

The study has reached the primary endpoints, and the secondary endpoints include risk of first HES flare over the study period, reduction in the annualised rate of HES flares, and improved fatigue scores compared to placebo.

GSK R&D chief scientific officer and 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.”

HES impacts patients’ day-to-day activities over time

HES, a rare group of inflammatory disorders is characterised by persistent overproduction of eosinophils, leading to infiltration into certain tissues, causing inflammation and organ damage in patients.

HES may result in complications ranging from fever and malaise to respiratory and cardiac problems, and the symptoms may progressively worsen and become life-threatening if left untreated.

The company said that the study results showed consistent safety with the known profile of mepolizumab, making it the first treatment to reduce HES flares.

In addition, Mepolizumab was granted the US Food and Drug Administration (FDA) Fast Track and Orphan Drug designation, along with the European Medicines Agency (EMA) Orphan Drug Designation for the treatment of HES.

GSK said that mepolizumab is not approved for use in HES, and it intends to use the study data to advance the regulatory submissions in 2020.

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.”