Actively Recruiting
Phase 2 Study of Oral Zelquistinel (GATE-251) or Placebo for Major Depressive Disorder Symptoms Reduction
Led by Syndeio Biosciences, Inc · Updated on 2026-05-27
164
Participants Needed
32
Research Sites
9 weeks
Total Duration
On this page
Sponsors
S
Syndeio Biosciences, Inc
Lead Sponsor
W
Worldwide Clinical Trials
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are evaluating zelquistinel, a drug that acts on the NMDA receptor, to see if it can reduce symptoms of major depressive disorder (MDD) in adults aged 18 to 64. This Phase 2 clinical trial aims to compare the effects of zelquistinel with a placebo, while also monitoring the safety and medical issues that might arise from taking the drug. The study is designed as a randomized, double-blind, placebo-controlled trial to gather reliable data on its effectiveness and safety. Participants will take either a single 6 mg tablet of zelquistinel or a placebo tablet once a week for six weeks. The study includes up to 28 days for screening, 42 days of treatment, and a 4-week follow-up period. During the treatment phase, participants visit the clinic weekly to receive their tablet and have their depression severity assessed. Both the active drug and placebo tablets look identical to maintain the study's double-blind design. Throughout the trial, researchers will assess depression severity using the Hamilton Depression Rating Scale-17 at each weekly visit. They will also record any adverse events or medical problems reported since the last visit. The study monitors participants' overall health, including clinical global impressions of severity and safety measures, for up to 98 days. This careful evaluation helps determine both the effects of the drug on depression symptoms and its safety profile.
CONDITIONS
Brief Title
A Phase 2 Study of Zelquistinel or Placebo for the Reduction of Symptoms of Major Depressive Disorder
Who Can Participate
Eligibility Criteria
You may qualify if you...
- Male or female subject.
- Aged 18 to 64 years, inclusive.
- Diagnosed with a first or recurrent episode of major depressive disorder lasting between 3 weeks and 18 months.
- Hamilton Depression Rating Scale-17 score of 18 or higher at screening and baseline with less than 25% change between visits.
- Hamilton Anxiety Rating Scale score of 15 or higher at screening and baseline.
- Insomnia Severity Index score of 10 or higher at screening and baseline.
- Female subjects must be surgically sterile, menopausal for at least 2 years, or use birth control if of childbearing potential with a negative pregnancy test before dosing.
- Male subjects must use medically acceptable contraception during the study.
- Ability to understand study requirements and willing to comply.
- Provides written informed consent.
- Able to communicate with study staff and complete assessments.
- Moderately ill or worse with a Clinical Global Impressions-Severity score of 4 or higher at screening and baseline.
You will not qualify if you...
- Treatment-resistant major depressive disorder with inadequate response to 2 or more antidepressants during current episode.
- Current diagnosis of bipolar disorder, certain personality disorders, OCD, ADHD, PTSD, panic attacks, or psychotic disorders.
- Score above 4 on the Clinician-Administered Dissociative States Scale at screening.
- Active seizure disorder or traumatic brain injury with symptoms.
- Use of esketamine, ketamine, psychedelic or experimental agents for depression within past 12 months.
- Use of other experimental agents not for depression within past 3 months.
- Use of FDA-approved antidepressants or certain other medications within 14 days prior to baseline.
- Use of cannabis or cannabis-derived products within 14 days prior to baseline.
- Positive drug abuse tests.
- Treatment with medical devices or digital therapies for CNS conditions within 90 days.
- History of ECT, vagus nerve stimulation, deep brain stimulation, or rTMS within 5 years or failed ECT response.
- Significant kidney or liver dysfunction.
- Abnormal heart rate or blood pressure readings.
- Evidence of alcohol or substance abuse.
- Use of nicotine products within 14 days prior to randomization.
- Use of barbiturates unless stable dose for 3 months.
- Infections like HIV, COVID-19, hepatitis B/C, syphilis.
- Thyroid dysfunction or unstable diabetes.
- Pregnant, nursing, or planning pregnancy during study.
- Night shift work during study period.
- Recent cancer except certain skin or cervical cancers.
- Recent changes in psychotherapy.
- Use of prohibited medications or herbal therapies.
- Allergy to study drug or related compounds.
- Prior participation in this or related studies.
- Body mass index over 40.
- Employment related conflicts.
- Significant risk for suicidal behavior or recent suicidal attempts.
- Investigator judgment of unsuitability for study participation.
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - up to 28 days
Participants are screened for eligibility to participate in the trial.
1 screening and enrollment visit
Duration - 42 days
Participants receive either zelquistinel or placebo once weekly to assess the reduction of symptoms of major depressive disorder.
Weekly visits for 6 weeks
Duration - 4 weeks
Participants are monitored for 4 weeks after treatment to assess ongoing safety and symptom changes.
1 follow-up visit
Trial Site Locations
Total: 32 locations
1
NoesisPharma, LLC
Phoenix, Arizona, United States, 85028
Actively Recruiting
2
Del Sol Research Management
Tucson, Arizona, United States, 85710
Actively Recruiting
3
Catalina Research Institute, LLC
Montclair, California, United States, 91763
Actively Recruiting
4
Excell Research, Inc
Oceanside, California, United States, 92056
Actively Recruiting
5
Anderson Clinical Research
Redlands, California, United States, 92374
Actively Recruiting
6
Studyops Inc
San Francisco, California, United States, 94102
Actively Recruiting
7
Lumos Clinical Research Center
San Jose, California, United States, 95124
Actively Recruiting
8
Sunwise Clinical Research
Walnut Creek, California, United States, 94596
Not Yet Recruiting
9
Clinical Neuroscience Solutions, Inc
Jacksonville, Florida, United States, 32256
Not Yet Recruiting
10
Premier Clinical Research Institute Inc
Miami, Florida, United States, 33122
Not Yet Recruiting
11
Aqualane Clinical Research
Naples, Florida, United States, 34105
Actively Recruiting
12
EquiPath Health and Research Tampa Bay, LLC
Riverview, Florida, United States, 33578
Actively Recruiting
13
Neuroscience Research Institute
West Palm Beach, Florida, United States, 33407
Actively Recruiting
14
Denali Health Atlanta, LLC
Stone Mountain, Georgia, United States, 30038
Actively Recruiting
15
EmVenio Research
Chicago, Illinois, United States, 60622
Actively Recruiting
16
Tandem Clinical Research
Metairie, Louisiana, United States, 70006
Actively Recruiting
17
Sunstone Therapies
Rockville, Maryland, United States, 20850
Actively Recruiting
18
Continental Clinical Solutions
Towson, Maryland, United States, 21204
Actively Recruiting
19
Vitalix Clinical
Worcester, Massachusetts, United States, 01608
Actively Recruiting
20
Rochester Center for Behavioral Medicine
Rochester Hills, Michigan, United States, 48307
Actively Recruiting
21
Neurobehavioral Research, Inc
Cedarhurst, New York, United States, 11516
Not Yet Recruiting
22
IMA Clinical Research - NYC Midtown
New York, New York, United States, 10036
Actively Recruiting
23
IMA Clinical Research - NYC Uptown
New York, New York, United States, 10128
Actively Recruiting
24
UNC Health Rex
Raleigh, North Carolina, United States, 27607
Not Yet Recruiting
25
Insight Clinical Trials LLC
Independence, Ohio, United States, 44131
Not Yet Recruiting
26
Lehigh Center for Clinical Research
Allentown, Pennsylvania, United States, 18103
Not Yet Recruiting
27
Scranton Medical Institute, LLC
Moosic, Pennsylvania, United States, 18507
Terminated
28
Adams Clinical
Philadelphia, Pennsylvania, United States, 19104
Actively Recruiting
29
Psychiatric Consultants, PC
Franklin, Tennessee, United States, 37067
Actively Recruiting
30
Elevate Synapsis, LLC
Atascocita, Texas, United States, 77346
Actively Recruiting
31
Synapsis Bio
Atascocita, Texas, United States, 77346
Not Yet Recruiting
32
Adams Clinical Dallas
DeSoto, Texas, United States, 75115
Not Yet Recruiting
Research Team
K
Karen Raudibaugh
S
Sharon Ortiz
How is the study designed?
Study Type
INTERVENTIONAL
Masking
QUADRUPLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
TREATMENT
Number of Arms
2
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