AstraZeneca’s Fasenra has been awarded Orphan Drug Designation in the US for the treatment of hypereosinophilic syndrome (HES).

The drug is a monoclonal antibody that binds directly to IL-5 receptor α on eosinophils and attracts natural killer cells to induce rapid and near-complete depletion of eosinophils via apoptosis (programmed cell death).

A Phase II clinical trial of Fasenra for the treatment of HES has been conducted by the US National Institutes of Health in collaboration with AstraZeneca, with results expected to be published later in 2019. In the trial, Fasenra depleted blood eosinophils at week 12 compared with the placebo, with evidence of eosinophil clearance in affected tissue at week 24.

Mene Pangalos, executive vice president, R&D BioPharmaceuticals, said: “In patients with hypereosinophilic syndrome, high levels of eosinophils contribute to a range of debilitating symptoms and can even lead to life-threatening organ damage. Based on results from the Phase II trial, we believe Fasenra has the potential to address critical unmet medical needs in patients living with hypereosinophilic syndrome.”

HES is a group of rare disorders in which high numbers of eosinophils are found in the blood and tissue which can cause progressive organ damage over time, and if left untreated, can be fatal.

The US Food and Drug Administration grants ODD status to medicines intended for the treatment, diagnosis or prevention of rare diseases or disorders that affect fewer than 200,000 people in the US.