A Study to Assess Adverse Events of Fosigotifator (ABBV-CLS-7262) in Adults With Major Depressive Disorder

A Phase 1 b Randomized, Double-blind, Placebo-Controlled, Experimental Medicine Study of Fosigotifator in Adults 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. The main goal of the study is to evaluate how safe and effective fosigotifator is in treating MDD.

Fosigotifator (ABBV-CLS-7262) is a new treatment being developed for adult patients with depression. This study is double-blinded, which means that neither the patients nor the study doctors know who is given fosigotifator and who is given placebo. Participants will be randomly assigned to one of the two groups to receive fosigatofator or placebo. There is 1 in 2 chance that participants will receive placebo. Approximately 106 adult participants with MDD will be enrolled in approximately 15 sites across the world.

Participants will receive oral fosigotifator or matching placebo. Duration of the study is approximately 144 days.

There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular weekly 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.

Inclusion Criteria:

• Body mass index of 18 to 33 kg/m2 at the time of consent.
• Meet the Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) criteria for MDD based on the Structured Clinical Interview for DSM-5.
• Current major depressive episode of at least 6 weeks to less than 24 months in duration at Screening (Visit 1 ).
• Meets the following disease activity criteria mentioned in the protocol.
• Requires antidepressant therapy (ADT) per the investigator's opinion or, if currently taking ADT, must be able to safely discontinue ADT at least 7 days prior to the first dose of study drug at Baseline (Visit 2).

Exclusion Criteria:

- Primary psychiatric illness other than MDD.