focusing the researches in targeted radioisotope therapy (TRT). Recently, TRT attracted attention because a newly-developed commercially available pharmaceutical, Ra-223 chloride (trade name; Xofigo), an alpha particle emitting TRT agent. Despite the conventional TRT agents, such as I-131, Sr-89 and Y-90, are beta emitting phamaceuticals, Ra-223 chloride is a first-ever alpha particle emitting TRT product and shows a strong therapeutic effect in patients with bone metastases from prostate

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... because of its poweful cell killing effect of alpha particle irradiation. In TRT research fields, there are several other promising alpha particle emitting TRT agents, and one of these promising alpha particle emitting TRT agents is Ac-225 labelled PSMA-617 (Prostate Specific Membrane Antigen-617), which is a newly developed TRT agent and showed a suprising therapeutic effect in two metastatic prostate cancer patients in end-stage (case report in J Nucl Med 2016). QST and our department recently developed and reported one promising candidate for TRT, meta-At-211 astato-benzylguanidine (At-211-MABG). At-211-MABG is also an alpha-emitting radiopharmaceutical targeting the treatment of neuroendocrine tumors, such as malignant pheochromocytoma. In this session, we would like to show our recent advance in the research of At-211-MABG. One of our research goals is to develop Japan's first-ever Japanese-made pharmaceutical products for TRT including Ac-225 labelled TRT agents. In addition, we would like to show our strategies in the future development of preclinical and clinical researches, dosimetric researches, and regulatory science, especially in the field of alpha emitter TRT pharmaceutical products.