US FDA delays Merck KGaA's filing on MS drug cladribine

In a move that will delay the approval of German drug major Merck KGaA's multiple sclerosis drug cladribine, the US Food and Drug Administration has issued a 'refuse to file' letter on the firm's New Drug Application for the compound as a therapy for relapsing forms of MS.

Merck's shares fell 4.5% to 62.54 euros by 14.00 GMT on November 30, the leading decliner among German blue chips stocks.

'The company will work closely with the FDA to fully understand FDA's concerns and define a path forward for a successful resubmission of this application at the earliest point in time,' said Elmar Schnee, executive board member of Merck and head of the Merck Serono division. 'We remain focused on delivering on our promise to transform the way people living with multiple sclerosis approach their therapy options,' he added.