Development of the First Aliphatic 18 F-Labeled Tetrazine Suitable for Pretargeted PET Imaging-Expanding the Bioorthogonal Tool Box

• Published in: Journal of medicinal chemistry Vol. 64; no. 20; pp. 15297 - 15312
• Main Authors: Battisti, Umberto M, Bratteby, Klas, Jørgensen, Jesper T, Hvass, Lars, Shalgunov, Vladimir, Mikula, Hannes, Kjær, Andreas, Herth, Matthias Manfred
• Format: Journal Article
• Language: English
• Published: United States 28.10.2021
• Subjects: Animals; Cell Line, Tumor; Drug Development; Female; Fluorine Radioisotopes; Humans; Isotope Labeling; Mice; Mice, Inbred BALB C; Mice, Nude; Molecular Structure; Neoplasms, Experimental - diagnostic imaging; Positron-Emission Tomography; Radiopharmaceuticals - chemical synthesis; Radiopharmaceuticals - chemistry
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/acs.jmedchem.1c01326

Pretargeted imaging of nanomedicines have attracted considerable interest because it has the potential to increase imaging contrast while reducing radiation burden to healthy tissue. Currently, the tetrazine ligation is the fastest bioorthogonal reaction for this strategy and, consequently, the state-of-art choice for chemistry. We have recently identified key properties for tetrazines in pretargeting. We have also developed a method to F-label reactive tetrazines using an aliphatic nucleophilic substitution strategy. Here, we combined this knowledge and developed an F-labeled tetrazine for pretargeted imaging. In order to develop this ligand, a small SAR study was performed. The most promising compound was selected for labeling and subsequent positron-emission-tomography imaging. Radiolabeling was achieved in satisfactory yields, molar activities, and high radiochemical purities. [ F] displayed favorable pharmacokinetics and remarkable target-to-background ratios-as early as 1 h post injection. We believe that this agent could be a promising candidate for translation into clinical studies.