Merck, based in Darmstadt, Germany, failed to win FDA support for its multiple sclerosis pill cladribine.

The FDA asked for additional studies to better understand the medicine’s risks. Merck plans to seek an end-of-review meeting with the FDA to determine whether data already collected is sufficient to address the concerns.  

Merck withdrew its European application to sell cladribine last month after regulators said the drug’s benefits do not outweigh its risks. Cladribine, originally a cancer drug, is sold in Russia and Australia under the brand name Movectro.