Agios Reports Second Quarter 2016 Financial Results - Data from PKR Activators at EHA Demonstrated Proof-of-Concept for AG-348 and Proof-of-Mechanism for AG-519; Program Moving Toward Pivotal Development in PK Deficiency

Agios Reports Second Quarter 2016 Financial Results

- Data from PKR Activators at EHA Demonstrated Proof-of-Concept for AG-348 and Proof-of-Mechanism for AG-519; Program Moving Toward Pivotal

Development in PK Deficiency with Molecule Selection by Year-End 2016 -

- $200 Million Upfront Payment Received for New

Metabolic Immuno-Oncology Collaboration with Celgene -

CAMBRIDGE, MA., August 4, 2016 Agios Pharmaceuticals, Inc. (NASDAQ: AGIO),

a leader in the fields of cancer metabolism and rare genetic metabolic disorders, today reported business highlights and financial results for the second quarter ended June 30, 2016.

Second quarter achievements marked tremendous progress towards our 2016 goals across our research and development programs, said David Schenkein,

M.D., chief executive officer at Agios. At EHA, we established clear proof-of-concept for AG-348 in pyruvate kinase deficiency, validating our novel approach to treat rare genetic metabolic disorders by correcting the underlying enzymatic

defect and potentially establishing the first treatment for patients with this serious disease. This milestone sets the stage for pivotal development of our PKR activator program. In addition, our new strategic collaboration with Celgene enables

Agios to expand into the emerging field of metabolic immuno-oncology, an important new field of cancer research. With full worldwide rights for AG-120, we now have another wholly owned investigational medicine we discovered with the potential to

benefit patients waiting for better therapies. As we move into the second half of the year, our focus is on the execution of our late-stage programs and several clinical updates across both IDH and PKR portfolios.

SECOND QUARTER 2016 HIGHLIGHTS & UPDATES

Activator Program for the Treatment of Pyruvate Kinase Deficiency:

Data presented at the 21st Congress of the European Hematology Association (EHA) in

June validated Agios novel approach to the treatment of rare genetic metabolic disorders by correcting the underlying enzymatic defect with a small molecule.

In May, Agios and Celgene announced a new global strategic collaboration focused on metabolic immuno-oncology, an emerging field of cancer research focused on

altering the metabolic state of immune cells to enhance the body s immune response to cancer.

2016 EXPECTED MILESTONES IN CANCER METABOLISM

IDH Mutant Inhibitors in Hematologic Malignancies:

Mutant Inhibitors in Solid Tumors:

Metabolism Research:

2016 EXPECTED MILESTONES IN RARE GENETIC METABOLIC DISORDERS

SECOND QUARTER 2016 FINANCIAL RESULTS

equivalents and marketable securities as of June 30, 2016 were $512.3 million, compared to $375.9 million as of December 31, 2015. The increase in cash was driven by cash received from Celgene totaling $243.5

million, which included a $200 million upfront payment from the May 2016 collaboration agreement, $25 million related to a substantive clinical development milestone for the AG-221 program and $18.5 million of program funding related to our

collaboration agreements. The cash received from Celgene was offset by a decrease in cash related to expenditures to fund operating activities of $104.7 million during the six months ended June 30, 2016.

Collaboration revenue was $7.0 million for the quarter ended June 30, 2016, compared to $13.2 million for the comparable period in

2015. For the second quarter of 2015, collaboration revenue included $8.8 million related to the delivery of the U.S and ex-U.S. licenses for AG-881.

Research and development (R&D) expense was $50.8 million, including $6.6 million of stock-based compensation expense, for the quarter ended

June 30, 2016, compared to $36.4 million, including $4.6 million in stock-based compensation expense, for the quarter ended June 30, 2015. The increase in R&D expense was primarily due to increased costs to support

advancement of the company s lead investigational medicines toward later-stage development. Celgene is responsible for all development costs for AG-221 and certain development costs for AG-881 and reimburses the company for development costs

incurred for these investigational medicines.

General and administrative (G&A) expense was $12.6 million, including $4.4 million of

stock-based compensation expense, for the quarter ended June 30, 2016, compared to $8.9 million, including $3.6 million of stock-based compensation expense, for the quarter ended June 30, 2015. The increase in G&A

expense was largely due to increased headcount and other professional expenses to support growing operations.

Net loss for the quarter ended

June 30, 2016 was $56.0 million, compared to a net loss of $31.9 million for the comparable period in 2015.

Agios will host a conference call and live webcast with slides today at 8:30 a.m. ET to discuss second quarter 2016 financial results and

recent business activities. To participate in the conference call, please dial 1-877-377-7098 (domestic) or 1-631-291-4547 (international) and refer to conference ID 56383998. The live webcast can be accessed under Events &

Presentations in the Investors & Media section of the company s website at www.agios.com. The archived webcast will be available on the company s website beginning approximately two hours after the event.

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.

About Agios/Celgene Collaboration

AG-221 and AG-881 are part of Agios global strategic collaboration with Celgene Corporation. Under the terms of the collaboration, Celgene has worldwide

development and commercialization rights for AG-221 (CC-90007). Agios continues to conduct clinical development activities within the AG-221 development program and is eligible to receive up to $120 million in payments on achievement of certain

milestones and royalties on net sales. Additionally, Agios has the right to co-promote AG-221 in the U.S. along with Celgene. For AG-881, the companies have a joint worldwide development and 50/50 profit share collaboration, and Agios is eligible to

receive regulatory milestone payments of up to $70 million.

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 of IDH1/IDH2 and pyruvate kinase-R mutations as therapeutic targets; the potential benefits of Agios product candidates targeting IDH1/IDH2 or pyruvate kinase-R mutations or other genetic

mutations, including AG-221, AG-120, AG-881, AG-348 and AG-519; its plans and timelines for the clinical development of AG-221, AG-120, AG-881, AG-348 and AG-519; its plans regarding future data presentations; its financial guidance regarding the

amount of cash, cash equivalents and marketable securities that the company will have as of December 31, 2016; and the potential benefit of its strategic plans and focus. 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, 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, except as required by law.

Consolidated Balance Sheet Data

Consolidated Statements of Operations Data

(in thousands, except share and per share data)

Agios Pharmaceuticals:

Kendra Adams, 617-844-6407

Senior Director, Investor &

Senior Manager, Investor & Public Relations