Major Depressive Disorder (MDD) is a condition where people feel sad and lose interest in things they used to enjoy. It can make them feel tired and change how they eat and sleep. This study looks at how safe and effective a new medicine, Fosigotifator, is for treating MDD. This study is called double-blinded, meaning neither the patients nor the doctors know who gets the actual medicine and who gets a fake one (placebo). About 106 adults with MDD will join from around the world. They will take either the real medicine or a placebo by mouth for around 144 days. During this time, participants will visit the hospital or clinic weekly for check-ups, blood tests, and questionnaires.

• The study lasts about 144 days with weekly hospital or clinic visits.
• Participants may face a higher treatment burden compared to regular treatment.
• Patients have a 50% chance of getting the placebo instead of the real medicine.