INFO:Epimmune Reports Promising Results on PADRE(TM) Universal Vaccine Immune Stimulant

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Epimmune Reports Promising Results on PADRE Universal Vaccine Immune

Stimulant

January 26, 2000

SAN DIEGO, Jan. 25 /PRNewswire/ via NewsEdge Corporation -

Epimmune Inc. (Nasdaq: EPMN) today announced the publication of data in The

Journal of Immunology showing that constructs composed of PADRE,

together with carbohydrate antigens, are potent immunogens that elicit

strong antibody responses specific to the target antigen. The Company

believes these data provide further support that PADRE could prove important

in improving vaccines against a number of infectious diseases and cancers.

Carbohydrate antigens are important vaccine targets for a number of

infectious diseases including bacteria that cause pneumonia and meningitis

as well as many cancers including breast, colon, lung, prostate, and

melanoma. The primary objective of carbohydrate-based vaccines is to

stimulate the large quantities of IgG antibodies that are most effective in

the treatment or prevention of disease. The results of the Epimmune study

demonstrate that combining PADRE with carbohydrate antigens results in the

stimulation of large quantities of IgG antibodies that specifically

recognize the target carbohydrate.

" Antibodies are important components of the immune system that recognize and

bind to antigens, thus tagging them for destruction by the immune system, "

said Chesnut, Ph.D., Executive Vice President of Research and

Development at Epimmune. " While it has been known that combining certain

proteins with carbohydrate antigens can drive the immune response to produce

IgG antibodies, the unique features of PADRE provide the potential to

simplify the structure of carbohydrate vaccines, while enhancing efficacy

and safety. "

The PADRE technology consists of a family of small (13 amino acid),

synthetic proprietary molecules that are potent immunostimulants. When

combined with disease-specific antigens, PADRE induces important

" co-stimulatory " signals that potentiate the antigen-specific immune

response, driving it to produce long-lived, high affinity IgG antibodies.

The Company believes that the small size of PADRE compared to proteins

traditionally used to make vaccines targeting carbohydrate antigens offers

several advantages: (1) PADRE can be easily synthesized and readily

characterized when linked to the antigen, whereas traditionally used

proteins complicate manufacturing; (2) the antibody responses generated are

primarily antibodies specific to the disease-specific antigen (not

antibodies to PADRE), whereas traditionally used proteins generate high

anti-protein responses, which can render the vaccine ineffective and (3);

PADRE could aid in the development of " combination vaccines " where it can be

difficult to combine effectively a number of different, much larger

protein-antigen conjugates. In addition, since PADRE is not derived from an

infectious organism, it has the potential to cause fewer side effects. PADRE

has been used in several investigator initiated human clinical studies and

has been shown to be safe and well tolerated.

The published study examined two PADRE-carbohydrate constructs for their

ability to induce antibody responses directed against the carbohydrate

antigens. Each construct was composed of a single PADRE molecule attached to

a single carbohydrate molecule, resulting in a simple vaccine configuration.

This type of conjugate vaccine differs from the more complex carbohydrate

vaccines currently produced, which typically are composed of multiple

carbohydrate molecules attached to a single large protein carrier molecule.

The results showed that test mice immunized with the PADRE-carbohydrate

vaccine constructs produced high-titer, high-affinity IgG antibody

responses, which were comparable to the responses induced by carbohydrate

vaccine constructs that used a large, complex protein. The results also

showed that PADRE constructs induce responses in which a much higher

proportion of the antibody (up to 1500 fold) is specific for the

carbohydrate antigen compared to the conjugate containing the complex

protein, where much of the antibody response is specific for the protein and

not for the carbohydrate antigen.

The study entitled " Linear PADRE T Helper Epitope and Carbohydrate B Cell

Epitope Conjugates Induce Specific High Titer IgG Antibody Responses "

appears in the February 2000 issue of The Journal of Immunology (Vol. 164,

pp. 1625-1633).

" Since obtaining these published results, we have extended PADRE research to

evaluate additional bacterial antigens as well as cancer-specific

carbohydrate antigens, " said Deborah Schueren, President and CEO of

Epimmune. " Preliminary results from these further studies continue to

suggest that PADRE could prove important for developing vaccines for a

number of infectious diseases and cancers. We are currently evaluating

several vaccine candidates internally and under collaboration with

pharmaceutical companies for possible addition to our development pipeline

this year. "

Epimmune is developing novel vaccines for infectious diseases and cancer,

building on its expertise and intellectual property in the field of T-cell

recognition and activation. In the cancer field, Epimmune is collaborating

with G.D. Searle & Co., a wholly-owned subsidiary of Monsanto Co., to

develop immune stimulating products for the treatment of breast, colon, lung

and prostate cancers. Epimmune is also pursuing development of therapeutic

vaccines for hepatitis C, hepatitis B and HIV, and prophylactic vaccines for

hepatitis C, HIV and malaria. For more information on Epimmune, access

www.epimmune.com.

This press release includes forward-looking statements that reflect

management's current views of future events. Actual results may differ

materially from the above forward-looking statements due to a number of

important factors, including but not limited to the risks associated with

the Company's patent rights (including the scope of any patents that issue

and the Company's ability to enforce its patents and other proprietary

rights), the Company's ability to develop vaccines using epitopes,

achievement of research and development objectives by the Company and any

collaborator, the timing and cost of conducting human clinical trials, the

regulatory approval process, and the possibility that testing may reveal

undesirable and unintended side effects or other characteristics that may

prevent or limit the commercial use of proposed products. These factors are

more fully discussed in Cytel Corporation's Form 10-K for 1998 and other

periodic reports filed with the Securities and Exchange Commission.

SOURCE Epimmune Inc.

CONTACT: Deborah Schueren, President and CEO of Epimmune Inc., 858-860-2513;

or Media: Atkins of IR PR Strategies, LLC, 858-860-0266

Web site: http://www.epimmune.com (EPMN)

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