Mepolizumab granted approval by FDA for the treatment of hypereosinophilic syndrome

Mepolizumab, an anti-interlukin-5 (IL-5) monoclonal antibody, has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of children ≥ 12 years of age and adult patients with hypereosinophilic syndrome (HES) for ≥ 6 months without another identifiable non-blood related cause of the disease. This is the first approval for patients with HES in almost 14 years, and was based on a phase III study evaluating the efficacy and safety of mepolizumab versus placebo in patients with HES, where mepolizumab demonstrated a significant reduction in the frequency of flares and blood eosinophil levels compared with placebo. Read more data from this study here.

HES represent a group of rare myeloproliferative neoplasms characterized by elevated eosinophil levels, which may lead to organ damage and can be life threatening if not treated. IL-5 is known to play a role in eosinophil growth, and mepolizumab has been approved for the treatment of diseases which are driven by eosinophils, such as asthma and eosinophilic granulomatosis.

Mepolizumab has been associated with herpes zoster infections and vaccination is advised if medically appropriate.