PET Imaging of Peripheral Benzodiazepine Receptors in Patients With Carotid Atherosclerosis

Healthy Clinical Trial

Official title:

PET Imaging of Peripheral Benzodiazepine Receptors in Patients With Carotid Atherosclerosis

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00547976
• Other study ID #: 080006
• Secondary ID: 08-M-0006
• Status: Completed
• Phase: Phase 1
• First received: October 20, 2007
• Last updated: April 26, 2012
• Start date: October 2007
• Est. completion date: August 2009

Study information

• Verified date: April 2012
• Source: National Institutes of Health Clinical Center (CC)
• Contact: n/a
• Is FDA regulated: No
• Health authority: United States: Federal Government
• Study type: Interventional

Clinical Trial Summary

Inflammation in the vascular wall is important in atherosclerosis and the blockage of the artery. The peripheral benzodiazepine receptor is involved in inflammation and in this protocol we will attempt to take pictures, using PET camera, of inflammation in patients with atherosclerosis and compare those of healthy people.

Description:

Objective

Inflammation in the vascular wall plays an important role in the pathophysiology of atherosclerosis, including development of plaque, plaque destabilization and rupture. Clinical and basic scientific data demonstrate the importance of peripheral white blood cells in this process. Therefore, a noninvasive method to detect inflammatory activity in atherosclerosis may be of great value to help determine prognosis, direct therapy and perhaps assess novel therapies for stabilization of atherosclerotic plaque.

The peripheral benzodiazepine receptor (PBR) is distinct from central benzodiazepine receptors associated with GABAA receptors and has been associated with immune function. PBR is expressed in macrophages, therefore, they may be a clinically useful marker to detect inflammation. Our preliminary autoradiographic data demonstrate specific PBR binding in carotid atherosclerosis samples. Though PBR has been imaged in vivo with positron emission tomography (PET) using [(11)C]1-(2-chlorophenyl-N-methylpropyl)-3-isoquinoline carboxamide (PK11195), we developed a new ligand, [(11)C]N-acetyl-N-(2-methoxybenzyl)-2-phenoxy-5-pyridinamine (PBR28) that shows greater specific signal than [(11)C]PK11195 in non-human primates.

The objective of this protocol is to assess the utility of [(11)C]PBR28 PET to detect inflammation in unstable atherosclerosis plaques and large vessels with inflammation.

Study population

Twenty patients with carotid atherosclerosis, 20 patients with large vessel vasculitis including Takayasu's and Giant Cell arteritis, and 20 age-matched healthy subjects will have one PET scan.

Design

A [(11)C]PBR28 PET scan and a [18 F] fluorodeoxyglucose (FDG) PET scan will be performed in patients with carotid atherosclerosis. If the patient has endarterectomy after the PET scan, endarterectomy samples will be evaluated by in vitro autoradiography using [3H]PK 11195 and immunohistological staining with macrophage markers. Patients with large vessel vasculitis and healthy subjects will also have a [(11)C]PBR28 PET scan [18 F]FDG PET scan.

Outcome measures

Binding of [(11)C]PBR28 in atherosclerotic lesions, aortic arch and its branches will be compared with the binding in the contralateral carotid artery and those in healthy subjects. Binding of [(11)C]PBR28 will also be compared with accumulation of [18 F]FDG in each region. In addition, if the patients with atherosclerosis have endarterectomy, the binding in the atherosclerotic lesions will be compared with immunohistological staining of macrophage markers.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 5
• Est. completion date: August 2009
• Est. primary completion date: August 2009
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 18 Years to 89 Years

Eligibility

• INCLUSION CRITERIA

Age 18 - 89

Ability to provide written informed consent

EXCLUSION CRITERIA

Severe systemic disease based on history, physical examination or laboratory tests that would prevent participation in the study

Prior participation in other research protocols in the last year such that radiation exposure would exceed the annual guideline of RSC

Pregnancy and breast feeding

Claustrophobia

Inability to lie flat for a few hours for the PET scans

Medically unstable

The blood glucose level is greater than 150 mg/dL after fasting

Any other condition which in the opinion of the PI would prevent satisfactory participation in and completion of the study.

Study Design

Allocation: Non-Randomized, Endpoint Classification: Pharmacokinetics Study, Intervention Model: Parallel Assignment, Masking: Open Label, Primary Purpose: Diagnostic

Related Conditions & MeSH terms

• Atherosclerosis
• Carotid Artery Diseases
• Healthy

Intervention

Drug:
• [C-11]PBR28

Locations

Country	Name	City	State
United States	National Institutes of Health Clinical Center, 9000 Rockville Pike	Bethesda	Maryland
United States	Suburban Hospital	Bethesda	Maryland

Sponsors (1)

Lead Sponsor	Collaborator
National Institute of Mental Health (NIMH)

Country where clinical trial is conducted

United States, 

References & Publications (3)

Anholt RR, De Souza EB, Oster-Granite ML, Snyder SH. Peripheral-type benzodiazepine receptors: autoradiographic localization in whole-body sections of neonatal rats. J Pharmacol Exp Ther. 1985 May;233(2):517-26. — View Citation

Anholt RR, Murphy KM, Mack GE, Snyder SH. Peripheral-type benzodiazepine receptors in the central nervous system: localization to olfactory nerves. J Neurosci. 1984 Feb;4(2):593-603. — View Citation

Banati RB. Visualising microglial activation in vivo. Glia. 2002 Nov;40(2):206-17. Review. — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Binding of [11C]PBR28 at peripheral benzodiazepine receptor		3 years	No
Secondary	PET [F-18]FDG uptake		3 years	No