This is an open label study to compare three new generation TAU radioligands, 18F-RO948
(formerly known as 18F-6958948), 18F-MK6240, and [18F]GTP1for imaging of taupathy and
demonstrate their absence of off-target binding in patients with Alzheimer disease (AD) and
older healthy controls (OC). The study will directly compare AD and OC with these three
next-generation TAU radioligands and compare each of them with historical data of the current
most widely used first generation radioligand, 18F-AV1451. Upto38 (30 AD (Amyloid +)and 8 OC
(Amyloid -), matched for age and sex with A+ subjects) male and female subjects aged 50-100
will be enrolled in this study protocol: up to 8 for Cohort 1, up to 8 for Cohort 2, and up
to 22 for Cohort 3. The study consists of three cohorts: Cohort 1: Up to8 AD subjects (A+;
CDR 0.5 and 1)will receive two PET scans in random order, with receiving either18F-RO948
or18F-MK6240 at the first scan. A third scan with 18F-GTP1is possible, depending on timing
and radiotracer availability Cohort 2:Up to8 OC (A-; CDR=0)subjects will receive two PET
scans in random order, with receiving either18F-RO948or 18F-MK6240 at the first scan. A third
scan with 18F-GTP1is possible, depending on timing and radiotracer availability Cohort 3:Up
to 22 (A+; CDR = 0, .5 and 1) subjects will receive three PET scans in random order, with
receiving 18F-RO94818F-MK6240 or18F-GTP1at the first scan. Efforts will be made to include
about 1/3 CDR = 0, 1/3 CDR .5, and 1/3 CDR 1 in Cohort 3.