[(18)F]T807, a novel tau positron emission tomography imaging agent for Alzheimer's disease

Alzheimers Dement. 2013 Nov;9(6):666-76. doi: 10.1016/j.jalz.2012.11.008. Epub 2013 Feb 12.

Abstract

Objective: We wished to develop a highly selective positron emission tomography (PET) imaging agent targeting PHF-tau in human Alzheimer's disease (AD) brains.

Methods: To screen potential tau binders, human AD brain sections were used as a source of native paired helical filament (PHF)-tau and Aβ rather than synthetic tau aggregates or Aβ fibrils generated in vitro to measure the affinity and selectivity of [(18)F]T807 to tau and Aβ. Brain uptake and biodistribution of [(18)F]T807 in mice were also tested.

Results: In vitro autoradiography results show that [(18)F]T807 exhibits strong binding to PHF-tau-positive human brain sections. A dissociation constant (Kd) of [(18)F]T807 (14.6 nM) was measured using brain sections from the frontal lobe of AD patients. A comparison of autoradiography and double immunohistochemical staining of PHF-tau and Aβ on adjacent sections demonstrated that [(18)F]T807 binding colocalized with immunoreactive PHF-tau pathology, but did not highlight Aβ plaques. In vivo studies in mice demonstrated that [(18)F]T807 was able to cross the blood-brain barrier and washed out quickly.

Conclusions: [(18)F]T807 demonstrates high affinity and selectivity to PHF-tau as well as favorable in vivo properties, making this a promising candidate as an imaging agent for AD.

Keywords: Alzheimer’s disease; Amyloid β; Autoradiography; Imaging; Tau; [(18)F]T807.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / diagnosis*
  • Amyloid beta-Peptides / metabolism
  • Animals
  • Autoradiography
  • Brain / diagnostic imaging*
  • Brain / pathology
  • Case-Control Studies
  • Female
  • Fluorine Radioisotopes*
  • Humans
  • Male
  • Mice
  • Mice, Transgenic
  • Middle Aged
  • Positron-Emission Tomography
  • Protein Binding / drug effects
  • Protein Binding / genetics
  • Tissue Distribution
  • tau Proteins / chemistry*
  • tau Proteins / drug effects*
  • tau Proteins / genetics

Substances

  • Amyloid beta-Peptides
  • Fluorine Radioisotopes
  • tau Proteins