Infinity Reports Topline Data from Phase 2 Study of Retaspimycin Hydrochloride, Its Hsp90 Inhibitor, in Patients with Non-Small

  Infinity Reports Topline Data from Phase 2 Study of Retaspimycin
  Hydrochloride, Its Hsp90 Inhibitor, in Patients with Non-Small Cell Lung
  Cancer

                  – Trial Did Not Meet Efficacy Endpoints –

     – Company to Focus Efforts on PI3K Portfolio, Including IPI-145, and
                            Preclinical Pipeline –

Business Wire

CAMBRIDGE, Mass. -- September 25, 2013

Infinity Pharmaceuticals, Inc. (NASDAQ: INFI) today announced topline data
from its Phase 2 study of retaspimycin hydrochloride (HCl), a potent and
selective heat shock protein 90 (Hsp90) inhibitor, in patients with non-small
cell lung cancer (NSCLC) who had a history of smoking. In this double-blind,
randomized, placebo-controlled study, retaspimycin HCl did not meet its
pre-specified efficacy endpoints for demonstrating an improvement in overall
survival in the total patient population or in patients with squamous cell
carcinoma. In the study, the safety profile of retaspimycin HCl plus docetaxel
was comparable to docetaxel and placebo. Infinity expects to present the final
data in a peer-reviewed setting after all analyses are complete. The company
will not initiate any new trials with retaspimycin HCl.

“Although our Phase 1b data in patients with non-small cell lung cancer were
encouraging and there was a strong biological rationale for the combination
treatment, further development of retaspimycin HCl plus docetaxel in this very
challenging disease is not merited based on data from this rigorously
conducted study. We appreciate the support of the patients and caregivers who
participated in this trial,” stated Julian Adams, Ph.D., president of research
and development at Infinity. “We will now focus our clinical research and
development effort on IPI-145, our lead PI3K-delta,gamma inhibitor, for which
we have encouraging data in patients with life-threatening hematologic
malignancies.”

Based on encouraging preliminary activity observed in a Phase 1 study of
IPI-145, Infinity’s potent, oral inhibitor of phosphoinositide-3-kinase
(PI3K)-delta and PI3K-gamma, in patients with advanced hematologic
malignancies (blood cancers), the company is conducting a Phase 2 trial of
IPI-145 in patients with indolent non-Hodgkin lymphoma and planning a Phase 3
trial in patients with chronic lymphocytic leukemia. IPI-145 also has
therapeutic potential in inflammatory diseases, and the company is conducting
a Phase 2 trial of IPI-145 in patients with rheumatoid arthritis as well as an
exploratory, signal-finding Phase 2a study of IPI-145 in mild, allergic
asthma. Additionally, Infinity is conducting preclinical studies of IPI-443,
its second oral PI3K-delta and PI3K-gamma inhibitor, which also has the
potential to treat hematologic malignancies and inflammatory diseases.

Details and Topline Data for Phase 2 Study of Retaspimycin HCl Plus Docetaxel

Retaspimycin HCl did not meet its pre-specified efficacy endpoints for
demonstrating an improvement in overall survival in the total patient
population or in patients with squamous cell carcinoma. In addition, the
combination did not show a treatment benefit in patient populations defined by
pre-specified biomarkers, including KRAS, p53 and plasma levels of
Hsp90-alpha. The safety profile of retaspimycin HCl plus docetaxel was
comparable to docetaxel and placebo.

The Phase 2, randomized, placebo-controlled study evaluated the efficacy and
safety of retaspimycin HCl plus docetaxel compared to placebo plus docetaxel
in 226 patients with second- or third-line NSCLC who were naïve to docetaxel
treatment and had a smoking history. Patients received 450 mg/m^2 retaspimycin
HCl or placebo dosed weekly in combination with the standard dose of docetaxel
dosed once every three weeks during a 21-day cycle. The co-primary efficacy
endpoints were overall survival in the entire patient population and overall
survival in patients with squamous cell carcinoma.

Infinity today also announced that it will complete enrollment of the final
cohort of patients in its separate, exploratory study of retaspimycin HCl in
combination with everolimus (an mTOR inhibitor) in NSCLC patients with a KRAS
mutation by the end of 2013 to conclude its development of retaspimycin HCl.

About Infinity Pharmaceuticals, Inc.

Infinity is an innovative biopharmaceutical company dedicated to discovering,
developing and delivering best-in-class medicines to people with
difficult-to-treat diseases. Infinity combines proven scientific expertise
with a passion for developing novel small molecule drugs that target emerging
disease pathways. For more information on Infinity, please refer to the
company’s website at 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. Such forward-looking
statements include those regarding the company’s expectations about: plans to
present data from its trial of retaspimycin HCl in combination with docetaxel
in patients with NSCLC; plans not to initiate new trials with retaspimycin
HCl; plans to focus clinical research and development efforts on IPI-145;
plans for a Phase 3 trial in patients with chronic lymphocytic leukemia;
timing for the completion of enrollment in its ongoing trial of retaspimycin
HCl in combination with everolimus and conclusion of development of
retaspimycin HCl; and its strategic plans and goals with respect to its
business. Such statements are subject to numerous important 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 will initiate clinical trials, enroll patients, or
report data in the time frames it has estimated, that any product candidate
Infinity is developing will successfully complete necessary preclinical and
clinical development phases or that development of any of Infinity’s product
candidates will continue. Further, there can be no guarantee that any positive
developments in Infinity’s product portfolio will result in stock price
appreciation. Management’s expectations and, therefore, any forward-looking
statements in this press release could also be affected by risks and
uncertainties relating to a number of other factors, including the following:
Infinity’s 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. FDA and
other regulatory authorities, investigational review boards at clinical trial
sites and publication review bodies; Infinity’s ability to obtain and maintain
requisite regulatory approvals and to enroll patients in its clinical trials;
cash requirements and unplanned cash expenditures; development of agents by
Infinity’s competitors for diseases in which Infinity is currently developing
its product candidates; adverse economic and market conditions, 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 filed with theSecurities and Exchange Commission (SEC) onAugust 8,
2013, and other filings filed by Infinity with theSEC. 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.

Contact:

Infinity Pharmaceuticals, Inc.
Jaren Irene Madden, 617-453-1336
Jaren.Madden@infi.com
http://www.infi.com