Recruiting
Phase 2

ALTO-300

Sponsor:

Alto Neuroscience

Code:

NCT05922878

Conditions

Major Depressive Disorder

Eligibility Criteria

Sex: All

Age: 18 - 70

Healthy Volunteers: Not accepted

Interventions

ALTO-300

Placebo

Study Details

Brief summary:

The purpose of this study is to determine efficacy differences between ALTO-300 and placebo, used adjunctively to an antidepressant, related to patient characteristics.

Conditions

Major Depressive Disorder

Study ID

NCT05922878

Start date

Jun 8, 2023

Status verified date

Jun, 2025

Completion date

Dec, 2026

Anticipated

Primary completion date

Dec, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 70

Healthy Volunteers: Not accepted

Inclusion Criteria:

  • Have a diagnosis of moderate to severe major depressive disorder (MDD)
  • At Visit 1, currently taking a single SSRI, SNRI, or bupropion for at least 6 weeks with no dose modifications in the past 2 weeks by Visit 2
  • Willing to comply with all study assessments and procedures
  • Must not be pregnant or breastfeeding at time of enrollment or throughout study

Exclusion Criteria:

  • Evidence of unstable medical condition
  • Nightly use of sleep medication
  • Diagnosed bipolar disorder, psychotic disorder, or dementia
  • Current moderate or severe substance use disorder
  • Has a history of hypersensitivity or allergic reaction to ALTO-300 or any of its components/excipients
  • Concurrent or recent participation in another clinical trial for mental illness involving an investigational product or device

Study Design

Enrollment

321 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: ALTO-300

Participants will receive ALTO-300 capsule once daily in the evening, from Day 1 to Day 42 in double blind (DB) treatment period. Eligible participants who will enter the open-label (OL) treatment period will receive ALTO-300 capsule once daily in the evening from OL baseline until the end of OL period/early termination visit (Up to 8 weeks).

placebo comparator: Placebo

Participants will receive matching placebo capsule once daily in the evening, from Day 1 to Day 42 in double blind (DB) treatment period.

Interventions

ALTO-300

ALTO-300 capsule QD

Placebo

Placebo capsule QD

Primary outcome measure

  • To assess efficacy of adjunctive ALTO-300 versus placebo on symptoms of MDD in a pre-defined subgroup of participants as measured by the change over time up to week 6 in the Montgomery-Åsberg Depression Rating Scale (MADRS). [ Time Frame: Change over time for up to week 6 ]

Central Contacts and Locations

Central contacts

Alto Neuroscience

650-200-0412clinical@altoneuroscience.com

Locations

Site 200

Recruiting

Phoenix, Arizona, United States, 85012

Site 187

Recruiting

Yuma, Arizona, United States, 85364

Site 193

Recruiting

Rogers, Arkansas, United States, 72758

Site 218

Recruiting

Bellflower, California, United States, 90706

Site 217

Recruiting

Glendale, California, United States, 91206

Site 335

Recruiting

Lafayette, California, United States, 94549

Site 209

Recruiting

Los Angeles, California, United States, 90064

Site 219

Recruiting

Mather, California, United States, 95655

Site 194

Recruiting

Mission Viejo, California, United States, 92691

Site 197

Recruiting

Temecula, California, United States, 92591

Site 203

Recruiting

Colorado Springs, Colorado, United States, 80918

Site 349

Recruiting

Evergreen, Colorado, United States, 80439

Site 214

Recruiting

Norwalk, Connecticut, United States, 06851

Site 159

Recruiting

Clermont, Florida, United States, 34711

Site 225

Recruiting

Miami Gardens, Florida, United States, 33014

Site 190

Recruiting

Miami Lakes, Florida, United States, 33016

Site 161

Recruiting

Okeechobee, Florida, United States, 34972

Site 221

Recruiting

Tampa, Florida, United States, 33629

Site 220

Recruiting

West Palm Beach, Florida, United States, 33407

Site 224

Recruiting

Savannah, Georgia, United States, 31405

Site 208

Recruiting

Snellville, Georgia, United States, 30078

Site 119

Recruiting

Boise, Idaho, United States, 83702

Site 310

Recruiting

Chicago, Illinois, United States, 60634

Site 215

Recruiting

Jackson, Mississippi, United States, 39216

Site 344

Recruiting

Las Vegas, Nevada, United States, 89102

Site 114

Recruiting

Albuquerque, New Mexico, United States, 87108

Site 192

Recruiting

Staten Island, New York, United States, 10314

Site 199

Recruiting

Hickory, North Carolina, United States, 28601

Site 202

Recruiting

Cincinnati, Ohio, United States, 45215

Site 195

Recruiting

Oklahoma City, Oklahoma, United States, 73112

Site 216

Recruiting

Allentown, Pennsylvania, United States, 18104

Site 350

Recruiting

Media, Pennsylvania, United States, 19063

Site 352

Recruiting

Moosic, Pennsylvania, United States, 18507

Site 347

Recruiting

Fort Worth, Texas, United States, 76104

Site 196

Recruiting

Richmond, Texas, United States, 77407

Site 207

Recruiting

Clinton, Utah, United States, 84015

Site 211

Recruiting

Roanoke, Virginia, United States, 24018

More Information

Sponsor

Alto Neuroscience

Last update posted

Jul 24, 2025

Last verified

Jun, 2025

Trial information was received from ClinicalTrials.gov and was last updated on 2026-10-08. This information was provided to ClinicalTrials.gov by Alto Neuroscience on 2025-07-24. Recruitment status is synced daily from ClinicalTrials.gov and may not reflect the sponsor's current status. Confirm during your call.