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August 30, 2004

MedImmune Discontinues Rheumatoid Arthritis and Psoriasis Trials for Vitaxin(R)

Oncology Programs for Development-Stage Monoclonal Antibody Continue

GAITHERSBURG, Md., Aug. 30 /PRNewswire-FirstCall/ -- MedImmune, Inc. (Nasdaq: MEDI) announced today that it has decided to terminate Phase 2 testing of Vitaxin(R) in patients with rheumatoid arthritis (RA) and psoriasis based on preliminary data suggesting lack of clinical benefit in these inflammatory diseases. There were no safety concerns identified in the preliminary analyses. MedImmune's oncology program for Vitaxin continues to advance with studies in melanoma and prostate cancer.

About Vitaxin

Vitaxin targets the alpha-v beta-3 integrin, which is a protein expressed on the surface of newly forming blood vessels, certain tumor types and on a number of other cell types, including macrophages and osteoclasts. Based on preclinical models, the alpha-v beta-3 integrin has been implicated in a number of disease processes, including the growth and metastasis of tumors, the bone destruction in RA and the inflammatory process in psoriasis.

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-                             08/30/2004
    /CONTACT:  Media: Jamie Lacey, +1-301-398-4035, or 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:  MTC HEA
SU:

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