Preparation and evaluation of L- and D-5-[ 18 F]fluorotryptophan as PET imaging probes for indoleamine and tryptophan 2,3-dioxygenases

Automated synthesis of PET radiotracers by copper‐mediated 18F‐fluorination of organoborons: Importance of the order of addition and competing protodeborylation

“…The general decrease (and unpredictability) in RCC, when copper-mediated fluorodeborylation is automated in a synthesis module, along with the formation of the protoarene side product, was first noted in our earlier report. 2 While we note that several groups have since used this chemistry as-is to produce a number of different radiotracers, [12][13][14][15] we nevertheless felt that these two issues left opportunities for improvement. As such, we have focused upon optimizing the chemistry for routine use in the automated production of doses in high yield, purity, and specific activity.…”

IDO1 in cancer: a Gemini of immune checkpoints

“…Recent developments for noninvasive in vivo metabolite imaging may provide a solution for this technical hurdle. 105,106 It should be noted, however, that systemic Trp levels can be affected by TDO, which is expressed in the liver constitutively and induced in some types of cancer, 42 suggesting that evaluation of this amino acid is not necessarily a sole reflection of IDO1 enzyme activity. Finally, understanding how IDO1 works in cancer cells, versus noncancer cells, in terms of the enzyme and signal transduction properties, is essential for targeting the full effects of this pleiotropic mediator of immune suppression.…”

PET imaging of medulloblastoma with an 18F-labeled tryptophan analogue in a transgenic mouse model

“…As such, a number of amino acid-based radiotracers have been developed and used for the evaluation of amino acid-involved biological process in tumors 8 . Among them, tryptophan-based PET tracers show great promise for brain tumor imaging [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] .…”