AZ's Fasenra also works in rare organ damage diseases

AstraZeneca’s asthma drug Fasenra also works in a group of rare diseases that can lead to potentially fatal organ damage, a mid-stage trial has shown.

Results of the phase 2 trial, published in the New England Journal of Medicine, demonstrated that Fasenra (benralizumab) worked in hypereosinophilic syndrome (HES).

HES is a group of rare and potentially fatal disorders characterised by high numbers of eosinophils in blood and tissues that can cause progressive and potentially life-threatening organ damage.

Eosinophils are types of white blood cells that usually play a role in fighting off disease, but are overstimulated in certain diseases, and begin to attack a patient's own body instead.

The drug nearly completely depleted the eosinophils in the trial AZ conducted in partnership with the US National Institutes of Health (NIH).

Fasenra is an antibody that binds to the IL-5 receptor found on the surface of eosinophils, and it is thought that once this happens natural killer cells are able to approach and destroy the eosinophils.

In the randomised phase of the 20-patient trial, the primary efficacy endpoint was the percentage of patients who reduced absolute blood eosinophil counts by 50% or more at week 12.

This was achieved by 90% of patients treated with Fasenra compared with 30% of patients treated with placebo, a statistically significant difference.

In the open-label phase of the trial, 74% of patients maintained a reduction in eosinophil counts and had clinical improvements in their symptoms through week 48.

Of these patients, 64% were able to taper background HES medications. In patients from whom tissue biopsies were obtained (gastrointestinal tract and skin) there was near-complete depletion of eosinophils following treatment with Fasenra.

At the start of the phase 2 trial, patients had significantly elevated levels of blood eosinophils ranging from 1,000 to 21,580 cells per μl.

During the 48-week treatment period, the three most frequently reported adverse events attributed to Fasenra included headache, elevated lactate dehydrogenase (LDH) concentration and chills.

The observed increases in LDH occurred after the first dose of Fasenra and resolved within 48 hours. The trial was a collaboration between AstraZeneca and the US National Institute of Allergy and Infectious Diseases (NIAID), part of the US National Institutes of Health.

Fasenra is approved as an add-on maintenance treatment for severe, eosinophilic asthma in the US, EU, Japan and other countries.

Mene Pangalos, AZ's president of BioPharmaceuticals R&D, said: “We are encouraged by these trial results for Fasenra in hypereosinophilic syndrome and the data are potentially important given the limited treatment options for this debilitating disease.”