Preparation and preliminary biological evaluation of 177Lu-NOTATATE / 中华核医学与分子影像杂志

ABSTRACT

Objective:To explore the optimal labeling conditions of 177Lu-1, 4, 7-triazacyclononane-1, 4, 7-triacetic acid (NOTA)- D-Phe1-Tyr3-Thr8-octreotide (TATE), and evaluate its biodistribution and imaging characteristics in mice. Methods:The reaction temperature, pH, reaction time and other labeling conditions were changed to realize the rapid labeling of NOTATATE by 177Lu. The optimal labeling conditions, radiochemical purity, in vitro stability, plasma protein binding rate, and lipid-water partition coefficient were determined. Twenty-four normal KM mice were divided into 6 groups by random number table method. After injected with 3.7 MBq 177Lu-NOTATATE through tail vein, they were sacrificed at 0.5, 1, 4, 24 h and 4, 6 d respectively to research the biological distribution (injection dose rate per gram of tissue percentage, %ID/g). Six normal mice were randomly divided into 2 groups and injected with 11.1 MBq 177Lu-NOTATATE and 177Lu-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA)TATE, respectively. SPECT planar imaging was performed at 1, 2, 3 h after injection. Another 8 mice were divided into 4 groups, injected with 3.7, 7.4, 18.5 MBq 177Lu-NOTATATE and saline respectively for an acute toxicity test. Results:At pH 5 and reaction temperature between 95 ℃ and 100 ℃ for 15 min, the labeling rate could reach more than 98%. After being placed in human serum for 24 h, the radiochemical purity was still higher than 95%. The plasma protein binding rate of 177Lu-NOTATATE was (58.6±1.9)% and the lipid-water partition coefficient was 0.048±0.014. In normal mice, the concentration of radioactivity is mainly in the liver, kidney and spleen, especially in the kidney (up to (29.120±1.204) %ID/g after 0.5 h of injection), which is less distributed in the blood and excreted rapidly. Compared with 177Lu-DOTATATE, 177Lu-NOTATATE was excreted faster by the kidney. The toxicity study results revealed that no damage was observed in mice of each group, and no obvious damage or inflammatory changes were observed in organ tissue sections. Conclusions:The optimal labeling condition of 177Lu-NOTATATE were determined in this study. The physical, chemical, and biological properties of 177Lu-NOTATATE were proved to be good and safe, and it was excreted faster by the kidney than 177Lu-DOTATATE. The results of this study lay a foundation for further clinical transformation research.