A New Labelling Method of 99mTc-PSMA-HBED-CC

Objective68Ga-PSMA-HBED-CC (68Ga-PSMA-11) was approved by the US FDA as the first PSMA-targeted PET imaging drug for patients with prostate cancer. However, the utility of 68Ga-PSMA-HBED-CC may be limited due to PET/CT or PET/MR accessibility and 68GaCl3 availability produced from 68Ge/68Ga generator or cyclotron. Thus, in-house preparation of 99mTc-PSMA-HBED-CC was developed as an alternative to 68Ga-PSMA-HBED-CC to be ubiquitous and affordable in the worldwide population. MethodsA solution of 99mTc-pertechnetate was added to PSMA-HBED-CC and 4% SnCl2{middle dot}2H2O in a 10 mL sterile vial. The mixture was heated at 100{degrees}C for 15 minutes and then allowed to cool to room temperature. Labeling conditions were optimized to maximize the radiochemical yield of 99mTc-PSMA-HBED-CC. The chelation completeness was monitored using instant thin layer chromatography (iTLC), and the stability of 99mTc-PSMA-HBED-CC was subsequently evaluated. ResultsThe radiolabeling of 99mTc-PSMA-HBED-CC was succeeded using the appropriate amount of 10 {micro}g PSMA-HBED-CC 3 {micro}g SnCl2{middle dot}2H2O and 99mTc-pertechnetate 370 MBq at 100 {degrees}C for 15 mins, yielded the best result in high radiochemical yield (71.49 {+/-} 2.42%), radiochemical purity (98.29 {+/-} 2.65%), specific activity of 37.84 {+/-} 1.47 GBq/{micro}mol. 99mTc-PSMA-HBED-CC is stable with radiochemical purity of more than 95% within 4 hrs at room temperature. ConclusionA new labelling method of 99mTc-PSMA-HBED-CC was developed. Quality control parameters of 99mTc-PSMA-HBED-CC met the criteria in accordance with the European Pharmacopoeia.