Production of high specific activity rhenium-186 for radiotherapeutic applications and reformulation of a novel liquid brachytherapy agent

Abstract

The continued development of methods for the production and separation of high specific activity (HSA) rhenium-186 (t1/2 = 90.64 h, Eb-ave = 359 keV (71 percent), 306 keV (22 percent)) would largely increase its use as a therapeutic analogue to the widely used 99mTc (t1/2 = 6.01 h, Eg = 141 keV (89 percent)). Rhenium-186 has favorable decay properties that make it an attractive candidate for radioimmunotherapy, providing that the radionuclide can be obtained in high specific activity. The similar chemical characteristics of Re and Tc in theory may allow 186Re-based radiopharmaceuticals to be developed as therapeutic analogues to their 99mTc counterparts. In this research, two methods were evaluated for the production and separation of HSA 186Re, and several methods were also evaluated for their efficiency in the selective separation of 186Re post production, as well as high recovery of the costly enriched target material. Yttrium-90 (t1/2 = 64 h, Eb-max = 2.28 MeV (99.99 percent)) also displays excellent decay properties for targeted radiotherapy, which is exploited by the formulation of a novel liquid brachytherapy agent, BetaBrachTM. The HSA 90Y utilized for the current formulation of BetaBrachTM can be replaced by low specific activity (LSA) 90Y produced in a nuclear reactor. Replacing HSA 90Y with LSA 90Y may offer significant economic advantages if the demand for BetaBrachTM requires large scale production of 90Y. Thus, this work also evaluates the chemical and physical characterization of LSA 90Y formulated BetaBrachTM as well as its therapeutic efficacy.