OSU6162 as add-on in SSRI/SNRI-resistant Depression

This is a randomised, placebo-controlled, parallel-group trial comparing OSU6162 at flexible dosage with placebo as add-on to treatment with an SSRI/SNRI in patients with depression that have not responded to treatment with an SSRI/SNRI per se for at least 6 weeks. The study will last for 6 weeks, after which those not having responded will leave the trial and those having responded will be offered to continue treatment without unblinding for another 4 weeks.While assessment of the efficacy and safety of OSU6162 is the main objective of this study, possible differences between the two treatment groups with respect to a number of biomarkers in serum will also be explored.

Inclusion Criteria:Signed informed consent.Age: 25-65 on the day of screening.Meeting DSM-5 criteria for major depressive disorder as confirmed by the Mini International Neuropsychiatric Interview (MINI).A symptom-free period preceding the current episode within the past year confirmed at interview.Not significantly improved, as judged by both doctor and patient, after having been treated with one of the following SSRIs/SNRIs: citalopram, escitalopram, paroxetine, sertraline, fluoxetine, duloxetine, or venlafaxine for at least 6 weeks.Displaying a sum score of MADRS ≥22.In women of childbearing potential (WOCBP): negative result of a pregnancy test and a method of contraception with a failure rate of less than 1 %. Contraception must be used during the treatment and follow-up period. Acceptable forms of contraception are:Use of combined (estrogen and progestogen containing) hormonal contraception associated with inhibition of ovulationoralintravaginaltransdermalprogestogen-only hormonal contraception associated with inhibition of ovulation:oralinjectableimplantablePlacement of intrauterine device (IUD) or intrauterine hormone releasing system (IUS)Bilateral tubal occlusion or ligationVasectomised partner (with appropriate post-vasectomy documentation of the absence of sperm in the ejaculate and provided that male partner is the sole sexual partner of the WOCBP trial participant).Male patients must agree to use condoms during the study and for 2 weeks after the end of the study/last dose of IMP, unless their partner is using a highly efficient method of contraception, as described above.Exclusion Criteria:Meeting MINI criteria at interview for suicidality, manic episode, hypomanic episode, bipolar I, bipolar II, bipolar unspecified, bipolar I with psychotic symptoms, panic disorder, agoraphobia, social anxiety (social phobia), obsessive compulsive disorder, posttraumatic stress disorder, alcohol dependency, alcohol abuse, substance dependency (non-alcoholic), substance abuse (non-alcoholic), psychotic disorders, mood disorders with psychotic features, anorexia nervosa, bulimia nervosa, anorexia nervosa binge eating / purging type, generalised anxiety disorder, or antisocial personality disorder.A history of substance/alcohol abuse within 2 years prior to screening.A previous diagnosis of a personality disorder, autism spectrum disorder, attention-deficit/hyperactivity disorder, or intellectual disability.Any other previously diagnosed or suspected CNS disorder that according to the investigator renders the patient unsuitable for participation in the trial.Any factor that according to the investigator renders it unlikely that the patient will comply with the instructions regarding treatment, visits etc.Any somatic illness that according to the investigator renders the patient unsuitable for participation in the trial.Any signs or symptoms of somatic illness resulting from assessment of vital signs, physical examination, clinical laboratory tests, and 12-lead ECG that according to the investigator renders the patient unsuitable for participation for safety reasons, including a QTc-time on ECG exceeding 450 ms in men and 460 ms in women.Any change in dosage of said SSRI/SNRI within 4 weeks prior to screening or at any time during the course of the trial.Treatment with any other psychoactive drug than said SSRI/SNRI with the exception of occasional use of benzodiazepines and benzodiazepine-like anxiolytics or hypnotics and occasional use of antihistaminergic sedatives (without anti-dopaminergic effects) within 4 weeks prior to screening and at any time during the course of the trial.Patients who are receiving concomitant therapy with potent cytochrome P450 enzyme inhibitors (e.g., bupropion, fluvoxamin, ketoconazol, itraconazole, telitromycin, clarithromycin, protease inhibitors, quinidine, and terbinafine).Ongoing treatment with drugs with a narrow therapeutic window where either lower or higher serum levels are potentially harmful (including but not limited to warfarin along with other anticoagulants, digoxin along with other antiarrythmics, anticonvulsants prescribed for treatment of epilepsy, cyclosporine, immunosuppressants, and lithium).Current treatment with any prescribed or OTC drug that according to the investigator renders the subject unsuitable for participation in the trial.Previous intake of OSU6162.Current participation in another clinical trial.Nursing women.