Study of the automated synthesis of the radiopharmaceutical [18F]fluoroestradiol

Abstract

Breast cancer is the second leading cause of cancer death among women worldwide, with an incidence increase of 25 % per year. Approximately 75 % of breast cancer cells express estrogen receptors. The 16α-[18F]fluoro-17β-estradiol, [18F]FES, is a radiopharmaceutical that binds to estrogen receptors applied in PET-CT molecular images for non-invasive diagnosis of primary and metastatic breast cancer. The objective of this work was to study the synthesis of the [18F]FES in the GE TRACERlab® MXFDG module, using the Chemical Kit and the ABX® disposable cassette. Moreover, to determine the process yield and the analytical parameters to be used in the routine production of this radiopharmaceutical. Automated synthesis took place in 75 minutes and included percolation of [18F]fluoride (18F-) in an anion exchange cartridge, elution of the cartridge, azeotropic drying in 3 steps, labeling of the precursor 3-methoxymethyl-16β,17β-epiestriol-O-cyclic sulfone (MMSE) and a hydrolysis step. The product was purified in the module by solid-phase extraction (SPE) cartridges. The radiochemical yield was reproductive, despite initial [18F]fluorine activity, and the results of quality control tests suggest that the radiopharmaceutical meets the acceptance criteria established in official monographs for other radiopharmaceuticals labeled with 18-fluor. In vivo biodistribution studies in healthy mice and mice bearing MCF7 tumors showed the specific uptake on breast tumor cells.