Corixa Technology May Be Useful for Testing U.S. Blood Supply for Presence of Deadly Parasite.

Business Editors, Health/Medical Writers

BIOWIRE2K

SEATTLE--(BUSINESS WIRE)--Sept. 12, 2002

Corixa Corp. (Nasdaq:CRXA), a developer of immunotherapeutics, today announced that it presented evidence to the U.S. Food and Drug Administration (FDA) showing that one of its proprietary recombinant antigens may be useful for screening the nation's blood supply for the potential presence of a deadly parasite known as Trypanosoma cruzi (T. cruzi).

The FDA has recognized the potential for introduction of T. cruzi into the U.S. blood supply, and is interested in the development and evaluation of tests that can be used to prevent transmission by transfusion of blood or blood products.

T. cruzi causes Chagas' disease, a chronic infection that primarily affects the nervous system and heart, causing severe neurological disorders, as well as swelling or denervation of nervous tissue in the heart, colon and esophagus. The organism can circulate in the blood for many years after infection, and can lead to transfusion-acquired infection if blood from an infected donor is transfused into a recipient.

David Persing, M.D., Ph.D., vice president of Molecular Biology and director of Diagnostics Development at Corixa, discussed the diagnostic test performance of Corixa's unique polyvalent antigen, known as TcF, during a public forum session of the Blood Products Advisory Council meeting organized by the FDA on Sept. 12, 2002, in Rockville, Md. The test measures serum antibody against the antigen. Serum antibody would not exist in the blood of individuals not previously exposed to T. cruzi.

"In studies to date, the TcF recombinant antigen has been able to detect nearly all patients infected with T. cruzi, and avoids many of the problems of false positivity and unreliability associated with older assays that used whole organisms for antibody detection," said Dr. Persing. "Testing for this antibody could be an important step toward protecting our nation's blood supply from this dangerous contaminant."

Chagas' disease often goes undiagnosed because its symptoms are also associated with heart disease and a variety of other disorders. In about one-third of acute cases, a chronic form of the disease develops some 10-20 years later, causing irreversible damage to the heart, esophagus and colon. Patients with severe Chagas' disease become progressively more ill and ultimately die, usually from heart failure. According to the World Health Organization, Chagas' disease is endemic in 21 countries, with 16 million-18 million people infected and 100 million more at risk. Contaminated blood transfusions are suspected to be the primary way in which the parasite has been transmitted to industrialized countries.

Antigen Discovery at Corixa

Corixa scientists correlate antigens they have discovered with patient immune responses, identifying proteins that are recognized by the human immune system and are therefore antigenic. Antigen discovery research culminates in the isolation of pathogen, tumor or auto-antigen genes that encode proteins with significant potential to become the targets of diagnostics, vaccines or other immunotherapeutic products. These antigens may be in the form of either recombinant proteins or biosynthetically produced peptides.

About Corixa

Corixa is a developer of immunotherapeutics with a commitment to treating and preventing autoimmune diseases, cancer and infectious diseases by understanding and directing the immune system. Corixa is focused on immunotherapeutic products and has a broad technology platform enabling both fully integrated vaccine design and the use of its separate, proprietary product components on a standalone basis. Corixa currently has 18 programs in clinical development.

The company partners with numerous developers and marketers of pharmaceuticals, targeting products that are Powered by Corixa(TM) technology with the goal of making its potential products available to patients around the world. Corixa was founded in 1994 and is headquartered in Seattle, with additional operations in Hamilton, Mont., and South San Francisco. For more information, please visit Corixa's Web site at http://www.corixa.com/ or call the company's investor relations information line at (877) 4CORIXA (426-7492) or 877/426-7492.

Corixa Forward-Looking Statements

Except for the historical information presented, certain matters discussed in this press release are forward-looking statements. Forward-looking statements are based on the opinions and estimates of management at the time the statements are made. They are subject to certain risks and uncertainties that could cause actual results to differ materially from any future results, performance or achievements expressed or implied by such statements. Factors that could affect Corixa's actual results include, but are not limited to the risk that Corixa's proprietary technology is not used to screen the U.S blood supply for the presence of serum antibodies against T. cruzi and the "Important Factors That May Affect Our Business, Our Results of Operations and Our Stock Price," described in Corixa's Quarterly Report on Form 10-Q for the quarter ended June 30, 2002, copies of which are available from Corixa's investor relations department. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this release.