FDA OKs Mepolizumab (Nucala) for Hypereosinophilic Syndrome

Megan Brooks

September 28, 2020

The US Food and Drug Administration (FDA) has expanded the indication for mepolizumab (Nucala, GlaxoSmithKline) to include patients with hypereosinophilic syndrome (HES).

Mepolizumab is indicated for adults and children aged 12 years and older with HES for 6 months or longer without an identifiable nonhematologic secondary cause.

"[This] approval marks the first time in over a decade that there is a new FDA-approved treatment option for patients with hypereosinophilic syndrome," Ann Farrell, MD, director, Division of Nonmalignant Hematology, FDA Center for Drug Evaluation and Research, said in a news release.

"FDA is committed to helping develop safe and effective treatment options for this group of rare and debilitating blood diseases and other rare conditions," said Farrell.

Third Indication

Mepolizumab, an anti-interleukin-5 biologic, is already approved in the United States for the treatment of children as young as 6 years with severe eosinophilic asthma and for adults with eosinophilic granulomatosis with polyangiitis.  

HES is a heterogeneous group of rare disorders characterized by persistent eosinophilia that damages multiple organs. Symptoms include skin rashes, itching, asthma, difficulty breathing, abdominal pain, vomiting, diarrhea, arthritis, muscle inflammation, congestive heart failure, deep venous thrombosis, and anemia.

The efficacy and safety of mepolizumab for HES was evaluated in a 32-week, randomized, double-blind, placebo-controlled study involving 108 patients aged 12 years and older.

All participants had uncontrolled HES, defined as at least two HES flares (worsening of symptoms or eosinophil threshold requiring an escalation in therapy) within the past 12 months and a blood eosinophil count of 1000 cells/µL or higher at screening.

Mepolizumab or placebo was administered by subcutaneous injection every 4 weeks.

Over the 32-week study, when added to standard of care, treatment with mepolizumab led to 50% fewer HES flares compared with placebo (28% vs 56%; P = .002). The time to first HES flare was also longer, on average, for patients treated with mepolizumab.

The most common side effects of mepolizumab in patients with HES include upper respiratory tract infection and pain in extremities. It should not be given to patients with a history of hypersensitivity to mepolizumab or one of its ingredients.

Herpes zoster infections have occurred in patients receiving mepolizumab. Health care providers should consider vaccination if medically appropriate.

In a company press release, Hal Barron, MD, GSK chief scientific officer and president of R&D, said, "HES is a complex, life-threatening condition that impacts nearly 5000 patients in the US. [This] approval gives these patients access to a biologic treatment for the first time and demonstrates our commitment to maximizing Nucala's impact on eosinophil-driven diseases."

Also commenting in the release, Mary Jo Strobel, executive director, American Partnership For Eosinophilic Disorders (APFED), said, "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."

The FDA granted the mepolizumab application for treatment of HES fast track and priority review designations, as well as orphan drug designation.

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