GlaxoSmithKline’s non-inhaled, biologic therapy for a difficult-to-treat form of severe asthma has taken a giant leap towards market with simultaneous filings on both sides of the Atlantic.

Mepolizumab is being developed as a maintenance treatment for severe eosinophilic asthma in patients who experience exacerbations despite high-dose oral or inhaled corticosteroids (ICS) and an additional controller (such as long-acting beta-2 agonist), a group for whom there remain few treatment options.

More specifically, in the US GSK is seeking approval for the drug as an add-on maintenance treatment for severe eosinophilic asthma in patients aged 12 years and older with a history of exacerbations, while in Europe it is as an add-on treatment in adult patients with a history of exacerbations and/or dependency on systemic corticosteroids.

Administered by subcutaneous injection every four weeks, mepolizumab is a monoclonal antibody that inhibits interleukin 5 and thus reduces the number of eosinophils in the tissues, blood and sputum, high levels of which can trigger both asthma and symptom exacerbations.

In study MEA115588, mepolizumab 75mg cut the frequency of clinically significant exacerbations of asthma by 47% versus placebo, while the 100mg dose cut the amount by 53%.

Real world rival?

However, writing in the New England Journal of Medicine in September, asthma expert Parameswaran Nair suggested that in the real world, less expensive treatments already on the market could work just as well if patients simply took them as prescribed.

“Even in the most well-characterised patients with severe asthma, the lack of adherence to the prescribed therapy is the most common cause of poor asthma control," Professor Nair wrote, pointing out that “the judicious use of currently available therapies…has been shown to lead to substantial reductions in exacerbations, decreases that are clinically equivalent to those reported for biologic therapies and are likely to be more cost-effective”.

Nevertheless, analysts believe IL-5 products, including Teva’s soon-to-be-filed reslizumab, could expand the asthma market by billions of dollars.