Longitudinal PET Imaging of Antipsychotic Binding to the Dopamine-3 Receptor in Schizophrenia
15 juli 2026 bijgewerkt door: Ragy Girgis, New York State Psychiatric Institute
This is a clinical trial in which 40 participants with schizophrenia will be randomized to 15 days of treatment with cariprazine (CAR) or brexpiprazole (BREX) in a single-blind manner.
[11C]PHNO PET scans will be obtained before treatment and after 1 day and 15 days of treatment to examine the effects of antipsychotic medications on the dopamine-3 receptor (D3R).
The overall objectives of the current study are to: 1) measure the acute binding of CAR/BREX to the D3R; 2) measure D3R availability for evidence of upregulation following subchronic administration of CAR/BREX in the same set of patients; 3) examine relationships between subchronic binding of CAR/BREX to, and upregulation of, the D3R vs. D2R and changes in positive symptoms, negative symptoms, and cognitive deficits.
Relationships between subchronic binding of CAR/BREX and EPS will be explored.
Studie Overzicht
Toestand
Nog niet aan het werven
Interventie / Behandeling
Gedetailleerde beschrijving
There is a great need for the development of new treatments for schizophrenia (SCZ).
Aside from the recently approved muscarinic agonist xanomeline, all current treatments have been assumed to function by blocking dopamine-2 receptors (D2Rs).
Interest in the dopamine-3 receptor (D3R) was encouraged by preclinical findings that D3R antagonists reverse cognitive impairment and improve negative symptoms.
In vivo imaging of the D3R became possible with the development of [11C]-(+)-PHNO, a D3R-preferring radioligand.
However, while numerous preclinical studies have demonstrated that the D3R is relevant to both the neurobiology and treatment of SCZ, in vivo studies initially and surprisingly reported that, after several weeks of administration, antipsychotic medications may not bind to the D3R and may paradoxically increase levels of the D3R.
These findings were discrepant with our own findings in non-human primates and individuals with SCZ demonstrating that acute doses of antipsychotic medications bind to the D3R and D2R in ratios predicted by their in vitro binding profiles.
In a later study conducted by our group, 10 days of chronic dosing of the D2R-preferring antipsychotic medication brexpiprazole (BREX) also led to increased levels of the D3R at 1mg and negligible binding at 4mg.
Finally, in our study of the D3R-preferring antipsychotic medication cariprazine (CAR), there was robust binding to the D3R and D2R after both acute and subchronic dosing.
These seemingly discrepant findings may be related to methodological differences, differences in the binding profiles of D2R- vs. D3R-preferring antipsychotic medications, or to homeostatic responses to chronic antipsychotic treatment (i.e., upregulation).
Upregulation is a potentially critical, though underexamined, effect common to all D2R/D3R-binding antipsychotic medications, including partial agonists.
It has been hypothesized to be largely responsible for differences in occupancy estimates from single and repeat dose studies and contribute to waning effects of antipsychotic medications and tardive dyskinesia.
The goals of this proposal are to elucidate the contribution of D3R, compared to D2R, binding to antipsychotic action, both acutely (SA1) and subchronically (SA2), in the same patients.
The relationship between occupancy, upregulation, and clinical effects (SA3, EA) will be investigated.
Studietype
Ingrijpend
Inschrijving (Geschat)
100
Fase
- Fase 1
Contacten en locaties
In dit gedeelte vindt u de contactgegevens van degenen die het onderzoek uitvoeren en informatie over waar dit onderzoek wordt uitgevoerd.
Studiecontact
- Naam: Ragy Girgis, MD
- Telefoonnummer: 646-774-5553
- E-mail: ragy.girgis@nyspi.columbia.edu
Deelname Criteria
Onderzoekers zoeken naar mensen die aan een bepaalde beschrijving voldoen, de zogenaamde geschiktheidscriteria. Enkele voorbeelden van deze criteria zijn iemands algemene gezondheidstoestand of eerdere behandelingen.
Geschiktheidscriteria
Leeftijden die in aanmerking komen voor studie
- Volwassen
Accepteert gezonde vrijwilligers
Nee
Beschrijving
Inclusion Criteria:
- Individuals, any gender or sex, aged 18 to 55, inclusive at screen
- Capable of understanding the study procedures and able to provide informed consent
- Diagnosed with schizophrenia, schizoaffective, or schizophreniform disorder
- Negative urine toxicology
- Antipsychotic free (by choice and for reasons unrelated to the study), and for at least 3 weeks (4 for aripiprazole or LAIs) at the time of the baseline PET scan, inclusive of any antipsychotic-free time prior to consent. [Any patient who requires inpatient hospitalization or acute medication treatment for clinical stabilization during the medication free period will not be included in this study; any participant who in the clinical judgment of the PIs or any involved clinician is not stable or appropriate for a medication free period will not be included.]
- PANSS total score > 80 and < 120 (inclusive)
Exclusion Criteria:
- Diagnosis of substance use disorder within the previous month
- A history of poor or inadequate response or hypersensitivity to CAR or BREX for any reason
- EKG abnormality that is clinically significant including a QTc interval > 450 msec for men and > 470 msec for women,
- Pregnant or breast-feeding women. Women of child-bearing potential must have a negative serum β-hCG pregnancy test at Visit 1, must have been using an acceptable method of contraception for 30 days before the study (i.e., before the first PET or MRI scan, whichever comes first), and must agree to do so for the whole study and 30 days after (unless post-menopausal or surgically sterile)
- Any clinically significant or unstable medical/neurological illness, condition, or disorder that is anticipated to potentially compromise participant safety on study medication
- Any material in the body that is a contraindication for MRI procedures or participated in prior nuclear medicine procedures in the past year that exceed FDA-defined limits when combined with radiation dosimetry from PET scanning in this protocol to avoid exceeding annual dosimetry limits (metal screener repeated before MRI scan). Individuals exposed to radiation in the workplace in the previous year will be excluded.
- Acute risk for suicide (i.e., score of 4-5 within the previous month or 6 within the previous 3 months on the CSSRS) or violence/homicide (e.g., homicidal ideation), or history of severe violent behavior or behavioral dyscontrol while antipsychotic-free
- A history of treatment resistance to antipsychotics or who have a duration of illness of greater than 20 years
- Claustrophobia
- Use of nicotine products within the previous month (prior to first PET scan)
Studie plan
Dit gedeelte bevat details van het studieplan, inclusief hoe de studie is opgezet en wat de studie meet.
Hoe is de studie opgezet?
Ontwerpdetails
- Primair doel: Ander
- Toewijzing: Gerandomiseerd
- Interventioneel model: Parallelle opdracht
- Masker: Enkel
Wapens en interventies
Deelnemersgroep / Arm |
Interventie / Behandeling |
|---|---|
|
Experimenteel: Cariprazine 1mg
Cariprazine 1mg daily for 15 days
|
Cariprazine is an antipsychotic medication
This is the radiotracer that will be used to examine antipsychotic binding to D2 and D3 receptors in this study.
It is experimental and used for imaging purposes.
|
|
Experimenteel: Cariprazine 2mg
Cariprazine 2mg daily for 15 days
|
Cariprazine is an antipsychotic medication
This is the radiotracer that will be used to examine antipsychotic binding to D2 and D3 receptors in this study.
It is experimental and used for imaging purposes.
|
|
Experimenteel: Cariprazine 3mg
Cariprazine 3mg daily for 15 days
|
Cariprazine is an antipsychotic medication
This is the radiotracer that will be used to examine antipsychotic binding to D2 and D3 receptors in this study.
It is experimental and used for imaging purposes.
|
|
Experimenteel: Cariprazine 4mg
Cariprazine 4mg daily for 15 days
|
Cariprazine is an antipsychotic medication
This is the radiotracer that will be used to examine antipsychotic binding to D2 and D3 receptors in this study.
It is experimental and used for imaging purposes.
|
|
Experimenteel: Brexpiprazole 1mg
Brexpiprazole 1mg daily for 15 days
|
This is the radiotracer that will be used to examine antipsychotic binding to D2 and D3 receptors in this study.
It is experimental and used for imaging purposes.
Brexpiprazole is an antipsychotic medication
|
|
Experimenteel: Brexpiprazole 2mg
Brexpiprazole 2mg daily for 15 days
|
This is the radiotracer that will be used to examine antipsychotic binding to D2 and D3 receptors in this study.
It is experimental and used for imaging purposes.
Brexpiprazole is an antipsychotic medication
|
|
Experimenteel: Brexpiprazole 3mg
Brexpiprazole 3mg daily for 15 days
|
This is the radiotracer that will be used to examine antipsychotic binding to D2 and D3 receptors in this study.
It is experimental and used for imaging purposes.
Brexpiprazole is an antipsychotic medication
|
|
Experimenteel: Brexpiprazole 4mg
Brexpiprazole 4mg daily for 15 days
|
This is the radiotracer that will be used to examine antipsychotic binding to D2 and D3 receptors in this study.
It is experimental and used for imaging purposes.
Brexpiprazole is an antipsychotic medication
|
Wat meet het onderzoek?
Primaire uitkomstmaten
Uitkomstmaat |
Maatregel Beschrijving |
Tijdsspanne |
|---|---|---|
|
Acute D2 and D3 Receptor Occupancy
Tijdsspanne: Day 1
|
Delta BPND in poscommissural putamen and midbrain
|
Day 1
|
|
Upregulation of D3 receptor following subchronic administration of antipsychotics
Tijdsspanne: Day 15
|
The availability of D3Rs following two weeks of antipsychotic treatment will be measured.
|
Day 15
|
Secundaire uitkomstmaten
Uitkomstmaat |
Maatregel Beschrijving |
Tijdsspanne |
|---|---|---|
|
Positive and Negative Syndrome Scale (PANSS) Total Positive Symptoms
Tijdsspanne: 15 days
|
Correlations between changes in PANSS total positive symptoms and receptor binding will be examined.
|
15 days
|
|
Positive and Negative Syndrome Scale (PANSS) Total Negative Symptoms
Tijdsspanne: 15 days
|
Correlations between changes in PANSS total negative symptom scores and receptor binding will be examined.
|
15 days
|
|
MATRICS Cognitive Deficits (Composite Score)
Tijdsspanne: 15 days
|
Correlations between changes in cognitive deficits (MATRICS composite score) and receptor binding will be examined.
|
15 days
|
Andere uitkomstmaten
Uitkomstmaat |
Maatregel Beschrijving |
Tijdsspanne |
|---|---|---|
|
Abnormal Involuntary Movement Scale (AIMS) Score
Tijdsspanne: 15 days
|
Correlations between changes in extrapyramidal side effect scores (AIMS) and receptor binding will be examined.
|
15 days
|
|
Simpson-Angus Scale (SAS) Score
Tijdsspanne: 15 days
|
Correlations between changes in extrapyramidal side effect scores (SAS) and receptor binding will be examined.
|
15 days
|
|
Barnes Akathisia Rating Scale (BARS) Score
Tijdsspanne: 15 days
|
Correlations between changes in extrapyramidal side effect scores (BARS) and receptor binding will be examined.
|
15 days
|
Medewerkers en onderzoekers
Hier vindt u mensen en organisaties die betrokken zijn bij dit onderzoek.
Studie record data
Deze datums volgen de voortgang van het onderzoeksdossier en de samenvatting van de ingediende resultaten bij ClinicalTrials.gov. Studieverslagen en gerapporteerde resultaten worden beoordeeld door de National Library of Medicine (NLM) om er zeker van te zijn dat ze voldoen aan specifieke kwaliteitscontrolenormen voordat ze op de openbare website worden geplaatst.
Bestudeer belangrijke data
Studie start (Geschat)
1 december 2026
Primaire voltooiing (Geschat)
30 augustus 2030
Studie voltooiing (Geschat)
30 november 2030
Studieregistratiedata
Eerst ingediend
11 juli 2026
Eerst ingediend dat voldeed aan de QC-criteria
15 juli 2026
Eerst geplaatst (Werkelijk)
20 juli 2026
Updates van studierecords
Laatste update geplaatst (Werkelijk)
20 juli 2026
Laatste update ingediend die voldeed aan QC-criteria
15 juli 2026
Laatst geverifieerd
1 juli 2026
Meer informatie
Termen gerelateerd aan deze studie
Trefwoorden
Aanvullende relevante MeSH-voorwaarden
Andere studie-ID-nummers
- NYSPI2026-31
- 1R01MH139651-01A1 (Subsidie/contract van de Amerikaanse NIH)
Plan Individuele Deelnemersgegevens (IPD)
Bent u van plan om gegevens van individuele deelnemers (IPD) te delen?
JA
Beschrijving IPD-plan
Data will be shared via the NIH data archive.
IPD-tijdsbestek voor delen
Data will be shared after the study has been completed, as per NIH guidelines.
Informatie over medicijnen en apparaten, studiedocumenten
Bestudeert een door de Amerikaanse FDA gereguleerd geneesmiddel
Ja
Bestudeert een door de Amerikaanse FDA gereguleerd apparaatproduct
Nee
Deze informatie is zonder wijzigingen rechtstreeks van de website clinicaltrials.gov gehaald. Als u verzoeken heeft om uw onderzoeksgegevens te wijzigen, te verwijderen of bij te werken, neem dan contact op met register@clinicaltrials.gov. Zodra er een wijziging wordt doorgevoerd op clinicaltrials.gov, wordt deze ook automatisch bijgewerkt op onze website .