Open-Label of SPN-820 in Adults With Major Depressive Disorder

Prior treatment

• Diagnosis within the last 12 months before screening or current diagnosis of PTSD, OCD, panic disorder, acute stress disorder, or has a history of intellectual disability, autism, or cluster A or B personality disorder.
• History of substance use disorder within 6 months prior to screening or is currently using or has a positive result (urine drug screen) at screening or baseline for drugs of abuse.
• History of alcohol use disorder within 6 months prior to screening.

Other illness

• Lifetime history of psychotic disorder, including but not limited to schizophrenia, MDD with psychotic features, or bipolar I/II disorder with and without psychotic features.
• Suicidal behavior or suicidal ideation of type 4 or type 5 based on the C-SSRS in the 1 year before screening; a history of suicide attempt in the last 2 years; or more than 2 lifetime suicide attempts.

Lab values

• Clinically significant abnormal laboratory profiles, vital sign measurements, or ECGs prior to baseline.

Other

• MADRS total score improvement of ≥25% from the highest to the lowest score from screening to baseline.
• In the investigator's opinion, is unlikely to comply with the protocol or is unsuitable for any other reason.

• Male or female subject, aged 18 to 65 years (inclusive) at screening.
• Diagnosis of MDD according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) for either recurrent or single episode MDD without psychotic features that is confirmed by the Mini International Neuropsychiatric Interview (MINI) at screening.
• MADRS total score of ≥22 for the current major depressive episode (MDE) at screening and baseline (day 1) before study medication (SM) administration.
• CGI-S score of ≥4 (moderately ill or worse) at screening and baseline (day 1) before SM administration.
• Stable, therapeutic dose of one of the following protocol-defined ADTs for the current MDE for ≥6 weeks prior to screening: citalopram, escitalopram, paroxetine, fluoxetine, sertraline, duloxetine, venlafaxine (immediate release or extended release), desvenlafaxine, vilazodone, levomilnacipran, vortioxetine, bupropion, or dextromethorphan/bupropion.
• Stable therapeutic dose of the approved ADT throughout the study.