Evaluation of Human Absorbed Dose of 177Lu-DOTA-Trastuzumab Based on its Biodistribution Studies in Rats

In this study, Trastuzumab was labeled with 177Lu, and its dosimetric calculation was performed considering the assessment of the absorbed dose in the organs of human body. 177Lu chloride was prepared after 7 days irradiation of enriched Lu2O3 in the Tehran Research Reactor at the thermal neutron flux of 4×1013 cm-2 s-1, and the specific activity of 70-80 GBq/mg. 177Lu-DOTA-Trastuzumab was obtained with an overall radiochemical purity of >98% under the optimized conditions. Biodistribution studies of the radioimmunoconjugate in normal rats were carried up to 168 h. Relative organ mass extrapolation method was used for calculation of the human absorbed dose. Because of the highest accumulation activity in reticuloendothelial system, liver and spleen have received the maximum dose of 0.95 and 0.89 mSv/MBq, respectively.