News Pressroom

August 18, 2004

MedImmune Begins Phase 1 Clinical Trial for Its Anti-Interleukin-9 Monoclonal Antibody

Novel Treatment May Provide Therapeutic Option for Asthma Sufferers

GAITHERSBURG, Md., Aug. 18 /PRNewswire-FirstCall/ -- MedImmune, Inc. (Nasdaq: MEDI) announced today that it has begun dosing patients in a Phase 1 clinical trial with an anti-interleukin-9 (IL-9) monoclonal antibody (MAb). Data from preclinical studies in models of asthma suggest that IL-9 neutralizing MAbs may help reduce airway hyper-reactivity, mucous production and inflammation. The company is evaluating this molecule as a potential new treatment for symptomatic, moderate-to-severe persistent asthma.

"With the initiation of this trial, MedImmune adds asthma to its portfolio of targets for treating and preventing respiratory diseases in adults and children," said Dr. Edward M. Connor, MedImmune's senior vice president, clinical development and chief medical officer. "We are working toward reducing the impact of respiratory illnesses with antibody therapies, such as our flagship product Synagis(R) (pavilizumab) -- which is approved for prevention of serious respiratory syncytial virus (RSV) disease in high-risk infants -- and with vaccines like FluMist(R) (Influenza Virus Vaccine Live, Intranasal)."

MedImmune's Phase 1 anti-IL-9 antibody trial is an open-label dose- escalation study in 24 healthy adult volunteers designed to evaluate safety and tolerability and to gather pharmacokinetics and immunogenicity data. Volunteers will receive 0.3 milligrams per kilogram (mg/kg), 1.0 mg/kg, 3.0 mg/kg or 9.0 mg/kg of the antibody.

Interleukins are hormone-like proteins produced by immune cells that regulate the intensity and duration of immune and allergic responses. One of at least 29 naturally occurring interleukins in the human body, IL-9 has a wide spectrum of biologic activities associated with the symptoms of asthma including airway hyper-reactivity, mucous production, lung infiltration of inflammatory cells and IgE (an immune globulin associated with allergic disease) production.

According to the U.S. Centers for Disease Control and Prevention (CDC), more than 20 million Americans reported having asthma in 2001, including more than six million children. In 2000, the CDC reported that there were more than 10 million asthma-related outpatient visits to private physician offices and hospital clinics (nearly 5 million of these involved children under 18). The National Institutes of Health (NIH) have estimated asthma-related healthcare costs in the U.S. at $14 billion annually.

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 approximately 1,800 employees worldwide, MedImmune is headquartered in Maryland. For more information, visit the company's website at http://www.medimmune.com.

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 is received, such products will ultimately achieve commercial success.

SOURCE  MedImmune, Inc.
    -0-                             08/18/2004
    /CONTACT:  Media: Jamie Lacey, +1-301-398-4035; Investors: Peter Vozzo,
+1-301-398-4358, or John Filler, +1-301-398-4086, all of MedImmune, Inc./
    /Web site:  http://www.medimmune.com/
    (MEDI)

CO:  MedImmune, Inc.
ST:  Maryland
IN:  BIO HEA MTC
SU:  SVY

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