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Study of 11C-M503 for Tauopathies

This study is investigating a new imaging agent called 11C-M503 to see how it moves through your body, how it's processed, and how much of it reaches your brain. The goal is to use 11C-M503 with a PET scan (Positron Emission Tomography, a type of imaging test) to measure abnormal alpha-synuclein protein deposits in the brains of people with Parkinson's disease (PD). Researchers will compare the results from people with PD to those with multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and healthy volunteers. The study aims to enroll up to 70 participants between 40 and 85 years old. The current status of this study is unclear.

Study design
This is an interventional study involving up to 70 participants. It aims to compare brain uptake of 11C-M503 in people with different neurological conditions and healthy volunteers.
What's involved
You would undergo an 11C-M503 PET scan lasting two hours, a Brain MRI, an Amyloid PET scan, and neurological assessments, including a video interview.
Compensation
Not stated in the trial record.
Follow-up
The study measures organ biodistribution and PET uptake of the tracer at 4 weeks.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT06303921

Study of Biodistribution, Metabolism, Excretion and Brain Uptake11C-M503

Recruiting
EARLY_PHASE1Ages 40–85InterventionalDiagnostic
University of Pennsylvania
~70 participants
Updated 2026-04-24 on ClinicalTrials.gov
What's tested:11C-M503 PETBrain MRIAmyloid PETNeurological assessments

At a glance

Recruiting sites
3 of 3 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Organ Biodistribution or Dosimetry
Measured over 4 weeks
+1 more outcome measured

Conditions

Tauopathies

Explore related trials

Multiple System AtrophyParkinson DiseaseProgressive Supranuclear Palsy

Where it's being run

3 sites across 3 states
Connecticut1
Missouri1
Pennsylvania1

Study leadership

  • Ilya M Nasrallah, MD, PhD · PRINCIPAL_INVESTIGATOR · University of Pennsylvania

Who to contact

Erin Schubert
[email protected]
215-662-3041
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Patients in all cohorts will be male or female adults from 40 to 85 years of age.
Participants must be informed of the investigational nature of this study and be willing to provide written informed consent and participate in this study in accordance with institutional and federal guidelines prior to study-specific procedures or Participants who are deemed unable to provide informed consent must have a designated study partner present for consent and to accompany them to study visits
Investigators will ask PD/MSA/PSP participants to agree to brain donation but this choice is not mandatory for participation in this study.

Exclusion

Females who are pregnant or breast feeding will be excluded, a urine pregnancy test will be performed in women of child-bearing potential prior to injection of 11C -M503, 11C-PiB or 18F-Florbetaben
Forms of parkinsonism other than PD, PSP and MSA as defined above
Major psychiatric disorder (e.g. schizophrenia or bipolar disorder) - major depressive disorder is allowed
History of significant or ongoing alcohol abuse or substance abuse or dependence based on medical record review or self-reported
Contraindications or inability to tolerate imaging, arterial line or IV placement or blood draw procedures in the opinion of an investigator or treating physician
Contraindication to MRI, such as non-compatible implanted medical device
Any current medical condition, illness, or disorder as assessed by medical record review and/or self-reported that is considered by a physician or investigator to be a condition that could compromise participant safety or successful participation in the study

What this trial measures

  • Organ Biodistribution or Dosimetry4 weeks

    Determine biodistribution of the radioactive investigational drug, 11C-M503 and calculate human dosimetry. A second IV or an arterial line may be placed in the arm contralateral to the side of injection for blood metabolite analysis and/or radioactive counts at various times during the scanning session. Biodistribution, metabolism, excretion and pilot brain uptake data will be collected and human dosimetry will be calculated.

  • PET Uptake of Tracer4 weeks

    Determine whether there is selective uptake of 11C-M503 in people with MSA compared to healthy volunteers, PD and PSP participants.