Radiosynthesis, In Vitro and In Vivo Evaluation of [F-18]CBD-2115 as a First-in-Class Radiotracer for Imaging 4R-Tauopathies

• CBD-2115 was selected from a library of 148 compounds based on a pyridinyl-indole scaffold as a first-in-class 4R-tau radiotracer. In vitro binding assays showed [H-3]CBD-2115 had a K-D value of 6.9 nM and a nominal B-max of 500 nM in 4R-tau expressing P301L transgenic mouse tissue. In binding assays with human brain tissue homogenates, [H-3]CBD-2115 has a higher affinity (4.9 nM) for progressive supranuclear palsy specific 4R-tau deposits than [H-3]flortaucipir (45 nM) or [H-3]MK-6240 (>50 nM). [F-18]CBD-2115 was reliably synthesized (3-11% radiochemical yield with molar activity of 27-111 GBq/mu mol and >97% radiochemical purity). Dynamic PET imaging was conducted in mice, rats, and nonhuman primates, and all species showed initial brain uptake of 0.5-0.65 standardized uptake value with fast clearance from normal tissues. [H-3]CBD-2115 could be a useful lead radioligand for further research in 4R-tauopathies, and PET radiotracer development will focus on improving brain uptake and binding affinity.

Ämnesord

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

Nyckelord

PET; tau; 4R-tau; fluorine-18; CBD-2115

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