Testing a new treatment for adults with major depressive disorder

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

Phase2; Phase3 Interventional Otsuka Pharmaceutical Development & Commercialization, Inc. · NCT05593029

This study is testing a new treatment called SEP-363856 to see if it can help adults with major depressive disorder who haven't found relief from other antidepressants.

Quick facts

PhasePhase2; Phase3
Study typeInterventional
Enrollment1030 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorOtsuka Pharmaceutical Development & Commercialization, Inc. Industry-sponsored
Locations1 site (New York, New York)
Trial IDNCT05593029 on ClinicalTrials.gov

What this trial studies

This trial evaluates the safety and efficacy of SEP-363856, a novel adjunctive therapy, in adults diagnosed with major depressive disorder (MDD). It is a multicenter, randomized, double-blind, placebo-controlled study that will assess flexible dosing of the treatment over a specified period. Participants must have experienced an inadequate response to one to three previous antidepressant treatments during their current depressive episode. The study aims to provide insights into the effectiveness of SEP-363856 in improving symptoms of MDD.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18-65 with a primary diagnosis of major depressive disorder and a current episode lasting between 8 weeks and 2 years.

Not a fit: Patients who have not responded to more than three antidepressant treatments in their current episode or have certain psychiatric disorders will not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could offer a new option for patients with major depressive disorder who have not responded adequately to existing therapies.

How similar studies have performed: Other studies have shown promise with similar approaches, but the specific treatment SEP-363856 is being evaluated for its unique efficacy.

Eligibility criteria

Show full inclusion / exclusion criteria
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.

Where this trial is running

New York, New York

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Major Depressive DisorderMDDSEP-363856Antidepressant TherapyADTDepressionDepressive DisorderMajor Mood Disorders
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.