Sage Therapeutics Announces Second Quarter 2017 Financial Results and Provides Pipeline Update Enrollment completed in Phase 3 STATUS Trial of brexanolone in SRSE; reiterate Q3 2017 guidance for top-line results Positive

Sage Therapeutics Announces Second Quarter 2017 Financial Results and Provides Pipeline Update

Enrollment completed in Phase 3 STATUS Trial of brexanolone in SRSE; reiterate Q3 2017 guidance for top-line results

Positive scientific advice from European Medicines Agency on development of brexanolone in PPD provides regulatory path in EU

Updated guidance for SAGE-217 Phase 2 placebo-controlled trial in major depressive disorder; top-line results now expected in 2H 2017 due to

strong pace of enrollment

Conference Call Today at 4:30 PM ET

CAMBRIDGE, Mass., August 3, 2017 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 second quarter ended June 30, 2017.

Throughout our six-year history, we have explored innovative methods of drug discovery and development, as well as clinical trial design, in pursuit of

novel treatments for CNS disorders that may address gaps in the efficacy and safety profile of current therapies, said Jeff Jonas, M.D., chief executive officer of Sage. Our deliberate, thoughtful, and disciplined approach facilitated

the potential for two Phase 3 data readouts and multiple other clinical milestone events in the second half of this year. I m extremely proud of the progress our team has made in a diverse set of disease areas with the goal of positioning Sage

for success as a multi-product CNS leader.

Brexanolone in SRSE - Completion of Enrollment in Phase 3 STATUS Trial

Sage recently completed enrollment in the Phase 3 STATUS Trial, the first ever global, randomized, double-blind, placebo-controlled trial in super-refractory

status epilepticus (SRSE). Sage continues to expect to report top-line results from the STATUS Trial in the third quarter of 2017, following completion of all study follow-up periods and data analysis.

Brexanolone in PPD Positive Scientific Advice from European Medicines Agency

In 2016, the European Medicines Agency (EMA) granted PRIority MEdicines (PRIME) designation to brexanolone for the treatment of postpartum depression (PPD).

Sage conducted its PRIME meeting with EMA authorities earlier this year and recently received positive scientific advice. Incorporating the scientific advice from the EMA, Sage believes its proposed Phase 3 program, if successful, will be sufficient

to support a European Marketing Authorization Application (MAA) to the EMA for the PPD indication. Scientific Advice is a procedure offered by the EMA to stakeholders for clarification of questions arising during development of medicinal products

and focuses on development strategies rather than pre-evaluation of data to support an MAA.

SAGE-217 in MDD Phase 2 Trial Update

Sage is currently conducting a multi-center, double-blind, placebo-controlled, randomized Phase 2 clinical trial of SAGE-217 in major depressive disorder

(MDD). Due to the robust pace of enrollment, Sage now plans to increase expected enrollment to approximately 88 patients with moderate to severe MDD, from approximately 66 patients. Sage anticipates reporting top-line results from the Phase 2 trial

in the second half of 2017, rather than in 2018.

SAGE-217 in Parkinson s Disease Phase 2 Trial Update

Based on a positive activity signal observed in the Part A open-label portion of the Phase 2 program of SAGE-217 in Parkinson s disease, Sage recently

initiated an open-label Part B study to evaluate SAGE-217 as an adjunctive treatment in approximately 10 tremor-predominant Parkinson s disease patients. Top-line results from the Part B study are expected in the second half of 2017.

Expected Near-Term Clinical Milestones

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. Sage is pursuing a data-driven approach to CNS drug development by employing efficient human proof-of-concept studies both to uncover activity signals and to help understand future trial

methodology, before investing in larger clinical programs.

Financial Results for the Second Quarter of 2017

Conference Call Information Sage will host a conference call and webcast today at 4:30 PM

ET to discuss its second quarter financial results and recent corporate 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

1-866-450-8683 (toll-free domestic) or 1-281-542-4847 (international) and using the conference ID 58436410. 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

central nervous system (CNS) disorders. Sage has a portfolio of novel product candidates targeting critical CNS receptor systems, GABA and NMDA. Sage s lead program, brexanolone (SAGE-547), is in Phase 3 clinical development for

super-refractory status epilepticus, a rare and severe seizure disorder, and for postpartum depression. Sage is developing its next generation modulators, including SAGE-217 and SAGE-718, in various CNS disorders. For more information, please visit

Forward-Looking Statements

Various statements in this release concern Sage s future expectations, plans and prospects, including without limitation: our expectations regarding

development of our product candidates and their potential in the treatment of various CNS disorders; the expected timing of initiation and completion of clinical trials; the anticipated availability and announcement of data and results from clinical

trials of our product candidates; our plans for evaluation of new indications and new compounds; our expectations regarding the regulatory pathway for brexanolone (SAGE-547), including our belief that the results of the current development program

for brexanolone in SRSE and PPD, if successful, will be sufficient for MAA filings in the EU; our expectations regarding a potential future commercial launch of brexanolone, if successfully developed and approved, and the potential for our success

as a multi-product company; and our expectations with respect to future cash use and 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: we may experience slower than expected clinical site

initiation and enrollment in our clinical trials, or the potential need for additional analysis or data or the need to enroll additional patients, leading to possible delays in completion of trials or in the availability of data; we may not be able

to generate supportive non-clinical data or to successfully demonstrate the efficacy and safety of our product candidates at each stage of clinical development; success in our non-clinical studies or in earlier stage clinical trials may not be

repeated or observed in ongoing or

future studies involving the same compound or other product candidates, and ongoing and future pre-clinical and clinical results may not support further development of product candidates or be

sufficient to gain regulatory approval to launch and commercialize any product; decisions or actions of regulatory agencies may affect the initiation, timing, progress and cost of clinical trials, and our ability to proceed with further clinical

studies of a product candidate or to obtain marketing approval or may result in restrictions in an approved indication or the need for additional clinical trials, including the risk that regulatory authorities may, despite prior advice, decide that

the clinical and non-clinical data from our development programs are not sufficient to support approval; 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 and manufacture of our products which may delay our timing or increase our expenses and use of cash, as well as those risks more fully discussed in the section entitled Risk

Factors in our most recent Quarterly Report on Form 10-Q, as well as 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.

Paul Cox, Sage Therapeutics

Maureen L. Suda, Suda Communications LLC

Sage Therapeutics, Inc. and Subsidiaries

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Sage Therapeutics, Inc. and Subsidiaries

Condensed Consolidated Statements of Operations

(in thousands, except share and per share data)