Agios Reports First Quarter 2017 Financial Results IDHIFA (enasidenib) Granted Priority Review by FDA with

Agios Reports First Quarter 2017 Financial Results

IDHIFA (enasidenib) Granted Priority Review by FDA with August 30,

2017 PDUFA Date; Updated Data from Phase 1/2 Trial in IDH2m R/R AML to be Presented at ASCO

Ivosidenib Phase 1 125-Patient Expansion Cohort in IDH1m R/R AML Fully Enrolled; NDA Submission on Track for Year End 2017

AG-348 Granted Fast Track Designation in PK Deficiency by FDA; Updated Data from DRIVE PK

Trial to be Presented at EHA

$287 Million Follow-on Offering Extends Cash

Runway Through at Least the End of 2019

CAMBRIDGE, Mass., May 4, 2017 Agios Pharmaceuticals, Inc. (NASDAQ:

AGIO), a leader in the field of cellular metabolism to treat cancer and rare genetic diseases, today reported business highlights and financial results for the first quarter ended March 31, 2017. In addition, Agios highlighted select corporate

milestones and data presentations for its preclinical and clinical development programs.

Our team made significant progress during the first

quarter advancing our late-stage pipeline and preparing for the first product launch from our research and discovery engine, which is an important milestone for our organization, said David Schenkein, M.D., chief executive officer at Agios.

We are on track to execute against our remaining key 2017 goals, including finalizing the design of our global pivotal program for AG-348 in PK deficiency in the third quarter and submitting both an NDA

for ivosidenib in R/R AML and our sixth IND, for AG-270, a development candidate focused on MTAP-deleted tumors, by the end of the year.

FIRST QUARTER 2017 HIGHLIGHTS & RECENT PROGRESS

IDH Mutant Inhibitors:

Rare Genetic Diseases:

ANTICIPATED 2017 DATA PRESENTATIONS

KEY UPCOMING MILESTONES

IDH Mutant Inhibitors in Hematologic Malignancies

Inhibitors in Solid Tumors

Rare Genetic Diseases

FIRST QUARTER 2017 FINANCIAL RESULTS

revenue was $10.5 million for the quarter ended March 31, 2017, compared to $31.3 million for the comparable period in 2016. The decrease in revenue was primarily due to the fact that in the first quarter of 2016, the company

recognized a $25 million milestone payment related to the initiation of the Phase 3 IDHENTIFY trial of IDHIFA (enasidenib).

Research and development (R&D) expense was $62.7 million, including $7.0 million of stock-based compensation expense, for the quarter ended

March 31, 2017, compared to $44.0 million, including $5.5 million of stock-based compensation expense, for the quarter ended March 31, 2016. 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 IDHIFA (enasidenib) and certain

development costs for AG-881, and reimburses Agios for development costs incurred

for these investigational medicines. In addition, Celgene was responsible for approximately half of development costs for ivosidenib during the quarter ended March 31, 2016. As of August

2016, Agios is responsible for all ivosidenib development costs.

General and administrative (G&A) expense was $14.8 million, including

$3.7 million of stock-based compensation expense, for the quarter ended March 31, 2017, compared to $10.8 million, including $3.6 million of stock-based compensation expense, for the quarter ended March 31, 2016. The

increase in G&A expense was largely due to increased headcount and additional expenses to support our growing commercial organization.

the quarter ended March 31, 2017 was $66.2 million, compared to a net loss of $23.2 million for the quarter ended March 31, 2016.

Cash & Cash Guidance

Cash, cash equivalents and

marketable securities as of March 31, 2017 were $503.2 million, compared to $573.6 million as of December 31, 2016. The decrease in cash was driven by expenditures to fund operations of $79.4 million during the quarter ended

March 31, 2017. These items were offset by an increase in cash of $5.0 million of program funding received under our collaboration agreements with Celgene and $4.1 million received from employee stock award transactions.

In April, Agios completed an underwritten public offering of 5,808,080 shares of common stock, which includes the full exercise of the underwriters

option to purchase an additional 757,575 shares, at the offering price of $49.50 per share, resulting in proceeds, net of underwriting discounts and commissions, of approximately $270.2 million.

The company expects that its cash, cash equivalents and marketable securities as of March 31, 2017, together with the net proceeds from the recent

financing, anticipated interest income, and anticipated payments under our collaboration agreements, but excluding any additional program-specific milestone payments, will enable the company to fund its anticipated operating expenses and capital

expenditure requirements through at least the end of 2019.

CONFERENCE CALL INFORMATION

Agios will host a conference call and live webcast with slides today at 8:00 a.m. ET to discuss first quarter 2017 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 13557397. The live webcast can be accessed under Events & Presentations in the Investors

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 diseases 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

About Agios/Celgene Collaboration

IDHIFA (enasidenib) and AG-881 are part of Agios global

strategic collaboration with Celgene Corporation focused on cancer metabolism. Under the terms of the 2010 collaboration agreement, Celgene has worldwide development and commercialization rights for

IDHIFA (enasidenib). Agios continues to conduct clinical development activities within the IDHIFA (enasidenib) development program

and is eligible to receive reimbursement for those development activities and up to $95 million in remaining payments assuming achievement of certain milestones, and royalties on net sales. Celgene and Agios intend to co-commercialize IDHIFA (enasidenib) in the U.S. Celgene will reimburse Agios for costs incurred for its

co-commercialization efforts. 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. The program focused on MTAP-deleted cancers is part of a 2016 global co-development and co-commercialization

agreement with Celgene focused on metabolic immuno-oncology. Celgene has the option to participate in a worldwide 50/50 cost and profit share with Agios, under which Agios is eligible for up to $169 million in clinical and regulatory milestone

payments for the program.

Cautionary Note Regarding Forward-Looking Statement

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 Agios plans, strategies and expectations for its and its collaborator s preclinical, clinical and commercial advancement of its drug development programs including IDHIFA (enasidenib), ivosidenib, AG-881, AG-348 and AG-270; the potential benefits

of Agios product candidates; its key milestones for 2017; its plans regarding future data presentations; its financial guidance regarding the period in which it will have capital available to fund its operations; and the potential benefit of

its strategic plans and focus. The words anticipate, expect, intend, potential, milestone, goal, will, on track, upcoming, 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 or its collaborator, Celgene, 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 public

filings with the Securities and Exchange Commission. 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)

Senior Director, Investor & Public Relations

Renee Leck, 617-649-8299

Senior Manager, Investor & Public Relations

Holly Manning, 617-844-6630

Associate Director, Corporate Communications