Innovative. Independent. Inspired. 2 Safe Harbor Statement • This presentation 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 achievement of the I4 2012 goals; future clinical trial activity for IPI-504 and IPI-493; the presentation of preclinical and clinical data for IPI-504, IPI-493 and IPI-926; the filing of an IND for IPI-940; Infinity’s ability to build a commercial infrastructure; estimates of 2009 financial performance; and the expectation that Infinity will have capital to support its current operating plan through 2012. • 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 Infinity’s strategic alliance with Purdue Pharma and Mundipharma will continue for its expected term or that these entities will fund Infinity’s programs as agreed, or 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; unplanned cash requirements and expenditures; Infinity’s ability to meet its hiring objectives and build commercial capabilities; market acceptance of any products Infinity may successfully develop; Infinity's ability to obtain, maintain and enforce patent and other intellectual property protection for any product candidates it is developing; and Infinity’s reliance on the strategic alliance with Purdue Pharma and Mundipharma. • These and other risks which may impact management's expectations are described in greater detail under the caption "Risk Factors" included in Infinity's registration statement on Form S-3 filed with the Securities and Exchange Commission on January 9, 2009. • Further, any forward-looking statements contained in this presentation 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. • All trademarks used in this presentation are the property of their respective owners. • Our Internet website is http://www.infi.com. We also maintain http://www.ringtrial.com with respect to information regarding the RING clinical trial. We regularly use our websites to post information regarding our business, product development programs and governance, and we encourage investors to use www.infi.com, particularly the information in the section entitled “Investors/Media,” as a source of information about us. References to our websites in this presentation are not intended to, nor shall they be deemed to, incorporate information on our websites into this presentation by reference. 2 2 | 
