* FDA has not requested extra data, further studies
* Genzyme to work with FDA to resubmit as soon as possible (Adds background)
PARIS, Aug 27 (Reuters) - The U.S. health regulator has asked Sanofi's rare disease division Genzyme to redo the filing of its marketing application for multiple sclerosis drug candidate Lemtrada, Genzyme said, though no additional clinical studies are needed.
Genzyme said on Monday it had received a so-called Refuse to File letter from the U.S. Food and Drug Administration (FDA), asking the company to change the presentation of the data so the agency can "better navigate the application".
The FDA has not requested additional data or further studies, Genzyme said in a statement, adding it was confident it could resubmit the application as soon as possible.
The drug, chemically known as alemtuzumab, is also used under a different dosage to treat leukaemia or blood cancer but Genzyme said last week it was pulling that version, branded as Campath, to prepare for the launch of Lemtrada.
Lemtrada could be launched in 2013 if it wins approval and will be given far less frequently and in lower doses than Campath. The withdrawal will enable Sanofi to adjust Lemtrada's price closer to that of rival multiple sclerosis drugs such as Novartis's Gilenya.
Sanofi, which has worked on the drug with Germany's Bayer, submitted a supplemental biologics licence application to the FDA and a marketing authorisation application to the European Medicines Agency for Lemtrada in June. (Reporting by Caroline Jacobs, Editing by Lionel Laurent)