A Phase 1 interventional study of CITY-RBP4 and Placebo in Stargardt Disease 1, STGD1 and Healthy Volunteers, sponsored by City Therapeutics. Recruiting at 1 site in Australia. Open to participants aged 12 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-23.
Sponsored by City Therapeutics · Phase 1, Interventional, and Treatment
This is a first-in-human (FIH), multicenter, randomized, double-masked, placebo-controlled adaptive clinical study evaluating the safety, tolerability, pharmacokinetic (PK), and pharmacodynamic (PD) of CITY-RBP4, following single-ascending doses and multiple doses, via subcutaneous (SC) administration.
The study consists of 3 sequential parts:
66 studies on the registry are indexed under Stargardt Disease; 25 are open to participants now.
This study's planned enrollment of 48 is above the median of 30 across 43 interventional studies indexed under Stargardt Disease.
Browse Stargardt Disease studies →City Therapeutics is the lead sponsor of 2 studies on the registry; 2 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Key Inclusion Criteria (Part A):
Key Exclusion Criteria (Part A):
Key Inclusion Criteria (Parts B and C)
Key Exclusion Criteria (Parts B and C)
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Postmenopausal
Periods have stopped for good: usually no period for 12 months in a row without another medical reason, sometimes confirmed by a blood test (FSH).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Clinically significant
Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Drug: CITY-RBP4
Drug: Placebo
Drug: CITY-RBP4
Drug: Placebo
siRNA (subcutaneous injection)
Saline (subcutaneous injection)
Incidence, severity, and relationship of treatment-emergent adverse events (TEAEs)
To evaluate the safety and tolerability of single and multiple doses of CITY-RBP4 in healthy adults and participants with Stargardt disease Type 1 (STGD1)
Time frame: Through study completion, up to Day 360
Plasma concentrations of CITY-RBP4
To characterize the pharmacokinetic (PK) profile of CITY-RBP4 after single and multiple doses of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Day 1 to Day 2
Urine concentrations of CITY-RBP4
To characterize the pharmacokinetic (PK) profile of CITY-RBP4 after a single dose of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Part A and B only: Day 1 to Day 2
Maximum plasma concentration (Cmax)
To characterize the pharmacokinetic (PK) profile of CITY-RBP4 after single and multiple doses of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Day 1 to Day 2
Time to maximum plasma concentration (Tmax)
To characterize the pharmacokinetic (PK) profile of CITY-RBP4 after single and multiple doses of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Day 1 to Day 2
Area under plasma concentration-time curve (AUC)
To characterize the pharmacokinetic (PK) profile of CITY-RBP4 after single and multiple doses of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Day 1 to Day 2
Terminal elimination half-life (t1/2)
To characterize the pharmacokinetic (PK) profile of CITY-RBP4 after single and multiple doses of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Day 1 to Day 2
Apparent clearance (CL/F)
To characterize the pharmacokinetic (PK) profile of CITY-RBP4 after single and multiple doses of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Day 1 to Day 2
Amount excreted unchanged (Ae)
To characterize the pharmacokinetic (PK) profile of CITY-RBP4 after a single dose of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Part A and B only: Day 1 to Day 2
Change from baseline in plasma RBP4 concentrations
evaluate the pharmacodynamic (PD) effects of CITY-RBP4 on plasma retinol-binding protein 4 (RBP4) levels after single and multiple doses of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Up to Day 360
Change from baseline in serum retinol concentrations
To evaluate the pharmacodynamic (PD) effects of CITY-RBP4 on serum retinol levels after single and multiple doses of CITY-RBP4 in healthy adults and participants with STGD1
Time frame: Up to Day 360
Plan to share: Undecided
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