A Phase 2 Study of Zelquistinel or Placebo for the Reduction of Symptoms of Major Depressive Disorder

The goal of this clinical trial is to learn if zelquistinel works to treat depression in adults. It will also learn about the safety of zelquistinel. The main questions it aims to answer are: Does zelquistinel reduce depression scores in participants compared to participants who take a placebo (a look-alike tablet that contains no zelquistinel1)? What medical problems are observed in participants who take zelquistinel? Participants will take one tablet of zelquistinel or placebo every week for 6 weeks. Participants will visit the clinic every week of the 6 week period to have the severity of their depression evaluated.