T807 (AV-1451) is a novel tracer of tau positron emission tomography (PET).

In vitro autoradiography results show that [18F]T807 exhibits strong binding to PHF-tau positive human brain sections with Kd of 14.6 nM. Comparison of autoradiography and double immunohistochemical staining of adjacent sections of PHF-tau and Ab showed that [18F] T807 binding is colocalized with immunoreactive PHF-tau pathology, but does not highlight Ab plaques[1]. [18F]T807 strongly binds to tau lesions primarily made of paired helical filaments in Alzheimer’s brains e.g. intra and extraneuronal tangles and dystrophic neurites. [18F]T807 off-target binding to neuromelanin- and melanin-containing cells and, to a lesser extent, to brain hemorrhagic lesions is identified[2].

[18F]T807 can cross the blood-brain barrier and ished out quickly in mice models. [18F]T807 clears rapidly from the brain, with activity values decreasing from 4.43% ID/g at 5 minutes to 0.62% ID/g at 30 minutes. Kidney elimination is a significant clearance pathway, resulting in a maximum tracer concentration of 14.99% ID/g in the kidneys at 5 minutes, which decreases to 5.52% ID/g at 30 minutes. The accumulation of activity in muscle and bone remain relatively low throughout the PET scan[1].