Preliminary study on internal dose estimation of ¹⁷⁷Lu-DOTA Trastuzumab in human based on the biodistribution data of mice

A new radiopharmaceutical for treating Breast Cancer of HER-2 type, ¹⁷⁷Lu DOTA-Trastuzumab, had been successfully produced by The Centre for Radioisotope and Radiopharmaceutical Technology-BATAN. With regard to the patient safety, the new drug development process need internal dosimetry data obtained of preclinical study in animal. Hence, this study has been objected to estimate the internal radiation dose in human by performing the biodistribution test in mice. In this study, the biodistribution test was done for 25 mice and sacrificed at 1, 2, 3, 4, 24, 48 hour after the injection of ¹⁷⁷Lu DOTA-Trastuzumab. There were 11 organs, namely brain, stomach, intestine, heart, kidneys, liver, lungs, muscle, bone, spleen, and urinary bladder, have been investigated by observing the uptake in each organ during the proposed time. The result of biodistribution test then were being calculated into injection dose per gram human organ (%ID/gr). To estimate the internal dose in human, the data of %ID/gram in human need to be plotted to calculate the residence time which will be need as the input for OLINDA/EXM, a tool for calculating internal dosimetry in Nuclear Medicine fields. As a result, three organs that have been estimated receiving the highest internal radiation dose due to the administration of ¹⁷⁷Lu DOTA Trastuzumab are: lungs, liver, and ovaries at approximately 0.063; 0.046 and 0.025 mSv/MBq respectively. To conclude, the total internal dose in human reference model due to the administration of ¹⁷⁷Lu-DOTA Trastuzumab has been estimated to be 0.21 mSv/MBq. (author)