UK drug giant GlaxoSmithKline has withdrawn its application to market mepolizumab for the treatment of the rare inflammatory disorder hypereosinophilic syndrome in Europe.

HES is a potentially fatal condition characterised by very high levels of white blood cells known as eosinophils, which leads to widespread inflammation and ultimately organ damage. As there is no licensed cure for the condition, current standard of care is based on the administration of corticosteroids.

Mepolizumab is a humanised monoclonal antibody designed to treat FIP1 (a certain gene) negative forms of the condition, and its submission to the European Medicines Agency was based on a promising performance in late stage clinical trials.

In a Phase III study published in the New England Journal of Medicine last year, eosinophil levels were seen to return to normal in 95% of patients receiving the drug plus steroids, compared to 45% of those taking a ghost pill/steroid regimen. Furthermore, 47% were able to cut down on steroids during the course of the 36-week study versus
However, feedback from the Agency’s Committee for Medicinal Products for Human Use indicated that mepolizumab would not be given the regulatory seal of approval without additional data on its clinical benefits to further support its application, and so the company took the decision to withdraw its submission at this time.

Difficult decision
David Gordon, vice president of Biopharm R&D at GSK, said the decision has been “extremely hard to take” particularly as HES is a disease with very limited treatment options. “Nevertheless,” he added, “we are committed to exploring new options to develop mepolizumab as a treatment for HES and we will continue to make it available to patients who are currently benefiting from mepolizumab through our compassionate use programme”.

The company was also quick to stress that withdrawal of the EU application “does not preclude GSK from making a new application at a later stage”, and added that development programmes for other indications, such as severe asthma, will continue as scheduled.