A Study of Esketamine Nasal Spray Plus a New Standard-of-care Oral Antidepressant or Placebo Nasal Spray Plus a New Standard-of-care Oral Antidepressant in Adult and Elderly Participants With Treatment-resistant Depression

Depression is a major cause of morbidity and mortality, with global estimates of 300 million treated and untreated individuals worldwide. In its severe forms, depression is the most common diagnosis associated with suicide. Esketamine (S-ketamine) is the S-enantiomer of ketamine. Ketamine profoundly affects fast excitatory glutamate transmission, increases brain-derived neurotrophic factor release, and stimulates synaptogenesis, in contrast to conventional antidepressants (ADs) which are modulatory transmitters. The goal of any new antidepressant (AD) treatment would be the rapid and long-lasting relief of depressive symptoms. The study includes screening phase (2 weeks, with possible extension up to 4 weeks), Induction phase (Week 1 to Week 4), Maintenance once-weekly phase (Week 5 to Week 8), Maintenance flexible-frequency phase (Week 9 to Week 32) and Follow-up phase (2 Weeks Duration). Total duration of study will be approximately up to 36 weeks. The safety will be monitored throughout the study.