[Indications and Practice of a New Radionuclide Therapy, 177Lu-DOTATATE in Japan]

Peptide receptor radionuclide therapy(PRRT)is a pioneer drug in the rapid development of radio-theranostics, and a paradigm-shifting approach to treat neuroendocrine tumor( NET). The NETTER-1 trial for NETs of the midgut is currently the only global phase Ⅲ prospective clinical trial demonstrating the efficacy and safety of PRRT. In Japan, phase Ⅰ and Ⅰ/Ⅱ trials for lung and gastroenteropancreatic NETs were also conducted, and regulatory approval was granted in June of 2021. Although regulatory approval was obtained in Japan without specifying the primary organ or the history of treatment, there is limited evidence at this time, and guidelines recommend use after the second-line for midgut NETs and in the last phase for all other NETs. PRRT is expected to be utilized as upfront therapy, and the results of ongoing prospective clinical trials are awaited. The effect of PRRT is corelated with accumulation rate of somatostatin receptor scintigraphy(SRS). Sometime accumulation rate of SRS is not constant among multiple tumors in even one patient, then effective use of PRRT is depending on detailed exploration for result of SRS of each tumor. In order to perform this treatment in Japan, a special ward dedicated to radionuclide therapy or at least" a special measures patient room" prescribed by laws and regulations is necessary." A special measures patient room" is a general patient room with temporary isolation and taking radiation protection countermeasure, instead of the special exhaust and drainage systems of radionuclide therapy ward. On the other hand, in order to operate the rooms, it is necessary to set up and decontaminate the rooms for each treatment, which requires specialized knowledge and manpower. Since there is a growing demand for radionuclide therapies, it is important to promote the appropriate introduction of this therapy and to establish a collaborative network for this purpose.