PD, PK, and Safety of ALTO-203 in Patients With MDD

Double-Blind, Single and Multiple Dose Study to Determine Pharmacodynamic Markers, Pharmacokinetic Parameters, and Safety of ALTO-203 in Patients With Major Depressive Disorder

The goal of this clinical trial is to determine the pharmacodynamic effects of ALTO-203 in patients with MDD in a randomized, placebo-controlled, single-dose crossover treatment period. Additionally, safety, tolerability, and PK will be assessed in a subsequent randomized placebo-controlled multi-dose parallel-group treatment period of 28 days.

Participants will complete subjective response questionnaires and perform cognitive tasks during the single-dose period, in which participants will receive ALTO-203 25 μg and 75 μg, as well as placebo. During the multiple-dose period, participants will receive either ALTO-203 25 μg, 75 μg , or placebo. Safety will be assessed over the single dose and 28-day multiple dose periods.

Inclusion Criteria:

• Have a diagnosis of moderate major depressive disorder (MDD)
• Presence of anhedonia symptoms
• Not taking antidepressant at Screening Visit 2
• Willing to comply with all study assessments and procedures

Exclusion Criteria:

• Evidence of unstable medical condition
• Diagnosed bipolar disorder, psychotic disorder, or dementia
• Concurrent use of prohibited medications
• Current moderate or severe substance use disorder
• Concurrent or recent participation in another clinical trial for mental illness involving an investigational product or device