Clinical trial Recruiting at 30 sites Phase 2 Interventional Ages 18 to 70

Evaluating ALTO-300 for treating major depressive disorder

Official title: A Randomized, Double-Blind, Placebo-Controlled Study of ALTO-300 With an Open-Label Extension in Adults With Major Depressive Disorder

Run by Alto Neuroscience · NCT05922878 · Data updated 2026-11-12

This study is testing if adding ALTO-300 to standard antidepressants can help people with moderate to severe depression feel better compared to a placebo.

Quick facts

PhasePhase 2
Study typeInterventional
Ages18 Years to 70 Years
SexAll
Enrollment325 (estimated)
SponsorAlto Neuroscience
Industry-sponsored
Locations75 sites (Phoenix, Arizona and 74 other locations)
StatusRecruiting
StartedJune 8, 2023
Main results expectedDecember 2026
Study endsDecember 2026
Registry record updatedOctober 26, 2026
Trial IDNCT05922878 on ClinicalTrials.gov

Is this trial a fit for you?

Likely a good fit

Ideal candidates are adults diagnosed with moderate to severe major depressive disorder who are currently stable on a single antidepressant.

Probably not a fit

Patients with unstable medical conditions, bipolar disorder, or those using sleep medications may not benefit from this study.

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This study aims to assess the efficacy of ALTO-300 compared to a placebo when used alongside a standard antidepressant in patients diagnosed with moderate to severe major depressive disorder (MDD). Participants must have been on a stable dose of an SSRI, SNRI, or bupropion for at least six weeks prior to enrollment. The study will analyze how patient characteristics influence the treatment outcomes. The trial is designed to provide insights into the potential benefits of ALTO-300 in enhancing depression treatment.

Why it matters

Potential benefit: If successful, this treatment could offer a new adjunctive option for patients struggling with major depressive disorder.

How similar studies have gone: While this approach is being explored, similar studies have shown promise in evaluating adjunctive treatments for depression.

Who can join: the full rules

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Have a diagnosis of moderate to severe major depressive disorder (MDD)
* At Visit 1, currently taking a stable dose of 1 or 2 antidepressants (e.g., SSRI, SNRI, bupropion, or gepirone) 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

Where it's running

  • Site 200
    Phoenix, Arizona, United States
    Recruiting
  • Site 193
    Rogers, Arkansas, United States
    Recruiting
  • Site 218
    Bellflower, California, United States
    Recruiting
  • Site 335
    Lafayette, California, United States
    Recruiting
  • Site 335
    Lafayette, California, United States
    Recruiting
  • Site 219
    Mather, California, United States
    Recruiting
Show 44 more locations
  • Site 267
    Moorpark, California, United States
    Recruiting
  • Site 197
    Temecula, California, United States
    Recruiting
  • Site 343
    Denver, Colorado, United States
    Recruiting
  • Site 221
    Tampa, Florida, United States
    Recruiting
  • Site 238
    Fayetteville, Georgia, United States
    Recruiting
  • Site 236
    Boise, Idaho, United States
    Recruiting
  • Site 288
    Worcester, Massachusetts, United States
    Recruiting
  • Site 240
    Mankato, Minnesota, United States
    Recruiting
  • Site 265
    Minneapolis, Minnesota, United States
    Recruiting
  • Site 264
    St Louis, Missouri, United States
    Recruiting
  • Site 344
    Las Vegas, Nevada, United States
    Recruiting
  • Site 114
    Albuquerque, New Mexico, United States
    Recruiting
  • Site 283
    New York, New York, United States
    Recruiting
  • Site 287
    Rose Hill, North Carolina, United States
    Recruiting
  • Site 268
    Winston-Salem, North Carolina, United States
    Recruiting
  • Site 202
    Cincinnati, Ohio, United States
    Recruiting
  • Site 316
    Austin, Texas, United States
    Recruiting
  • Site 239
    Conroe, Texas, United States
    Recruiting
  • Site 275
    Houston, Texas, United States
    Recruiting
  • Site 320
    Houston, Texas, United States
    Recruiting
  • Site 353
    Plano, Texas, United States
    Recruiting
  • Site 234
    San Marcos, Texas, United States
    Recruiting
  • Site 235
    Stephenville, Texas, United States
    Recruiting
  • Site 277
    Fairfax, Virginia, United States
    Recruiting
  • Site 189
    Phoenix, Arizona, United States
    Withdrawn
  • Site 187
    Yuma, Arizona, United States
    Active not recruiting
  • Site 318
    Carlsbad, California, United States
    Active not recruiting
  • Site 217
    Glendale, California, United States
    Active not recruiting
  • Site 209
    Los Angeles, California, United States
    Active not recruiting
  • Site 194
    Mission Viejo, California, United States
    Terminated
  • Site 203
    Colorado Springs, Colorado, United States
    Active not recruiting
  • Site 345
    Evergreen, Colorado, United States
    Active not recruiting
  • Site 349
    Evergreen, Colorado, United States
    Active not recruiting
  • Site 214
    Norwalk, Connecticut, United States
    Withdrawn
  • Site 159
    Clermont, Florida, United States
    Terminated
  • Site 225
    Miami Gardens, Florida, United States
    Active not recruiting
  • Site 190
    Miami Lakes, Florida, United States
    Active not recruiting
  • Site 161
    Okeechobee, Florida, United States
    Active not recruiting
  • Site 220
    West Palm Beach, Florida, United States
    Active not recruiting
  • Site 224
    Savannah, Georgia, United States
    Active not recruiting
  • Site 208
    Snellville, Georgia, United States
    Terminated
  • Site 293
    Stone Mountain, Georgia, United States
    Not yet recruiting
  • Site 317
    Blackfoot, Idaho, United States
    Withdrawn
  • Site 119
    Boise, Idaho, United States
    Active not recruiting

+25 more sites. See ClinicalTrials.gov for the full list.

Study contacts

Similar studies

Other studies for the same condition or treatment. Recruiting studies are listed first.

  • Dupilumab for Major Depressive Disorder

    This study tests whether dupilumab can engage immune targets in adults with major depressive disorder to see if it can help with depressive symptoms.

    Recruiting Phase 2 Icahn School of Medicine at Mount Sinai · New York, New York · NCT07908563

  • Accelerated vs Standard iTBS for Major Depression

    This trial tests whether giving more accelerated iTBS sessions is better tolerated and more effective than the standard schedule for adults with major depressive disorder.

    Recruiting Military Hospital 175 · Ho Chi Minh City · NCT07768397

  • Psilocybin with Structured Integrated Reframing Therapy for trauma-related MDD and PTSD

    This trial tests whether psilocybin therapy, alone or with Structured Integrated Reframing Therapy (SIRT), helps people with trauma-related major depressive disorder who are already on a stable antidepressant.

    Recruiting Phase 3 Khyber Medical University Peshawar · Islamabad, Capital and 2 other locations · NCT07703722

  • Magnesium Bisglycinate Added to Your Depression Treatment

    This study tests whether adding magnesium bisglycinate to your current antidepressant can help reduce depressive symptoms and improve sleep and daily functioning for adults with major depressive disorder.

    Recruiting All India Institute of Medical Sciences, Bhubaneswar · Bhubaneswar, Odisha · NCT07633080

  • Motif XCS System for treatment-resistant depression

    This study tests whether the Motif XCS System is safe and tolerable and might help people with treatment-resistant major depressive disorder.

    Recruiting at 4 sites Motif Neurotech, Inc. · Atlanta, Georgia and 3 other locations · NCT07594483

  • A Phase 3 test of DT120 for major depressive disorder

    DT120 is tested against placebo in adults with major depressive disorder to see if it can help reduce depressive symptoms.

    Recruiting at 23 sites Phase 3 Definium Therapeutics US, Inc. · Little Rock, Arkansas and 25 other locations · NCT07592689

How to take part

  1. Review the eligibility criteria above with your treating physician.
  2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
  3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.
Last reviewed 2026-11-14 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.