MedImmune Receives Complete Response Letter from FDA for FluMist, an Intranasal Flu Vaccine

GAITHERSBURG, Md. -- MedImmune, Inc. announced today that it has received a Complete Response Letter (CRL) from the U.S. Food and Drug Administration (FDA) for its Biologics License Application (BLA) for FluMist (Influenza Virus Vaccine Live, Intranasal), a nasally delivered flu vaccine. FDA is requesting clarification and additional information relating to data previously submitted. No additional clinical trials have been requested.

"We are pleasantly surprised to have received this Complete Response Letter from the FDA earlier than anticipated," said David M. Mott, MedImmune's chief executive officer. "We expect to fully respond to the five questions contained in the letter within a week and look forward to continuing to work with the FDA toward the approval of FluMist."

If approved by the FDA, FluMist would be the first and only intranasal influenza vaccine in the United States, and would be marketed by MedImmune and Wyeth Pharmaceuticals, a division of Wyeth as part of an ongoing global collaboration agreement.

On December 17, 2002, the FDA's Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted favorably on the questions of safety and efficacy for FluMist in preventing influenza in healthy children, adolescents and adults ages 5 through 49. Advisory committees provide the FDA with independent opinions and recommendations from outside experts on applications to market new drugs and on FDA policies. While advisory committee recommendations are valuable, all final decisions related to a regulated product are made by the FDA.

The original BLA for FluMist was submitted to the FDA in October 2000 by Aviron, a California-based vaccines company MedImmune acquired in January 2002. Subsequently, MedImmune has submitted answers to questions raised by the FDA in two previous CRLs issued by the FDA in August 2001 and July 2002, respectively.

FluMist is a live, attenuated vaccine delivered as a nasal mist being developed by MedImmune for the prevention of influenza. Clinical trials suggest that FluMist is effective in reducing the incidence of influenza in healthy children and adults. FluMist also offers certain potential advantages in its administration by nasal spray, such as eliminating the unpleasantness of needle-based injectable vaccines and local injection site reactions.

Influenza is the most common cause of medically attended acute respiratory illness in the U.S. often involving fever, chills, muscle weakness, cough, sore throat, nasal congestion, headache and general malaise. According to the Centers for Disease Control and Prevention and the American Lung Association, 20 to 50 million people are infected annually in the U.S., causing 70 million lost work days(1), 38 million lost school days(2), and 20,000 to 50,000 deaths per year (primarily in the elderly)(3). The annual burden of the disease to society has been estimated at $15 billion.

(1) Adams PF, Hendershot GE, Marano MA. Current estimates from the

National Health Interview Survey, 1996 National Center for Health

Statistics. Vital Health Sta. 10(200) 1999

(2) Adams PF, Hendershot GE, Marano MA. Current estimates from the

National Health Interview Survey, 1996 National Center for Health

Statistics. Vital Health Sta. 10(200) 1999

(3) CDC. ACIP/MMWR. 2002; 51 (no, RR-3):1-31

Source: MedImmune, Inc.