Corixa Receives Multiple U.S. Patents in Oncology Programs.

Business Editors, Health/Medical Writers

SEATTLE--(BW HealthWire)--Aug. 9, 2001

Corixa Corporation (Nasdaq:CRXA), a developer of immunotherapeutics, today announced that the U.S. Patent and Trademark Office (USPTO) has issued the Company three patents, including a method potentially useful in establishing the optimal radiation dose given to a patient based on the patient's specific traits -- a method used in administering Bexxar(TM)(tositumomab, iodine I 131 tositumomab).

Corixa is seeking marketing approval of Bexxar for the treatment of relapsed or refractory, low-grade or transformed low-grade B-cell non-Hodgkin's lymphoma.

The first patent awarded to Corixa -- U.S. Patent 6,251,362 -- relates to the administration of radiopharmaceutical compounds for the therapy of cancer and other diseases. Radiopharmaceuticals are compounds composed of radioactive isotopes often bound to other molecules. When radioactive labels are attached to monoclonal antibodies that are specific for a particular diseased tissue, the antibodies can selectively direct radiation to the specific disease site. However, if a patient is given too much of a given radioactive isotope-antibody conjugate, normal tissue can be adversely affected, creating unwarranted and dangerous toxicities. U.S. patent 6,251,362 covers the administration and dosing of radiopharmaceuticals to minimize toxicity while keeping the dosage high enough to successfully treat the disease. The patent covers a variety of methods of determining radioisotope levels in patients after therapeutic administration, including, but not limited to, imaging.

Additional patents issued today include U.S. Patents 6,262,245 and 6,261,562 covering DNA sequences and methods of use for multiple prostate antigens potentially useful as vaccine or antibody targets.

"The granting of these patents provides us with strong protection of our technology and intellectual property in the United States," said Steven Gillis, Ph.D., chairman and chief executive officer at Corixa. "Specifically, the radiopharmaceutical compound patent further protects Corixa's approach of accurate and optimized dosing when administering a radioimmunotherapy like Bexxar. We are pleased that the U.S. Patent Office has granted us protection for these additional methods in the dosing process. We are pleased with these successes as we continue to pursue comprehensive protection of Corixa's intellectual property."

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 16 programs in clinical development and 22 programs in preclinical development, including its most advanced product candidate, Bexxar for the treatment of non-Hodgkin's lymphoma.

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, Washington, with additional operations in Hamilton, Montana and South San Francisco, California. For more information, please visit Corixa's Web site at www.corixa.com or call the company's investor relations information line at 1.877.4CORIXA or 877/426-7492.

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 "Factors Affecting Our Operating Results, Our Business and Our Stock Price," described in Corixa's Quarterly Report on Form 10-Q for the quarter ended March 31, 2001, 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.