Sage Therapeutics Announces First Quarter 2021 Financial Results and Highlights Pipeline and Business Progress Company on-track to initiate placebo-controlled Phase 2 trial with SAGE-718 in Huntington s disease in late 2

Sage Therapeutics Announces First Quarter 2021 Financial Results and

Highlights Pipeline and Business Progress

Company on-track to initiate placebo-controlled Phase 2 trial with

SAGE-718 in Huntington s disease in late 2021, as the target for the first indication for SAGE-718, following encouraging signals in Phase 1 data

PARADIGM Study with SAGE-718 showed improved performance from baseline on multiple tests of

executive function over 14 days of treatment in patients with Parkinson s disease cognitive impairment, further supporting development in disorders associated with cognitive dysfunction

Positive topline data from Phase 2 KINETIC Study showed statistically significant reduction in tremor score with SAGE-324 compared to placebo at Day 29 in adults with essential tremor

Continued positive data

demonstrated for the 30 and 50 mg doses of zuranolone in open-label SHORELINE Study of zuranolone in patients with major depressive disorder

Conference call today at 8:00 a.m. ET

CAMBRIDGE, Mass. May 4, 2021 Today, Sage Therapeutics, Inc. (NASDAQ: SAGE), a biopharmaceutical company

committed to developing novel therapies with the potential to transform the lives of people with debilitating disorders of the brain, reported business highlights and financial results for the first quarter ended March 31, 2021.

Sage started 2021 with significant advances across our depression, neurology and neuropsychiatry franchises, and the progress we ve made so far

this year sets us up for near-, medium- and long-term value creation opportunities as we further advance our deep organic pipeline, said Barry Greene, chief executive officer at Sage Therapeutics. In the first quarter alone, we

demonstrated the significant potential of our innovative development-stage therapeutics that modulate the GABA and NMDA pathways, through the positive clinical data demonstrated in studies of zuranolone,

SAGE-324 and now SAGE-718. We are making great progress toward our goal of becoming the leading brain health company and a

top-tier biopharmaceutical company, with multiple upcoming catalysts that I believe represent important steps on our mission of delivering medicines that matter to address the ongoing crisis in brain

First Quarter 2021 and Recent Portfolio Updates

Sage is advancing a portfolio of clinical programs featuring internally discovered novel chemical entities with the potential to become differentiated products

designed to improve brain health by targeting the GABAA and NMDA receptor systems. Dysfunction in these systems is thought to be at the core of numerous brain health disorders.

Depression Franchise

Sage s depression franchise

features zuranolone, Sage s next-generation positive allosteric modulator (PAM) of GABAA receptors being evaluated in clinical development as a treatment for various affective

disorders, and ZULRESSO (brexanolone) CIV injection, approved by the U.S. Food and Drug Administration (FDA) as the first treatment specifically indicated for postpartum

depression (PPD). Zuranolone has received breakthrough therapy designation from the FDA for the treatment of major depressive disorder (MDD). Sage is jointly developing zuranolone in the U.S. with Biogen.

Zuranolone is being evaluated as a potential rapid-acting, short-course treatment for PPD and MDD in the NEST

and LANDSCAPE clinical trial programs. Four Phase 3 clinical studies with zuranolone are ongoing. If successful, these programs may support paths to approval with three distinct opportunities to address patient needs: PPD, acute rapid response

therapy (RRT) in MDD when co-initiated with a new standard antidepressant, and as-needed treatment of MDD.

The Company expects the following zuranolone data readouts in 2021:

Sage plans to align with the FDA on data to support a potential future new drug application (NDA). Additional development plans for zuranolone in indications

beyond MDD and PPD will be determined as part of the Company s strategic collaboration with Biogen.

SAGE-324, a next-generation PAM of

GABAA receptors and Sage s lead neurology program, is in development as a potential oral therapy for neurological conditions, such as essential tremor (ET), epilepsy and

Parkinson s disease (PD). Sage is jointly developing SAGE-324 in the U.S. with Biogen.

The following milestones are expected for the neurology franchise in late 2021:

Additional development plans for SAGE-324

will be determined as part of the Company s strategic collaboration with Biogen.

Neuropsychiatry Franchise

SAGE-718, Sage s first-in-class

NMDA receptor PAM and lead neuropsychiatric drug candidate, is in development as a potential oral therapy for cognitive disorders associated with NMDA receptor dysfunction, potentially including Huntington s disease (HD), PD and

Alzheimer s disease (AD).

In the Phase 2a open-label PARADIGM Study, eight patients aged 50 to 75 years old with mild cognitive impairment due

to PD received SAGE-718 3 mg daily for two-weeks.

Findings from the PARADIGM Study extend Sage s understanding of the potential impact of SAGE-718 on multiple

domains of cognition. To date, SAGE-718 has demonstrated improvements in executive function in phase 1 and phase 2a studies and these findings add to the Company s confidence in the potential for SAGE-718 to become an important treatment for disorders associated with cognitive dysfunction, including HD, PD and AD.

Based on data generated with SAGE-718 to date, the Company intends to pursue several paths forward for SAGE-718 in parallel:

The following milestones are expected for the neuropsychiatry franchise in late 2021:

Sage expects to complete certain Phase 1 clinical studies for two programs in its early development pipeline in 2021,

SAGE-689 (single ascending dose) and SAGE-904 (single ascending dose and multiple ascending dose).

Results from the planned Phase 1

studies will inform further development of these programs.

Additionally, the Company recently announced plans to advance

SAGE-319 and SAGE-421 to preclinical studies.

Other Development Opportunities

Sage s Phase 3 trial with brexanolone in patients with advanced COVID-19 related acute respiratory

distress syndrome (ARDS) is ongoing. The Company expects data from this trial in 2021.

ANTICIPATED 2021 MILESTONES

FINANCIAL RESULTS FOR THE FIRST QUARTER 2021

Conference Call Information

will host a conference call and webcast today, Tuesday, May 4, at 8:00 a.m. ET to discuss its first quarter 2021 financial results and recent corporate updates. The live webcast can be accessed on the investor page of Sage s website at

investor.sagerx.com. 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 biopharmaceutical company committed to developing novel therapies with the potential to transform the lives of people with debilitating

disorders of the brain. We are pursuing new pathways with the goal of improving brain health, and our depression, neurology and neuropsychiatry franchise programs aim to change how brain disorders are thought about and treated. Our mission is to

make medicines that matter so people can get better, sooner. For more information, please visit www.sagerx.com.

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

views and expectations regarding our planned research and development activities and related timelines, including plans for reporting data, initiation of new activities, and advancement of our pipeline; our belief in the potential profile and

benefit of our product candidates, and the opportunity to help patients in various indications; the potential regulatory pathways for our product candidates and potential lead indications; our goal to deliver medicines that we hope will help

patients; our mission to become the leading brain health company and top-tier bio-pharmaceutical company; our statements regarding the vision, opportunity and potential

for our business and potential value creation opportunities; and our expectations with respect to 2021 year-end cash. These statements constitute forward-looking statements as that term is defined in the

Private Securities Litigation Reform Act of 1995. 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: success in non-clinical studies or in earlier clinical trials or at interim time

periods may not be repeated or observed in ongoing or future studies, and ongoing and future non-clinical and clinical results may not meet their primary or key secondary endpoints or be sufficient to file for

or gain regulatory approval to market the product without further development work or may not support further development at all; we may encounter adverse events at any stage of development that negatively impact further development or that require

additional nonclinical and clinical work which may not yield positive results; we may encounter different or more severe adverse events at the higher doses we are studying in our ongoing trials; we may encounter issues with the efficacy or

durability of short-term treatment, or co-initiated treatment with zuranolone or safety and efficacy concerns with respect to retreatment that require additional studies be conducted; the impact of the COVID-19 pandemic on our clinical development timelines may be more significant than we expect and may negatively impact expected site initiation, enrollment or conduct in our clinical trials, or cause us to pause

trials or not be able to use data, in each case which may significantly impact our ability to meet our expected timelines or may significantly impact the integrity or sufficiency of the data from our trials or increase our costs or cause us to have

to change our plans; we may encounter other delays in initiation, conduct or completion of our ongoing and planned clinical trials, including as a result of slower than expected site initiation or enrollment, the need or decision to expand the

trials or other changes, that may impact our ability to meet our expected timelines and increase our costs; the FDA may ultimately decide that the design or results of our completed and planned clinical trials for any of our product candidates, even

if positive, are not sufficient for regulatory approval in the indications that are the focus of our development plans; other 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; the anticipated benefits of our ongoing collaborations may never be achieved and the need to align with our collaborators may hamper or delay our development and

commercialization efforts or increase our costs; our business may be adversely affected and our costs may increase if any of our key collaborators fails to perform its obligations or terminates our collaboration; the internal and external costs

required for our ongoing and planned activities, and the resulting impact on expense and use of cash, may be higher than expected which may cause us to use cash more quickly than we expect or change or curtail some of our plans or both; we may never

be able to generate meaningful revenues from sales of ZULRESSO or to generate revenues at levels we expect or at levels necessary to justify our investment; we may not be successful in our development of any of our product candidates in any

indication we are currently pursuing or may in the future pursue; our expectations as to year-end cash may prove not to be correct for other reasons such as changes in plans or actual events being different

than our assumptions; we may be opportunistic in our future financing plans even if available cash is sufficient; the number of patients with the diseases or disorders for which our products are developed or the unmet need for additional treatment

options may be significantly smaller than we expect; and we may encounter technical and other unexpected hurdles in the development and manufacture of our product candidates or the commercialization of our marketed product which may delay our timing

or change our plans, increase our costs or otherwise negatively impact our business; 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.

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

ZULRESSO can cause serious side effects, including:

ZULRESSO can cause other serious side effects, including:

The most common side effects of ZULRESSO include:

Call your doctor for medical advice about side effects. You may report side effects to FDA at