The purpose of this study is to evaluate the efficacy, safety and tolerability of vortioxetine, once daily (QD), compared with placebo in adults with major depressive disorder.

The drug that was tested in this study is called Vortioxetine. Vortioxetine is being tested to treat depression in adults who have major depressive disorder (MDD). This study looked at MDD relief in people who took varying dosages of vortioxetine.

The study enrolled 469 patients. Participants were randomly assigned (by chance, like flipping a coin) to one of the three treatment groups-which remained undisclosed to the patient and study doctor during the study (unless there was an urgent medical need):

• Vortioxetine 10 mg
• Vortioxetine 15 mg
• Placebo (dummy inactive capsule) - this was a capsule that looked like the study drug but had no active ingredient.

All participants were asked to take one capsule at the same time each day throughout the study.

This multi-center trial was conducted in the United States. The overall time to participate in this study was up to 14 weeks. Participants made 7 visits to the clinic, and were contacted by telephone 4 weeks after the last dose of study drug for a follow-up assessment.

Inclusion Criteria:

• Suffers from a major depressive episode (MDE) recurrent as the primary diagnosis according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) criteria.
• The reported duration of the current MDE is at least 3 months.
• Has a Montgomery Åsberg Depression Rating Scale (MADRS) total score of 26 or greater at Screening and Baseline Visits.
• Has a Clinical Global Impression - Severity of Illness (CGI-S) score of 4 or greater at Screening and Baseline Visits.

Exclusion Criteria:

• Has received any investigational compound <30 days before Screening or 5 half-lives prior to Screening.

• Has received Lu AA21004 in a previous clinical study.

• Has 1 or more the following:

  1. Any current psychiatric disorder other than MDD as defined in the DSM-IV-TR .
  2. Current or history of: manic or hypomanic episode, schizophrenia or any other psychotic disorder, including major depression with psychotic features, mental retardation, organic mental disorders, or mental disorders due to a general medical condition as defined in the DSM-IV-TR.
  3. Diagnosis of alcohol or other substance abuse or dependence (excluding nicotine or caffeine) as defined in the DSM-IV-TR that had not been in sustained full remission for at least 2 years prior to Screening.
  4. Presence or history of a clinically significant neurological disorder (including epilepsy).
  5. Neurodegenerative disorder (Alzheimer disease, Parkinson disease, multiple sclerosis, Huntington disease, etc).
  6. Any Axis II disorder that might compromise the study.

• The current depressive symptoms of the patient were considered by the investigator to have been resistant to 2 adequate antidepressant treatments of at least 6 weeks duration each.

• Has received electroconvulsive therapy, vagal nerve stimulation, or repetitive transcranial magnetic stimulation within 6 months prior to Screening.

• Was currently receiving formal cognitive or behavioral therapy, systematic psychotherapy, or planned to initiate such therapy during the study.

• Has a significant risk of suicide according to the investigator's clinical judgment or had a score ≥5 on item 10 (suicidal thoughts) of the MADRS or had made a suicide attempt in the previous 6 months.

• Was required to take excluded medications or it was anticipated that would require treatment with at least 1 of the disallowed concomitant medications during the study.

• Has a clinically significant unstable illness, for example hepatic impairment or renal insufficiency, or a cardiovascular, pulmonary, gastrointestinal, endocrine, neurological, rheumatologic, immunologic, hematological, infectious, dermatological disorder or metabolic disturbance. NOTE: For the purposes of this study, the following conditions were considered unstable due to the potential impact on assessment of MDD response: pain disorder, chronic fatigue syndrome, fibromyalgia, and obstructive sleep apnea.

• Has 1 or more laboratory value outside the normal range, based on the blood or urine samples taken at the Screening Visit, that were considered by the investigator to be clinically significant; or the patient has any of the following values at the Screening Visit:

  1. A serum creatinine value >1.5 times the upper limits of normal (× ULN).
  2. A total serum total bilirubin value >1.5 × ULN.
  3. A serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) value >2 × ULN.

• Has a thyroid stimulating hormone value outside the normal range.

• Has clinically significant abnormal vital signs.

• Has an abnormal electrocardiogram.