Early study termination due to insufficient efficacy.

The purpose of this study is to assess how well aticaprant works compared to placebo when given in addition to antidepressant therapy (selective serotonin reuptake inhibitor [SSRI] or serotonin-norepinephrine reuptake inhibitor [SNRI]) in preventing return of depression symptoms in participants with major depressive disorder who experience a loss of interest and pleasure and who achieve a stable response after treatment with adjunctive aticaprant.

Inclusion Criteria:

• Be medically stable based on physical examination (including a brief neurologic examination), medical history, vital signs (including blood pressure), and 12-lead electrocardiogram (ECG) performed at screening and OL baseline
• Be medically stable based on clinical laboratory tests performed at screening
• Meet DSM-5 diagnostic criteria for recurrent or single episode MDD, without psychotic features upon clinical assessment and confirmed by the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-5th Edition (DSM-5) Axis I Disorders-Clinical Trials version (SCID-CT)
• Have symptoms of anhedonia based on clinical assessment and confirmed by presence of anhedonia (positive response to major depressive episode (MDE) module symptom Item 2) on the SCID-CT at screening

Exclusion Criteria:

• Has had no response to 2 or more consecutive antidepressant treatments administered at adequate dose and duration in the current episode of depression including the current selective SSRI/SNRI assessed using the Massachusetts General Hospital Antidepressant Treatment Response Questionnaire (MGH ATRQ)
• Has a history or evidence of clinically meaningful noncompliance with current antidepressant therapy
• Has a history of moderate-to-severe substance use disorder including alcohol use disorder according to DSM-5 criteria within 6 months before screening
• Has homicidal ideation/intent, per the investigator's clinical judgment, or has suicidal ideation with some intent to act within 3 months prior to the start of the screening phase
• Has cognitive impairment per investigator judgment that would render the informed consent invalid or limit the ability of the participant to comply with the study requirements

The data sharing policy of the Janssen Pharmaceutical Companies of Johnson & Johnson is available at www.janssen.com/clinical-trials/transparency. As noted on this site, requests for access to the study data can be submitted through Yale Open Data Access (YODA) Project site at yoda.yale.edu

If an investigator wishes to publish information from the study, a copy of the manuscript must be provided to the sponsor for review at least 60 days before submission for publication or presentation. If requested by the sponsor in writing, the investigator will withhold such publication for up to an additional 60 days to allow for filing of a patent application.