Evaluation Comparing Tau PET Radiotracers, [18F]GTP1 and [18F]PI-2620 or [18F]MK-6240 in Subjects With Normal Cognition or Prodromal to Moderate Alzheimer's Disease

Study Overview
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Brief Summary
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The study aims to compare tau targeted radiotracers [18F]GTP1 and [18F]PI-2620 or [18F]MK-6240 in subjects with normal cognition or prodromal to moderate Alzheimer's disease (AD).

Official Title
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Phase 1 Evaluation Comparing Tau PET Radiotracers, [18F]GTP1 and [18F]PI-2620 or [18F]MK-6240 in Subjects With Normal Cognition or Prodromal to Moderate Alzheimer's Disease

Conditions
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Alzheimer Disease (AD)

Intervention / Treatment
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* Drug: [18F]GTP1
* Drug: [18F]PI-2620
* Drug: [18F]MK-6240


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria Cognitively normal subjects aged 65 to 90 years and prodromal to mild AD subjects aged 50 to 90 years, inclusive at the time of screening. Prodromal to moderate AD subjects: Meet the National Institute on Aging - Alzheimer's Association (NIA-AA) core clinical criteria for mild cognitive impairment (MCI) due to AD, probable AD dementia or AD dementia Have a Clinical Dementia Rating (CDR) score of 0 (cognitively normal) or 0.5 (prodromal to moderate AD) at screening Have an Mini-Mental State Examination (MMSE) score 10-30 inclusive Have Aβ PET imaging demonstrating Aβ binding based on qualitative visual read at screening or using an acceptable historical PET scan (cognitively normal subjects will be assessed with Aβ PET at screening but will not be required to demonstrate Aβ binding). A brain MRI consistent with normal cognition or that supports a diagnosis of prodromal to moderate AD, with no evidence of other significant neurologic pathology. A previously acquired research MRI within the last 12 months may be used if deemed acceptable by the investigator and no significant clinically relevant changes have occurred since the prior MRI was obtained The subject has an appropriate study partner capable of participating in CDR assessment and, if necessary, of accompanying the subject For cognitively normal subjects only: History of at least one first degree relative with diagnosis of Alzheimer's disease (self-reported by the potential subject and/or confirmed by the study partner). Exclusion Criteria Current or prior history of any alcohol or drug abuse within the last 2 years Prior participation in other research protocols or clinical care in the last year in addition to the radiation exposure expected from participation in this clinical study, such that radiation exposure exceeds the effective dose of 50 millisievert (mSv), which would be above the acceptable annual limit established by the US Federal Guidelines Evidence of clinically significant gastrointestinal, cardiovascular, hepatic, renal, hematological, neoplastic, endocrine, alternative neurological, immunodeficiency, pulmonary, or other disorder or disease MRI evidence of cerebrovascular disease, infectious disease, space-occupying lesions, normal pressure hydrocephalus, or other central nervous system (CNS) disease Implants that have not been certified for MRI or history of claustrophobia in MRI, unless an acceptable previously acquired research MRI is available

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: [18F]PI-2620 PET, then [18F]GTP1 PET<br>Participants will undergo one [18F]PI-2620 PET imaging session, then one [18F]GTP1 PET imaging session. Prior to each session, participants will be administered a bolus intravenous injection of approximately 5 millicurie (mCi) of [18F]PI-2620 or 7mCi of [18F]GTP1. | Drug: [18F]GTP1<br>* Participants will receive a bolus IV of approximately 7mCi of [18F]GTP1 radiotracer.<br>Drug: [18F]PI-2620<br>* Participants will receive a bolus IV of approximately 5mCi of [18F]PI-2620 radiotracer.<br>|
| Experimental: [18F]GTP1 PET, then [18F]MK-6240<br>Participants will undergo one [18F]GTP1 PET imaging session, then one [18F]MK-6240 PET imaging session. Prior to each session, participants will be administered a bolus intravenous injection of approximately 5 millicurie (mCi) of [18 F]MK-6240 or 7mCi of [18F]GTP1. | Drug: [18F]GTP1<br>* Participants will receive a bolus IV of approximately 7mCi of [18F]GTP1 radiotracer.<br>Drug: [18F]MK-6240<br>* Participants will receive a bolus IV of approximately 5mCi of [18F]MK-6240 radiotracer.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Percentage of Participants with Adverse Events (AEs) |  | Up to approximately 4 days after administration of each radiotracer | 
| Brain tau burden as measured by [18F]PI-2620 - PET |  | Approximately 1 hour after injection of [18F]PI-2620 | 
| Brain tau burden as measured by [18F]GTP1 - PET |  | Approximately 1 hour after injection of [18F]PI-2620 | 
| Brain tau burden as measured by [18F]MK-6240 - PET |  | Approximately 1 hour after injection of [18F]MK-6240 |