Recent development in selective Tau tracers for PET imaging in the brain

Abnormal Tau deposition is a crucial pathological hallmark of various neurodegenerative disorders defined as tauopathies, of which Alzheimer's disease is the most prominent one. To date, a large number of chemical entities with different structures have been developed as Tau imaging tracers for the early diagnosis of tauopathies. Several of them with excellent bio-properties are currently being assessed in clinical trials, and more recently, the Tauvid™ ([ 18 F]Flortaucipir, also known as [ 18 F]AV1451 or [ 18 F]T807) as the first Tau tracer was approved by the U.S. Food and Drug Administration in 2020. This review summarized the latest development of Tau tracers and analyzed their chemical structures, with particular attention to the effects of chemical structures on biological properties. In addition, we also discuss the limitations of current Tau imaging tracers, issues that need attention in the development of new tracers, and possible future directions. In the past few years, several Tau imaging tracers with different chemical scaffolds were developed for the early diagnosis of tauopathies. Among these tracers, [ 18 F]Flortaucipir as the first Tau tracer was approved by the U.S. Food and Drug Administration in 2020. This review summarized the structural and biological characteristics of these tracers and discussed the future directions in this field.