A Study to Assess Change in Disease Activity and Adverse Events of Oral Icalcaprant in Adult Participants With Major Depressive Disorder

Major depressive disorder (MDD; depression) is a mood disorder that causes a continued feeling of sadness and loss of interest. It is a common and serious illness that can cause both emotional and physical symptoms such as feelings of sadness, irritability, not being able to focus on activities, tiredness, changes in eating habits, and aches and pains. This study will assess the changes in disease activity and adverse events of oral Icalcaprant in adult participants with major depressive disorder who are currently experiencing a major depressive episode (MDE). Icalcaprant is an investigational drug being developed for the treatment of depressive episodes in adult participants with major depressive disorder. Participants are placed in 1 of 3 groups, called treatment arms. There is a 1 in 3 chance that a participant will be assigned to placebo treatment. Around 195 adult participant with major depressive disorder will be enrolled in approximately 35 sites in North America. Participants will receive oral capsules of Icalcaprant or matching placebo once daily for 6 weeks, with a 30-day safety follow-up. There may be a higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, checking for side effects and completing questionnaires.