Clinical Trial Data with Predix's Lead Drug Candidate for Anxiety to Be Presented at Scientific Conference; 46th Annual New Clinical Drug Evaluation Unit Meeting To Highlight Advances in Clinical Interventions To Benefit Mental Illness.

LEXINGTON, Mass. -- Predix Pharmaceuticals, which recently announced a definitive agreement to merge with EPIX Pharmaceuticals (Nasdaq:EPIX), announced today that Sanjay Mathew, M.D., from Mt. Sinai School of Medicine, will be presenting Phase II data on Predix's lead drug candidate for generalized anxiety disorder, PRX-00023, at the 46th Annual New Clinical Drug Evaluation Unit (NCDEU) meeting on June 13.

The NCDEU conference is co-sponsored by the National Institute of Mental Health, the National Institutes of Health and the American Society for Clinical Psychopharmacology and brings together academic researchers from multiple disciplines involved in clinical trials, investigators with the pharmaceutical industry and representatives from government agencies, including the U.S. Food and Drug Administration.

"The Phase II data to be presented illustrates the clinical progress being made with Predix's lead drug candidate for the treatment of generalized anxiety disorder," said Michael G. Kauffman, M.D., Ph.D., president and CEO of Predix. "This data follows the recent publication highlighting PRX-00023 in the Journal of Medicinal Chemistry, as well as our earlier-than-expected completion of enrollment in our first Phase III pivotal trial in generalized anxiety disorder. We expect to provide preliminary Phase III data later this year."

The schedule for the poster presentation is listed below:

Date:   Tuesday, June 13, 2006 from 12:00-2:00 p.m.
Title: "Preliminary Evidence of Short-Term Efficacy of a Novel,
Non-Azapirone Selective 5-HT1A Agonist in Generalized Anxiety
Disorder"
Presenter: Sanjay Mathew, M.D.; Mt. Sinai School of Medicine, New
York, NY

About PRX-00023

PRX-00023 is Predix's lead drug candidate and represents a novel, highly selective, non-azapirone class of 5-HT1A agonists discovered using the company's proprietary G-Protein Coupled Receptor (GPCR) modeling, screening and lead optimization technology. Buspirone is currently the only 5-HT1A agonist approved in the United States for the treatment of anxiety, but is taken three times a day, requires approximately three to four weeks of dose adjustment to reach therapeutic levels, and may cause lightheadedness, nausea, headache and restlessness. Several other 5-HT1A agonists have shown efficacy in Phase II and III clinical trials in depression. However, most of these drugs belong to a chemical class of drugs called azapirones, and their development has been hindered by poor tolerability at therapeutic doses, need for dosing up to three times daily, and the requirement of gradual dose escalation to effective doses because of side effects such as nausea, dizziness, and restlessness which are thought to be caused by azapirones binding to non-5-HT1A GPCRs.

In contrast, PRX-00023 is designed to have minimal affinity for the GPCRs believed to be associated with the side effects of 5-HT1A agonists that are in the azapirone chemical class, and to have a more convenient dosing profile than azapirones. PRX-00023 has a half-life of 12 hours, allowing it to be administered once daily.

The Journal of Medicinal Chemistry, the official peer-reviewed journal of the American Chemical Society, recently published a paper highlighting PRX-00023's novel discovery process as illustrative of a new paradigm in drug discovery utilizing in silico methods together with medicinal chemistry that resulted in a substantially reduced discovery timeline for this drug candidate.

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 three internally discovered drug candidates into clinical trials and has six 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. Predix has two other clinical-stage drug candidates: PRX-03140 for the treatment of Alzheimer's disease, which is expected to enter Phase IIa later this year; and, 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. 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.