Corixa Deciphers the Genome of the Major Organism Responsible for Acne, Clearing the Way for the Development of New Acne Treatments and Vaccines.

Business and Health Editors

SEATTLE--(BUSINESS WIRE)--April 5, 2001

Corixa Corporation (Nasdaq:CRXA), a developer of immunotherapeutics, today announced it has decoded the genome of the major microbial agent involved in the development of human acne, Propionibacterium acnes (P. acnes).

Acne is the most commonly diagnosed skin disorder in the United States.

In 2000, Corixa contracted with Paris-based Genset SA to sequence the P. acnes genome. Subsequently, Genset has determined the precise order of approximately 2.8 million base pairs of the P. acnes genome. Corixa plans to use this information in conjunction with its proprietary antigen discovery technology to accelerate development of potential new acne treatments and vaccines.

To date, Corixa scientists have mapped and characterized over 150 P. acnes proteins. The Company has determined that more than 30 of these proteins are recognized as antigens by the immune systems of volunteers with a history of severe acne. The identification of multiple candidate antigens is an important first step in the design of a vaccine for acne. In addition to its use in vaccine development, Corixa believes that the genomic information can be used to identify targets for new anti-microbial drugs that may be less toxic and more effective than current acne drugs. A presentation of the company's approaches in these areas of investigation is being made today at the World Vaccine Congress in Montreal, Quebec, by Dr. David Persing, M.D., Ph.D., vice president at Corixa.

"We are extremely pleased with the progress of this project, which represents only one of several programs within our extensive discovery pipeline," said Steven Gillis, Ph.D., chairman and chief executive officer at Corixa. "We believe that the combination of a proprietary genomic intellectual property position, Corixa's innovative antigen discovery approaches and proprietary adjuvant and delivery technologies provides us with a significant jump start toward the development of a potential vaccine for acne. We look forward to our continued progress on this program."

About Acne

Acne is an inflammatory disorder of the skin's oil glands (sebaceous glands) that results in plugged pores and outbreaks of lesions commonly referred to as pimples. Acne lesions usually occur on the face, neck, back, chest, and shoulders. Nearly 17 million people in the United States have acne, making it the most common skin disease in this country. Although acne is not a serious health threat, severe acne can lead to disfigurement and permanent scarring.

Acne lesions begin by the clogging of skin's pores, or follicles, with oil and dead skin cells. The mixture of oil and cells allows the bacterium P. acnes (which normally lives in skin pores) to grow to large numbers in the plugged follicles. In cases of acne, plugged follicles burst, spilling their contents into the surrounding tissue. Lesions or pimples develop because components of P. acnes that are present in the follicle contents, promote inflammation. Current methods of treatment for acne consist of antibiotics, topical peroxides and retinoic acid derivatives (retinoids) that are largely aimed at controlling P. acnes growth and preventing the plugging of skin pores. A vaccine for P. acnes, if proven effective at suppressing P. acnes growth or reducing its inflammatory effects, may be less toxic and provide more lasting benefit than current therapies. Such a vaccine could become an important part of the overall management strategy for acne.

More information on acne is available at the NIH website: http://www.nih.gov/niams/healthinfo/acne/acne.htm.

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(TM), a monoclonal antibody conjugated to a radioisotope.

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, Wash., with additional operations in Hamilton, Montana and Redwood City, California and South San Francisco, California. For more information, please visit Corixa's website at www.corixa.com or call the company's investor relations information line at 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 failure of the P. acnes technology to lead to a safe or effective vaccine and the "Factors Affecting Our Operating Results, Our Business and Our Stock Price," described in our Annual Report on Form 10-K for the year ended December 31, 2000, copies of which are available from our 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.