A Study of ONO-1110 in Patients With Major Depressive Disorder

• ONO-1110 (Drug): ONO-1110 tablets once a day
• Placebo (Drug): Placebo tablets once daily

Primary outcomes

• Change in HAM-D17(Hamilton depression rating scale 17 items) total score from baseline to Week 8 of the treatment period [Up to 16 weeks]

Secondary outcomes

• The transition of HAM-D17(Hamilton depression rating scale 17 items) total score from baseline to Week 8 of the treatment period [Up to 16 weeks]
• Responder rates of HAM-D17(Hamilton depression rating scale 17 items) total score at 1, 2, 4, 6, and 8 weeks of the treatment period [Up to 16 weeks]: Responder is defined as a reduction of 50% or more in HAM-D17(Hamilton depression rating scale 17 items) total score from baseline
• Remitted patient rates of HAM-D17(Hamilton depression rating scale 17 items) score at 1, 2, 4, 6, and 8 weeks of the treatment period [Up to 16 weeks]: Remitted patient is defined as a total HAM-D17(Hamilton depression rating scale 17 items) total score of 7 or less.
• Change in the total MADRS(Montgomery-Åsberg depression rating scale) score from baseline to Week 8 of the treatment period [Up to 16 weeks]
• Transition of HAM-A(Hamilton Anxiety Scale) total score from baseline to Week 8 of the treatment period [Up to 16 weeks]
• Transition of CGI-S(Clinical Global Impression of illness Severity) score from baseline to Week 8 of the treatment period [Up to 16 weeks]
• Transition of QIDS-J(Quick Inventory of Depressive Symptomatology) total score from baseline to Week 8 of the treatment period [Up to 16 weeks]
• Transition of CGI-I(Clinical Global Impression of Impression Important) score from baseline to Week 8 of the treatment period [Up to 16 weeks]
• Plasma ONO-1110 concentrations [Up to 16 weeks]
• Adverse Events [Up to 16 weeks]

Sex: All, ages: 18 Years to 65 Years

Inclusion Criteria:

1. Japanese (sex not specified)
2. Participants who, in the opinion of the principal (or sub-investigator), are capable of understanding the content of the clinical trial and complying with its requirements
3. Participants diagnosed with major depressive disorder based on DSM-5-TR (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision) criteria, as determined through an interview using the M.I.N.I. (Mini-international neuropsychiatric interview)
4. Outpatients
5. Participants whose current depressive episode has lasted for at least 2 months but no more than 12 months
6. Participants with a HAM-D17 (Hamilton depression rating scale 17 items) total score of 18 or higher and a CGI-S (Clinical global impression-Improvement) score of 4 or higher

Exclusion Criteria:

1. Participants with a current or past history of psychiatric or neurological disorders that meet any of the following criteria:

   * Participants with a comorbid psychiatric disorder other than major depressive disorder as defined by DSM-5-TR (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision) (assessed using the M.I.N.I.(Mini-international neuropsychiatric interview))
   * Participants with major depressive disorder with mixed features, psychotic features, or catatonia as defined by DSM-5-TR (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision)
   * Participants with a current or past history of schizophrenia or other psychotic disorders as defined by DSM-5-TR (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision)
   * Participants with neurodevelopmental disorders or personality disorders as defined by DSM-5-TR (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision)
   * Participants with a current or past history of clinically significant neurological disorders (including epilepsy)
   * Participants with neurodegenerative diseases (such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, etc.)
2. Participants who, in the opinion of the principal (or sub-investigator), have not responded to at least two different antidepressants, each administered at an adequate dose for at least 6 weeks, during the current or past depressive episode.
3. Participants who have used adjunctive treatments such as lithium, triiodothyronine/thyroxine, lamotrigine, valproate, carbamazepine, or atypical antipsychotics, or who have used combination therapy with antidepressants for the current depressive episode.

• Project Leader, Study director, Ono Pharmaceutical Co., Ltd.