A Long-term Comparison of Esketamine Nasal Spray Versus Quetiapine Extended Release, Both in Combination With a Selective Serotonin Reuptake Inhibitor/Serotonin-Norepinephrine Reuptake Inhibitor, in Participants With Treatment Resistant Major Depressive Disorder

A depressive state with classical symptoms such as low (depressive/sad) mood, markedly diminished interest in activities, significant weight loss/gain, insomnia or hypersomnia, psychomotor agitation/retardation, excessive fatigue, inappropriate guilt, diminished concentration, and recurrent thoughts of death, persisting for more than 2 weeks is classified as major depressive disorder (MDD). The mechanism of action of ketamine is distinct from conventional antidepressants (ADs), which target the monoamines (serotonin, norepinephrine, and/or dopamine). Esketamine, the S-enantiomer of ketamine, is approved and widely used for the induction and maintenance of anesthesia via intramuscular or intravenous (IV) administration. There is a significant unmet need to develop novel AD treatments based on the relevant psychophysiological pathways underlying MDD. The goal of any novel treatment would be the rapid and long-lasting relief of depressive symptoms, especially in participants with treatment-resistant depression (TRD), who lack a sufficient response to the currently available treatment strategies. The study consists of a Screening Phase (up to 14 days), an Acute Phase (8 Weeks), a Maintenance Phase (24 Weeks) and a Safety Follow-up Phase (2 Weeks). Safety assessment includes adverse event, serious adverse events, physical examination, vital signs, electrocardiogram, clinical safety laboratory assessments, suicidal risk monitoring. The total duration of the study is approximately 36 Weeks for all participants.