A Trial of the Safety and Efficacy of SEP-363856 in the Treatment of Adults With Major Depressive Disorder

February 13, 2026 updated by: Otsuka Pharmaceutical Development & Commercialization, Inc.

A Phase 2/3, Multicenter, Randomized, Double-blind, Placebo-controlled Trial of the Safety and Efficacy of Flexible Doses of SEP-363856 as Adjunctive Therapy in the Treatment of Adults With Major Depressive Disorder

Demonstrate ability of SEP-363856 to be superior to placebo as an adjunctive therapy to ADT in change from baseline in depressive symptoms (MADRS & CGI-S) in MDD patients who had an inadequate response to prior ADT therapy.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

929

Phase

  • Phase 2

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Bulgaria
      • Pazardzhik, Bulgaria, 4400
        • Diagnostic Consultive Center Higya AD
      • Plovdiv, Bulgaria, 4002
        • Ambulatory for Group Practice for Specialized Psychiatrics Help PHILIPOPOLIS OOD
      • Sofia, Bulgaria, 1113
        • Medical Center Sveti Naum
      • Varna, Bulgaria, 9020
        • DCC-Mladost M OOD
      • Vratsa, Bulgaria, 3000
        • Mental Health Center Vratsa
  • Canada
    • Ontario
      • Chatham, Ontario, Canada, N7L 1C1
        • Chatham-Kent Clinical Trials Research Centre
      • Ottawa, Ontario, Canada, K1Z 7K4
        • Institute of Mental Health Research IMHR
      • Toronto, Ontario, Canada, M6J 1H4
        • Centre for Addiction and Mental Health (CAMH & University of Toronto)
  • Czechia
      • Klecany, Czechia, 25067
        • National Institute of Mental Health
      • Prague, Czechia, 10000
        • CLINTRIAL s.r.o.
    • Central Bohemia
      • Kladno, Central Bohemia, Czechia, 272 01
        • Brain-Soultherapy s.r.o.
    • Plzeň Region
      • Ptzen, Plzeň Region, Czechia, 30100
        • A-shine s.r.o.
  • Germany
      • Westerstede, Germany, 26655
        • Arztepartnerschaft Dr. med. J. Springhub/ W. Schwarz-Studienzentrum Nord-West
    • Hesse
      • Wiesbaden, Hesse, Germany, 65189
        • Velocity Clinical Research Wiesbaden
    • MA
      • Chemnitz, MA, Germany, 09111
        • Pharmakologisches Studienzentrum Chemnitz GmbH
    • Mecklenburg
      • Schwerin, Mecklenburg, Germany, 19053
        • Somni Bene Institut for Medical Research
    • Mecklenburg-Vorpommern
      • Stralsund, Mecklenburg-Vorpommern, Germany, 18439
        • Private Practice Kusserow
  • Hungary
      • Budapest, Hungary, 1033
        • Clinexpert Kft.
      • Budapest, Hungary, M6J 1H4
        • Semmelweis University
  • Poland
      • Lublin, Poland, 20-109
        • Centrum Medyczne Luxmed Sp.z. o.o.
      • Szkolkarska 32, Poland, 62-002
        • Indywidualna SpecjalistycznaPraktyka Lekarska AgnieszkaRemlinger-Molenda
    • Greater Poland Voivodeship
      • Poznan, Greater Poland Voivodeship, Poland, 60-192
        • Praktyka Lekarska Malgorzata Wojtanowska-Bogacka
    • Kuyavian-Pomeranian Voivodeship
      • Bydgoszcz, Kuyavian-Pomeranian Voivodeship, Poland, 85-794
        • Osrodek Badan Klinicznych Clinsante
    • OH
      • Bialystok, OH, Poland, 15-404
        • MlynowaMed - Bialystok
  • United States
    • Alabama
      • Birmingham, Alabama, United States, 35294
        • University of Alabama at Birmingham
    • Arizona
      • Scottsdale, Arizona, United States, 85260
        • Scottsdale Clinical Research
      • Tucson, Arizona, United States, 85715
        • DelSol Research
    • Arkansas
      • Bentonville, Arkansas, United States, 72712
        • Pillar Clinical Research
    • California
      • Culver City, California, United States, 90230
        • ProScience Research Group
      • Encino, California, United States, 91316
        • Wr-Pri, Llc
      • Garden Grove, California, United States, 92845
        • Collaborative NeuroScience Research , LLC
      • Long Beach, California, United States, 90807
        • Alliance Research
      • Orange, California, United States, 92868
        • ATP Clinical Research, Inc.
      • Redlands, California, United States, 92374
        • Anderson Clinical Research
      • Santee, California, United States, 92071
        • California Mental Behavioral Health
      • Sherman Oaks, California, United States, 91403
        • Schuster Medical Research Institute SMRI
      • Temecula, California, United States, 92591
        • Viking Clinical Research
      • Torrance, California, United States, 90504
        • Collaborative Neuroscience Research LLC
      • Walnut Creek, California, United States, 94596
        • Sunwise Clinical Research with is in Lafayette, CA
    • Connecticut
      • Hartford, Connecticut, United States, 06106
        • Institute of Living Hartford Hospital
    • Florida
      • Jacksonville, Florida, United States, 32256
        • Clinical Neuroscience Solutions Inc.
      • Maitland, Florida, United States, 32751
        • K2 Medical Research
      • Miami, Florida, United States, 33125
        • Central Miami Medical Institute
      • Orlando, Florida, United States, 32807
        • Combined Research Orlando Phase I-IV
      • Orlando, Florida, United States, 32801
        • Clinical Neuroscience Solutions Inc. dba CNS Healthcare
      • Tampa, Florida, United States, 33629
        • Interventional Psychiatry of Tampa Bay
      • Tampa, Florida, United States, 33607
        • K2 Medical Research
    • Georgia
      • Atlanta, Georgia, United States, 30318
        • Advanced Discovery Research LLC
      • Snellville, Georgia, United States, 30078
        • Renew Health Clinical Research
    • Illinois
      • Chicago, Illinois, United States, 60614
        • MetroMed Clinical Trials
      • Warrenville, Illinois, United States, 60555
        • AMR Convention Research
    • Louisiana
      • Shreveport, Louisiana, United States, 71101
        • Benchmark Research
    • Maryland
      • Gaithersburg, Maryland, United States, 20877
        • Cenexel CBH (CBH Health)
    • Massachusetts
      • Boston, Massachusetts, United States, 02116
        • Copley Clinical
      • Roslindale, Massachusetts, United States, 02131
        • Boston Clinical Trials
      • Watertown, Massachusetts, United States, 02471
        • Adams Clinical
      • Worcester, Massachusetts, United States, 01608
        • Vitalix Clinical
    • Michigan
      • Bloomfield Hills, Michigan, United States, 48302
        • Neurobehavioral Medicine Group
    • Mississippi
      • Flowood, Mississippi, United States, 39232
        • Precise Research Centers
    • New Jersey
      • Cherry Hill, New Jersey, United States, 08002
        • Center For Emotional Fitness
    • New York
      • Brooklyn, New York, United States, 11229
        • Integrative Clinical Trials
      • Inwood, New York, United States, 11096
        • Basil Clinical
      • New York, New York, United States, 10128
        • The Medical Research Network, LLC
      • New York, New York, United States, 10036
        • Manhattan Behavioral Medicine PLLC
      • New York, New York, United States, 10029
        • Berman Clinical
    • Ohio
      • Cincinnati, Ohio, United States, 45215
        • Patient Priority Clinical Studies LLC
      • Columbus, Ohio, United States, 43210
        • The Ohio State University
    • Oklahoma
      • Oklahoma City, Oklahoma, United States, 73116
        • Sooner Clinical Research
    • Pennsylvania
      • West Chester, Pennsylvania, United States, 19380
        • Suburban Research Associates
    • Tennessee
      • Memphis, Tennessee, United States, 38119
        • Clinical Neuroscience Solutions Inc.
    • Texas
      • Austin, Texas, United States, 78754
        • Community Clinical Research, Inc.
      • Austin, Texas, United States, 78737
        • Donald J. Garcia, Jr., MD, PA
      • Dallas, Texas, United States, 75251
        • FutureSearch Trials of Dallas
      • Fort Worth, Texas, United States, 76104
        • North Texas Clinical Trials
      • Houston, Texas, United States, 77081
        • DM Clinical Research - Belliare
    • Utah
      • Millcreek, Utah, United States, 84124
        • Psychiatric And Behavioral Solutions, LLC
    • Washington
      • Everett, Washington, United States, 98201
        • Core Clinical Research

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Male and Female subjects between 18-65 years of age, with a primary diagnosis of major depressive disorder and in a current major depressive episode
  • Current major depressive episode must be at least 8 weeks and no longer than 2 years in duration
  • History of an inadequate response to at least 1 and no more than 3 antidepressant treatments in the current major depressive episode

Exclusion Criteria:

  • Subjects who report an inadequate response to more than 3 antidepressant treatments in the current episode
  • Subjects with a lifetime history of schizophrenia spectrum or other psychotic disorder, bipolar or related disorder, major or mild neurocognitive disorder, neurodevelopmental disorder of greater than mild severity or of a severity that impacts the participant's ability to consent/ follow study directions/ or otherwise safely participate in the study, borderline or antisocial personality disorder.
  • Subjects with a current diagnosis of post-traumatic stress disorder, obsessive compulsive disorder, panic disorder, or eating disorder (including anorexia nervosa or bulimia).
  • Sexually active subjects, who could become pregnant, not agreeing to practice 2 sponsor approved methods of birth control or remain abstinent during the trial and for 30 days (females) or 90 days (males) after last dose of study drug.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: SEP-363856 & ADT (Antidepressant Therapy)
Drug: SEP-363856
Tablet
Placebo Comparator: Placebo & ADT (Antidepressant Therapy)
Other: Placebo
Placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Montgomery Åsberg Depression Rating Scale (MADRS)
Time Frame: From baseline to week 14

Change from the baseline to the Montgomery Åsberg Depression Rating Scale (MADRS) total score.

The Montgomery Åsberg Depression Rating Scale consists of 10 items, each rated from 0 to 6 (for a total score of 0 to 60). A higher score represents a higher severity of the level of depression.
From baseline to week 14

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Clinical Global Impression - Severity of Illness (CGI-S)
Time Frame: From baseline to week 14

Change from baseline in the Clinical Global Impression - Severity of Illness (CGI-S).

Clinical Global Impression - Severity of Illness will be measured on a scale from 1-7 where a higher score represents a higher severity of disease.
From baseline to week 14

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Otsuka Pharmaceutical Development & Commercialization, Inc.

Collaborators

Sumitomo Pharma Co., Ltd.
Sumitomo Pharma America, Inc.

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

November 9, 2022

Primary Completion (Actual)

November 6, 2025

Study Completion (Actual)

November 13, 2025

Study Registration Dates

First Submitted

October 10, 2022

First Submitted That Met QC Criteria

October 20, 2022

First Posted (Actual)

October 25, 2022

Study Record Updates

Last Update Posted (Actual)

February 18, 2026

Last Update Submitted That Met QC Criteria

February 13, 2026

Last Verified

November 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 382-201-00001

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Anonymized Individual participant data (IPD) that underlie the results of this study will be shared with researchers to achieve aims pre-specified in a methodologically sound research proposal. Small studies with less than 25 participants are excluded from data sharing.

IPD Sharing Time Frame

Data will be available after marketing approval in global markets, or beginning 1-3 years following article publication. There is no end date to the availability of the data.

IPD Sharing Access Criteria

Otsuka will share data on the Vivli data sharing platform which can be found here: https://vivli.org/ourmember/Otsuka/

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • SAP
  • ICF

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Major Depressive Disorder

Clinical Trials on Placebo

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Panama

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe