Pilot Decentralized Trial

To understand the relationship between baseline biology and score change in the Montgomery-Asberg Depression Rating Scale (MADRS) with ALTO-100 from start of dosing to end of treatment

The Montgomery-Åsberg Depression Rating Scale (MADRS) measures the severity of depression where smaller scores indicate less depression and higher scores suggest more severe depression. Possible scores for this 10 item version range from 0 to 60. The score change from the start of dosing (Day 1) to the end of treatment (Day 56) is the primary outcome.

Time frame: Measured at Day 1, Day 14, Day 28, Day 42, Day 56

To understand the relationship between baseline biology and score change in the Clinical Global Impression scale - Severity (CGI-S) with ALTO-100 from Screening to end of treatment

The Clinical Global Impression scale - Severity (CGI-S) measures the severity of psychopathology in general where smaller scores indicate less illness and higher scores suggest more severe illness. Possible scores for this scale range from 1 to 7. The score change from Screening (Day \[-21\]) to the end of treatment (Day 56) is the primary outcome.

Time frame: Measured at Screening, Day 1, Day 14, Day 28, Day 42, Day 56

Number of Participants with Adverse Events (AEs) as a Measure of Safety and Tolerability of ALTO-100

An adverse event is any untoward medical event that occurs in a participant administered an investigational product, and it does not necessarily indicate only events with clear causal relationship with the relevant investigational product.

Time frame: From the signing of the ICF until the follow-up visit (up to 13 weeks)

Number of Participants With Clinically Significant Laboratory Abnormalities as a Measure of Safety and Tolerability of ALTO-100

Blood samples for serum chemistry and hematology will be collected for clinical laboratory testing.

Time frame: From the signing of the ICF until the end-of-treatment visit (up to 13 weeks)