<i>In Silico</i> Discovery and Subsequent Characterization of Potent 4R-Tauopathy Positron Emission Tomography Radiotracers
Thomas J. A. Graham, Anton Lindberg, Junchao Tong, Jeffrey S. Stehouwer, Neil Vasdev, Robert H. Mach, Chester A. Mathis
Abstract
High Resolution Image Download MS PowerPoint Slide A chemical fingerprint search identified Z3777013540 (1-(5-(6-fluoro-1 H -indol-2-yl)pyrimidin-2-yl)piperidin-4-ol; 1 ) as a potential 4R-tau binding ligand. Binding assays in post-mortem Alzheimer’s disease (AD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD) brain with [ 3 H] 1 provided K D (nM) values in AD = 4.0, PSP = 5.1, and CBD = 4.5. In vivo positron emission tomography (PET) imaging in rats with [ 18 F] 1 demonstrated good brain penetration and rapid clearance from normal brain tissues. A subsequent molecular similarity search using 1 as the query revealed an additional promising compound, Z4169252340 (4-(5-(6-fluoro-1 H -indol-2-yl)pyrimidin-2-yl)morpholine; 21 ). Binding assays with [ 3 H] 21 provided K D (nM) values in AD = 1.2, PSP = 1.6, and CBD = 1.7 and lower affinities for binding aggregated α-synuclein and amyloid-beta. PET imaging in rats with [ 18 F] 21 demonstrated a higher brain penetration than [ 18 F] 1 and rapid clearance from normal brain tissues. We anticipate that 1 and 21 will be useful for the identification of other potent novel 4R-tau radiotracers.