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

Inclusion Criteria:

1. Japanese (sex not specified)

2. Participants who, in the opinion of the principal (or sub-investigator), are capableof understanding the content of the clinical trial and complying with itsrequirements

3. Participants diagnosed with major depressive disorder based on DSM-5-TR (Diagnosticand Statistical Manual of Mental Disorders, Fifth Edition, Text Revision) criteria,as determined through an interview using the M.I.N.I. (Mini-internationalneuropsychiatric interview)

4. Outpatients

5. Participants whose current depressive episode has lasted for at least 2 months butno more than 12 months

6. Participants with a HAM-D17 (Hamilton depression rating scale 17 items) total scoreof 18 or higher and a CGI-S (Clinical global impression-Improvement) score of 4 orhigher

Exclusion Criteria:

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

• Participants with a comorbid psychiatric disorder other than major depressivedisorder as defined by DSM-5-TR (Diagnostic and Statistical Manual of MentalDisorders, Fifth Edition, Text Revision) (assessed using theM.I.N.I.(Mini-international neuropsychiatric interview))

• Participants with major depressive disorder with mixed features, psychoticfeatures, or catatonia as defined by DSM-5-TR (Diagnostic and StatisticalManual of Mental Disorders, Fifth Edition, Text Revision)

• Participants with a current or past history of schizophrenia or other psychoticdisorders as defined by DSM-5-TR (Diagnostic and Statistical Manual of MentalDisorders, Fifth Edition, Text Revision)

• Participants with neurodevelopmental disorders or personality disorders asdefined by DSM-5-TR (Diagnostic and Statistical Manual of Mental Disorders,Fifth Edition, Text Revision)

• Participants with a current or past history of clinically significantneurological 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 notresponded to at least two different antidepressants, each administered at anadequate 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 atypicalantipsychotics, or who have used combination therapy with antidepressants for thecurrent depressive episode.