Preclinical Data on Predix Pharmaceuticals' 5-HT6 Antagonist for Obesity and Cognitive Impairment to Be Presented at Serotonin Club Meeting in Japan; PRX-07034 Recently Entered a Phase I Clinical Trial.

LEXINGTON, Mass. -- Predix Pharmaceuticals, which recently announced a definitive agreement to merge with EPIX Pharmaceuticals (NASDAQ:EPIX), announced today that preclinical data from studies in obesity and cognitive impairment with PRX-07034, a highly selective, proprietary 5-HT6 receptor antagonist, will be presented at the Serotonin Club Meeting 2006. Predix recently entered PRX-07034 into Phase I clinical development as a small-molecule drug candidate with the potential to treat obesity and also cognitive impairment (associated with Alzheimer's disease or schizophrenia).

The Serotonin Club is an international association for biomedical scientists who are interested in any aspect of research on serotonin (5-HT). It was established over 18 years ago and global membership is over 600 scientists. Serotonin Club Meeting 2006, an official Satellite Meeting of the 15th IUPHAR World Congress of Pharmacology (Beijing China) is being held at Hokkaido University, in Sapporo, Japan.

Researchers from academia and Predix will present data from preclinical models which suggest that PRX-07034 may significantly reduce food intake without impacting normal satiety-related behavior. Findings from a study using a well-established preclinical model to assess memory function suggest a positive effect of PRX-07034, and results further suggest a synergistic effect when PRX-07034 was administered in combination with Aricept(R), an approved drug for the treatment of Alzheimer's disease.

"We are encouraged by these preclinical studies that lead us to believe that PRX-07034 may provide a novel, safe and effective approach to treating obesity and also for cognitive impairment," said Silvia Noiman, Ph.D., MBA, founder and senior vice president of global pipeline management of Predix Pharmaceuticals. "We look forward to learning more about the effects of this product candidate as it moves through the clinic."

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.

About Predix Pharmaceuticals Holdings, Inc.

Predix, based in Lexington, MA, is a pharmaceutical company focused on the discovery and development of novel, highly selective, small-molecule drugs that target G-Protein Coupled Receptors (GPCRs) and ion channels. Using its proprietary drug discovery technology and approach, Predix has advanced four internally-discovered drug candidates into clinical trials and has five additional programs in preclinical development and discovery. Predix is expected to complete the first of at least two pivotal Phase III clinical trials for generalized anxiety disorder for its lead drug candidate, PRX-00023, in the second half of 2006. In addition to PRX-00023, Predix has three other clinical-stage drug candidates: PRX-03140 for the treatment of Alzheimer's disease, which is expected to enter Phase IIa later this year; PRX-08066 for the treatment of pulmonary hypertension (PH) and PH associated with chronic obstructive pulmonary disease, which recently completed a Phase Ib trial and is expected to enter Phase IIa in mid-2006; and, PRX-07034, which recently entered a Phase I trial and is expected to be developed for the treatment of obesity and also cognitive impairment associated with Alzheimer's disease or schizophrenia. Additional information about Predix can be found on the company's website at www.predixpharm.com.

Additional Information About the Merger And Where To Find It

EPIX has filed a registration statement on Form S-4 with the Securities and Exchange Commission containing a joint proxy statement/prospectus in connection with the proposed merger with Predix. Investors and security holders are advised to read the joint proxy statement/prospectus (including any amendments or supplements thereto) regarding the proposed merger because it contains important information about EPIX, Predix and the proposed transaction and other related matters. The joint proxy statement/prospectus will be sent to stockholders of EPIX and Predix seeking their approval of the proposed transaction. Investors and security holders may obtain a free copy of the joint proxy statement/prospectus and any amendments or supplements thereto and other documents filed by EPIX at the Securities and Exchange Commission's web site at www.sec.gov. The joint proxy statement/prospectus and such other documents may also be obtained for free by directing such request to EPIX Pharmaceuticals, Inc. 161 First Street, Cambridge, Massachusetts, Attn: Investor Relations, tel: [phone]; e-mail: [e-mail] or Predix Pharmaceuticals Holdings, Inc., 4 Maguire Road, Lexington, Massachusetts 02421, Attn: Investor Relations, tel: [phone]; e-mail: [e-mail].

EPIX and Predix and their respective directors, executive officers and other members of management and employees may be deemed to be participants in the solicitation of proxies with respect to the adoption of the merger agreement and the transactions associated with the merger. A description of any interests that EPIX and Predix directors and executive officers have in the merger is included in the registration statement containing the proxy statement/prospectus that has been filed with the Securities and Exchange Commission and is available free of charge as indicated above.

Safe Harbor Statement

Certain statements in this news release concerning Predix's business are considered "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. These statements include, but are not limited to, those relating to the timing and results of future clinical development of PRX-00023, the potential efficacy of PRX-00023 and the expected safety and tolerability of PRX-00023 as compared to other drugs treating anxiety. Any or all of the forward-looking statements in this press release can be affected by inaccurate assumptions Predix might make or by known or unknown risks and uncertainties, including, but not limited to: the early stage of product development; uncertainties as to the future success of ongoing and planned clinical trials; and the unproven safety and efficacy of products under development. Consequently, no forward-looking statement can be guaranteed, and actual results may vary materially. Predix undertakes no obligation to publicly update forward-looking statements, whether because of new information, future events or otherwise, except as required by applicable law.