(Reuters) -Denmark's H Lundbeck A/S has agreed to buy Longboard Pharmaceuticals ( LBPH ) in a $2.6 billion deal to boost its pipeline of treatments for neuro-rare conditions, sending shares of the U.S.-based company up 43.9% in premarket trading.

The companies said Lundbeck will acquire all of Longboard's shares for $60 per share, which represents a premium of 54.2% to the stock's last close of $38.90.

Longboard's lead drug candidate, bexicaserin, for seizures associated with a group of epilepsies is in late-stage development.

(Reporting by Manas Mishra and Puyaan Singh in Bengaluru; Editing by Shinjini Ganguli)