Duvelisib in Inflammation Asthma ASPIRA (RA)

UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): October 16, 2014

Infinity Pharmaceuticals, Inc. (Exact name of registrant as specified in charter)

Delaware 000-31141 33-0655706 (State or other jurisdiction (Commission (IRS Employer of incorporation) File Number) Identification No.)

780 Memorial Drive, Cambridge, MA 02139 (Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code: (617) 453-1000

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 7.01. Regulation FD Disclosure From time to time, we intend to conduct meetings with third parties in which our current corporate slide presentation is presented. A copy of this slide presentation, dated October 16, 2014 is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

The information responsive to Item 7.01 of this Form 8-K and Exhibit 99.1 hereto shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933 or the Exchange Act, except as expressly set forth by specific reference in such a filing.

Item 8.01. Other Events On October 16, 2014 we issued a press release announcing data from our Phase 2a study of duvelisib (IPI-145) in patients with mild, allergic asthma. A copy of this press release is filed as Exhibit 99.2 to this Current Report on Form 8-K and is incorporated herein by reference.

Item 9.01. Financial Statements and Exhibits

(d) The following exhibits are included in this report:

Exhibit No. Description 99.1 Presentation dated October 16, 2014 99.2 Press release dated October 16, 2014 SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

INFINITY PHARMACEUTICALS, INC.

Date: October 16, 2014 By: /s/ Lawrence E. Bloch, MD, JD Lawrence E. Bloch, MD, JD EVP, Chief Financial Officer and Chief Business Officer Exhibit 99.1

Building a Fully Integrated Biopharmaceutical Company

October 2014 Forward-Looking Statements

This presentation 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: the receipt of upfront, milestone, royalty and other payments under the agreement with AbbVie; the therapeutic and commercial potential of duvelisib; the therapeutic potential of PI3K delta,gamma inhibition; the expected benefits of the collaboration with AbbVie; program goals for 2014, including the timing and type of data to be reported from, as well as progress in, clinical trials of its PI3K program; plans to initiate additional clinical trials in its PI3K program; plans to announce a development strategy for its PI3K delta,gamma inhibitors; and the company’s ability to execute on its plans and strategies. 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 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 Infinity's strategic collaboration with AbbVie will continue or 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; a failure of Infinity and/or AbbVie to fully perform under the strategic collaboration and/or an early termination of the collaboration and license agreement; 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; unplanned cash requirements and expenditures; development of agents by Infinity’s competitors for diseases in which Infinity is currently developing or intends to develop its product candidates; 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 (SEC) on August 11, 2014, and other filings filed by Infinity with the SEC. 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. Infinity’s website is http://www.infi.com. Infinity regularly uses its website to post information regarding its business, product development programs and governance. Infinity encourages investors to use www.infi.com, particularly the information in the section entitled “Investors/Media,” as a source of information about Infinity. References to www.infi.com in this presentation are not intended to, nor shall they be deemed to, incorporate information on www.infi.com into this presentation by reference.

2 Duvelisib: Potential to Transform the Standard of Care in Hematologic Malignancies

Most advanced PI3K- inhibitor in clinical development

Highly active in both B-cell and T-cell malignancies

Generally well tolerated* Most AEs are low-grade and/or asymptomatic Consistent with co-morbidities in patients with advanced hematologic malignancies Clinical trial experience has informed strategies to optimize use of duvelisib

Phase 2 and Phase 3 registration trial under way

*Flinn et al., ASH 2013. 3 Strategic Partnership with AbbVie for Duvelisib in Oncology

Partnership Terms:

Financial $275M up-front payment $530M in potential development and commercial milestones Up to $405 million for the achievement of milestones through first commercial sale

Development Infinity will fund the trials it conducts, up to $667 million, after which costs will be shared equally Infinity and AbbVie will equally share funding for trials conducted by AbbVie

Commercial 50/50 profit share in U.S. Tiered royalty payments ex-U.S., ranging from 23.5% to 30.5% of net sales 4 Duvelisib: Potential to Transform the Standard of Care in Hematologic Malignancies

5 Duvelisib: Potential to Transform the Standard of Care in Hematologic Malignancies

Highly active in both B-cell and T-cell malignancies

R/R: Relapsed/refractory IWCLL: International Workshop on Chronic Lymphocytic Leukemia PTCL: Peripheral T-cell lymphoma CTCL: Cutaneous T-cell lymphoma DLBCL: Diffuse large B-cell lymphoma 6 Duvelisib Highly Active in R/R iNHL: 73% ORR

• 73% ORR includes one Waldenström Macroglobulinemia patient with a minor response (MR) without adenopathy (not shown above) • Generally well tolerated and AEs transient ( 25 mg BID)

Douglas et al., ASH 2013. 7 Duvelisib Early Evidence of Durable Responses in iNHL 53% (8 of 15 Patients) Progression Free for Over One Year

R/R iNHL patients, n=15 ( 25 mg BID)

Douglas et al., ASH 2013 8 Duvelisib: Maintaining Patients on Study Going Forward

Adverse Event Expected Management in Phase 3 Study

Early intervention; drug interruption until resolution; Pneumonitis retreat with same dose Steroids allowed

ALT/AST Dose interruption until resolution; retreat with same dose

Dose interruption until resolution; retreat with same dose Diarrhea Steroids allowed

Drug interruption during active infection and antibiotics as Infections indicated and recommended for immunocompromised patients; retreat with same dose

9 DYNAMO™: Phase 2 Study of Duvelisib in Refractory iNHL Enrolling

duvelisib ~120 iNHL patients* (25 mg BID)

Open-label, single-arm monotherapy study under way Primary endpoint: Objective response rate Regulatory support for potential accelerated approval

*Includes follicular lymphoma (FL), marginal zone lymphoma (MZL), small lymphocytic lymphoma (SLL) Clinicaltrials.gov NCT01882803. 10 Relapsed/Refractory iNHL Response Rates

100 Partial Response Complete Response

19% 21% 80 72% 71%

19% 21% 60 54% 47% 8% 53% 50% 40 20% 46%

20 27%

0 Rituxan (R) Zydelig™ Zydelig™ + R duvelisib duvelisib + R Phase 2 Phase 2 Phase 1 Phase 1 Phase 3 N = 75 N = 72 N = 32 N = 14 N = 200

Goy EHA 2012, Benson ASCO 2013, Douglas ASH 2013 11 DYNAMO+R: Planned Phase 3 Study of Duvelisib in Previously Treated Follicular Lymphoma

duvelisib (25 mg BID) ~400 + rituximab Patients with Relapsed FL rituximab

Randomized, placebo-controlled combination study

Regulatory support that DYNAMO+R could serve as confirmatory trial for DYNAMO™

Clinicaltrials.gov NCT02204982 12 Expanding Development of Duvelisib in iNHL

Frontline Phase 1b/2 Combination duvelisib in combination with Planned for 2014 Gazyva™ or Rituxan ®

Relapsed Combination Planned for 2014

Registration Focused

Refractory Monotherapy

13 Duvelisib: Potential to Transform the Standard of Care in Hematologic Malignancies

Highly active in both B-cell and T-cell malignancies

R/R CLL • 98% (42/43) achieved a reduction in adenopathy by CT assessment, all doses • 89% (24/27) nodal response rate ( 50% reduction in adenopathy), 25 mg BID Treatment-naïve CLL • Nodal responses in 3/6 patients, including 2 patients with p53 mutation, 25 mg BID

Flinn et al., ASH 2013 15 Time on Study: R/R CLL Patients at 25 mg BID Early Patient Experiences Inform Potential to Optimize Future Patient Management

Long-term progression free

Patients enrolled in 2013, Progression free, data maturing

Discontinued All discontinuations from patients enrolled before 2013

75% (6/8) patients treated for 1 year remain progression-free on treatment 8 recently enrolled patients (< 6 months) in early follow-up for PFS Flinn et al., ASH 2013 16 AEs Grade 3 in CLL Patients 25 mg BID (All Causality 5%) Hematologic and Infectious AEs More Common in Heavily Pretreated R/R CLL Patients

Flinn et al., ASH 2013 17 DUO™: Phase 3 Study of Duvelisib in R/R CLL Enrolling

duvelisib (25 mg BID) (n = ~150) ~300 patients R

ofatumumab (IV) (n = ~150)

• Randomized, monotherapy study • Primary endpoint: Progression-free survival by independent review

Clinicaltrials.gov NCT02004522 18 Duvelisib: Potential to Transform the Standard of Care in Hematologic Malignancies

• Highly active in both B-cell and T-cell malignancies

Progressive disease: CTCL (4 of 15 patients); PTCL (5 of 11 patients)

• Early evidence of activity in CTCL and PTCL with duvelisib up to 75 mg BID • Safety profile in line with comorbidities seen in patients with advanced TCL

Horwitz et al., T-cell Lymphoma Forum 2014 20 Duvelisib Early Evidence of Activity in Aggressive B-cell NHL

Doses up to 75 mg BID (n=14) • Most frequent Grade 3 AEs: Neutropenia (32%), febrile neutropenia, diarrhea, fatigue, pneumonia, ALT/AST increase, and dyspnea (9% each)

Campbell et al., ASH 2013 21 Duvelisib: Potential to Transform the Standard of Care in Hematologic Malignancies

• Most advanced PI3K- inhibitor in clinical development

• Highly active in both B-cell and T-cell malignancies

• Generally well tolerated* – Most AEs are low-grade and/or asymptomatic – Consistent with co-morbidities in patients with advanced hematologic malignancies – Clinical trial experience has informed strategies to optimize use of duvelisib

• Phase 2 and Phase 3 registration trial under way

*Flinn et al., ASH 2013 22 Duvelisib Translational Research

23 Malignant B-Cell Growth and Survival Is Also Supported by T-Cells and Myeloid Cells Via PI3K-Dependent and PI3K-Independent Mechanisms

JA Burger. Curr Hematol Malig Rep (2012); Stevenson et al. Blood (2011); Woyach et al Blood (2012); Kridel et al. J Clin Invest (2012); Herman et al. Blood (2010); Davids and Burger. Open J Hematol. (2012); Hollengriel et al. Blood (2014); Burger and Kipps. Blood (2006); Zangnai et al. J. Exp. Med. (2007); Bangara et al. Blood (2011); Os et al. Cell Reports (2013); Giannoni et al. Haematologica (2014); M. Seiffert. EHA Meeting June 12, 2014; Schmid et al. Cancer Cell (2011) ;Hoellenriegel et al Blood (2011); Lannutti et al. Blood (2011); Burger et al. Blood (2000); Reif et al. J Immunol (2004) Duvelisib Is a Potent Inhibitor of Proliferation of CLL Cells Induced by Tumor Microenvironment Cytokines

Percent Inhibition of pAKT/Ki67 Double Positive CLL Cells

duvelisib PI3K- PI3K-

*Highly potent (low nM) PI3K isoform-selective compounds target either PI3K- or PI3K- with >100-fold selectivity over the other PI3K isoforms

Ki67 is a marker of proliferation CLL cells stimulated with IL-2, IL10, CD40L

Adams, AACR Special Conference September 2014 25 Role for PI3K- in Migration of CLL Associated Peripheral T-Cells in Patients

Inhibition of CXCL12-induced Migration of CD3+ T-cells in CLL PBMCs

100 EC50 PI3K- 694nM 50 PI3K- 10nM

0.01 1 100 10000 Concentration (nM)

One Donor

Adams, AACR Special Conference September 2014 26 Isobologram Analysis: Synergistic Growth Inhibition in Hematologic Cell Lines

Combination Index 1

0.8 antagonistic

0.6

0.4

0.2 synergistic

0 0 0.2 0.4 0.6 0.8 1 [Drug 2 Fraction]

Adams, AACR Special Conference September 2014 27 Duvelisib and Ibrutinib Show Growth Inhibition Synergy in DLBCL and Follicular Lymphoma Cell Lines

Combination Index

TMD-8 (DLBCL)

0 .5 1 [Ibrutinib] x 0.0077 uM

Combination Index

WSU-NHL (FL)

0 .5 1 [Ibrutinib] x 1.0 uM Adams, AACR Special Conference September 2014 28 PI3K- and PI3K- Inhibition Show Increased Growth Suppression Compared to Inhibition of Either Isoform Alone

Combination Index

0 .5 1 [PI3K- ] x 1.4 uM

Farage DLBCL cell line

Adams, AACR Special Conference September 2014 29 Duvelisib First-in-Class Opportunity in Inflammatory Diseases

30 First-in-Class Opportunity in Inflammatory Diseases

Rheumatoid Arthritis Asthma IPI-443

• Robust controlled • Exploratory • PI3K- inhibitor Phase 2 trial ongoing Phase 2A trial ongoing • Determine development • Topline data in 2014 • Topline data in 2014 strategy following RA and asthma data

31 Phase 2a Trial in Mild, Allergic Asthma

14 Days (C1,2) Washout Period 14 Days (C1,2) 5 Days (C3) 5 Days (C3)

Duvelisib Duvelisib

14-18 subjects per cohort R N=50 Placebo Placebo

• Double-blind, randomized, placebo-controlled, two-period crossover • Designed to evaluate safety and activity as measured by FEV 1 – Dosing: • Cohort 1 (n=14): 1 mg BID for 14 days • Cohort 2 (n=18): 5 mg BID for 14 days • Cohort 3 (n=18): 25 mg BID for 5 days

ClinicalTrials.gov NCT01653756 32 Clinical Improvement in Late-Phase Asthmatic Response Observed at 25 mg BID (5-day Treatment)

Mean (±SE) Change in FEV1 Over Time Post Allergen Challenge

Primary Endpoints p-value

FEV1 maximum reduction in early-phase asthmatic response (EAR) 0.802

FEV1 maximum reduction in late-phase asthmatic response (LAR) 0.052

Secondary Endpoint

FEV1 AUC (area under the curve) over the entire assessment period 0.013

EAR LAR

Time (Hours) Post Allergen Challenge

Duvelisib Placebo 33 Early Proof-of-Activity in Allergen Challenge Study

• Primary endpoint (FEV 1) was not met at any of the doses tested • Clinical improvement in the late-phase asthmatic response at the 25 mg BID dose (p = 0.052) • Multiple secondary and exploratory endpoints achieved at 25 mg BID

– FEV1 AUC (area under the curve) over the assessment period (p = 0.013) – Methacholine challenge (p = 0.036), a measure of airway hyper-reactivity – Decreases in key serum mediators of airway inflammation • Well tolerated with no serious adverse events • Data support further development of PI3K- , inhibitors in asthma

34 ASPIRA: Phase 2 Trial in Moderate-to-Severe RA

0.5 mg duvelisib BID + methotrexate

1 mg duvelisib BID + methotrexate

Randomize 3:1 5 mg duvelisib BID + methotrexate N = ~316 R

Placebo + methotrexate

• Randomized, double-blind, placebo-controlled study evaluating three dose levels of duvelisib • Designed to evaluate safety, activity and PK – Primary endpoint: ACR20 at 12 weeks

ClinicalTrials.gov NCT01851707 35 IPI-443: Maximizing Value of PI3K- , Franchise

• PI3K portfolio enables the evaluation of relative attributes of PI3K- inhibition • Nonclinical studies of IPI-443 to enable Phase 1 development completed

36 Anticipated 2014 Year-End Pipeline

Preclinical Phase 1 Phase 2 Phase 3 Duvelisib in Heme Malignancies iNHL DYNAMO™ DYNAMO+R Combo with Gazyva™or Rituxan® (frontline) CLL DUO™ Frontline (monotherapy) Combo with Gazyva (prior BTK use) Additional Phase 1 exploration

Duvelisib in Inflammation Asthma ASPIRA (RA)

PI3K Pipeline Development IPI-443

Study expected to begin 2014 *R (rituximab); B (bendamustine) 37 Anticipated 2014 Milestones

Duvelisib in Hematologic Malignancies Initiate DYNAMO+RTM Initiate Phase 1b/2 trial in front-line iNHL in combination with GazyvaTM or Rituxan® Initiate Phase 1b trial in R/R CLL in combination with Gazyva in patients with prior BTK use

Duvelisib in Inflammation Report topline data from ASPIRA trial in RA Report topline data from Phase 2a asthma trial

PI3K Pipeline Expansion Determine the development strategy for IPI-443

38 Building a Fully Integrated Biopharmaceutical Company

www.infi.com PI3K- and PI3K- Support the Growth and Survival of B-cell and T-cell Malignancies

40 B-Cell Receptor (BCR) Signaling Through the PI3K Pathway

41 Lenz and Staudt. N Engl J Med. 2010;362(15):1417-29; Compagno et al. Nature 2009;459(7247):717-21; Chen et al.Blood 2008; 111: 2230-37. Duvelisib: Maintaining Patients on Study Going Forward

42 Phase 1 Trial in Healthy Subjects Study Design

Part 1: Single Ascending Dose • Randomized, double-blind, placebo-controlled • Doses evaluated: 1, 2, 5, 10, 25 and 30 mg

Part 2: Multiple Ascending Dose (14 days dosing) • Randomized, double-blind, placebo-controlled • Doses evaluated: 1, 2 and 5 mg BID; 10 mg QD

• Objectives: Tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) following single and repeat doses • 84 subjects evaluated

43 IPI-145 Phase 1 Trial in Healthy Subjects Safety Findings

• IPI-145 well tolerated at doses up to 10 mg daily for 14 days

• No signs or symptoms attributable to treatment (e.g., headache, common cold symptoms, fatigue, dizziness) at any dose level

• No unusual or opportunistic viral or other infections

• No safety related laboratory findings attributable to treatment at any dose level

– No findings in electrocardiograms, hematologic (e.g., hemoglobin, white blood cells, platelets), liver (e.g., transaminases, bilirubin, alkaline phosphatase) or other biochemical parameters (e.g., glucose, creatinine)

Porter et al. ACR 2012. 44 IPI-145 Demonstrates Dose-Dependent Effect in Preclinical Model of Collagen Induced Arthritis

n = 4/Normal Controls n = 8/Treatment Group Vehicle

0.1 mg/kg IPI-145 (*day 14)

0.5 mg/kg IPI-145 (*day 13-17)

5.0 mg/kg IPI-145 (*day 12-17)

10.0 mg/kg etanercept (*day 12-17)

10.0 mg/kg IPI-145 (*day 12-17)

Normal control (*day 11-17)

*p < 0.05

Palombella. New York Academy of Sciences 2012; Porter et al., ACR 2012. 45 Duvelisib Prevents Inflammation and Protects Joint Bone and Cartilage in the Rat CIA Model

Summed Histopathology Scores Scoring components: Inflammation Pannus Cartilage Damage Bone Resorption

* * * * * * * * * * * * * Duvelisib Palombella, Keystone 2013. *p< 0.05 compared to vehicle Exhibit 99.2

Contact: Infinity Pharmaceuticals, Inc. Jaren Irene Madden, 617-453-1336 [email protected] http://www.infi.com

INFINITY REPORTS TOPLINE DATA FROM PHASE 2A EXPLORATORY STUDY OF DUVELISIB IN PATIENTS WITH MILD, ALLERGIC ASTHMA

– Early Evidence for Proof-of-Activity in Allergen Challenge Study –

– Data Provide Rationale for Further Evaluation of PI3K-Delta,Gamma Inhibitors in Asthma –

CAMBRIDGE, Mass. – October 16, 2014 – Infinity Pharmaceuticals, Inc. (NASDAQ: INFI) today announced encouraging topline data from its Phase 2a exploratory study of duvelisib (IPI-145), its oral inhibitor of phosphoinositide-3-kinase (PI3K)-delta and PI3K-gamma, in patients with mild, allergic asthma. Data from this randomized, double-blind, placebo-controlled, cross-over study demonstrated that duvelisib was well tolerated and met several secondary and exploratory endpoints in an allergen challenge study.

Clinical improvement was observed in the late-phase asthmatic response FEV1 (a standard lung function test that measures the amount of air that can be exhaled in one second) among patients who received duvelisib administered at the highest dose tested, 25 mg twice daily (BID) for five days; however the primary endpoint of the study was not met as it did not reach statistical significance (p = 0.052). Multiple secondary clinical endpoints measuring improvements in lung function following duvelisib administration were achieved with statistical significance and were associated with changes in key cytokines and chemokines involved in the asthmatic response. Taken together, these data demonstrate early proof-of-activity in this allergen challenge study. “This is the first clinical study to suggest that inhibition of PI3K-delta and PI3K-gamma plays a role in improving lung function for patients with asthma. In this exploratory study, duvelisib showed evidence of activity across several important clinical measures, including improvement in the late-phase asthmatic response and significant corresponding changes in several key mediators of airway inflammation,” stated Julian Adams, Ph.D., president of research and development at Infinity. “These data support further development of PI3K-delta,gamma inhibitors in more severe forms of asthma, for which there is a medical need.”

“In addition to asthma, we are also studying duvelisib for the treatment of rheumatoid arthritis. We expect to report data from ASPIRA, Infinity’s Phase 2 study of duvelisib with background methotrexate in patients with moderate-to-severe rheumatoid arthritis, by the end of the year. The results of both clinical studies will inform Infinity’s development strategy for its PI3K-delta,gamma program in inflammation,” Dr. Adams continued.

Phase 2a Study of Duvelisib in Asthma The Phase 2a, randomized, double-blind, placebo controlled, exploratory study was designed to evaluate the activity and safety of duvelisib in 50 patients with mild, allergic asthma following an inhalational allergen challenge. Patients were randomized to receive treatment with placebo followed by duvelisib or duvelisib followed by placebo in a two-period cross-over design, with duvelisib administered at either 1 mg BID (n = 14) or 5 mg BID for 14 days (n = 18), or 25 mg BID for five days (n = 18). The study included a washout period between the two treatment periods of this cross-over study, in which each patient serves as his own control.

The study primary endpoint of significantly improving the maximum early-phase or late-phase asthmatic response as measured by FEV1 was not met at any of the doses tested. However, clinical improvement in the late-phase response was observed at the 25 mg BID dose (p = 0.052) and multiple secondary efficacy endpoints were significantly positive at the 25 mg BID dose, including an improvement in FEV1 AUC (area under the curve) over the entire assessment period (p = 0.013) and a decrease in patients’ sensitivity to methacholine treatment, a measure of airway hyper-reactivity (p = 0.036). Additionally, the 5 mg BID and 25 mg BID doses of duvelisib significantly decreased serum levels of key mediators of airway inflammation.

In the study, duvelisib was well tolerated at all three dose levels studied. No serious adverse events were reported, and there were no clinically significant safety findings.

Infinity expects to present the final data in a peer-reviewed setting after all analyses are complete. In addition, the company anticipates determining its next steps for development of PI3K-delta,gamma inhibitors in inflammation after evaluating the results from the ASPIRA study in rheumatoid arthritis, which are expected by the end of 2014. About PI3K-Delta and PI3K-Gamma The PI3Ks are a family of enzymes involved in multiple cellular functions, including cell proliferation and survival, cell differentiation, cell migration and immunity. The Class 1 PI3K-delta and PI3K-gamma isoforms are preferentially expressed in leukocytes (white blood cells), where they have distinct and predominantly non-overlapping roles in key cellular functions, including cell proliferation, cell differentiation, cell migration and activation.1 Targeting PI3K-delta and PI3K-gamma may provide multiple opportunities to develop differentiated therapies for the treatment of hematologic malignancies as well as inflammatory diseases.

Duvelisib in Hematologic Malignancies Infinity and AbbVie Inc. are developing duvelisib for the treatment of advanced hematologic malignancies, or blood cancers. The companies are conducting the DUETTS™ (Duvelisib Trials in Hematologic Malignancies) program, a worldwide investigation of duvelisib in blood cancers. As part of the DUETTS program, patient enrollment is ongoing in DYNAMO™, a Phase 2 monotherapy study designed to evaluate the safety and efficacy of duvelisib in patients with refractory indolent non-Hodgkin lymphoma (iNHL) (ClinicalTrials.gov Identifier NCT01882803), and DUO™, a Phase 3 monotherapy study designed to evaluate the safety and efficacy of duvelisib compared to ofatumumab in patients with relapsed/refractory chronic lymphocytic leukemia (CLL) (NCT02004522). DYNAMO+R, a Phase 3 study of duvelisib in combination with rituximab in patients with previously treated follicular lymphoma (NCT02204982), is expected to start in 2014.

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: the therapeutic potential of PI3K-delta,gamma inhibition and of duvelisib; the timing of final data from the Phase 2a study evaluating duvelisib in asthma as well the timing of data from the ASPIRA study; plans to initiate additional clinical trials; determining next steps for development of its PI3K-delta,gamma inhibitors in inflammation; and its ability to execute on its strategic plans. 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 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 Infinity’s strategic collaboration with AbbVie will continue or 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; a failure of Infinity and/or AbbVie to fully perform under the strategic collaboration and/or an early termination of the collaboration and license agreement; 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; unplanned cash requirements and expenditures; development of agents by Infinity’s competitors for diseases in which Infinity is currently developing or intends to develop its product candidates; 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 (SEC) on August 11, 2014, and other filings filed by Infinity with the SEC. 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.

###

1 Winkler DG, Faia KL, DiNitto JP, et al. PI3K-d and PI3K-g inhibition by IPI-145 abrogates immune responses and suppresses activity in autoimmune and inflammatory disease models. Chem Biol 2013; 20:1-11.