A safety warning by the FDA that Lemtrada may cause cancer has boosted rival MS treatment Tysabri

"In our opinion, this will have a greater impact on Perrigo than Teva Pharmaceutical Industries Ltd.," says Clal Finance analyst Jonathan Kreizman. "The characteristics of Lemtrada are similar to those of Tysabri, because both drugs target more severe cases than Copaxone. Lemtrada and Tysabri are more effective than Copaxone, but have lower safety profiles."

Kreizman believes that Lemtrada's chances of FDA approval have been weakened. "This is very good news for Perrigo, because it leaves Tysabri with few rivals in its segment. This reduces the risk profile of the Elan acquisition by Perrigo."

In late July, Perrigo announced the acquisition of Elan for $8.6 billion. Elan's main asset is income from Tysabri, which sold its rights to the drug to Biogen Idec Inc. (Nasdaq: BIIB) in exchange for 12% royalties on sales. Tysabri had $1.6 billion in sales in 2012.
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