WASHINGTON, D.C., October 25, 2008 – MedImmune announced today it will present nine abstracts at the 48th Annual Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC)/46th Annual Meeting of Infectious Disease Society of America (IDSA). These abstracts advance the knowledge about respiratory syncytial virus (RSV) and influenza, providing valuable insight into infectious disease prevention and underscoring MedImmune's leadership in this disease category.

"MedImmune is committed to conducting innovative infectious disease research to determine how best to prevent serious illness that can negatively impact pediatric health, especially during this time of year," said Alexander A. Zukiwski, M.D., executive vice president and chief medical officer. "We believe the data being presented at this meeting will help lead to important new healthcare solutions, and our company is proud to advance our already robust research base to identify the best ways to help protect children."

MedImmune abstracts to be presented at ICAAC/IDSA on RSV include:

• Respiratory Syncytial Virus Therapy Utilizing Intranasally Delivered Motavizumab, a Monoclonal Antibody Against the Viral Fusion Protein (#V-4145) B. Richter, Tuesday, October 28, 2008, Hall C from 12:15 PM to 1:15 PM

  BACKGROUND: A primary cause of pneumonia and bronchiolitis in young children is RSV infection. This preclinical study examined the therapeutic effect of topically administered motavizumab.

• Therapeutic Addition of Motavizumab, a Monoclonal Antibody Against Respiratory Syncytial Virus, Modulates Epithelial Cell Responses to RSV Infection (#V-4146) S. Krishnan, Tuesday, October 28, 2008, Hall C from 12:15 PM to 1:15 PM

  BACKGROUND: RSV infection of epithelial cells leads to inflammatory host responses. This preclinical study tested whether motavizumab, a humanized monoclonal antibody against the RSV fusion (F) protein, could modulate epithelial cell immune responses to RSV. Lower and upper airway epithelial cells were infected with RSV and motavizumab or a control antibody was subsequently administered at various points post-infection to evaluate the therapeutic addition.

• Total Healthcare Costs of Preterm Infants with Medically Attended Respiratory Syncytial Virus Lower Respiratory Infection (#K-1429 ) D. Stewart, Sunday, October 26, 2008, Hall C from 12:15 PM to 1:15 PM

  BACKGROUND: While RSV lower respiratory infection (LRI) is the most common cause of hospitalization among infants under one year of age, the total healthcare costs of medically attended RSV LRI for babies of this age group is unknown. This retrospective, propensity-matched cohort assessment sought to determine first-year healthcare costs by examining premature infants born over a five-year period who were insured by a national U.S. health plan, including a subgroup analysis of babies born between 33 and 36 weeks gestation.

• In Vitro Mechanism of Action Studies of the RSV-Neutralizing Monoclonal Antibodies Palivizumab and Motavizumab (#V-4146) K. Huang, Tuesday, October 28, 2008, Hall C from 12:15 PM to 1:15 PM

  BACKGROUND: Synagis is the only licensed drug product available to help prevent lower respiratory tract RSV infection in premature infants, a leading cause of hospitalizations in this patient population. An affinity-optimized version of Synagis, motavizumab, has been subsequently developed. Since both Synagis and motavizumab bind the RSV fusion (F) protein, which plays a role in virus attachment and mediates the process of virus-cell fusion and cell-to-cell fusion, this study aimed to determine exactly how the drugs neutralize RSV. Four assays were used, which target four distinct steps during virus replication, to identify the mechanism.

• In Vitro and In Vivo Characterization of a Motavizumab-Resistant RSV A Mutant (#V-4148) F. J. Palmer-Hill, Tuesday, October 28, 2008, Hall C from 12:15 PM to 1:15 PM

  BACKGROUND: This study investigated the growth characteristics – both in vitro and in vivo – of an RSV mutant that was created in the laboratory and is resistant to neutralization by motavizumab, an affinity-optimized MAb directed against the RSV fusion (F) protein. The F protein of the MAb differs from a wild type RSV F protein, so comparisons were made.

• Characterization of Respiratory Syncytial Virus (RSV)Mutants Resistant to Antibody Neutralization with Novel Amino Acid Changes in the RSV Fusion Protein (#V-4149) N. K. Patel, Tuesday, October 28, 2008, Hall C from 12:15 PM to 1:15 PM

  BACKGROUND: Synagis is a MAb approved for the prevention of serious lower respiratory tract RSV infection in premature infants. Motavizumab was developed by affinity optimization of Synagis and is characterized by greater in vitro and in vivo neutralization activity against RSV. Previously, the selection of RSV mutants resistant to Synagis has been reported, characterized by amino acid changes in the RSV fusion (F) protein. This study sought to identify the selection and characterization of additional Synagis MAb-resistant mutants, as well as a novel motavizumab MAb-resistant mutant.

MedImmune abstracts to be presented at ICAAC/IDSA on influenza include:

• Influenza-like Illness and Employee Productivity – Results from the Child and Household Influenza-illness and Employee Function (CHIEF) (#K-4207) M. D. Rousculp, Tuesday, October 28, Room 150B from 2:450 PM to 3:00 PM

  BACKGROUND: This prospective cohort study of nearly 2,293 U.S. households evaluated the effect of employee and household member influenza-like illness on worker productivity. The households studied were employees from three large Fortune 500 companies. All households included in the study had at least one child. Households were surveyed monthly throughout the 2007-2008 influenza season to determine the impact of influenza-like illness on employees' work absenteeism and decreased productivity while on the job.

• Impact of Early and Late Influenza Vaccine Availability on In-Office Vaccination Opportunities (#G1-1208) R. Judelsohn, Sunday October 26, Hall C from 11:15 AM to 12:15 PM

  BACKGROUND: The CDC now recommends all children from six months to 18 years of age receive an annual influenza vaccination; however, a key barrier to implementation is the inconvenience to parents and providers around scheduling additional office visits to administer the vaccination. This study examined how many more vaccination opportunities exist if influenza vaccination availability were expanded beyond the typical October-to-December timeframe.

• Benefits Versus Risks of Live Attenuated Influenza Vaccine (LAIV) in Young Children (#G1-1204) G. Oster, Sunday October 26, Hall C from 11:15 AM to 12:15 PM

  BACKGROUND: In September 2007, approved use of LAIV in the U.S. was expanded to include children aged 24-59 months but with warning/precautions against use in younger children and children 24-59 months with a history of recurrent wheezing or asthma. Since some latter children may receive LAIV in clinical practice, its risks and benefits versus trivalent influenza vaccine (TIV) in this setting must be considered.