Optimizing a Cancer-Fighting Radioisotope for Targeted Therapy

Researchers at the University of Missouri are making significant advances in cancer treatment through the development of a potent radioisotope capable of precisely targeting and destroying cancer cells. This innovation is being cultivated at the university's Research Reactor (MURR), where scientists are focused on refining the production, purification, and formulation processes of Terbium-161, a promising radioisotope for radiopharmaceutical applications.

Led by associate professor Heather Hennkens from the Department of Chemistry, the research aims to optimize Terbium-161 so it can be effectively attached to targeting molecules. Once bonded, these molecules carry the radioactive payload directly to tumor sites, facilitating targeted destruction of cancer cells. This development opens new possibilities for non-invasive, precise cancer treatments.

Terbium-161 is in the same chemical family as Lutetium-177, which is already widely utilized in treating neuroendocrine tumors and prostate cancers. Due to their similar chemical properties, drugs designed for Lutetium-177 can often be adapted for use with Terbium-161, making the transition smoother for clinical applications. Both isotopes emit beta particles, which are high-energy electrons effective in destroying larger tumors.

What distinguishes Terbium-161 is its capacity to deliver a two-pronged attack on cancer cells. Besides beta particles, it emits low-energy Auger and conversion electrons that travel only short distances within tissues. These electrons cause substantial damage at a microscopic level, making Terbium-161 especially suitable for targeting dispersed or microscopic cancerous lesions, including metastatic clusters or circulating tumor cells.

As these isotopes are highly damaging, the success of such therapies depends heavily on pairing them with targeting molecules that can accurately deliver the radiation to cancerous tissues, sparing healthy ones. This targeted approach enhances efficacy and reduces side effects.

Furthermore, MURR’s work aims to establish a domestic supply chain for Terbium-161, adding this isotope to the list of medical isotopes produced in the U.S. and decreasing reliance on international sources. The team’s findings are detailed in a study titled "Production and purification of research scale 161Tb using cation-exchange semi-preparative HPLC for radiopharmaceutical applications," published in Radiochimica Acta. Collaborators include scientists from Brookhaven National Laboratory and the University of Washington.

This advancement represents a significant step towards more effective, targeted cancer therapies and strengthens the U.S. capacity to produce essential medical isotopes.