MedImmune, Inc. Completes Enrollment In Phase 3 Study Comparing Numax(TM) To Synagis(R)

GAITHERSBURG, Md., Dec. 15 /PRNewswire-FirstCall/ -- MedImmune, Inc. today announced that it has completed enrolling approximately 6,600 high-risk infants in a pivotal Phase 3 study comparing the safety and efficacy of Numax to Synagis (palivizumab). MedImmune also announced that it has completed enrollment of more than 620 patients in a separate, late-stage clinical study with Numax in children with hemodynamically significant congenital heart disease (CHD). MedImmune is developing Numax as a potential improvement to Synagis, which was introduced to the market in 1998 and has become the standard of care for the prevention of serious respiratory syncytial virus (RSV) disease in these infants.

"MedImmune's commitment to develop medicines to fight pediatric infectious diseases is evident in its ongoing anti-RSV clinical programs," said Genevieve Losonsky, M.D., vice president, clinical development, infectious disease. "To date, Synagis has been used to protect more than 700,000 infants in the United States from RSV. If the Phase 3 program is successful and Numax is approved, we may be able to provide enhanced RSV prophylaxis for infants at risk for serious RSV disease."

The 2005 impact of incremental recruiting and enrollment costs for both trials is anticipated to be approximately $10 million, which was not included in MedImmune's previously stated financial guidance for 2005, as issued on October 20, 2005.

Numax versus Synagis Phase 3 Study

The pivotal Phase 3 study is designed to compare the safety and efficacy of Numax with that of Synagis for reduction of RSV hospitalization in high- risk infants. Secondary endpoints include medically attended lower respiratory tract infections and otitis media (ear infections). The trial is a randomized, double-blind study involving approximately 6,600 high-risk infants at 300 centers in 24 countries within the Northern and Southern Hemispheres. Study participants consist of premature infants born at 35 weeks gestational age or less who were six months of age or younger at randomization, as well as children with chronic lung disease related to prematurity (CLD), who were 24 months of age or less at randomization. Each child receives an intramuscular injection of 15 mg/kg of Numax or Synagis each month during the RSV season for a total of five injections. The participants will be monitored throughout the trial for safety, medically attended outpatient visits for lower-respiratory- tract infections and otitis media, and hospitalizations.

Numax CHD Study

This randomized, double-blind, palivizumab-controlled study will evaluate the safety, tolerability, immunogenicity and pharmacokinetics of Numax in children with CHD. It is being conducted at approximately 160 sites in the Northern Hemisphere during the 2005-2006 RSV season. Study participants include infants with hemodynamically significant CHD who were 24 months of age or younger at randomization. Approximately 620 patients will receive an intramuscular injection of either 15 mg/kg of Numax or Synagis each month for five months. Children will be followed throughout the study for safety. Blood samples will be collected for assessment of immunogenicity and pharmacokinetics. Hospitalizations due to RSV will be assessed as a secondary endpoint.

About RSV

RSV is the most common respiratory infection in infancy or childhood. Approximately one-half of all infants are infected with RSV during the first year of life, and nearly all children have been infected at least once by the time they reach their second birthday. Children born prematurely as well as those with chronic lung disease or congenital heart disease are at highest risk for severe disease and hospitalization due to RSV. The virus may also cause severe illness in other high-risk groups such as the elderly, those with underlying respiratory or cardiac disease, and those with compromised immune systems (e.g., bone marrow transplant patients).

In addition to its Numax clinical program, MedImmune is also studying a vaccine that could potentially prevent both RSV and parainfluenzavirus type 3 (PIV-3). PIV-3 is another commonly occurring respiratory virus of childhood, causing bronchitis, bronchiolitis, croup, cough, fever and pneumonia.

About Numax

Numax is an investigational humanized monoclonal antibody (MAb) being evaluated for its potential to prevent serious lower respiratory tract disease caused by RSV in pediatric patients at high risk of RSV disease. Phase 1 and Phase 2 studies have recently been reported showing that Numax appears to have a similar safety and pharmacokinetic profile to Synagis in infants. Additionally, in early phase studies children treated with Numax had reduced RSV replication in the upper respiratory tract. In light of this latter finding, MedImmune is studying the potential for preventing upper respiratory tract infections such as otitis media with Numax in its pivotal Phase 3 trial. In addition to the two trials mentioned previously in this release, MedImmune is also conducting a Phase 3 study to assess whether Numax can reduce the incidence of RSV hospitalization in full-term Native American infants. This trial will also evaluate the effect of Numax on wheezing in these children.

About Synagis

Synagis is indicated for the prevention of serious lower respiratory tract disease caused by RSV in pediatric patients at high-risk of RSV disease, which is prominent in the Northern Hemisphere during the winter months. Synagis is a humanized MAb given by an intramuscular injection once a month during the RSV season. Synagis was approved in 1998 by the U.S. Food and Drug Administration (FDA); in 1999, by the European Medicines Evaluation Agency; and in 2002, by the Japanese Ministry of Health, Labor and Welfare. In 2003, the FDA expanded the U.S. label for Synagis for use in young children with hemodynamically significant congenital heart disease at risk of RSV disease. To date, Synagis has been approved in 62 countries, including the United States. Synagis has been used in more than half a million babies since 1998. Adverse events with Synagis may include upper respiratory tract infection, ear infection, fever, runny nose, rash, diarrhea, cough, vomiting, gastrointestinal upset and wheezing. Very rare cases of severe allergic reactions such as anaphylaxis (less than 1 case per 100,000 patients) have been reported following re- exposure to Synagis. Rare severe, acute hypersensitivity reactions have also been reported on initial exposure or re-exposure to Synagis. Synagis should not be used in patients with a history of a severe prior reaction to Synagis or its components. For full prescribing information for Synagis, see the company's website at

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 pediatric infectious diseases, cancer and inflammatory diseases. With more than 2,000 employees worldwide, MedImmune is headquartered in Maryland. For more information, visit the company's website at

This announcement may contain, in addition to historical information, certain forward-looking statements that involve risks and uncertainties. Such statements reflect management's current views and are based on certain assumptions. Actual results could differ materially from those currently anticipated as a result of a number of factors, including risks and uncertainties discussed in MedImmune's filings with the U.S. Securities and Exchange Commission. The company is developing several products for potential future marketing. There can be no assurance that such development efforts will succeed, that such products will receive required regulatory clearance or that, even if such regulatory clearance were received, such products would ultimately achieve commercial success.

MedImmune, Inc.

CONTACT: Media: Clarencia Stephen, +1-301-398-4073, Jamie Lacey,+1-301-398-4035, or Investors: Peter Vozzo, +1-301-398-4358, John Filler,+1-301-398-4086, all of MedImmune, Inc.

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