Sage Therapeutics Announces Third Quarter 2018 Financial Results and Highlights Pipeline and Business Progress FDA Advisory Committee Meeting outcome supports approval of ZULRESSO (brexanolone) injection as the first med

Sage Therapeutics Announces Third Quarter 2018 Financial Results and Highlights Pipeline and Business Progress

FDA Advisory Committee Meeting outcome supports approval of ZULRESSO (brexanolone) injection as the first medicine specifically

indicated for the treatment of postpartum depression (PPD)

Continuing to execute commercial strategy for ZULRESSO in PPD ahead of

PDUFA target date of December 19, 2018 and readiness for planned U.S. launch in late March

Completion of enrollment in Phase 3

clinical trial of SAGE-217 in PPD top-line results expected in January 2019

Expansion of depression franchise with initiation of Phase 2 clinical trial of SAGE-217 in bipolar

depression and multiple near-term trial initiations expected in major depressive disorder

Continued progress for SAGE-324 and SAGE-718 in early clinical pipeline

Conference call today at 8:00 AM ET

CAMBRIDGE, Mass., November 6, 2018 Sage Therapeutics, Inc. (NASDAQ: SAGE), a clinical-stage biopharmaceutical company developing novel

medicines to treat life-altering central nervous system (CNS) disorders, today reported business highlights and financial results for the third quarter ended September 30, 2018.

At Sage, our approach to scientific discovery and development is focused on transforming the lives of people with life-altering CNS disorders. Our first

program, in PPD, exemplifies this philosophy. Members of the PPD patient advocacy community and healthcare providers across the country have shared their sense of urgency with us they are seeking a new way of thinking about PPD and an

opportunity to rapidly alleviate suffering from this condition. If approved, ZULRESSO has the potential to meet these needs and to be an important new tool that healthcare providers can use to ease the burden of PPD for patients and their

families, said Jeff Jonas, M.D., chief executive officer of Sage. Sage is committed to helping women diagnosed with PPD access ZULRESSO, if it is approved. We are currently assessing potential patient support options to help lessen

financial barriers to access for women with PPD in need of treatment, where appropriate and permitted. We aspire to define a new normal for brain health and we re just getting started.

ZULRESSOTM (brexanolone) Injection Regulatory and

Pre-Launch Activities Updates:

Beyond ZULRESSO, Sage is advancing a portfolio of novel CNS product candidates targeting the GABA and NMDA receptor systems. Dysfunction in these systems is

known to be at the core of numerous psychiatric and neurological disorders.

Financial Results for the Third Quarter of 2018

Conference Call Information

conference call and webcast on Tuesday, November 6, 2018 at 8:00 AM ET to report its third quarter 2018 financial results and to discuss recent business updates. The live webcast can be accessed on the investor page of Sage s website at

investor.sagerx.com. The conference call can be accessed by dialing (866) 450-8683 (toll-free domestic) or (281) 542-4847 (international) and using the conference ID

1891169. A replay of the webcast will be available on Sage s website approximately two hours after the completion of the event and will be archived for up to 30 days.

About Sage Therapeutics

Sage Therapeutics is a

clinical-stage biopharmaceutical company committed to developing novel medicines to transform the lives of patients with life-altering CNS disorders. Sage s lead product candidate, ZULRESSO (brexanolone) injection, has completed Phase 3

clinical development for postpartum depression and a New Drug Application is currently under review with the U.S. Food and Drug Administration. Sage is developing a portfolio of novel product candidates targeting critical CNS receptor systems,

including SAGE-217, which is in Phase 3 development in major depressive disorder and postpartum depression. For more information, please visit www.sagerx.com.

Forward-Looking Statements

in this release concern Sage s future expectations, plans and prospects, including without limitation: our expectations regarding the potential for approval of our NDA for ZULRESSO in the treatment of PPD, including the target timing of a

decision by the FDA; our plans regarding the timing of launch of ZULRESSO in PPD and future commercial activities, if approved; our plans for determining the potential regulatory pathway for brexanolone injection in the EU; our statements regarding

plans and timelines for development of SAGE-217 and our other product candidates, including planned clinical and regulatory activities; our views as to the opportunity represented by Sage s portfolio and

business; and our expectations regarding increases in operating expense, use of cash and future cash needs. These forward-looking statements are neither promises nor guarantees of future performance, and are subject to a variety of risks and

uncertainties, many of which are beyond our control, which could cause actual results to differ materially from those contemplated in these forward-looking statements, including the risks that: the FDA may not agree with the recommendation of the

Advisory Committees, and may decide not to approve our NDA for ZULRESSO in PPD; the clinical and non-clinical data we have generated with our proprietary formulation of brexanolone to date may be determined by

the FDA, the EMA and other regulatory authorities to be insufficient to gain regulatory approval to launch and commercialize our product in PPD and regulatory authorities may determine that additional trials or data are necessary in order to file

for or obtain approval;

the FDA may not complete its review of our filing within the target timelines; even if ZULRESSO is successfully approved for PPD in the U.S., we may encounter issues, delays or other challenges

in launching or commercializing the product, including issues related to market acceptance and reimbursement, challenges associated with restrictions or conditions that may be imposed by regulatory authorities, including challenges related to

limiting the site of administration to a certified healthcare facility monitored by a qualified healthcare provider, and the necessity for a REMS; and challenges associated with the build of our sales and patient support organizations and their

activities, which in each case could limit the potential of our product; we may encounter unexpected safety or tolerability issues with ZULRESSO, SAGE-217 or any of our other product candidates in ongoing or

future development; we may not be successful in our development of SAGE-217 or any of our other product candidates in any indication we are currently pursuing or may in the future pursue; success in early

stage clinical trials may not be repeated or observed in ongoing or future studies of SAGE-217 or any of our other product candidates; ongoing and future clinical results may not support further development or

be sufficient to gain regulatory approval of our product candidates; we may decide that a development pathway for one of our product candidates in one or more indications is no longer feasible or advisable or that the unmet need no longer exists;

decisions or actions of the FDA or other regulatory agencies may affect the initiation, timing, design, size, progress and cost of clinical trials and our ability to proceed with further development or may impact the regulatory pathway; we may

experience slower than expected enrollment in ongoing clinical trials; the internal and external costs required for our activities, and to build our organization in connection with such activities, and the resulting use of cash, may be higher than

expected, or we may conduct additional clinical trials or pre-clinical studies, or engage in new activities, requiring additional expenditures and using cash more quickly than anticipated; and we may encounter

technical and other unexpected hurdles in the development, manufacture and potential future commercialization of our product candidates; as well as those risks more fully discussed in the section entitled Risk Factors in our most recent

Quarterly Report on Form 10-Q, and discussions of potential risks, uncertainties, and other important factors in our subsequent filings with the Securities and Exchange Commission. In addition, any

forward-looking statements represent our views only as of today, and should not be relied upon as representing our views as of any subsequent date. We explicitly disclaim any obligation to update any forward-looking statements.

Sage Therapeutics, Inc. and Subsidiaries

Condensed Consolidated Statements of Operations

(in thousands, except share and per share data)

Sage Therapeutics, Inc. and Subsidiaries

Condensed Consolidated Balance Sheets