Agios Reports Fourth Quarter and Full Year 2017 Financial Results All 2017 Key Milestones Achieved, Including First U.S. Product Approval from Agios Discovery Platform and NDA Submission for Second Product Candidate, Ivo

Agios Reports Fourth Quarter and Full Year 2017 Financial Results

All 2017 Key Milestones Achieved, Including First U.S. Product Approval from Agios

Discovery Platform and NDA Submission for Second Product Candidate, Ivosidenib, for

2018 Priorities Focus on Expanding Clinical and Research Programs to Drive Long-Term

2017 Year-End Cash, Cash Equivalents and Marketable Securities was $568M; January

Follow-on Offering of $516M Extends Cash Runway Through at Least the End of 2020

February 14, 2018 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

fourth quarter and year ended December 31, 2017. In addition, Agios highlighted select 2018 corporate milestones and data presentations for its clinical development programs.

2017 was an extraordinary year for Agios with the U.S. approval of IDHIFA , our first

internally discovered and developed drug, the NDA submission for our wholly owned medicine ivosidenib and our sixth IND submission since the company s inception, said David Schenkein, M.D., chief executive officer at Agios. It was a

data-rich year where we set the stage for building long-term value across our cancer and rare disease portfolios. Execution in 2018 will be equally critical as we ready our organization for the potential approval and launch of ivosidenib, initiate

our pivotal program for AG-348 in pyruvate kinase deficiency and advance our robust discovery portfolio.

KEY UPCOMING MILESTONES

The company plans to achieve the

following key milestones in 2018:

Rare Genetic Diseases:

ANTICIPATED KEY 2018 DATA PRESENTATIONS

FOURTH QUARTER 2017 HIGHLIGHTS & RECENT PROGRESS

FULL YEAR 2017 FINANCIAL RESULTS

Cash, cash equivalents

and marketable securities as of December 31, 2017 were $567.8 million, compared to $573.6 million as of December 31, 2016. The decrease in cash was driven by expenditures to fund operations of $306.8 million during the year

ended December 31, 2017. These expenditures were offset by an increase in cash driven by net proceeds of $270.2 million from the April follow on offering, $17.0 million of cost reimbursements under our collaboration agreements with

Celgene and $14.2 million received from employee stock transactions.

Revenue for the year ended December 31, 2017 was $43.0 million, which

includes $41.1 million of collaboration revenue and $1.9 million of royalty revenue from net sales of IDHIFA . Revenue for the year ended December 31, 2016 was

$69.9 million, which included a $25.0 million milestone payment related to the initiation of the Phase 3 IDHENTIFY trial with IDHIFA under the 2010 Agreement.

Research and development (R&D) expenses were $292.7 million, including $30.8

million of stock-based compensation expense, for the year ended December 31, 2017, compared to $220.2 million, including $25.4 million in stock-based compensation expense, for the year ended December 31, 2016. The

increase in R&D expense was primarily attributable to the ivosidenib program, including manufacturing and regulatory activities to prepare the NDA submission, start-up costs for the Phase 3 AGILE clinical

trial, and on-going site activation and patient enrollment of the Phase 3 ClarIDHy clinical trial. R&D expense also increased compared to the prior year due to IND enabling activities for AG-270.

General and administrative (G&A) expenses were $71.1 million, including $17.0

million of stock-based compensation expense, for the year ended December 31, 2017, compared to $50.7 million, including $16.7 million of stock-based compensation expense, for the year ended December 31, 2016.

The increase in G&A expense was primarily attributable to an increase of $21.1 million to support our growing commercial organization for the launch of IDHIFA and the potential

launch of ivosidenib in 2018.

Net loss for the year ended December 31, 2017 was $314.7 million, compared to a net loss of $198.5

million for the year ended December 31, 2016.

In January, Agios completed an underwritten public offering of 8,152,986 shares of common stock, which includes the full exercise of the underwriters

option to purchase an additional 1,063,433 shares, at the offering price of $67.00 per share, resulting in proceeds, net of underwriting discounts and commissions, of approximately $516.2 million.

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

financing, anticipated product and royalty revenue, anticipated interest income, and anticipated expense reimbursements, 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 2020.

CONFERENCE CALL INFORMATION

Agios will host a conference call and live webcast with slides today at 8:00 a.m. ET to discuss fourth quarter and full year 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 referring to conference ID 3198522. 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 an approved oncology precision medicine and multiple

first-in-class investigational therapies 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.

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 certain 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 any net sales. Celgene and Agios are currently co-commercializing 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 (methylthioadenosine phosphorylase)-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 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 Agios plans, strategies and expectations for its and its collaborator s preclinical, clinical and commercial advancement of its drug development programs including IDHIFA , ivosidenib, AG-881, AG-348 and AG-270; the potential benefits of

Agios product candidates; its key milestones for 2018; 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, believe, estimate, expect, intend, may, plan, predict, project, would,

could, potential, possible, hope, strategy, milestone, will, 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)

Renee Leck, 617-649-8299

Senior Manager, Investor Relations

Holly Manning, 617-844-6630

Associate Director, Corporate Communications