Infinity Reports Recent R&D Highlights and Third Quarter 2009 Results

-- Enrollment Open in All of Infinity's Ongoing Hsp90 Chaperone
Inhibitor Studies

-- Infinity Maintains Financial Strength to Advance Its Innovative
Product Pipeline
CAMBRIDGE, Mass., Nov. 9, 2009 (GLOBE NEWSWIRE) -- Infinity Pharmaceuticals,
Inc. (Nasdaq:INFI), an innovative cancer drug discovery and development company,
today reviewed recent R&D highlights and announced third quarter 2009 financial
results.

"During the past quarter, we have advanced our clinical and preclinical programs
and strengthened our operational capabilities, activities necessary to achieve
our mission of sustainably discovering, developing and delivering to patients
meaningful new medicines," said Adelene Q. Perkins, president and chief business
officer, Infinity. "We are in the distinctive position of having the cash
resources and committed capital to enable us to invest aggressively in the
advancement of our pipeline of innovative anti-cancer programs to achieve key
clinical inflection points."

Hsp90 Chaperone Inhibitor Program Highlights

Infinity is making progress in the clinical evaluation of its family of heat
shock protein 90 (Hsp90) chaperone inhibitors in multiple cancer indications.
Infinity's inhibitors include IPI-504 (retaspimycin hydrochloride) and orally
administered IPI-493. In the third quarter, Infinity received approval of
protocol amendments for its studies of IPI-504, which included dose and schedule
modifications. Patient enrollment is ongoing in all studies of IPI-504 and
IPI-493.

Infinity is currently enrolling patients in a Phase 2 clinical study of IPI-504
in combination with Herceptin(R) (trastuzumab) in patients with HER2-positive
metastatic breast cancer. The company has presented preclinical data
demonstrating that administration of IPI-504 results in the rapid degradation of
HER2 in both Herceptin-sensitive and Herceptin-resistant xenograft models, and
that administration of IPI-504 in these models produced substantial tumor growth
inhibition. Infinity anticipates presenting preliminary data from this Phase 2
study in 2010.

IPI-504 is also being evaluated in a Phase 1b study in combination with
Taxotere(R) (docetaxel) in patients with advanced solid tumors, with an
expansion arm focusing on patients with non-small cell lung cancer (NSCLC).
Infinity reported preliminary data from this study during the 2009 American
Society for Clinical Oncology (ASCO) Annual Meeting showing that the combination
of IPI-504 and Taxotere was generally well-tolerated in patients with a variety
of solid tumor malignancies, and that IPI-504 did not affect the clearance of
Taxotere. Infinity is currently enrolling patients in this trial and is
evaluating the combination of IPI-504 and Taxotere on multiple schedules of
administration.

Based on the preliminary Phase 2 clinical response rate (14.2 percent) reported
in patients with wild-type EGFR (epidermal growth factor receptor) expression
NSCLC (n=28) following single-agent administration of IPI-504, Infinity is using
a variety of molecular pathology techniques to understand the underlying genetic
profile of responding patients and to determine the optimal clinical development
strategy in NSCLC. This effort is ongoing, as is active consultation with NSCLC
experts such as Thomas J. Lynch, M.D., who recently joined Infinity's Board of
Directors. The company anticipates publishing the full results from the Phase 2
portion of this clinical study, and commencing further clinical development of
IPI-504 in NSCLC, in 2010.

"We are committed to the clinical development of IPI-504, and look forward to
generating data in 2010 that will further guide our clinical development and
potential registration paths," stated Julian Adams, Ph.D., president of research
and development and chief scientific officer, Infinity. "Infinity is holding
itself to a high performance standard, while rigorously and expeditiously
pursuing the development of IPI-504 at what we believe to be the optimal
biological dose in appropriate patient populations."

Infinity is also enrolling patients in a Phase 1 dose-escalation study of
IPI-493, its oral agent, in patients with advanced solid tumors. IPI-493 is
being evaluated on multiple schedules of administration to identify an optimal
dose and schedule for future development. Infinity expects to present
preliminary data from this study, and conduct further clinical evaluation of
IPI-493, in 2010.

In addition to the ongoing clinical trials of its Hsp90 chaperone inhibitors,
Infinity anticipates initiating by early 2010 a Phase 2 clinical study
evaluating IPI-504 in patients with advanced, dedifferentiated liposarcoma, a
form of soft tissue sarcoma. At the 2008 ASCO Annual Meeting, Infinity published
data reporting a Partial Response by RECIST (Response Evaluation Criteria in
Solid Tumors) in one of three patients with liposarcoma treated with IPI-504 in
a Phase 1 study in patients with refractory gastrointestinal stromal tumors
(GIST) and other soft tissue sarcomas; this patient experienced a tumor
reduction of 43 percent over eight cycles (24 weeks) of administration of
IPI-504. Infinity anticipates that this trial will enroll 40 patients, and that
IPI-504 will be administered as a single agent at a dose of 225 mg/m2 on a
three-week schedule of twice-weekly dose administration for two weeks, followed
by one week off. The objectives of this study are to determine the safety
profile and overall response rate of IPI-504 in patients with advanced,
dedifferentiated liposarcoma.

Further, Infinity expects to report final results from the RING trial, a study
of IPI-504 in patients with refractory GIST, in early 2010.

Hedgehog Pathway Inhibitor Program Highlights

Infinity is currently evaluating IPI-926, its novel, oral Hedgehog signaling
pathway inhibitor, in a Phase 1 clinical trial in patients with advanced solid
tumors. Infinity has previously presented data demonstrating significant
anti-tumor activity of IPI-926 in a number of preclinical studies, including in
models of pancreatic cancer, small cell lung cancer, ovarian cancer, and
medulloblastoma. IPI-926 has shown excellent pharmaceutical properties,
including oral bioavailability, long plasma half-life and duration of action,
and dose-dependent inhibition of tumor growth in preclinical studies. IPI-926 is
in the dose-escalation stage of the Phase 1 study. Infinity anticipates
presenting preliminary data from the Phase 1 study and initiating Phase 2
development in 2010.

Third Quarter 2009 Financial Results

Infinity ended the third quarter of 2009 with $140.5 million in cash and
investments. Based on its current operating plan, Infinity continues to project
a year-end cash and investments balance of $127-$137 million, without accessing
the $50 million line of credit available under its alliance with Purdue
Pharmaceutical Products, L.P. and Mundipharma International Corporation Ltd.
With this line of credit, Infinity projects that it has sufficient capital to
support its current operating plan into 2013, absent any business development
activities.

Total revenue for the third quarter of 2009 was $13.8 million. This revenue
consisted of $13.1 million for reimbursed R&D services and $0.7 million from the
amortization of deferred revenue associated with the grant of licenses under
Infinity's strategic alliance with Purdue and Mundipharma. This alliance
encompasses development and discovery activities for Infinity's entire pipeline,
excluding the company's Hsp90 chaperone inhibitor and Bcl-2 inhibitor programs.

R&D expense was $18.5 million for the third quarter of 2009, compared to $11.7
million for the third quarter of 2008. These results primarily reflect
differences in the accounting treatment of Infinity's program collaborations:

-- In the third quarter of 2009, all $13.1 million in reimbursable
expenses related to Infinity's alliance with Mundipharma and
Purdue are recorded as R&D expense; this amount is also recorded
as collaborative R&D revenue.

-- Infinity's R&D expense of $11.7 million for the third quarter of
2008 reflected total R&D expenditures by Infinity of $15.9
million, less $4.2 million that Infinity recorded as a credit to
R&D expense under the cost sharing provisions of its previous
alliance with AstraZeneca for Infinity's Hsp90 chaperone
inhibitor program. In December 2008, Infinity reacquired from
AstraZeneca all worldwide development and commercialization
rights to this program. Therefore, there was no credit recorded
to R&D expense in the third quarter of 2009.
In addition to the effect of the AstraZeneca reimbursed amounts, the increase in
R&D expense in the third quarter of 2009 is primarily due to increased
personnel, pharmaceutical development, and preclinical expenses to support
Infinity's advancing product development pipeline.

General and administrative expense was $4.6 million for the third quarter of
2009 as compared to $3.8 million in the third quarter of 2008. The increase
primarily reflects increased personnel and patent expenses.

Infinity's net loss for the third quarter of 2009 was $9.3 million as compared
to a net loss of $12.4 million for the third quarter of 2008. Basic and diluted
loss per common share was $0.36 for the third quarter of 2009 as compared to
$0.63 for the third quarter of 2008.

Conference Call on Monday, November 9, 2009, at 4:30 p.m. Eastern Time

Infinity management will host a conference call on Monday, November 9, 2009, at
4:30 p.m. EST to discuss the quarter results and provide an R&D update. A live
webcast of the conference call can be accessed in the Investors/Media section of
Infinity's website at http://www.infi.com. Callers may participate in the call
by dialing 1-888-359-3613 (domestic) and 1-719-457-2657 (international) five
minutes prior to the start time. An archived version of the webcast will be
available on Infinity's website for 30 days.

About Infinity Pharmaceuticals, Inc.

Infinity is an innovative cancer drug discovery and development company seeking
to discover, develop and deliver to patients best-in-class medicines for the
treatment of cancer and related conditions. Infinity combines proven scientific
expertise with a passion for developing novel small molecule drugs that target
emerging cancer pathways. Infinity's two most advanced programs in Hsp90
chaperone inhibition and Hedgehog signaling pathway inhibition are evidence of
its innovative approach to oncology drug discovery and development. 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 those
regarding the therapeutic potential of Infinity's Hsp90 chaperone and Hedgehog
signaling pathway inhibitors, estimates of 2009 financial performance, the
expectation that Infinity will have capital to support its current operating
plan into 2013, the presentation or publication of clinical data for IPI-504,
IPI-493 and IPI-926, and the timing for initiation of further clinical
development of IPI-504, IPI-493 and IPI-926. 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
Mundipharma and Purdue will continue for its expected term or that they will
fund Infinity's programs as agreed, or that any product candidate Infinity is
developing will successfully complete necessary preclinical and clinical
development phases. Further, there can be no guarantee that any positive
developments in Infinity's product portfolio will result in stock price
appreciation. Management's expectations could also 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, including in connection with business development activities;
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 the Securities and Exchange Commission
on November 9, 2009. 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.

Herceptin(R) and Taxotere(R) and are registered trademarks of Genentech, Inc.
and sanofi-aventis llc, respectively.

INFINITY PHARMACEUTICALS, INC.
Condensed Consolidated Balance Sheets
(unaudited)

September 30, December 31,
2009 2008
-------------------------------

Cash, cash equivalents and
available-for-sale securities,
including long term $140,482,784 $126,771,687
Other current assets 3,306,090 9,846,179
Property and equipment, net 5,584,099 5,320,439
Loan commitment asset from Purdue
entities, net 16,453,050 17,319,000
Other long-term assets 1,349,925 1,360,203
-------------------------------

Total assets $167,175,948 $160,617,508
===============================

Current liabilities $ 15,581,651 $ 16,030,742
Deferred revenue from Purdue
entities, less current portion 36,602,451 21,939,251
Other long-term liabilities 2,293,815 2,352,048
Total stockholders' equity 112,698,031 120,295,467
-------------------------------

Total liabilities and stockholders'
equity $167,175,948 $160,617,508
===============================

INFINITY PHARMACEUTICALS, INC.
Condensed Consolidated Statements of Operations
(unaudited)

Three Months Ended Nine Months Ended
September 30, September 30,
------------------------------------------------------
2009 2008 2009 2008
------------------------------------------------------

Collaborative
research
and
development
revenue * $ 13,775,745 $ 2,500,000 $ 36,370,000 $ 16,391,458

Operating
expenses:
Research
and devel-
opment 18,499,060 11,732,206 60,453,361 31,029,091
General and
admini-
strative 4,570,282 3,780,740 15,581,871 11,234,423
------------------------------------------------------

Total
operating
expenses 23,069,342 15,512,946 76,035,232 42,263,514
------------------------------------------------------

Loss from
operations (9,293,597) (13,012,946) (39,665,232) (25,872,056)

Other
(expense)/
income:
Interest
expense (433,272) (2,113) (866,943) (19,800)
Income from
residual
funding
after
reacqui-
sition of
Hsp90
program -- -- 12,450,000 --
Income from
NIH reim-
bursement -- -- 1,745,386 --
Interest and
investment
income 401,264 623,543 1,735,742 2,774,366
------------------------------------------------------
Net other
income
(expense) (32,008) 621,430 15,064,185 2,754,566
------------------------------------------------------

Net loss $ (9,325,605) $(12,391,516) $(24,601,047) $(23,117,490)
======================================================

Basic and
diluted
loss per
common
share $ (0.36) $ (0.63) $ (0.94) $ (1.17)
======================================================
Basic and
diluted
weighted
average
number of
common
shares
outstanding 26,154,557 19,759,766 26,062,217 19,722,255
======================================================

* 2009 amounts from Purdue entities only
-0-
CONTACT: Infinity Pharmaceuticals, Inc.
Monique Allaire
617-453-1105
Monique.Allaire@infi.com
http://www.infi.com