Newer radionuclide therapies

Over the past decade, a number of new and promising radionuclide therapies have undergone clinical translation from 'bench to bed' and this has extended the therapeutic applications of unsealed sources beyond the traditional use of ¹³¹I in thyroid disorders. We can classify the therapies into following categories: (a) Receptor targeted radionuclide therapies have been developed in various malignancies at their advanced/metastatic stages:¹⁷⁷Lutetium-DOTA-Octreotate Therapy in Somatostatin Receptor-Expressing Neuroendocrine Neoplasms and ¹⁷⁷Lu-PSMA-617 for metastatic castrate resistant prostate cancer. (b) Bone targeted therapies such as with ¹⁷⁷Lu-EDTMP/¹⁸⁸Re-HEDP or even alpha therapy with ²²³Ra for palliation of metastatic skeletal disease. The indigenously produced ¹⁷⁷Lutetium in the BARC reactors have aided in the development of the ¹⁷⁷Lu based therapeutics and kept this country in the forefront in this very promising area, with substantial cost containment. Rhenium-188 is another promising radionuclide for molecular radiotherapy with Eβ_max = 2.1 MeV with a maximum tissue penetration of 11 mm, Eγ = 155 keV (15%), t_1/2 = 17h and has the advantages of generator mode of production by elution of a ¹⁸⁸W/¹⁸⁸Re generator. (c) Intra-arterial therapy for Hepatocellular carcinoma: Efficient labelling of lipiodol with ¹⁸⁸Rhenium/¹³¹Iodine has demonstrated promising results for the treatment of hepatocellular carcinoma. (author)