Esketamine
DrugOpen-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.