GlaxoSmithKline plc has filed regulatory submissions in the USA and Europe for mepolizumab for approval as a maintenance treatment for patients with severe eosinophilic asthma, identified by a blood eosinophil count of at least 150 cells per microlitre at the start of treatment or 300 cells per microlitre in the past 12 months.

The submissions comprise: A Biologics Licence Application to the US Food and Drug Administrationas an add-on maintenance treatment for severe eosinophilic asthma in patients aged 12 years and older with a history of exacerbations.

A Marketing Authorisation Application to the European Medicines Agency as an add-on treatment for severe eosinophilic asthma in adult patients with a history of exacerbations and/or dependency on systemic corticosteroids.

Mepolizumab is a monoclonal antibody that is delivered in a 100mg dose via subcutaneous injection every four weeks. The regulatory submissions in the USA and Europe are based on studies of patients with severe asthma and include the phase III MENSA1 and SIRIUS2 studies published in the New England Journal of Medicine in September 2014 as well as the earlier phase IIb/III DREAM3 study published in the Lancet in 2012. Both the MENSA and SIRIUS studies evaluated patients with blood eosinophils of either 150 or more cells per microlitre at initiation of treatment or 300 or more cells per microlitre in the previous 12 months.

Dave Allen, Head, Respiratory Therapy Area Unit, R&D, said, “Severe asthma can have serious health consequences and for patients with elevated eosinophil levels whose disease remains uncontrolled despite taking medication, there are few treatment options. With the regulatory filings announced today, we are taking a further step towards making mepolizumab available for this difficult-to-treat group.”

Regulatory filings in other countries are planned during the course of 2014 and 2015. Mepolizumab is not currently approved for use anywhere in the world.

Currently the World Health Organization estimates that as many as 235 million people live with asthma worldwide. For many of these patients use of inhaled therapies can provide adequate control of their symptoms however there are as many as 10 percent who live with severe asthma and cannot achieve control with inhaled therapies.

Although asthma is a heterogeneous disease it is often characterised by an accumulation of eosinophils (white blood cells) in lung tissues and, in general, eosinophil levels correlate with severity and frequency of exacerbations. Interleukin-5 (IL-5) is the main promoter of eosinophil growth, activation and survival and provides an essential signal for the movement of eosinophils from the bone marrow into the lung.

Mepolizumab is an investigational humanised IgG1 monoclonal antibody specific for IL-5, which binds to IL-5, stopping it from binding to its receptor on the surface of eosinophils. Inhibiting IL-5 binding in this way reduces blood, tissue and sputum eosinophil levels. Mepolizumab is also being investigated in eosinophilic COPD and Eosinophilic Granulomatosis with Polyangiitis (EGPA).