Evaluation of hospital radiopharmacy-based ⁶⁸Ga-labeled radiopharmaceutical: ⁶⁸Ga-HBEDCC-PSMA-11

Development of ⁶⁸Ge/ ⁶⁸Ga generator system boosted development of 68-gallium-labeled radiopharmaceuticals. Recent development is use of nonmetallic silica-based adsorbed resin column. Its advantage is eluate with minimal metallic impurities, which improves labeling efficiency of 68-Ga-labeled radiopharmaceuticals. Introduction of ⁶⁸Ga-HBED-CC-PSMA ushered a new path in detection and staging of prostate cancer in PET-CT imaging. We performed labeling procedure of ⁶⁸Ga-PSMA-11 using eluate of nonmetallic ⁶⁸Ge/ ⁶⁸Ga generator. 5 µg of peptide (DKFZ-PSMA-11) in 900 µl of 0.25 M sodium acetate buffer was used for labeling. We performed 175 labeling procedures in a span of 14 months using two generators (n = 105 I st generator, n = 70 II nd generator). Elution was done using 4 ml of 0.05 M HCl. After heating for 5 min at 1000°C, labeled product was passed through C18 cartridge. Impurities were collected in waste vial. Extraction was done using ethanol. pH of waste and product was measured. Radiochemical purity of ⁶⁸Ga-PSMA-11 was determined by instant thin-layer chromatography method using silica adsorbed Al stripes and 0.1 M tri-sodium acetate, (1:1) acetonitrile:water as a solvent. Its stability was evaluated after 2 h. pH of product ⁶⁸Ga-PSMA-11 was shown as 5.5 and for waste as 4.0. We calculated labeling efficiency of ⁶⁸Ga-labeled product using both generators. Using first generator labeling efficiency of ⁶⁸Ga-PSMA-11 was 78%. Using second generator labeling efficiency of ⁶⁸Ga-PSMA was 79%. Radiochemical purity of labeled product was >98%. The product showed good stability over a period of 2 h as radiochemical purity was above 94%. ITG ⁶⁸Ge/ ⁶⁸Ga generator system showed high radiochemical yield of ⁶⁸Ga-HBED-CC-PSMA-11. We observed consistency in labeling efficiency of both generators. High radiochemical purity and stability of the labeled product ascertained its use as reliable radiopharmaceutical in diagnosis and staging of prostate cancer. (author)