The FDA sent a "refuse to file" letter to EMD Serono, an affiliate of Merck KgA, for the NDA for Cladribine Tablets, an oral formulation of Serono's cladrribine therapy for relapsing multiple sclerosis.

"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, Merck KGaA's head of pharmaceuticals. "We remain focused on delivering on our promise to transform the way people living with multiple sclerosis approach their therapy options."

Once an NDA is submitted to the FDA, the Agency has 60 days to review thesubmission and assess whether it is sufficiently complete to permit a substantive review. If it determines that the NDA does not reach that goal, the FDA issues a refuse to file letter to the applicant. EMD Serono plans to request a meeting with the FDA as soon as possible to discuss its comments on the NDA submission and to reach an understanding on what would be required for the Cladribine Tablets NDA to be accepted for review.