Study to Evaluate Efficacy and Safety of Ropanicant in MDD Patients

Inclusion Criteria: * Patients must meet the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) criteria for MDD without psychotic features based on the Mini International Neuropsychiatric Interview (MINI) with a current major depressive episode of at least 4 weeks of duration but no longer than 12 months. * Patients must have a Clinical Global Impression-Severity (CGI-S) score of ≥4. * Patients must have a Structured Interview Guide for the Hamilton Depression Rating Scale (SIGH-D) score of ≥20. * Patients must have a Snaith-Hamilton Pleasure Scale (SHAPS) score of ≥20. * Patients must have vision and hearing (corrected if needed) sufficient to comply with the testing procedures. Exclusion Criteria: * Patients who meet criteria for treatment-resistant depression (TRD) during the current major depressive episode, which is defined as being nonresponders (\<50% of symptom improvement) to 2 or more depression treatment periods of adequate dose and duration. * Patients not in good general health with clinically significant abnormalities as assessed by the investigator and determined by physical examination results, neurological examination results, ECG results, or laboratory assessments. * Female patients who are pregnant, planning to become pregnant during the study or within 30 days after the last administration of study drug, or breastfeeding. * Patients with bradycardia (\<50 bpm) or tachycardia (\>100 bpm) on the ECG results.