Actively Recruiting
A Phase 2 Study of Zelquistinel or Placebo for the Reduction of Symptoms of Major Depressive Disorder
Led by Syndeio Biosciences, Inc · Updated on 2026-04-13
164
Participants Needed
32
Research Sites
125 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
The goal of this clinical trial is to learn if zelquistinel works to treat depression in adults. It will also learn about the safety of zelquistinel. The main questions it aims to answer are: Does zelquistinel reduce depression scores in participants compared to participants who take a placebo (a look-alike tablet that contains no zelquistinel1)? What medical problems are observed in participants who take zelquistinel? Participants will take one tablet of zelquistinel or placebo every week for 6 weeks. Participants will visit the clinic every week of the 6 week period to have the severity of their depression evaluated.
CONDITIONS
Official 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 (MDD) lasting between 3 weeks and 18 months, confirmed by DSM-5 and SCID-5-CT
- Hamilton Depression Rating Scale-17 (HDRS-17) total score of 18 or higher at screening and baseline visits with no more than 25% change between visits
- Hamilton Anxiety Rating Scale (HARS) total score of 15 or higher at screening and baseline visits
- Insomnia Severity Index (ISI) total score of 10 or higher at screening and baseline visits
- Female participants must be surgically sterile, postmenopausal for at least 2 years, or use acceptable birth control with a negative pregnancy test before starting treatment
- Male participants must use medically acceptable contraception from randomization until the end of week 6 and inform female partners about birth control use
- Able to understand study requirements, willing to comply with restrictions, and able to communicate with study staff
- Provide written informed consent
- Capable of completing patient-reported outcomes and reliably rated on assessment scales
- Moderate or greater illness severity with a Clinical Global Impression - Severity (CGI-S) score of 4 or higher at screening and baseline visits
You will not qualify if you...
- Treatment-resistant MDD with inadequate response to two or more approved antidepressant medications during current episode
- Current diagnosis of bipolar disorder, antisocial personality disorder, obsessive-compulsive disorder, borderline personality disorder, ADHD, PTSD, or panic attacks
- Current or prior diagnosis of psychotic disorder or MDD with psychotic features
- Score above 4 on the Clinician-Administered Dissociative States Scale (CADSS) at screening
- Active seizure disorder
- Traumatic brain injury with current symptoms
- Treatment with esketamine, ketamine, psychedelic agents, or experimental depression treatments within past 12 months
- Treatment with other experimental agents not for depression within past 3 months
- Use of FDA-approved antidepressants or certain psychiatric medications within 14 days before baseline
- Use of cannabis or cannabis-derived products within 14 days before baseline and positive THC test
- Positive drug abuse test
- Use of medical devices or digital therapies for psychiatric conditions within 90 days
- History of electroconvulsive therapy or brain stimulation treatments within 5 years or failure of electroconvulsive therapy
- Significant kidney or liver dysfunction
- Resting pulse below 60 or above 100 bpm, or abnormal blood pressure or heart conduction measures
- Alcohol abuse or positive alcohol screen
- Substance abuse disorder within 12 months
- Use of nicotine products within 14 days before randomization
- Use of barbiturates unless stable dose for 3 months
- Infection with HIV, COVID-19, active hepatitis B or C, syphilis, or other ongoing infections
- Untreated or unstable hypothyroidism or diabetes
- Pregnancy, nursing, or planning pregnancy
- Working night shifts during study period
- Recent malignancy except certain skin or cervical cancers
- New or changed psychotherapy within 4 weeks before screening
- Use of prohibited medications or herbal supplements that affect psychiatric assessments
- Allergies or intolerance to study drug or related compounds
- Prior participation in this or related studies
- Body mass index over 40 kg/m2
- Employment or family relation to study sponsors or investigators
- Significant suicidal risk or history of suicidal attempts
- Investigator or sponsor medical monitors judge subject inappropriate for study
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
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
Not Yet 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
Not Yet 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
Not Yet 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
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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