- Development of18F-Labeled Bispyridyl Tetrazines for In Vivo Pretargeted PET Imaging
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Pretargeted PET imaging is an emerging and fast-developing method to monitor immunooncology strategies. Currently, tetrazine ligation is considered the most promising bioorthogonal reaction for pretargeting in vivo. Recently, we have developed a method to18F-label ultrareactive tetrazines by copper-mediated fluorinations. However, bispyridyl tetrazines—one of the most promising structures for in vivo pretargeted applications—were inaccessible using this strategy. We believed that our successful efforts to18F-label H-tetrazines using low basic labeling conditions could also be used to label bispyridyl tetrazines via aliphatic nucleophilic substitution. Here, we report the first direct18F-labeling of bispyridyl tetrazines, their optimization for in vivo use, as well as their successful application in pretargeted PET imaging. This strategy resulted in the design of [18F]45, which could be labeled in a satisfactorily radiochemical yield (RCY = 16%), molar activity (Am = 57 GBq/μmol), and high radiochemical purity (RCP > 98%). The [18F]45 displayed a target-to-background ratio comparable to previously successfully applied tracers for pretargeted imaging. This study showed that bispyridyl tetrazines can be developed into pretargeted imaging agents. These structures allow an easy chemical modification of18F-labeled tetrazines, paving the road toward highly functionalized pretargeting tools. Moreover, bispyridyl tetrazines led to near-instant drug release of iTCO-tetrazine-based ‘click-to-release’ reactions. Consequently,18F-labeled bispyridyl tetrazines bear the possibility to quantify such release in vivo in the future.
- Battisti, Umberto Maria,Bratteby, Klas Erik,García-Vázquez, Rocío,Herth, Matthias M.,Hvass, Lars,J?rgensen, Jesper Tranekj?r,Kj?r, Andreas,Shalgunov, Vladimir
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- Pyrazole derivatives
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This invention relates to pyrazole derivatives of formula (I) or pharmaceutically acceptable salts, solvates or derivatives thereof, and to processes for the preparation thereof, intermediates used in their preparation of, compositions containing them and the uses of such derivatives. The compounds of the present invention bind to the enzyme reverse transcriptase and are modulators, especially inhibitors thereof. As such, the compounds of the present invention are useful in the treatment of a variety of disorders including those in which the inhibition of reverse transcriptase is implicated. Disorders of interest include those caused by Human Immunodificiency Virus (HIV) and genetically related retroviruses, such as Acquired Immune Deficiency Syndrome (AIDS).
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