Novel Clinical Target in Fragile X Syndrome

Phase 1

Withdrawn

• Conditions: Fragile X Syndrome (FXS)
• Interventions: Drug: 18F-FTC-146

• Registration Number: NCT04314856
• Lead Sponsor: Guido A. Davidzon, MD, SM

Brief Summary

Fragile X syndrome (FXS) is the most common genetic cause of autism spectrum disorder (ASD). The investigators wish to examine brain distribution of sigma-1 receptors in young adult males with FXS using 18F-FTC-146 PET. This project will study the distribution of sigma-1 receptors in 15 young (18-30 years) male adults with FXS compared to 5 healthy adult volunteers.

Detailed Description

In this study, we measured sigma-1 receptor density in the regions of interest in brain known to be involved in executive functioning and cognition using 18F-FTC-146 PET. We then compared S1R density in areas ROIs not involved in executive functioning and cognition. This provided a framework for predicting functional impairment based on brain-behavior relationships.

The study had two aims. The first aim was to evaluate the reliability of 18F-FTC-146 brain uptake in healthy controls under test and retest conditions to establish a baseline measure of S1R density and quantify regional brain uptake of radiotracer in five healthy adults. The second aim was to characterize S1R density in brains of young adult males with FXS which will then be compared to healthy volunteers.

This was the very first PET study to image sigma-1 receptor density in participants with fragile X syndrome, thereby testing whether altered receptor density is present in brain in fragile X syndrome patients when compared to healthy volunteers. If confirmed, the current study would have provided compelling clinical-translational support for an important pathophysiological mechanism of cognition and executive function. The study had considerable potential for advancing the neurobiological understanding of fragile X syndrome in humans.

Study Timeline

• Study First Submitted: 2020-03-11
• Study First Submitted QC: 2020-03-17
• Study First Posted: 2020-03-19
• Study Start: 2021-01-12
• Primary Completion: 2022-06
• Study Completion: 2022-06
• Status Verified: 2022-11
• Last Update Submitted: 2022-11-10
• Last Update Posted: 2022-11-15

Recruitment & Eligibility

• Status: WITHDRAWN
• Sex: All
• Target Recruitment: Not specified

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Healthy Volunteers (Control)	18F-FTC-146	Adults aged 18-65 years undergo a PET/MRI scan using 18F-FTC-146 to determine sigma-1 receptor density. Test-retest studies will be performed where these individuals will each be injected twice with 18F-FTC-146.
Fragile X Syndrome	18F-FTC-146	Adult males aged 18-30 years diagnosed with FXS will undergo a PET/MRI scan using 18F-FTC-146 to determine sigma-1 receptor density. These participants will only be administered once with 18F-FTC-146.

Primary Outcome Measures

Name	Time	Method
Number of concordant readings of regional brain uptake of radiotracer [18F]FTC-146 as a measure of reliability under test-retest conditions	Up to 6 hours per scan performed on Day 0 (Test) and Day 7 (Retest)	Regional brain uptake of \[18F\]FTC-146 will be analyzed by kinetic modeling with metabolite-corrected arterial input functions to establish stability and reproducibility of \[18F\] FTC-146 in humans under test and retest conditions.; This outcome will be assessed in healthy volunteers only.
Difference in Non-displaceable Binding Potential (BPND) of [18F]FTC-146 in fragile X syndrome (FXS) patients relative to healthy volunteers	Up to 6 hours per scan performed on Day 0 (both groups) and Day 7 (healthy volunteers)	Binding potential provides an estimate of the S1R receptor distribution and affinity of \[18F\]FTC-146 to the S1R receptors. Binding potential measurements will be compared between participants with fragile X syndrome and control group with healthy volunteers to assess if there is a difference. Binding Potential (BPND) is estimated as the distribution volume ratio (DVR) -1.; DVR's of tracers are used in PET receptor studies where the radiopharmaceutical can be specifically bound to receptors; nonspecifically bound to other macromolecular components, or free in tissue (FT). DVR is calculated using a Logan Plot, which uses the dynamic PET images obtained during imaging and compartment modeling to graphically analyze by linear regression pharmacokinetic data for radiopharmaceuticals that undergo 'reversible' uptake.; Healthy volunteers will have scans at Day 0 and Day 7, and FXS patients will have a single scan on day 0. All scans will be analyzed.

Trial Locations

Locations (1)

Stanford University; 🇺🇸 Stanford, California, United States