ClinicalTrials.gov record NCT07348601
A Study of CSTI-500 in Patients With Prader-Willi Syndrome
A Proof-of-Concept Open-Label Clinical Trial to Evaluate the Safety, Tolerability, and Efficacy of CSTI-500 in Participants With Prader-Willi Syndrome
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Phase 2, open-label, proof-of-concept study of oral CSTI-500 in people aged 13–50 with genetically confirmed Prader-Willi Syndrome. Participants receive escalating doses in sequential low, medium, and high target exposure groups with blood levels used to guide individualized dosing. The study monitors safety, pharmacokinetics, ECGs, laboratory tests, vital signs, and caregiver-reported measures over a 12–14 week period.
What it is studying. The study is testing CSTI-500 given by mouth to see how well it is tolerated and whether safe blood levels can be achieved with individualized dosing. It will measure drug levels in blood (pharmacokinetics), record side effects and clinical safety tests (labs, ECGs, vital signs), and collect caregiver questionnaires about hyperphagia and behavior to explore possible effects on symptoms.
What the researchers hope to learn. To evaluate the safety and tolerability of CSTI-500 in people with Prader-Willi Syndrome; to characterize its pharmacokinetics (blood levels and exposure) with individualized dosing; and to explore effects on hyperphagia and behavioral measures using caregiver-reported questionnaires.
What this study is about
The study's own summary, as published on ClinicalTrials.gov. Underlined terms have a short explanation.
This is a proof-of-concept, open-label, dose-escalation study to evaluate the safety, tolerability, pharmacokinetics, and efficacy of CSTI-500 in participants with genetically confirmed Prader-Willi Syndrome (PWS) who are 13 to 50 years of age. Participants will receive increasing doses of CSTI-500, and blood levels will be measured to guide individualized dosing.
Interventions being studied
Being studied in this trial does not mean the treatment or procedure is approved or available for this condition.
- Drug
- CSTI-500
Eligibility
The criteria exactly as listed on ClinicalTrials.gov. Only the study team can say whether they apply to you.
Inclusion criteria
- Generally healthy male and female individuals between the ages of 13 and 50, inclusive
- Documented medical record history of PWS confirmed by genetic testing and PWS Nutritional Phase 3
- CGI-S score ≥4 at Screening and Baseline (behavioral)
- Screening HQ CT total scores ≥ 13
- Participants must not be taking SSRI, SNRI, DNRI (bupropion), tricyclic antidepressants, stimulants, antipsychotic medications, and MAO inhibitors within 30 days of screening and willing to not start taking these medications while on the study. Fluoxetine is exclusionary unless treatment has been discontinued >6 months prior to Screening.
- Caregiver/parent must agree to bring the subject to the site for the visits, remain with the subject during visit times when allowed and respond to any questions.
- Caregiver/parent is willing to provide informed consent and agrees to adhere to required study procedures including telemedicine visits, visit duration requirements, and offer consistent care.
- Caregivers must agree to complete all study required assessments.
- Participants who cannot consent for themselves and are able will provide assent.
- Female participants must not be pregnant or lactating. Nonpregnancy will be confirmed for all females by a urine pregnancy test conducted at Screening and at the Baseline Visit prior to enrollment into the study. If of childbearing potential, the subject/caregiver agrees to the use of one of the accepted contraceptive regimens from Screening to the first administration of the study medication, during the study, and for at least 30 days after the last dose of the study medication. An acceptable method of contraception includes one of the following:
- Hormonal contraceptives (birth control pills, injectable/implant/insertable hormonal birth control products, transdermal patch)
- Intrauterine device (with or without hormones)
- OR agrees to use a double barrier method (e.g., condom and spermicide) during the study and for at least 30 days after the last dose of the study medication.
- The investigator can use their judgement and familiarity with the participant's preferred and usual lifestyle to understand which form of birth control would be the best and also to determine if abstinence is an option that would achieve 100% effectiveness.
- If the female is of non-childbearing potential -surgically sterile (i.e., has undergone complete hysterectomy, bilateral oophorectomy, or tubal ligation) or is postmenopausal (at least 1 year without menses) as confirmed by follicle-stimulating hormone (FSH) levels of ≥ 40 mIU/mL. No contraceptive use is required.
- Unless, sterile, a male study subject/caregiver must agree to use a double barrier method (e.g., condom and spermicide).
- For adults, supine systolic blood pressure must be ≤140 mmHg and ≥100 mmHg; diastolic blood pressure must be ≤80 mmHg and ≥60 mmHg at Screening. Heart rate must be ≥50 bpm and ≤100 bpm. Heart rate increase on standing must be within acceptable range (see exclusion criterion 10).
- For adolescents, a systolic and diastolic BP that is between the 5th and 90th percentile for age and sex.
- a. Two repeat measurements within 10 minutes of the first reading are permitted at the discretion of the Investigator. If this option is used, the last obtained reading will be used for determination of eligibility. Averages will not be used.
- All concomitant medications including blood pressure medications and type 2 diabetic medications must be stable for ≥3 months prior to screening (≤10% change) and there must be no medication changes (dose change, initiation, discontinuation) intentionally planned during the study. Supplements and vitamins are not considered concomitant medications for eligibility purposes.
- Stated willingness to comply with all study procedures including visits, restrictions, and availability for the duration of the study.
Exclusion criteria
- Participation in any clinical study with an investigational drug/device within 3 months prior to screening or during the study
- PWS diagnosis of UPD (maternal uniparental disomy).
- Current use of DCCR or if used previously, must be off at least 4 weeks before screening.
- Recent use (within 3 months) of weight loss agents including prescription, herbal medications, and weight loss supplements. Ozempic, for diabetes, would be exclusionary due to its effect on weight loss.
- History of bariatric surgery or major surgery within 6 months of screening or planned during the study.
- Any malignancy in the 2 years prior to screening (excluding basal cell carcinoma or squamous cell carcinoma of the skin or cervical carcinoma in situ that have been successfully treated).
- Current liver, pulmonary, cardiac, or GI disease that would be expected to adversely affect study participation. Stable disease, e.g., asthma or controlled hypertension is not excluded. Liver disease or liver injury as indicated by abnormal liver function tests, ALT, AST, alkaline phosphatase, or serum bilirubin (≥3X ULN for any of these tests).
- a. Participants with impaired liver function (Child-Pugh Scores A, B, C)
- Unexplained history or presence of combination of unexplained symptoms e.g., dizziness, syncope, fatigue, palpitations/tachycardia, headaches, or exercise intolerance.
- Prohibited Medications include SSRI, SNRI, DNRI (bupropion), tricyclic antidepressants, stimulants, antipsychotics, MAO inhibitors, fluoxetine, mood stabilizers, and GLP-1 agonists
- Presence of postural orthostatic tachycardia syndrome (POTS) for any reason, defined as:
- For participants aged 19 or older, sustained heart rate increase of >30 bpm or an increase to 120 bpm or greater within 3 minutes of standing.
- For participants aged 13-19, a sustained heart rate increase of >40 bpm or an increase to 120 bpm or greater within 3 minutes of standing.
- Associated with related symptoms that are worse with upright posture and that improve with recumbence.
- A clinically significant abnormal finding on 12-lead electrocardiogram (ECG) at Screening. Note QT corrected according to Fridericia's formula (QTcF) interval of ≥450 msec will be exclusionary [QTc = QT/(RR\^0.33)]. The ECG may be repeated once for confirmatory purposes if initial values obtained exceed the limits specified.
- Any clinically significant cardiac arrhythmia (e.g., atrial fibrillation, Adams-Stokes's disease, Wolff-Parkinson-White syndrome, atrioventricular block 2nd or 3rd degree).
- Heart failure classified per the New York Heart Association (NYHA) as level II or greater.
- Myocardial infarction, stroke, or confirmed TIA within the last 5 years.
- Estimated glomerular filtration rate (eGFR) ≤ 90 mL/min/1.73m² for ages 13 to <18 years of age. For adults ≥18 years of age, body-surface area corrected eGFR and exclusion with eGFR <90 mL/min.
- Uncontrolled Type 2 diabetes as defined by HbA1c ≥ 9% at Screening.
- Insulin-dependent Type 1 diabetes.
- Positive screen for hepatitis B surface antigen (HBsAg), hepatitis C virus (HCV) antibodies with detected circulating ribonucleic acid (RNA), or HIV 1 and 2 antibodies.
- Uncontrolled thyroid disease.
- Known hypersensitivity to any component of investigational product.
- History or active psychotic symptoms, or medical conditions which the investigator believes will interfere significantly with study compliance. Participants with a history of other severe psychiatric disorders, e.g., schizophrenia, major depressive disorder, bipolar disorder, or other DSM-V disorders.
- History of any suicidal behavior.
- Known alcohol or substance abuse.
- Moderate to strong inhibitors/inducers of CYP2D6, CYP3A4 and CYP2C9, including grapefruit juice. Substrates of CYP1A2 and CYP2B6.
- Any other medical, physical, or personal issues which, in the opinion of the investigator, would interfere with the subject's ability to complete the trial per protocol.
- Inability to swallow the oral capsules whole with water.
Study description and what participation involves
The registry record has no detailed description beyond the summary above.
AI summaryWhat participation may involve, in plain languageShow ▾Hide ▴
AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.
Participants will take oral CSTI‑500 capsules in an open‑label, dose‑escalation plan with individualized dose adjustments guided by blood drug levels (pharmacokinetic sampling). They will attend clinic visits for safety monitoring (blood tests, vital signs, 12‑lead ECGs), regular blood samples for drug levels, and caregiver‑completed questionnaires about hyperphagia and behavior. Dose changes may occur based on measured blood levels and tolerability; caregivers must be available for visits and study assessments. The protocol requires ability to swallow capsules whole and includes about 12 weeks of on‑study assessments for the main outcome measures (safety monitoring extends through the 14‑week safety window reported).
How the study is structured. An interventional, open-label, phase 2 dose-escalation study (no placebo, no masking). Participants are assigned to sequential target exposure groups (low → medium → high) and receive oral CSTI-500 with dose adjustments guided by scheduled blood level measurements. Safety monitoring includes reported adverse events, laboratory tests, 12-lead ECGs, and vital signs; caregivers complete symptom and behavior questionnaires. Key outcome measurements are taken over 12–14 weeks.
Questions you could ask
These questions are suggestions for a conversation with the study team or your own clinician, not advice.
- The listed sites are in United States. Is any of them reachable for me, and does the study help with travel?
- Which of the eligibility criteria would need to be checked with tests before I could join?
More on Prader-Willi syndrome
Important dates
- Study start
- May 2026 (estimated)
- Primary completion
- June 2027 (estimated)
- Study completion
- June 2027 (estimated)
- Target enrollment
- 12 participants (estimated)
- Last updated on registry
- May 15, 2026
- Data verified
- Oct 10, 2026
Sponsor and research team
The lead sponsor funds and oversees the trial. A pharmaceutical or biotech company sponsor typically means the study is testing that company's drug or device; a hospital, university, or government agency usually indicates investigator-initiated or publicly funded research.
- Lead sponsor
- ConSynance Therapeutics
Central study contact
If you're interested in participating, the central contact can answer general questions about the study — including eligibility requirements and how to find a recruiting site near you. Actual eligibility is determined by the site's medical team.
- Beth Mack 📞 859-426-5035 ✉ bethmack@lbr-regulatory.com
Participating sites (1)
- Vanderbilt University Medical CenterRecruiting
Nashville, Tennessee, 37232 · United States
- Elizabeth Roof · 6153433330 · elizabeth.roof@vanderbilt.edu
Terms used on this page · explanations by MedicalUpdates.ai
- open-label
- No masking is used, so the assigned intervention is not deliberately hidden from participants or study staff.
- dose-escalation
- Groups of participants receive increasing doses of a treatment, one group after another, to find a dose that can be given safely.
- pharmacokinetics
- How the body absorbs, distributes, breaks down and removes a drug. It is studied by measuring drug levels or related substances at set times after a dose.
- Phase 3
- A later-stage study, usually with more participants, designed to give stronger evidence about how well a treatment works and how safe it is. It often compares the treatment with standard care or a placebo, and results may support an application for approval.
- at Screening
- The checks done before enrolment to see whether a person qualifies, such as tests, scans or a review of medical history.
- Baseline
- Measurements taken at the start of the study, before any study treatment, so that later results can be compared with them.
- CT
- An X-ray scan that builds detailed cross-section images of the body. 'High-resolution' CT (HRCT) is used to look closely at the lungs.
- informed consent
- The process of explaining a study, including its risks and what participation involves, so that a person can decide freely whether to take part. Consent is usually documented in writing, and a participant can choose to leave the study later.
- assent
- A child's or dependent adult's agreement to take part, given alongside the formal consent of a parent or legal representative.
- enrollment
- The number of participants a study plans to include, or has included. 'Estimated' means the planned number; 'actual' means the number who joined.
- childbearing potential
- Studies often ask participants who could become pregnant, or could father a child, to use contraception during the study and for a period afterwards, because the effect of the treatment on a pregnancy is unknown.
- concomitant medications
- Other medicines a participant takes during the study. Some must be reported; some are restricted.
- investigational drug
- A treatment that is being tested and has not been approved for this use. It may be approved for a different condition. Being studied does not mean it works or is available outside the study.
- ULN
- The highest value of a blood test that a laboratory considers normal. Criteria such as '≤ 3 × ULN' mean the result must be no more than three times that value.
- Prohibited Medications
- A medicine that participants may not use during the study, usually because it could interfere with the study treatment or its measurement.
- electrocardiogram
- A recording of the heart's electrical activity. QTc is one measurement from it; some drugs are avoided if it is prolonged.
- Estimated glomerular filtration rate
- A blood-test estimate of how well the kidneys are filtering. Lower numbers mean reduced kidney function; many studies set a minimum value.
- Inclusion Criteria
- The conditions a person must meet to be considered for the study, for example a confirmed diagnosis, an age range or a test result.
- Exclusion Criteria
- The conditions that rule a person out even if they meet the inclusion criteria, for example other illnesses, certain medicines or pregnancy.
The study record on this page is reproduced from ClinicalTrials.gov, a database of the U.S. National Library of Medicine, where it was submitted by the study sponsor. MedicalUpdates.ai does not own this content, is not affiliated with or endorsed by ClinicalTrials.gov, NIH, or the U.S. Government, and does not verify the record. Plain-language notes, the glossary and the questions above are added by this site; text in the boxes marked "AI summary" was written by an AI model and may contain errors. Registry records change over time. Check the original record for the current version and discuss eligibility or participation with a qualified healthcare professional.
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