MedImmune, Inc. Replies To FDA's Complete Response Letter For New Formulation Of FluMist(R)

GAITHERSBURG, Md., Aug. 14 /PRNewswire-FirstCall/ -- MedImmune, Inc. (Nasdaq: MEDI - News) announced today that it has submitted its response to the Complete Response Letter (CRL) received from the U.S. Food and Drug Administration (FDA) for CAIV-T (cold adapted influenza vaccine, trivalent). The FDA had requested clarification and additional information on the data previously submitted by MedImmune in its supplemental biologics license application (sBLA). In this sBLA, MedImmune is seeking approval to switch formulations from frozen FluMist (Influenza Virus Vaccine Live, Intranasal), currently approved in healthy individuals 5 to 49 years of age, to the refrigerator-stable CAIV-T formulation, for the same population.

"We believe that our responses adequately address the FDA's questions as contained in the letter," commented Linda J. Peters, senior vice president, regulatory affairs. "Pending FDA review and approval, we remain on track with our plans to launch thimerosal-free, refrigerator-stable CAIV-T in time for the 2007-2008 influenza season."

MedImmune submitted a separate sBLA to the FDA on July 28, 2006 for the use of CAIV-T in children 12 months to 59 months of age who do not have a history of wheezing or asthma. This supplement included data from MedImmune's pivotal Phase 3 trial involving approximately 8,500 children between 6 months and 59 months of age. In this trial, efficacy of the vaccine was observed across all age groups of children in the study. Children vaccinated with CAIV-T had 55-percent fewer overall confirmed cases of influenza compared to recipients of the injectable vaccine. The study also showed that CAIV-T vaccination resulted in 89-percent fewer cases of matched H1N1 strains and 79- percent fewer cases of circulating mismatched H3N2 strains as compared to the flu shot.

FluMist Available Now for 2006-2007 Influenza Season

This year, MedImmune was the first influenza vaccine manufacturer to have product available in the U.S. for the 2006-2007 influenza season. The company began shipping FluMist in late July to help enable healthcare providers to immunize healthy individuals 5 to 49 years of age as soon as they receive doses of the vaccine. This affords these providers the opportunity to leverage the busy back-to-school season to accomplish immunization before influenza season begins, which should ease the burden in physicians' offices associated with fall and late-season immunization. The CDC's July 28 Morbidity and Mortality Weekly Report stated: "Administration of live, attenuated influenza vaccine is encouraged as soon as it is available and throughout the season."(1)

About FluMist

FluMist is indicated for active immunization for the prevention of disease caused by influenza A and B viruses in healthy children and adolescents, 5 to 17 years of age, and healthy adults, 18 to 49 years of age. There are risks associated with all vaccines, including FluMist. Like any vaccine, FluMist does not protect 100 percent of individuals vaccinated. In studies of people between the ages of 5 and 49 years, runny nose was the most commonly reported side effect. Other common side effects included various cold-like symptoms, such as headache, cough, sore throat, tiredness/weakness, irritability, and muscle aches.

FluMist should not be used, under any circumstances, in anyone with an allergy to any part of the vaccine, including eggs; in children and adolescents receiving aspirin therapy; in people who have a history of Guillain-Barre syndrome; and in people with known or suspected immune system problems. Pregnant women and people with certain medical conditions, asthma, or reactive airways disease should not get FluMist.

Please see the Prescribing Information at http://www.flumist.com/pdf/prescribinginfo.pdf, visit http://www.flumist.com, or call 1-877-633-4411 for additional information.

About CAIV-T

CAIV-T is an investigational intranasal, cold-adapted trivalent influenza vaccine. It is the refrigerator-stable formulation of FluMist, which is a frozen, live attenuated cold-adapted trivalent influenza vaccine. To date, the safety, tolerability and efficacy of CAIV-T has been studied in both healthy and at-risk populations between the ages of 6 weeks and 98 years.

On May 1, 2006 at the Pediatric Academic Societies' annual meeting, MedImmune presented its pivotal Phase 3 study for CAIV-T, entitled, "Comparison of the Efficacy and Safety of Cold-Adapted Influenza Vaccine, Trivalent With Trivalent Inactivated Influenza Vaccine in Young Children 6 to 59 Months of Age." The study included 8,475 children at 249 sites in 16 countries in North America, Europe, the Middle East and Asia. Study participants were randomized one-to-one to receive either CAIV-T or the flu shot during the 2004-2005 influenza season. Each participant also received a placebo nasal spray or placebo injection to preserve the double-blind design of the study. Participants were followed through the influenza season and evaluated to identify illnesses caused by influenza virus. The trial included more than 6,300 previously unvaccinated children and nearly 50 percent of the children enrolled were less than 2 years of age.

The results of this trial showed that CAIV-T was 55 percent more effective than the trivalent injectable inactivated influenza vaccine (TIV) in reducing influenza illness caused by any influenza strain in children 6 months to 59 months of age, including both matched and mismatched strains. The influenza attack rate was 8.6 percent for study participants receiving the flu shot compared to 3.9 percent for those who received CAIV-T (P<0.001). Against matched strains alone, CAIV-T was 45 percent more effective than the flu shot (attack rates: TIV = 2.4 percent, CAIV-T = 1.4 percent; P<0.001). In this study, CAIV-T also appeared to be 89 percent more effective than the flu shot in reducing influenza illness caused by the matched H1N1 A strain (attack rates: TIV = 0.7 percent, CAIV-T = 0.1 percent; P<0.001) and 79 percent more effective than the flu shot against the circulating mismatched H3N2 A strain (attack rates: TIV = 4.5 percent, CAIV-T = 0.9 percent; P<0.001). There were no cultures of mismatched H1N1 strains or matched H3N2 strains detected in the trial. While there were 16-percent fewer children with illnesses associated with B strains in the CAIV-T group compared to TIV (attack rates: TIV= 3.5 percent, CAIV-T = 2.9 percent), this difference was not statistically significant.

In the study, the overall incidence of adverse events and serious adverse events was similar in both groups except for a higher incidence of runny nose and nasal congestion in CAIV-T recipients (4.4 - 11.1 percent increase) and a higher incidence of injection site reactions in those receiving the flu shot (3.6 - 7.6 percent increase). A statistically significant increase in the incidence of medically significant wheezing was seen in CAIV-T recipients 6 months to 23 months of age within 42 days following vaccination. Post-hoc analyses showed higher all-cause hospitalizations occurring through 180 days after vaccination in CAIV-T recipients 6 months to 11 months of age. Risk- benefit analyses showed a favorable profile for CAIV-T as compared to TIV in children 12 months to 59 months of age without a prior history of wheezing or asthma.

About MedImmune, Inc.

MedImmune strives to provide better medicines to patients, new medical options for physicians, rewarding careers to employees, and increased value to shareholders. Dedicated to advancing science and medicine to help people live better lives, the company is focused on the areas of infectious diseases, cancer and inflammatory diseases. With more than 2,300 employees worldwide, MedImmune is headquartered in Maryland. For more information, visit the company's website at http://www.medimmune.com.

This announcement contains, in addition to historical information, certain "forward-looking statements" regarding the regulatory approval process and development plans for CAIV-T. Such forward-looking statements are based on current expectations and involve inherent risks and uncertainties, including factors that could delay, divert or change current expectations and could cause actual outcomes and results to differ materially from current expectations. In addition to risks and uncertainties discussed in MedImmune's filings with the U.S. Securities and Exchange Commission, no assurance exists that development efforts for CAIV-T will succeed, that CAIV-T will receive required regulatory approval or that, even if regulatory approval is received, CAIV-T will be commercially successful. MedImmune undertakes no obligation to update any forward-looking statement, whether as a result of new information, future events or otherwise except as may be required by applicable law or regulation.

(1) Smith, NM. Prevention and Control of Influenza: Recommendations of the

Advisory Committee on Immunization Practices (ACIP). Morbidity and

Mortality Weekly Report. 2006/July 28; 55: RR-10.

Source: MedImmune, Inc.

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