The FDA has approved Nucala (mepolizumab) for the treatment of adult and pediatric patients aged 12 years and older with Hypereosinophilic Syndrome (HES) for ≥ six months without an identifiable non-hematologic secondary cause, according to GlaxoSmithKline plc (GSK).

The approval makes Nucala the first and only targeted biologic treatment to be approved for patients with this eosinophil-driven disease in the US.

Dr Hal Barron, Chief Scientific Officer and President R&D, GSK, said: “HES is a complex, life-threatening condition that impacts nearly 5,000 patients in the US. Today’s approval gives these patients access to a biologic treatment for the first time and demonstrates our commitment to maximising Nucala’s impact on eosinophil-driven diseases.”

The FDA approval follows a priority review of data from a clinical development programme that included positive results from a pivotal phase 3 study, recently published in the Journal of Allergy and Clinical Immunology. The study showed 50 percent fewer patients experienced a HES flare (worsening of symptoms or eosinophil threshold requiring an escalation in therapy) when treated with Nucala, compared to placebo, when added to standard of care treatment over the 32-week study period (28% vs 56%; p=0.002).

According to Dr. Gerald Gleich, MD, allergist, immunologist and a HES expert: “Patients with HES often suffer from debilitating flares of their disease. Reducing them is an important treatment goal. For the first time, we now have a biologic treatment option to offer appropriate patients with this complex disease.”

Patients with HES have a persistent and marked overproduction of eosinophils, a type of white blood cell. Reducing the overproduction of eosinophils to normal levels can help people with eosinophil-driven diseases such as HES.

Mary Jo Strobel, Executive Director, American Partnership for Eosinophilic Disorders (APFED) added: “HES can take many years to diagnose and most patients go through a long and frustrating journey that continues even after the diagnosis is confirmed as treatment roadmaps are often unclear and limited. APFED welcomes this approval of Nucala for HES as it gives our community hope.”

Nucala is currently used as an add-on maintenance therapy for severe eosinophilic asthma and for the treatment of eosinophilic granulomatosis with polyangiitis (EGPA), and is being investigated in several other eosinophil-driven diseases.