Agios Reports Second Quarter 2017 Financial Results IDHIFA (enasidenib) Granted Approval from FDA as First Targeted Therapy for Patients with IDH2m R/R AML and First Product Approved from Agios Discovery Platform Trial D

Agios Reports Second Quarter 2017 Financial Results

IDHIFA (enasidenib) Granted Approval from FDA as First Targeted Therapy for

with IDH2m R/R AML and First Product Approved from Agios Discovery Platform

Trial Designs Finalized for Two Pivotal Studies for AG-348 in Pyruvate Kinase Deficiency;

Studies on Track to Begin in 1H2018

Initiated Ivosidenib Phase 3 Study (AGILE) in Newly Diagnosed IDH1m AML; NDA

Submission for R/R AML on Track for Year End 2017

CAMBRIDGE, Mass., August 8, 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 second quarter ended June 30, 2017. In addition, Agios highlighted select corporate milestones and preclinical and clinical data from our

clinical development programs.

Our second quarter progress was followed by a remarkable milestone for any biotechnology company, the full approval

of our first product, IDHIFA , a treatment for patients with IDH2m R/R AML developed in partnership with Celgene, said David Schenkein, M.D., chief executive officer at Agios. We

are pursuing a similar regulatory strategy for ivosidenib, our wholly owned IDH1m inhibitor, and we remain on track to submit our NDA by year-end. With the pivotal program designed for AG-348 in PK deficiency, we are working to initiate two trials in the first half of 2018 for this rare anemia, which currently has no approved therapies.

SECOND QUARTER 2017 HIGHLIGHTS & RECENT PROGRESS

IDH Mutant Inhibitors:

Rare Genetic Diseases

EXPECTED 2H 2017 DATA PRESENTATIONS

KEY UPCOMING MILESTONES

The company expects to achieve

the following key milestones:

SECOND QUARTER 2017 FINANCIAL RESULTS

revenue was $11.3 million for the quarter ended June 30, 2017, compared to $7.0 million for the comparable period in 2016. Collaboration revenue increased compared to the prior year period partially due to reimbursement by Celgene of

our share of the commercialization effort for IDHIFA .

Research and development (R&D)

expense was $79.8 million, including $8.2 million of stock-based compensation expense, for the quarter ended June 30, 2017, compared to $50.8 million, including $6.6 million in stock-based compensation expense, for the

quarter ended June 30, 2016. The increase in R&D expense was primarily attributable to activities related to the ivosidenib program, including manufacturing-related activities needed to prepare for a potential NDA submission in 2017, 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. In addition, Celgene was

responsible for approximately half of the development costs for ivosidenib during the quarter ended June 30, 2016. As of August 2016, Agios is responsible for all ivosidenib development costs. R&D expense also increased compared to the

quarter ended June 30, 2016 due to preparations for initiation of the AG-348 pivotal program in the first half of 2018, including manufacturing-related activities. Lastly, the $3.0 million upfront

payment as part of the Aurigene license agreement was included in R&D during the quarter ended June 30, 2017.

General and administrative (G&A) expense was $16.1 million, including $4.0 million stock-based

compensation expense, for the quarter ended June 30, 2017, compared to $12.6 million, including $4.4 million of stock-based compensation expense, for the quarter ended June 30, 2016. The increase in G&A expense was attributed

to an increase of $1.0 million in personnel costs related to an increase in our internal headcount and an increase of $1.9 million related to support our growing commercial organization.

Net loss for the quarter ended June 30, 2017 was $83.1 million, compared to a net loss of $56.0 million for the quarter ended June 30,

Cash, cash equivalents and marketable securities as of June 30, 2017 were $715.9 million, compared to $573.6 million as of December 31,

2016. The increase in cash was driven by net proceeds of $270.2 million from the April financing, $8.1 million of program funding received under our collaboration agreements with Celgene and $6.8 million received from employee stock award

transactions. This was offset by expenditures to fund operations of $142.5 million during the six months ended June 30, 2017.

expects that its cash, cash equivalents and marketable securities as of June 30, 2017, together with anticipated interest income, and anticipated expense reimbursements 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 second 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 61600194. 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.

IDHIFA (enasidenib) is

indicated for the treatment of adult patients with relapsed or refractory acute myeloid leukemia with an isocitrate dehydrogenase-2 (IDH2) mutation as detected by

an FDA-approved test.

Important Safety Information

WARNING: DIFFERENTIATION SYNDROME

Patients treated with IDHIFA have experienced symptoms of differentiation syndrome, which can be fatal if not treated. Symptoms may include fever, dyspnea,

acute respiratory distress, pulmonary infiltrates, pleural or pericardial effusions, rapid weight gain or peripheral edema, lymphadenopathy, bone pain, and hepatic, renal, or multi-organ dysfunction. If differentiation syndrome is suspected,

initiate corticosteroid therapy and hemodynamic monitoring until symptom resolution.

WARNINGS AND PRECAUTIONS

Differentiation Syndrome: See Boxed WARNING. In the clinical trial, 14% of patients treated with IDHIFA experienced differentiation syndrome.

Differentiation syndrome has been observed with and without concomitant hyperleukocytosis, as early as 10 days and at up to 5 months after IDHIFA initiation. If differentiation syndrome is suspected, initiate systemic corticosteroids and hemodynamic

monitoring until improvement. Taper corticosteroids only after resolution of symptoms. Differentiation syndrome symptoms may recur with premature discontinuation of corticosteroids. If severe pulmonary symptoms requiring intubation or ventilator

support and/or renal dysfunction persist for more than 48 hours after initiation of corticosteroids, interrupt IDHIFA until signs and symptoms are no longer severe. Hospitalization for close observation and monitoring of patients with pulmonary

and/or renal manifestation is recommended.

Embryo-Fetal Toxicity: Based on animal embryo-fetal toxicity studies, IDHIFA can cause

embryo-fetal harm when administered to a pregnant woman. Advise females of reproductive potential and males with female partners of reproductive potential to use effective contraception during treatment with IDHIFA and for at least 1 month after the

last dose. Pregnant women, patients becoming pregnant while receiving IDHIFA, or male patients with pregnant female partners should be apprised of the potential risk to the fetus.

Many drugs are excreted in human milk and because of the potential for adverse reactions in breastfed infants, advise women not to breastfeed during treatment

with IDHIFA and for at least 1 month after the last dose.

Please see full Prescribing Information, including Boxed WARNING

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 at www.agios.com.

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 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-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