A Phase II, 6-week, Multicenter, Randomized, Double-blind, Double-dummy, Placebo-controlled, Parallel Group Trial With a Quetiapine Arm to Evaluate the Efficacy, Tolerability and Safety of Oral BI 1358894 in Patients With Major Depressive Disorder With Inadequate Response to Antidepressants.

This study is open to adults with depression (major depressive disorder) for whom standard treatment with antidepressants alone does not work sufficiently. The purpose of the trial is to find out whether a medicine called BI 1358894 helps to improve symptoms of depression. Four different doses of BI 1358894 are tested in the study. Participants continue their standard antidepressant therapy throughout the study. Participants are put into 6 groups by chance. Participants in 4 of the 6 groups take different doses of BI 1358894, and placebo. Participants in the fifth group take quetiapine, a medicine already used to treat depression, and placebo. Participants in the sixth group take placebo only. Participants take BI 1358894, quetiapine, or placebo as tablets. Placebo tablets look like BI 1358894 or quetiapine tablets but do not contain any medicine. Each participant takes tablets twice a day. Participants are in the study for about 3 months. During this time, they visit the study site about 8 times and get about 2 phone calls. At the visits, doctors ask participants about their symptoms. The results between the BI 1358894 groups, the quetiapine group, and the placebo group are then compared. The doctors also regularly check the general health of the participants.