Study of deupsilocin besilate (CYB003) in adults with major depressive disorder comparing two doses against placebo

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What is this study about?

This clinical trial investigates a new treatment for Major Depressive Disorder, a serious mental health condition characterized by persistent feelings of sadness and loss of interest in daily activities. The study tests a medication called CYB003 (containing deupsilocin besilate) given as oral capsules, comparing it with placebo to evaluate its effectiveness in treating depression symptoms.

The purpose of this research is to assess how well two different doses of CYB003 work compared to placebo in treating adults with depression. The study medication will be given twice over a period of several weeks, with participants receiving either CYB003 capsules (8 mg or 16 mg) or placebo capsules. Throughout the study, participants will continue taking their current antidepressant medication.

During the trial, participants will attend multiple clinic visits where their depression symptoms will be evaluated using various assessment tools. The study will track changes in depression symptoms over 84 days to determine if the treatment is effective. The medication’s safety will also be monitored throughout the study period.

1 Initial assessment

Your eligibility for the trial will be confirmed through a detailed assessment of your major depressive disorder (MDD) symptoms

A medical professional will verify your current antidepressant medication use and confirm that you have been on a stable dose for at least 4 weeks

Your body mass index (BMI) must be 40 kg/m² or less

2 First treatment day (Day -1)

You will undergo baseline assessments and measurements

If you are of childbearing potential, a pregnancy test will be conducted

3 First dosing session (Day 1)

You will receive either CYB003 capsules or a placebo capsule for oral use

The dosing session will last up to 8 hours

During this time, you must refrain from using nicotine

4 First follow-up assessment (Day 2)

Your response to the treatment will be evaluated

Your depression symptoms will be measured using standardized assessments

5 Second dosing session (Day 22)

You will receive a second dose of either CYB003 or placebo

The session will follow the same format as the first dosing session

6 Second follow-up assessment (Day 23)

Your response to the second treatment will be evaluated

7 Assessment at Day 42

A comprehensive evaluation of your depression symptoms will be conducted

This is a key timepoint for measuring the treatment’s effectiveness

8 Final assessment (Day 84)

Final evaluation of your response to the treatment

Assessment of sustained improvement in depression symptoms

Completion of quality of life questionnaires

Who Can Join the Study?

Age must be between 18 and 85 years at screening
Male participants who can produce sperm must use a condom with spermicide during the study and for 12 weeks after the last dose if their partner can become pregnant
Female participants who can become pregnant must use highly effective contraception during the study and for 12 weeks after the last dose, and have negative pregnancy tests before starting
Women who no longer have periods must be either post-menopausal (no periods for at least 12 months) or have had surgery to remove reproductive organs
Must provide written informed consent and agree to follow study requirements
Must have a diagnosis of Major Depressive Disorder (single episode lasting 4-24 months or recurring episodes) that first occurred before age 60
Depression must be moderate to severe, as measured by specific assessment tools
Depression symptoms must remain stable between screening and first day of study
Must be taking a stable dose of antidepressant medication for at least 4 weeks before screening, with inadequate improvement (less than 50% better)
If receiving counseling or therapy, it must be stable for at least 12 weeks before screening and remain unchanged during the study
Body Mass Index (BMI) must be 40 or less
Must be able to avoid using nicotine for up to 8 hours during dosing sessions
Must be registered with a healthcare professional who can confirm diagnosis and previous treatments

Who Cannot Join the Study?

History of resistance to antidepressant treatments or failure to respond to 3 or more adequate antidepressant treatments
Presence of other mental health conditions like bipolar disorder, schizophrenia, or severe personality disorders
Current substance abuse or dependence within the past 6 months
Significant risk of suicide or self-harm
Serious medical conditions that are not well-controlled
Pregnancy or breastfeeding
Use of certain medications that might interact with the study drug
Participation in another clinical trial within the past 30 days
History of seizures or other neurological disorders
Severe liver or kidney problems
Unstable heart conditions
History of allergic reactions to similar medications
Unable to comply with study procedures or follow-up visits
Cognitive impairment that could interfere with understanding study requirements

Where you can join this trial?

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Other Sites

Site Name	City	Country
Mtz Clinical Research Powered By Pratia	Warsaw	Poland
INEP medical s.r.o.	Prague	Czechia
Promente Sp. z o.o.	Bydgoszcz	Poland
A-Shine s.r.o.	Plzen	Czechia
Uniwersytecki Szpital Kliniczny W Bialymstoku	Bialystok	Poland
General Hospital Of Thessaloniki Papageorgiou	Thessaloniki	Greece
Central Institute of Mental Health	Mannheim	Germany
Charite Universitaetsmedizin Berlin KöR	Berlin	Germany
Saarland University Hospital	Homburg	Germany
Instytut Psychiatrii I Neurologii	Warsaw	Poland
Eginitio Hospital	Athens	Greece
La Nua Day Hospital Mental Health Centre	Galway	Ireland
Tallaght Adult Mental Health Service	Dublin	Ireland
Cgfpake Bawmb Kcvftgubzhr Phcovhaw Sfr z oayl	Gdansk	Poland
Pujew suuuot	Prague	Czechia
Ggcebc Utdgkssrxm Fpcekaddb	Frankfurt	Germany
Ushyaxmfqedbka Cquhxrl Kkcsmcvcf	Gdansk	Poland
Uduyhrryjg Gmrxczh Hauhzthl Awxavqv	Athens	Greece

Trial status

Country	Status	Recruitment Start
Czechia	Not yet recruiting	01.08.2025
Germany	Not yet recruiting	01.08.2025
Greece	Recruiting	01.08.2025
Ireland	Recruiting	01.08.2025
Poland	Recruiting	01.08.2025

Trial locations

CYB003 is an investigational medication being studied for the treatment of Major Depressive Disorder (MDD). It is being tested at two different dose levels to evaluate its effectiveness in treating depression symptoms. The medication is administered twice during the study to see how it affects people with depression compared to those who receive a placebo.

This is an experimental treatment, and its full safety and effectiveness profile is still being evaluated through this clinical trial. The study aims to determine if this new medication can help reduce symptoms in adults who have Major Depressive Disorder.

Major Depressive Disorder – A serious mood disorder characterized by persistent feelings of sadness, loss of interest in activities, and decreased energy that last for at least two weeks. The condition affects how a person thinks, feels, and handles daily activities, such as sleeping, eating, or working. People with this disorder often experience changes in appetite, difficulty sleeping or oversleeping, loss of energy, and difficulty concentrating. The disorder can also cause physical symptoms such as unexplained aches and pains. This condition can occur as a single episode or can be recurrent throughout a person’s life.

Trial ID:

2024-519270-40-00

Protocol code:

CYB003-003

NCT ID:

NCT06793397

Trial Phase:

Therapeutic confirmatory (Phase III)

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Study of deupsilocin besilate (CYB003) in adults with major depressive disorder comparing two doses against placebo

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?