A Long-term, Safety and Efficacy Study of Intranasal Esketamine in Treatment-resistant Depression

The purpose of this open-label, multicenter study is to assess the long term safety and efficacy of intranasal esketamine plus an oral antidepressant in participants with treatment-resistant depression (TRD).

This is an open-label (the researchers and participants know the treatment the participant is receiving), multicenter (more than 1 study site), long-term safety and efficacy study of intranasal esketamine plus an oral antidepressant in participants with treatment-resistant depression (TRD). Participants will enter the study either directly (direct-entry participants) or after completing the Double-Blind Induction Phase of ESKETINTRD3005 (transferred-entry participants). The study consists of 4 phases: Screening Phase (4 weeks), Open-Label Induction Phase (4 weeks), Open-Label Optimization/Maintenance phase (48 weeks), and Follow up Phase (4 weeks). Transferred entry non-responders in the ESKETINTRD3005 may enter study at the Open-Label Induction Phase and responders in the ESKETINTRD3005 may enter Optimization/Maintenance phase. In the Open-Label Induction Phase, participants will self-administer flexibly-dosed intranasal esketamine (participants who are less than (\<) 65 years old self-administer 56 mg or 84 mg dose, participants who are greater than or equal to (\>=) 65 years old self-administer 28 mg, 56 mg or 84 mg dose) twice weekly for 4 weeks. The starting dose for all participants \>= 65 years old will be 28 mg. In addition, each direct-entry participants will be assigned to receive 1 of 4 selected oral antidepressant medications (escitalopram or sertraline or duloxetine or venlafaxine extended release \[XR\]), initiated on Day 1 of the open-label induction phase and continued through the duration of the study. Transferred-entry participants will continue their same antidepressant from ESKETINTRD3005 through the duration of this study. Participants who are responders at the end of the Open-Label Induction phase and transferred-entry responder participants (from study ESKETINTRD3005) will enter the Optimization/Maintenance Phase where intranasal esketamine treatment sessions will be reduced from that in the induction phase (twice weekly) to weekly for the first 4 weeks of this phase, and then individualized to either once weekly or once every other week based on the severity of depressive symptoms. Participants' safety and depressive symptoms will be assessed and monitored throughout the study.

Eligibility Criteria:
Inclusion Criteria:

A). For Direct-Entry Participants

* At the time of signing the informed consent form (ICF), participant must be a man or woman ≥18 (or older if the minimum legal age of consent in the country in which the study is taking place is greater than \[\>\]18)
* At the start of the screening phase, participant must meet the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) diagnostic criteria for single-episode major depressive disorder (MDD) (if single-episode MDD, the duration must be greater than or equal to \[\>=\] 2 years) or recurrent MDD, without psychotic features, based upon clinical assessment and confirmed by the Mini-International Neuropsychiatric Interview (MINI)
* At screening, participant must have a MADRS total score of \>=22
* At the start of the screening phase, participants must have had nonresponse to \>=2 oral antidepressant treatments in the current episode of depression, as assessed using the the MGHATRQ and confirmed by documented records (example medical/pharmacy/prescription records or a letter from treating a physician, etc,) B). For Transferred-entry Participants
* All participants who completed the double-blind induction phase of ESKETINTRD3005 study, regardless of their response status, will be eligible to participate in this study, if they meet the study specific eligibility criteria

Exclusion Criteria:

A). For Direct-Entry Participants

* Participant's depressive symptoms have previously not responded to: Esketamine or ketamine in the current major depressive episode per clinical judgment or All of the 4 oral antidepressant treatment options available in the respective country for the open-label induction phase (that is, duloxetine, escitalopram, sertraline, and venlafaxine XR) in the current major depressive episode (based on Massachusetts General Hospital - Antidepressant Treatment Response Questionnaire \[ MGH-ATRQ\])
* Participant has a current or prior DSM-5 diagnosis of a psychotic disorder or MDD with psychotic features, bipolar or related disorders (confirmed by the MINI), obsessive compulsive disorder (current only), intellectual disability (DSM-5 diagnostic codes 317, 318.0, 318.1, 318.2, 315.8, and 319), autism spectrum disorder, borderline personality disorder, antisocial personality disorder, histrionic personality disorder, or narcissistic personality disorder
* Participant has homicidal ideation/intent, per the investigator's clinical judgment, or has suicidal ideation with some intent to act within 6 months prior to the start of the screening phase, per the investigator's clinical judgment or based on the Columbia Suicide Severity Rating Scale (C-SSRS)
* Participants with history of moderate or severe substance or alcohol use disorder according to DSM-5 criteria
* Participants who has a Mini Mental State Examination (MMSE) \<25; Has neurodegenerative disorder (example, Alzheimer's disease, vascular dementia, Parkinson's disease), or evidence of mild cognitive impairment (MCI) B). Transferred-Entry Participants
* Participant has taken any prohibited therapies that would not permit dosing on Day 1