Evaluation of [11C]FPEB, [18C]FPEB, and [11C]SP203 To Image mGluR5 Receptors In Brain
Trial Snapshot
- Phase
- Phase 1
- Status
- Completed
- Enrollment
- 19
- Locations
- 2
- Primary Endpoint
- Peak brain uptake, Time-stability of distribution volume, Ratio of specific to non-displaceable brain uptake
Study Overview
Brief Summary
Background:
- A small brain protein called the metabotropic glutamate receptor subtype 5 (mGluR5) may affect several brain diseases such as autism and depression. Researchers will use 2 radioactive chemicals ([11C]SP203 and [11C]FPEB) and a research drug (STX107) that can attach to the receptor, to figure out the best way to use positron emission tomography (PET) to see the mGluR5 receptor. They will use scans to monitor where the radioactivity goes.
Objectives:
- To find the best way to image the mGluR5 receptor in the brain.
Eligibility:
- Healthy volunteers ages 18 to 55.
Design:
- All participants will be screened with a medical exam at visit 1. In later visits, they may have a PET scan, when two small tubes are placed under the skin and they lie down in a scanner. They may have an MRI scan, when they lie down in a scanner.
- Part 1 participants will have 2 more visits. They will have a PET brain scan using [11C]FPEB and will have blood drawn. Then they will have an MRI brain scan.
- Part 2 participants will have 1 more visit, with a whole body PET scan using [11C]FPEB and blood drawn.
- Part 3 participants will have 4 more visits, including 1 overnight stay at a hospital. Over all the visits, they will have 4 PET scans and 1 MRI brain scan. They will receive the research drug and injections of both chemicals. Blood will be drawn during the scans.
Detailed Description
Objective:
Multiple PET ligands exist for imaging metabotropic glutamate receptor subtype 5 (mGluR5). The selection of best PET ligand to image mGluR5 is necessary for a larger clinical study in patient population but choosing such a ligand is likely difficult because the radioligands are evaluated under different conditions and in different subject populations.
The purpose of this study is to determine the best PET ligand for imaging mGluR5 receptors in brain of healthy subjects. This will be accomplished by measuring mGluR5 receptor occupancy in the same subject using two PET ligands having high affinity at mGluR5 [(11)C]SP203 and [(11)C]FPEB, and using STX107, a negative allosteric modulator at mGluR5 receptors to block the radioligand brain uptake. The two radioligands were chosen among many based on the recommendation from the mGluR5 working group. Two serial PET scans using [(11)C]SP203 and [(11)C]FPEB will be performed under baseline condition on one day and under receptor blocked condition on another day. As [(11)C]FPEB has not been evaluated in humans before, we plan to acquire brain and whole-body dosimetry scans before measuring receptor occupancy.
Furthermore, we wish to compare FPEB labeled with (11)C and (18)F in the same subject -two brain PET scans using [(11)C]FPEB and [(18)F]FPEB will be done serially in the same subject on the same day. FPEB labeled with (11)C has the same structure as FPEB labeled with (18)F and is therefore expected to yield similar binding measures.
Study population:
Study Design
- Study Type
- Interventional
- Allocation
- Non Randomized
- Intervention Model
- Single Group
- Primary Purpose
- Treatment
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to 55 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- Not provided
Exclusion Criteria
- Not provided
Outcomes
Primary Outcomes
Peak brain uptake, Time-stability of distribution volume, Ratio of specific to non-displaceable brain uptake
Time Frame: 2 years
Secondary Outcomes
No secondary outcomes reported