A Randomized, Double-Blind, Parallel-Group, Placebo-Controlled, Fixed Dose Study Evaluating the Efficacy and Safety of Orvepitant in Subjects With Major Depressive Disorder

The purpose of the current study is to test the safety and the anti-depressant effects of orvepitant, an investigational antidepressant. Efficacy will be assessed using standard depression symptom and severity rating scales (questionaires). The Hamilton Depression Rating Scale (HAM-D) will serve as the primary measure of efficacy, and . Secondary efficacy endpoints include the Bech Melancholia Scale (sum of items 1, 2, 7, 8, 10, and 13 of the 17-item HAM-D scale), the Quick Inventory of Depressive Symptomatology (QIDS-SR), the Clinical Global Impression- Global Improvement and Severity of Illness Scale (CGI-I and CGI-S, respectively), the HAM-D anxiety factor score (sum of items 10, 11, 12, 13, 15 and 17), the Cognitive and Physical Function Questionnaire (CPFQ) and a morning sleep questionnaire. Safety and tolerability will be assessed by monitoring adverse events (AEs or side effects), physical examinations (including vital signs such as blood pressure and heart rate), clinical laboratory assessments (blood tests), electrical recordings of the heart (electrocardiograms or ECG's), the Columbia Suicidality Severity Rating Scale (CSSRS), Sexual Function Questionnaire (SFQ), and weight change. Blood samples will be taken at different time points to assess blood levels of orvepitant in patients, allowing the relationship between amount of orvepitant in the body and efficacy to be studied. The primary objective of the study is to evaluate the antidepressant efficacy of orvepitant (30 and 60mg/day) versus placebo (a "sugar pill", with no active ingredients). The secondary objectives include assessing the safety and tolerability of orvepitant, assessing the profile of appearance and disappearance of orvepitant in the body (blood) following administration (i.e., assessing how long the drug remains in the body), and lastly to examine the relationship between blood levels of the drug and efficacy (i..e, the change in HAM-D total score relative to what it was before starting the study medication. Following an initial screening visit, subjects fulfilling the study entrance criteria will enter a pre-treatment screening phase to permit evaluation of the laboratory and electrocardiogram assessments and to confirm eligibility for inclusion into the study. This screening phase will be a minimum of 7 days, but no longer than 21 days. During the screening period, subjects may undergo up to three different assessments of their depressive symptoms, this may occur via a face-to-face interview or via an interview over the telephone. Upon completion of the screening period, eligible subjects will be randomly assigned at the baseline visit to one of three treatment regimens: orvepitant 30mg/day, orvepitant 60mg/day or placebo for a six-week treatment phase. The chances of receiving each of the three possible treatments will be equal. Orvepitant will be administered as tablets. Those subjects randomised to receive placebo will receive study medication identical in appearance to that received by subjects assigned to receive orvepitant. During the treatment phase, subjects will be required to return to the clinic at the end of Weeks 1, 2, 4 and 6. In addition, all subjects will be required to return for a follow-up visit 14 days after the last dose of study medication. In addition, all subjects with ongoing adverse events at the 14-day follow-up visit will be required to return for a further follow-up visit 28 days after the last dose of study medication. Male and female outpatients between the ages of 18 to 64 years inclusive with a primary diagnosis of Major Depressive Disorder will be enrolled into this study. A total of approximately 350 subjects are expected to be enrolled at approximately 20 different study sites in the U.S. and Canada.