Biogen Idec (NASDAQ: BIIB) announced that the U.S. Food and Drug Administration (FDA) has extended the initial Prescription Drug User Fee Act (PDUFA) date for its review of the Biologics License Application (BLA) for marketing approval of PLEGRIDY™, a subcutaneous pegylated interferon candidate for relapsing forms of multiple sclerosis (RMS). The PDUFA date has been extended by three months, which is the standard extension period. The FDA has indicated that the extension of the PDUFA date is required to allow additional time for review of the application. The agency has not asked for additional studies. About PLEGRIDY PLEGRIDY is a new molecular entity in which interferon beta-1a is pegylated to extend its half-life and prolong its exposure in the body. PLEGRIDY is a member of the interferon class of treatments, which is often used as a first-line treatment for MS. Regulatory authorities in the United States and the European Union accepted the marketing applications for the review of PLEGRIDY in RMS in 2013. www.biogenidec.com. About Biogen Idec Through cutting-edge science and medicine, Biogen Idec discovers, develops and delivers to patients worldwide innovative therapies for the treatment of neurodegenerative diseases, hemophilia and autoimmune disorders. Founded in 1978, Biogen Idec is the world’s oldest independent biotechnology company. Patients worldwide benefit from its leading multiple sclerosis therapies. For product labeling, press releases and additional information about the Company, please visit www.biogenidec.com.