A Study of Intranasal Esketamine Plus an Oral Antidepressant for Relapse Prevention in Adult Participants With Treatment-resistant Depression

Open-label induction phase: Direct entry participants start at a dose of 56 mg on Day 1. On Day 4, the dose may be increased to 84 mg or remain at 56 mg. From Day 8 to 22, dose may be increased to 84 mg, remain the same or be reduced to 56 mg from 84 mg per protocol, at investigator's discretion based on efficacy and/or tolerability. On Day 25, a dose reduction from 84 mg to 56 mg is permitted but no dose increase is permitted. Optimization Phase: Direct-entry and transferred-entry participants will self-administer intranasal esketamine (same dose) for first 4 weeks, then individualized to either once weekly or once every other week based on depressive symptoms. Maintenance Phase: All participants assigned to esketamine will self-administer intranasal esketamine once weekly or once every other week based on depressive symptoms.

Optimization Phase: Transferred-entry participant will self-administer intranasal placebo at weekly treatment sessions for the first 4 weeks of this phase, then individualized to either once weekly or once every other week based on depressive symptoms. Maintenance Phase: Direct-entry and transferred-entry participants assigned to placebo will self-administer matching intranasal placebo once weekly or once based on depressive symptoms.

Duloxetine could be selected as the oral antidepressant medication by the investigator based on review of Massachusetts General Hospital - Antidepressant Treatment Response Questionnaire (MGH-ATRQ) and relevant prior antidepressant medication information. The minimum therapeutic dose is 60 milligram per day (mg/day).

Escitalopram could be selected as the oral antidepressant medication by the investigator based on review of MGH-ATRQ and relevant prior antidepressant medication information. Escitalopram will be titrated upto a maximum dose of 20 mg/day, but if not tolerated the dose can be reduced to the minimum therapeutic dose of 10 mg/day.

Sertraline could be selected as the oral antidepressant medication by the investigator based on review of MGH-ATRQ and relevant prior antidepressant medication information. Sertraline will be titrated upto a maximum dose of 200 mg/day, but if not tolerated the dose can be reduced to the minimum therapeutic dose of 50 mg/day.

Venlafaxine Extended Release could be selected as the oral antidepressant medication by the investigator based on review of MGH-ATRQ and relevant prior antidepressant medication information. Venlafaxine Extended Release will be titrated upto a maximum dose of 225 mg/day, but if not tolerated the dose can be reduced to the minimum therapeutic dose of 150 mg/day.