* Withdraws bid to get mepolizumab approved for HES
* Still working on drug as treatment for difficult asthma
(Adds details, background)
LONDON, July 29 (Reuters) - GlaxoSmithKline (GSK.L) has pulled its application for European approval of its experimental drug mepolizumab, or Bosatria, as a treatment for a rare blood disorder called HES.
It is still working to develop the medicine for asthma.
Europe’s biggest drugmaker said on Wednesday it had reluctantly pulled the submission because additional clinical data would have been required to further demonstrate the drug’s benefit to patients with hypereosinophilic syndrome (HES).
HES is a rare disease characterised by the build-up of a type of white blood cell, known as an eosinophil, that can cause fever, respiratory and cardiac problems, or death in some patients with advanced disease.
Because of its mode of action, mepolizumab may also help a small group of asthma sufferers whose illness can be difficult to control. It has yet to be submitted to regulators for asthma and a spokesman said work in this area would continue.
Mepolizumab reduces the number of eosinophils by inhibiting an immune system signalling chemical called interleukin-5. (Reporting by Ben Hirschler; Editing by Hans Peters)