Longitudinal PET Imaging of Antipsychotic Binding to the Dopamine-3 Receptor in Schizophrenia
15 juillet 2026 mis à jour par: 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.
Aperçu de l'étude
Statut
Pas encore de recrutement
Les conditions
Intervention / Traitement
Description détaillée
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.
Type d'étude
Interventionnel
Inscription (Estimé)
100
Phase
- La phase 1
Contacts et emplacements
Cette section fournit les coordonnées de ceux qui mènent l'étude et des informations sur le lieu où cette étude est menée.
Coordonnées de l'étude
- Nom: Ragy Girgis, MD
- Numéro de téléphone: 646-774-5553
- E-mail: ragy.girgis@nyspi.columbia.edu
Critères de participation
Les chercheurs recherchent des personnes qui correspondent à une certaine description, appelée critères d'éligibilité. Certains exemples de ces critères sont l'état de santé général d'une personne ou des traitements antérieurs.
Critère d'éligibilité
Âges éligibles pour étudier
- Adulte
Accepte les volontaires sains
Non
La description
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)
Plan d'étude
Cette section fournit des détails sur le plan d'étude, y compris la façon dont l'étude est conçue et ce que l'étude mesure.
Comment l'étude est-elle conçue ?
Détails de conception
- Objectif principal: Autre
- Répartition: Randomisé
- Modèle interventionnel: Affectation parallèle
- Masquage: Seul
Armes et Interventions
Groupe de participants / Bras |
Intervention / Traitement |
|---|---|
|
Expérimental: 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.
|
|
Expérimental: 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.
|
|
Expérimental: 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.
|
|
Expérimental: 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.
|
|
Expérimental: 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
|
|
Expérimental: 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
|
|
Expérimental: 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
|
|
Expérimental: 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
|
Que mesure l'étude ?
Principaux critères de jugement
Mesure des résultats |
Description de la mesure |
Délai |
|---|---|---|
|
Acute D2 and D3 Receptor Occupancy
Délai: Day 1
|
Delta BPND in poscommissural putamen and midbrain
|
Day 1
|
|
Upregulation of D3 receptor following subchronic administration of antipsychotics
Délai: Day 15
|
The availability of D3Rs following two weeks of antipsychotic treatment will be measured.
|
Day 15
|
Mesures de résultats secondaires
Mesure des résultats |
Description de la mesure |
Délai |
|---|---|---|
|
Positive and Negative Syndrome Scale (PANSS) Total Positive Symptoms
Délai: 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
Délai: 15 days
|
Correlations between changes in PANSS total negative symptom scores and receptor binding will be examined.
|
15 days
|
|
MATRICS Cognitive Deficits (Composite Score)
Délai: 15 days
|
Correlations between changes in cognitive deficits (MATRICS composite score) and receptor binding will be examined.
|
15 days
|
Autres mesures de résultats
Mesure des résultats |
Description de la mesure |
Délai |
|---|---|---|
|
Abnormal Involuntary Movement Scale (AIMS) Score
Délai: 15 days
|
Correlations between changes in extrapyramidal side effect scores (AIMS) and receptor binding will be examined.
|
15 days
|
|
Simpson-Angus Scale (SAS) Score
Délai: 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
Délai: 15 days
|
Correlations between changes in extrapyramidal side effect scores (BARS) and receptor binding will be examined.
|
15 days
|
Collaborateurs et enquêteurs
C'est ici que vous trouverez les personnes et les organisations impliquées dans cette étude.
Dates d'enregistrement des études
Ces dates suivent la progression des dossiers d'étude et des soumissions de résultats sommaires à ClinicalTrials.gov. Les dossiers d'étude et les résultats rapportés sont examinés par la Bibliothèque nationale de médecine (NLM) pour s'assurer qu'ils répondent à des normes de contrôle de qualité spécifiques avant d'être publiés sur le site Web public.
Dates principales de l'étude
Début de l'étude (Estimé)
1 décembre 2026
Achèvement primaire (Estimé)
30 août 2030
Achèvement de l'étude (Estimé)
30 novembre 2030
Dates d'inscription aux études
Première soumission
11 juillet 2026
Première soumission répondant aux critères de contrôle qualité
15 juillet 2026
Première publication (Réel)
20 juillet 2026
Mises à jour des dossiers d'étude
Dernière mise à jour publiée (Réel)
20 juillet 2026
Dernière mise à jour soumise répondant aux critères de contrôle qualité
15 juillet 2026
Dernière vérification
1 juillet 2026
Plus d'information
Termes liés à cette étude
Mots clés
Termes MeSH pertinents supplémentaires
Autres numéros d'identification d'étude
- NYSPI2026-31
- 1R01MH139651-01A1 (Subvention/contrat des NIH des États-Unis)
Plan pour les données individuelles des participants (IPD)
Prévoyez-vous de partager les données individuelles des participants (DPI) ?
OUI
Description du régime IPD
Data will be shared via the NIH data archive.
Délai de partage IPD
Data will be shared after the study has been completed, as per NIH guidelines.
Informations sur les médicaments et les dispositifs, documents d'étude
Étudie un produit pharmaceutique réglementé par la FDA américaine
Oui
Étudie un produit d'appareil réglementé par la FDA américaine
Non
Ces informations ont été extraites directement du site Web clinicaltrials.gov sans aucune modification. Si vous avez des demandes de modification, de suppression ou de mise à jour des détails de votre étude, veuillez contacter register@clinicaltrials.gov. Dès qu'un changement est mis en œuvre sur clinicaltrials.gov, il sera également mis à jour automatiquement sur notre site Web .