Agios Reports Initial Data from Phase 1 Study of AG-519 in Healthy Volunteers - Data Demonstrate Favorable Safety Profile with up to 14 Days of Daily Dosing - - Robust Dose-Dependent Changes in ATP and 2,3-DPG Blood Leve

Agios Reports Initial Data from Phase 1 Study of AG-519 in Healthy Volunteers

- Data Demonstrate Favorable Safety Profile with up to 14 Days of Daily Dosing -

- Robust Dose-Dependent Changes in ATP and 2,3-DPG Blood Levels Observed Consistent with PKR Enzyme Activation -

- Company to Host Conference Call and Webcast Saturday, June 11 at 9:30am ET -

COPENHAGEN, June 9, 2016 Agios Pharmaceuticals, Inc. (Nasdaq:AGIO) today announced the initial data from the Phase 1 integrated single

ascending dose (SAD) and multiple ascending dose (MAD) clinical trial of AG-519 in healthy volunteers at the 21st Congress of the European Hematology Association (EHA) taking place June 9-12,

2016 in Copenhagen. These data provide early proof-of-mechanism for AG-519, a potent, oral, selective second pyruvate kinase-R (PKR) activator that is wholly owned by Agios. Agios is also developing AG-348, a first-in-class, oral PKR activator that

is being evaluated in an ongoing Phase 2 study, DRIVE-PK.

In this Phase 1 study, dosing of AG-519 over 14-days in healthy volunteers resulted in a

dose-dependent increase in PKR activity as evidenced by a substantial increase in ATP (adenosine triphosphate) and decrease in 2,3-DPG (2,3-diphosphoglycerate) levels, which are important biomarkers of PKR activation in healthy volunteers. These

data support the hypothesis that AG-519 enhances PKR activity and has the potential to correct the underlying defect of pyruvate kinase (PK) deficiency, a rare, potentially debilitating, congenital anemia.

Achieving proof-of-mechanism for AG-519, our second PKR activator, further advances Agios novel approach to the treatment of rare metabolic

disorders, said Chris Bowden, M.D., chief medical officer of Agios. These Phase 1 data from AG-519 bring us closer to our goal of delivering the first disease-modifying treatment for patients with PK deficiency.

Results from the Completed SAD Portion of the Phase 1 Study

Preliminary Results from the Ongoing MAD Portion of the Phase 1 Study

Conference Call Information

Agios will host a conference call and webcast from EHA to review the data from the AG-348 DRIVE-PK study and the AG-519 Phase 1 Study in Healthy Volunteers on

Saturday June 11, 2016 beginning at 9:30 a.m. ET (3:30 p.m. CEST). To participate in the conference call, please dial (877) 377-7098 (domestic) or (631) 291-4547 (international) and refer to conference ID 18475657. The webcast will be

accessible live or in archived form under Events & Presentations in the Investors and Media section of the company s website at www.agios.com.

PK deficiency is a rare inherited

disease that presents as hemolytic anemia, which is the accelerated destruction of red blood cells. The mutations in PKR enzymes cause a deficit in cellular energy within the red blood cell, as evidenced by lower pyruvate kinase enzyme activity and

a decline in ATP levels and a build-up of upstream metabolites, including 2,3-DPG.

The current standard of care for PK deficiency is supportive,

including blood transfusions, splenectomy, chelation therapy to address iron overload and/or interventions for other treatment- and disease-related morbidities. Currently, there is no approved therapy to treat the underlying cause of PK deficiency.

Boston Children s Hospital in collaboration with Agios is also conducting a natural history study to better understand the symptoms and

complications of PK deficiency, identify patients and treatment centers and capture other clinical data including quality of life measures and genetic information.

About Agios PK-R Activators

AG-348 and AG-519 are orally available, potent, selective small molecule activators of PKR. Both molecules were discovered by the Agios research team and the

company retains worldwide development and commercialization rights.

Agios is focused on discovering and developing novel investigational medicines to treat cancer and rare genetic metabolic disorders through scientific

leadership in the field of cellular metabolism. In addition to an active research and discovery pipeline across both therapeutic areas, Agios has multiple first-in-class investigational medicines in clinical and/or preclinical development. All Agios

programs focus on genetically identified patient populations, leveraging our knowledge of metabolism, biology and genomics. For more information, please visit the company s website at www.agios.com.

Cautionary Note Regarding 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 potential benefits of Agios product candidates targeting pyruvate kinase-R mutations, including AG-348 and AG-519; Agios plans for the further clinical development of AG-519; and its strategic

plans and prospects. The words anticipate, believe, estimate, expect, intend, may, plan, predict, project, would,

could, potential, possible, hope and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these identifying words. Such

statements are subject to numerous important factors, risks and uncertainties that may cause actual events or results to differ materially from Agios current expectations and beliefs. For example, there can be no guarantee that any product

candidate Agios is developing will successfully commence or complete necessary preclinical and clinical development phases, that positive safety and efficacy findings observed in early stage clinical trials will be replicated in later stage trials;

or that development of any of Agios product candidates will successfully continue. There can be no guarantee that any positive developments in Agios business 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 important factors, including: Agios 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; Agios ability to obtain and maintain requisite regulatory approvals and to enroll patients in its planned clinical trials; unplanned cash requirements and expenditures; competitive factors; Agios ability to

obtain, maintain and enforce patent and other intellectual property protection for any product candidates it is developing; Agios ability to maintain key collaborations, such as its agreements with Celgene; and general economic and market

conditions. These and other risks are described in greater detail under the caption Risk Factors included in Agios

Quarterly Report on Form 10-Q for the quarter ended March 31, 2016, and other filings that Agios may make with the

Securities and Exchange Commission in the future. Any forward-looking statements contained in this press release speak only as of the date hereof, and Agios expressly disclaims any obligation to update any forward-looking statements, whether as a

result of new information, future events or otherwise.

Kendra Adams, 617-844-6407

Senior Director, Investor &

Senior Manager, Investor & Public Relations

Dan Budwick, 973-271-6085

Senior Vice President, Media Relations

Pure Communications Inc.