A randomized, double-blind, placebo-controlled, parallel-group study to investigate the safety, tolerability, and pharmacodynamics of JNJ-54175446 in subjects with major depressive disorder.

1. Subjects must be males or females, 18 to 64 years of age, inclusive.
2. body mass index must be between 18 and 32 kg/m2 inclusive.
3. Related to symptoms of depression:
- Subject must meet the Diagnostic and Statistical Manual of Mental Disorders-IV or V diagnostic criteria for major depressive disorder (International Classification of Diseases code F32.x and F33.x), without psychotic features, as confirmed by the Mini International Neuropsychiatric Interview 6.0.
- Subject must have an Inventory of Depressive Symptomatology total score >=30 using the semistructured interview guide for the Inventory of Depressive Symptomatology-30.
4. Subject is, during this episode of depression, treatment naïve OR treated with at most one selective serotonine reuptake inhibitor over a minimum of 6 weeks and a maximum of 6 months, and subject is being treated at an adequate dose, showing a partial response at enrolment.
5. Subjects must be medically stable on the basis of clinical laboratory tests, medical history, vital signs, and 12-lead electrocardiogram performed at screening and baseline (for clinical laboratory tests only screening results will be considered). If the results of the serum chemistry panel, hematology, or urinalysis are outside the normal reference ranges, retesting of an abnormal lab value(s) that may lead to exclusion will be
allowed once during the screening phase. A retest of an abnormal electrocardiogram value will be allowed once in the screening phase. Blood pressure will be the average of 2 measurements.
- The subject may be included only if the investigator judges the abnormalities or deviations from normal to be not clinically significant or to be appropriate and reasonable for the population under study. This determination must be recorded in the subject's source documents and initialed by the investigator.
6. Men who are sexually active with a woman of childbearing potential and have not had a vasectomy must agree to use a barrier method of birth control e.g., either condom or partner with occlusive cap (diaphragm or cervical/vault caps) with spermicidal foam/gel/film/cream/suppository for the duration of the study plus 3 months after receiving the last dose of study drug, and all men must not donate sperm during the study and for 3 months after receiving the last dose of study drug. In addition, their female partners should also use an additional method of birth control (which may include a hormonal method, an intrauterine device or an intrauterine system) for at least the same duration.
7. Before randomization, a woman must be either:
- Not of childbearing potential: postmenopausal (>45 years of age with amenorrhea for at least 12 months, or any age with amenorrhea for at least 6 months and a serum follicle stimulating hormone level >40 IU/L); permanently sterilized (e.g., tubal occlusion, hysterectomy, bilateral salpingectomy); or otherwise be incapable of pregnancy
- Of childbearing potential and practicing a highly effective method of birth control consistent with local regulations regarding the use of birth control methods for subjects participating in clinical studies (i.e. one that results in a less than 1% per year failure rate when used consistently and correctly). This may include:
* Established and ongoing use of oral, patch, injected or implanted hormonal methods of contraception in combination with barrier
methods.
* Placement of an intrauterine device or intrauterine system in combination with barrier methods.
* The accepted barrier methods include:
- condom with spermicidal foam/gel/film/cream/suppository
- occlusive cap (diaphragm or cervical/vault caps) with spermicidal foam/gel/film/cream/suppository
* Male partner sterilization (the vasectomized partner should be the sole partner for that subject).
* True abstinence (when this is in line with the preferred and usual lifestyle of the subject).
Women must agree to continue using these methods of contraception throughout the study and for at least 3 months after receiving the last
dose of study medication.
Note: If the childbearing potential changes after start of the study (e.g., woman who is not heterosexually active becomes active) a woman must begin a highly effective method of birth control, as described above.
8. A woman of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test upon admission.
9. A woman must agree not to donate eggs (ova, oocytes) for the purposes of assisted reproduction during the study and for at least 3 months after receiving the last dose of study drug.
10. Subjects must have signed an informed consent document indicating that they understand the purpose of, and procedures required for the study and are willing to participate in the study and comply with the study procedures and restrictions.

Any potential subject who meets any of the following criteria will be excluded from participating in the study.
1. Has a primary Diagnostic and Statistical Manual of Mental Disorders-IV or V diagnosis of general anxiety disorder, panic disorder, obsessive compulsive disorder, posttraumatic
stress disorder, anorexia nervosa, or bulimia nervosa. Subjects with comorbid , general anxiety disorder, social anxiety disorder, or panic disorder for whom major depressive disorder is considered the primary diagnosis are not excluded.
2. Has a length of current major depressive episode >24 months despite adequate treatment
3. Has failed more than 2 treatments with a different pharmacological mode of action despite an adequate dose and duration during a previous, or the current depressive episode.
4. Has a current or recent history of clinically significant suicidal ideation within the past 6 months, corresponding to a score of 4 (active suicidal ideation with some intent to act, without specific plan) or 5 (active suicidal ideation with specific plan and intent) for ideation on the Columbia Suicide Severity Rating Scale,
or a history of suicidal behavior within the past year, as validated by the Columbia Suicide Severity Rating Scale at screening or Day 1. Subjects with a prior suicide
attempt of any sort, or prior serious suicidal ideation/plan > 6 months ago, should be carefully screened for current suicidal ideation and only
included at the discretion of the investigator.
5. Subject has a history of substance use disorder according to Diagnostic and Statistical Manual of Mental Disorders-V criteria, except nicotine or caffeine, within 6 months before Screening.
However, subjects who have completed a treatment for (alcohol) addiction more than 8 weeks prior to first dose administration and are
under continuous control of the study center, may be included if the risk to fall back is considered minimal and no significant abnormalities are
shown in clinical laboratory or other predose safety assessments.
6. Subject has positive test result(s) for alcohol or drugs of abuse (including barbiturates, methadone, opiates, cocaine, cannabinoids,
amphetamine/methamphetamine, benzodiazepines and ecstasy) at Screening and/or admission - Subjects with a positive alcohol or drug screen at Screening may have the test repeated once during the screening phase, based on the investigator's discretion. This determination, and the reason for permitting a repeat test, must be recorded in the subject's source documents and initialed by the investigator. A positive, repeat alcohol or drug screen is exclusionary.
7. Has a current diagnosis of a psychotic disorder, major depressive disorder with psychosis, bipolar disorder, an eating disorder, mental retardation, cluster B
personality disorder (e.g., borderline antisocial, narcissistic personality disorders), narcolepsy, central sleep apnea, sleep-related hypoventilation, circadian rhythm sleep-wake disorders, substance/medication-induced sleep disorder or parasomnias (non rapid eye movement sleep arousal disorders, nightmare disorder, rapid eye movement sleep behavior disorder).
8. Obstructive sleep apnea/hypopnea (apnea/hypopnea index >10) or restless legs syndrome (periodic leg movements with arousal index >15) as assessed on the first or second polysomnography recording during screening
9. Subject has used:
• Monoamine oxidase inhibitors within 12 weeks before screening
• Other antidepressive therapy except an selective serotonine reuptake inhibitor within 6 weeks before screening
• selective serotonine reuptake inhibitor >6 months without clinical success (worsening - no/minimal improvement clinical improvement)
10. Subject is unable to stop the following medication from screening and throughout the study:
• Any hypnotics including but not limited to:
o Benzodiazepines
o Sedating antihistamines, including chronic use of diphenhydramine.
o Zolpidem, zoplicon, eszopiclone and ramelteon
o S-adenosyl methionine
o Melatonin
• Antipsychotic drugs
• Lithium and other mood stabilizers
• Opiates
11. Use of any prescription or over-the-counter medication, herbal medication, vitamins, or mineral supplements within 14 days prior to study drug administration (not including paracetamol, acetaminophen, ibuprofen and hormonal contraceptives). The use of medication that is considered not to have any impact on the study results may be allowed after agreement between the investigator and the study responsible safety physician.
More Exclusion criteria : see protocol pages 37- 38