Esketamine (Intranasal Spray)
DrugOpen-Label Induction Phase: Participants will self-administer esketamine intranasally twice per week for 4 weeks as a flexible dose regimen (56 mg or 84 mg for those < 65 years; 28 mg, 56 mg or 84 mg for those >= 65 years). Participants >= 65 years old will start at a dose of 28 mg on Day 1. Optimization/Maintenance Phase: Participants will self-administer esketamine intranasally (56 mg or 84 mg for those < 65 years; 28 mg, 56 mg or 84 mg for those >= 65 years) once weekly then individualized to either once weekly or once every other week based on the severity of depressive symptoms. Transferred-entry responder participants from ESKETINTRD3005 >= 65 years old will start at a dose of 28 mg in Week 5.