A detailed description of the precursor synthesis is provided in the supplemental materials (available at http://jnm.snmjournals.org ). Purification was accomplished via reversed-phase high-performance liquid chromatography (HPLC).
64Cu and 68Ga labeling was performed in analogy to an established protocol for 177Lu labeling (19 (link)). A detailed description of the labeling procedures is provided in the supplemental materials. [64Cu]CuCl2 was purchased from DSD-Pharma GmbH. [68Ga]GaCl3 was provided by ITM Isotope Technologies Munich SE. The radiolabeled reference, 3 -[125I]I-Tyr6-MJ9 (Supplemental Fig. 1), was prepared according to reported procedures (19 (link),21 (link)). Characterization of all GRPR ligands is provided in Supplemental Figures 2–4.
The synthesis of [68Ga]Ga-AMTG according to good manufacturing practices for human PET/CT studies was performed using a good radiopharmaceutical practice module (Scintomics GmbH) while using an SC-01 gallium peptide labeling kit (ABX). [68Ga]GaCl3 was obtained from a GalliaPharm generator (Eckert & Ziegler) and was trapped on a PS-H+ cartridge (ABX), which was eluted by a sodium chloride solution. The eluate was transferred in the reactor containing the AMTG precursor and the 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer. The solution was heated and afterward transferred to a Sep-Pak C18 Light cartridge (Waters) for purification. After washing with water, the cartridge was eluted with ethanol and the solution was diluted with phosphate-buffered saline. The Cathivex-GV (Merck KGaA) was used as a sterile filter after the synthesis. Quality control included an instant thin-layer chromatography silica gel scan (NH4OAc/MeOH; Agilent), as well as an HPLC measurement against the corresponding reference compound, [natGa]Ga-AMTG. Compliance with the HEPES limit was determined by a spot test. Furthermore, a sterile filter integrity test, a limulus amebocyte lysate test, and a postapplication sterility test were performed. The ethanol concentration was measured by gas chromatography analysis.
64Cu and 68Ga labeling was performed in analogy to an established protocol for 177Lu labeling (19 (link)). A detailed description of the labeling procedures is provided in the supplemental materials. [64Cu]CuCl2 was purchased from DSD-Pharma GmbH. [68Ga]GaCl3 was provided by ITM Isotope Technologies Munich SE. The radiolabeled reference, 3 -[125I]I-Tyr6-MJ9 (Supplemental Fig. 1), was prepared according to reported procedures (19 (link),21 (link)). Characterization of all GRPR ligands is provided in Supplemental Figures 2–4.
The synthesis of [68Ga]Ga-AMTG according to good manufacturing practices for human PET/CT studies was performed using a good radiopharmaceutical practice module (Scintomics GmbH) while using an SC-01 gallium peptide labeling kit (ABX). [68Ga]GaCl3 was obtained from a GalliaPharm generator (Eckert & Ziegler) and was trapped on a PS-H+ cartridge (ABX), which was eluted by a sodium chloride solution. The eluate was transferred in the reactor containing the AMTG precursor and the 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffer. The solution was heated and afterward transferred to a Sep-Pak C18 Light cartridge (Waters) for purification. After washing with water, the cartridge was eluted with ethanol and the solution was diluted with phosphate-buffered saline. The Cathivex-GV (Merck KGaA) was used as a sterile filter after the synthesis. Quality control included an instant thin-layer chromatography silica gel scan (NH4OAc/MeOH; Agilent), as well as an HPLC measurement against the corresponding reference compound, [natGa]Ga-AMTG. Compliance with the HEPES limit was determined by a spot test. Furthermore, a sterile filter integrity test, a limulus amebocyte lysate test, and a postapplication sterility test were performed. The ethanol concentration was measured by gas chromatography analysis.
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