Acadia Pharmaceuticals has won European Commission approval for its Daybu as a treatment for neurobehavioral symptoms of Rett syndrome in patients five and older.

Acadia on Monday said the green light makes Daybu the first and only treatment approved in the European Union for Rett syndrome, a rare neurodevelopmental disorder.

The San Diego drugmaker said it will now begin pricing and reimbursement negotiations with relevant national authorities across the EU.

Acadia, which markets Daybu as Daybue in the U.S. and Canada, earlier this month said it expects global net product sales of the drug to reach $480 million to $510 million this year.