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

Last updated: October 15, 2025
Sponsor: Alto Neuroscience
Overall Status: Completed

Phase

2

Condition

Mood Disorders

Depression (Major/severe)

Depression

Treatment

ALTO-203 75 μg

ALTO-203 25 μg

Placebo

Clinical Study ID

NCT06391593
ALTO-203-201
  • Ages 25-64
  • All Genders

Study Summary

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.

Eligibility Criteria

Inclusion

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

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 illnessinvolving an investigational product or device

Study Design

Total Participants: 69
Treatment Group(s): 3
Primary Treatment: ALTO-203 75 μg
Phase: 2
Study Start date:
March 25, 2024
Estimated Completion Date:
April 21, 2025

Connect with a study center

  • Site 4058

    Tucson, Arizona 85704
    United States

    Site Not Available

  • Site 4058

    Tucson 5318313, Arizona 5551752 85704
    United States

    Site Not Available

  • Site 4082

    Oceanside, California 92056
    United States

    Site Not Available

  • Site 4023

    Torrance, California 90504
    United States

    Site Not Available

  • Site 4082

    Oceanside 5378771, California 5332921 92056
    United States

    Site Not Available

  • Site 4023

    Torrance 5403022, California 5332921 90504
    United States

    Site Not Available

  • Site 4059

    Clermont, Florida 34711
    United States

    Site Not Available

  • Site 4005

    Orlando, Florida 32801
    United States

    Site Not Available

  • Site 4059

    Clermont 4151352, Florida 4155751 34711
    United States

    Site Not Available

  • Site 4005

    Orlando 4167147, Florida 4155751 32801
    United States

    Site Not Available

  • Site 4031

    Atlanta, Georgia 30030
    United States

    Site Not Available

  • Site 4031

    Atlanta 4180439, Georgia 4197000 30030
    United States

    Site Not Available

  • Site 4054

    Pikesville, Maryland 21208
    United States

    Site Not Available

  • Site 4054

    Pikesville 4365387, Maryland 4361885 21208
    United States

    Site Not Available

  • Site 4036

    Las Vegas, Nevada 89121
    United States

    Site Not Available

  • Site 4036

    Las Vegas 5506956, Nevada 5509151 89121
    United States

    Site Not Available

  • Site 4022

    Berlin, New Jersey 08009
    United States

    Site Not Available

  • Site 4134

    Princeton, New Jersey 08540
    United States

    Site Not Available

  • Site 4022

    Marlton 4502911, New Jersey 5101760 08053
    United States

    Site Not Available

  • Site 4134

    Princeton 5102922, New Jersey 5101760 08540
    United States

    Site Not Available

  • Site 4075

    Westlake, Ohio 44145
    United States

    Site Not Available

  • Site 4075

    Westlake 5176517, Ohio 5165418 44145
    United States

    Site Not Available

  • Site 4040

    Austin, Texas 78737
    United States

    Site Not Available

  • Site 4072

    Houston, Texas 77081
    United States

    Site Not Available

  • Site 4040

    Austin 4671654, Texas 4736286 78737
    United States

    Site Not Available

  • Site 4072

    Houston 4699066, Texas 4736286 77081
    United States

    Site Not Available

  • Site 4007

    Clinton, Utah 84015
    United States

    Site Not Available

  • Site 4007

    Clinton 5773001, Utah 5549030 84015
    United States

    Site Not Available

  • Site 4033

    Bellevue, Washington 98007
    United States

    Site Not Available

  • Site 4033

    Bellevue 5786882, Washington 5815135 98007
    United States

    Site Not Available

Map preview placeholder

Not the study for you?

Let us help you find the best match. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.