Study Evaluating Safety and Efficacy of Ropanicant in MDD Patients

Inclusion Criteria:

• Participants must meet the DSM-5 criteria for MDD without psychotic features anddiagnosis confirmed by the Mini-International Neuropsychiatric Interview (MINI).

• Participants with a current major depressive episode of at least 4 weeks of durationprior to the screening visit.

• Participants must have an MADRS score of ≥25 at the screening and the baselinevisits.

• Participants must have a score of ≥4 on Clinical Global Impression - Severity (CGI-S) Scale at the screening and the baseline visits.

Exclusion Criteria:

• Participants who meet criteria for treatment-resistant depression during the currentmajor depressive episode, which will be defined as being non-responders (less than 50% of symptom improvement) to 2 or more depression treatment periods of adequatedose and duration as defined by the Massachusetts General Hospital (MGH)Antidepressant Treatment Response Questionnaire (ATRQ).

• Participants taking antidepressant treatment (SSRIs and SNRIs) or any medicationthat is contraindicated with the use of monoamine oxidase inhibitors (eg, opioids,stimulants) within 2 weeks (or 5 half-lives, whichever is longer) prior to baselineand until the end of study visit.

• Participants who do not agree to avoid tyramine rich diet from the start of dosingand until 2 weeks following last study drug administration.

• Participants who are habitual smokers or using nicotine products.