EPIX Pharmaceuticals Announces Findings from Obesity and Cognitive Impairment Studies at Society for Neuroscience Meeting.

Novel 5-HT6 Antagonist Currently in Phase 1 Clinical Development

LEXINGTON, Mass. -- EPIX Pharmaceuticals, Inc. (NASDAQ:EPIX) today announced that preclinical data from studies on obesity and cognitive impairment with PRX-07034, a novel, highly selective 5-HT6 receptor antagonist, are the focus of several poster presentations at the Society for Neuroscience (SFN) 36th annual meeting this week in Atlanta, Georgia. Data from these studies provide support for the ongoing Phase 1 clinical program of PRX-07034. This orally available drug candidate is currently being developed for the treatment for obesity and cognitive impairment.

EPIX presented data indicating that PRX-07034 improved cognitive functioning in several well-established preclinical models that may have relevance for cognitive deficits present in Alzheimer's disease and schizophrenia. PRX-07034 enhanced performance in a preclinical test of cognitive flexibility known as "set-shifting" as well as in a test of object recognition memory. In the object recognition test, low doses of PRX-07034, which had no significant efficacy alone, produced enhancement of memory when combined with a sub-efficacious dose of Aricept[R], an approved drug for Alzheimer's disease. PRX-07034 also completely reversed a scopolamine-induced deficit in memory, suggesting that PRX-07034 exerts a positive effect on the cholinergic system which is implicated in Alzheimer's disease.

Additional data presented at the SFN annual meeting support PRX-07034 as a potential treatment for obesity. In two preclinical models of obesity, PRX-07034 produced sustained weight loss along with reductions in plasma levels of glucose, insulin and leptin. The weight loss was specific to loss of fat content. Results suggest that PRX-07034 may provide a novel, effective and safe approach to the treatment of obesity.

"These preclinical results support our clinical development plan in both obesity and diseases related to cognitive impairment," said Michael Kauffman, M.D., Ph.D., chief executive officer of EPIX Pharmaceuticals. "Our Phase 1 trial of PRX-07034 in healthy volunteers to evaluate the safety, tolerability and pharmacokinetics of the drug candidate is ongoing, and we anticipate initiating a multiple dose Phase 1b study with this compound later this year."

Additional, supportive data for PRX-07034 in preclinical models of obesity is expected to be presented later this month in conjunction with the North American Association of the Study of Obesity (NAASO) conference in Boston, MA.

About PRX-07034

PRX-07034 is a novel, highly selective, small-molecule antagonist of a specific G-protein coupled receptor (GPCR) known as 5-HT6. PRX-07034 has shown cognitive-enhancing properties in preclinical animal models of memory impairment, as well as significant reductions of both food intake and body weight in several preclinical animal models of obesity. Indications are that the human 5-HT6 receptor is found mainly in the central nervous system with little or no expression in peripheral tissues, which may result in selectivity in drug targeting with fewer side effects.

On June 2, 2006, EPIX initiated a Phase 1 clinical trial for PRX-07034 to study the safety, tolerability and pharmacokinetics of single ascending doses of PRX-07034. EPIX expects to receive data from this trial in the fourth quarter of 2006.

About EPIX

EPIX Pharmaceuticals is a biopharmaceutical company focused on discovering, developing and commercializing novel pharmaceutical products through the use of proprietary technology to better diagnose, treat and manage patients. The company has a blood-pool imaging agent approved and marketed in Europe (Vasovist[TM]), and five internally-discovered therapeutic and imaging drug candidates currently in clinical trials targeting conditions such as depression, Alzheimer's disease, cardiovascular disease and obesity. These drug candidates include EP-2104R, a novel thrombus imaging agent which has completed a Phase 2a trial, PRX-08066 in Phase 2 clinical development for pulmonary hypertension associated with chronic obstructive pulmonary disease, and PRX-03140, which has completed a Phase 1b clinical trial in Alzheimer's patients. EPIX also has collaborations with leading organizations, including Amgen, Cystic Fibrosis Foundation Therapeutics, and Schering AG (Germany). For more information about EPIX, please visit the company's website at www.epixpharma.com.

This news release contains express or implied forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, that are based on current expectations of management. These statements relate to, among other things, our expectations regarding the progress and results of our clinical development program for PRX-07034 and other drug candidates. These statements are neither promises nor guarantees, but are subject to a variety of risks and uncertainties, many of which are beyond our control, and which could cause actual results to differ materially from those contemplated in these forward-looking statements. In particular, the risks and uncertainties include, among other things: risks that product candidates, including PRX-07034, may fail in the clinic or may not be successfully marketed or manufactured; risks relating to the our ability to advance the development of product candidates currently in the pipeline or in clinical trials, any failure to comply with regulations relating to our products and product candidates, including FDA requirements; failure to obtain the financial resources to complete development of product candidates; the risk that the FDA may interpret the results of our studies differently than we have; competing products may be more successful; our inability to interest potential partners in our technologies and products; our inability to achieve commercial success for our products and technologies; the possibility of delays in the research and development necessary to select drug development candidates; the risk that we may be unable to successfully secure regulatory approval of and market our drug candidates; and risks of new, changing and competitive technologies and regulations in the U.S. and internationally. Existing and prospective investors are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. We undertake no obligation to update or revise the information contained in this press release, whether as a result of new information, future events or circumstances or otherwise. For additional information regarding these and other risks that we face, see the disclosure contained in our filings with the Securities and Exchange Commission.

ARICEPT([R]) (donepezil HCl tablets) is a registered trademark of Eisai Co., Ltd.

Copyright [c] 2006 Eisai Inc. and Pfizer Inc.