Shares of Cambridge, MA-based Momenta Pharmaceuticals (NASDAQ: [[ticker:MNTA]]) are down more more than 50 percent from yesterday’s close of $13.38 on the news that the company’s lead drug candidate—a generic version of the Sanofi-Aventis blood-thinner Lovenox—has been deemed “not approvable” by the FDA. Momenta is developing the drug in partnership with the Sandoz division of Novartis in an attempt to capture a piece of Lovenox’s $1.9 billion U.S. market. In a press release, Momenta’s CEO said the company believes it has the data necessary to address the FDA’s concerns, which centered on the drug’s effect on the immune system.
