[161Tb]Tb-Thz-Phe-D-Trp-Lys-Thr-DOTA: A potential radiopharmaceutical for the treatment of neuroendocrine tumors

Thz-Phe-D-Trp-Lys-Thr-DOTA, a conjugate of the DOTA chelator and the Thz-Phe-D-Trp-Lys-Thr pentapeptide, was labeled with ¹⁵²Eu and ¹⁶¹Tb radionuclides, where ¹⁶¹Tb has decay characteristics suitable for its use in cancer therapy. For the [¹⁵²Eu]Eu-Thz-Phe-D-Trp-Lys-Thr-DOTA complex, the biodistribution in nude mice bearing IMR-32 tumors was evaluated for the first time. It was shown that the complexes of the conjugate demonstrate accumulation in the tumor at the level of DOTA-TATE, another peptide conjugate widely used in nuclear medicine for the diagnosis and therapy of neuroendocrine tumors, which allows Thz-Phe-D-Trp-Lys-Thr-DOTA to be considered as a potential biological vector for radiopharmaceuticals.