U.S. FDA approves Sanofi's MS drug Lemtrada

PARIS (Reuters) - The U.S. Food and Drug Administration has approved Sanofi's multiple sclerosis treatment Lemtrada, Sanofi said in a statement on Saturday. Lemtrada is already sold in Europe but last December U.S. regulators rejected it on security concerns, prompting analysts to slash their global sales forecasts for the drug. Sanofi said in its statement that "because of its safety profile" the use of Lemtrada should generally be reserved for patients who have had an inadequate response to two or more drugs indicated for the treatment of MS. Lemtrada is given in two courses via an intravenous drip for five days and for three days one year later. It is designed to re-program the immune system, but in doing so can make the body more vulnerable to other diseases. FDA staff had last year flagged risks of autoimmune diseases including blood disorders, infections and cancer. Lemtrada was at the core of Sanofi's $20 billion 2011 takeover of U.S. biotech Genzyme, which developed the drug. Sanofi's chief executive at the time, Chris Viehbacher, who was sacked by Sanofi's board last month, had championed the move into rare diseases as he sought new areas of growth to offset the impact of patent losses on big-selling drugs. Multiple sclerosis is a chronic, autoimmune condition which affects more than 2 million people worldwide and up to 500,000 in the United States. It attacks the central nervous system and can cause muscle weakness, pain and cognitive difficulties. The multiple sclerosis market is increasingly moving away from injectable treatments in favor of pills such as Novartis' Gilenya and Biogen Idec's < BIIB.O> Tecfidera. But Genzyme hopes Lemtrada's ability to reduce the risk of relapse of the disease will win it market share. Industry observers however expect it will be reserved for patients for whom other treatments are ineffective. Analysts on average expect the drug to generate sales of just $141 million next year and just under $400 million by 2018, according to Thomson Reuters Cortellis data. Germany's Bayer has an option to co-promote Lemtrada in the United States. (Reporting by Nathalie Huet, editing by Geert De Clercq and Jason Neely)