July 30, 2008

Infinity Initiates Clinical Development of IPI-493, Its Oral Anti-Chaperone Agent, in Patients With Advanced Solid Tumors; Initiation of Phase 1 Expands Infinity’s Leading Hsp90 Inhibitor Portfolio

CAMBRIDGE, Mass., July 30, 2008 (PRIME NEWSWIRE) -- Infinity Pharmaceuticals, Inc. (Nasdaq:INFI) today announced that it has initiated a Phase 1 clinical trial of IPI-493, its oral anti-chaperone agent, in patients with advanced solid tumors. IPI-493 has demonstrated significant oral availability, as well as potent and selective inhibition of heat shock protein 90 (Hsp90), in preclinical studies. IPI-493 expands the company's Hsp90 portfolio, which also includes IPI-504 (retaspimycin hydrochloride). IPI-504 is expected to enter Phase 3 development later this quarter. Hsp90 is a molecular chaperone that supports and stabilizes numerous cancer-causing proteins; inhibition of the Hsp90 chaperone via anti-chaperone therapy removes a critical source of support for cancer cells, leading to cancer cell death.

"The initiation of clinical development for IPI-493 augments our industry-leading portfolio of anti-chaperone agents and marks the second proprietary drug candidate discovered by Infinity scientists to enter human clinical trials," stated Julian Adams, Ph.D., president of research and development and chief scientific officer at Infinity. "By developing two distinct inhibitors of Hsp90, we will be able to explore the potential utility of anti-chaperone therapy in a variety of indications and be well-positioned to maximize the therapeutic potential of these agents."

The multi-center, Phase 1 study of oral IPI-493 is designed as a dose-escalation trial in patients with advanced solid tumors. The primary objectives of the study are to assess safety and tolerability and to identify a treatment regimen (dose and schedule) for subsequent studies of IPI-493. Anti-tumor activity of IPI-493 will be measured using computed tomography (CT) imaging using Response Evaluation Criteria in Solid Tumors, as well as disease specific markers. Pharmacokinetics parameters, biologic activity, and effects of IPI-493 on pharmacodynamic markers of biological activity will also be assessed. Additional information regarding the trial is available at www.clinicaltrials.gov.

"Despite recent advances in cancer treatment, there remains a very high level of unmet need in oncology," stated David S. Grayzel, M.D., vice president, clinical development and medical affairs. "Targeted anti-chaperone therapy via inhibition of Hsp90 represents a significant potential strategy for treating patients with cancer. An effective, oral inhibitor of Hsp90 is a highly desirable complement to the i.v. agent for patient convenience, dosing flexibility and the potential for combination with other anti-cancer agents in a number of treatment settings."

In addition to starting the Phase 1 trial of IPI-493, Infinity continues to advance its anti-chaperone program, which includes a planned Phase 3 registration study of IPI-504 in patients with refractory gastrointestinal stromal tumors (GIST). IPI-504 is also being evaluated in the Phase 2 portion of a Phase 1 / 2 trial in patients with non-small cell lung cancer and a Phase 1b trial in combination with docetaxel.

IPI-493 and IPI-504 are being jointly developed by Infinity and AstraZeneca/MedImmune.

About Anti-Chaperone Therapy and Heat Shock Protein 90 (Hsp90)

Despite recent therapeutic advances, current approaches to treating cancer remain incomplete. Cellular systems critical to the growth and survival of many tumors remain unaddressed by currently available treatments. Hsp90 is a central component of the cellular chaperone system -- a system that supports and stabilizes cancer-causing proteins such as c-Kit, EGFR, and HER2, enabling multiple forms of cancer to thrive. Inhibition of Hsp90 knocks out this critical source of support for cancer cells, leading to tumor growth inhibition and cancer cell death. Thus, targeted anti-chaperone therapy via inhibition of Hsp90 may represent a significant yet currently unaddressed strategy for treating patients with cancer. IPI-504 (i.v.) and oral IPI-493 are novel, targeted anti-chaperone agents that have shown potent and selective inhibition of Hsp90 in preclinical studies.

About Infinity Pharmaceuticals, Inc.

Infinity is an innovative cancer drug discovery and development company that is seeking to leverage its strength in small molecule drug technologies to deliver best-in-class medicines for the treatment of cancer and related conditions. For more information on Infinity, please refer to the company's website at http://www.infi.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of The Private Securities Litigation Reform Act of 1995. These statements involve risks and uncertainties that could cause actual results to be materially different from historical results or from any future results expressed or implied by such forward-looking statements. Such forward-looking statements include statements regarding the utility of anti-chaperone inhibitors of Hsp90, including, IPI-504 and IPI-493, to treat cancer; and future clinical trial activity for IPI-504 and IPI-493. Such statements are subject to numerous factors, risks and uncertainties that may cause actual events or results to differ materially from the company's current expectations. For example, there can be no guarantee that any product candidate Infinity is developing will successfully complete necessary preclinical and clinical development phases. In particular, management's expectations could be affected by risks and uncertainties relating to: results of clinical trials and preclinical studies, including subsequent analysis of existing data and new data received from ongoing and future studies; the content and timing of decisions made by the U.S. Food and Drug Administration and other regulatory authorities, investigational review boards at clinical trial sites, and publication review bodies; Infinity's ability to enroll patients in its clinical trials; Infinity's dependence on its collaboration with AstraZeneca/MedImmune; Infinity's ability to obtain additional funding required to conduct its research, development and commercialization activities; unplanned cash requirements and expenditures; and Infinity's ability to obtain, maintain and enforce patent and other intellectual property protection for any product candidates it is developing. These and other risks which may impact management's expectations are described in greater detail under the caption "Risk Factors" included in Infinity's quarterly report on Form 10-Q for the quarter ended March 31, 2008, as filed with the Securities and Exchange Commission on May 9, 2008. Further, any forward-looking statements contained in this press release speak only as of the date hereof, and Infinity expressly disclaims any obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise.


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 CONTACT:  Infinity Pharmaceuticals, Inc.           Monique Allaire           617-453-1105           [email protected]           http://www.infi.com