Oak Ridge revives isotope generators for mouse prostate cancer research

In a radiochemistry lab at Oak Ridge National Laboratory, Becca Hoerres is handling a tool that had disappeared from the site’s workflow for 15 years. The associate radiochemist has revived and modernized a tungsten-188/rhenium-188 generator, giving researchers a new way to obtain rhenium-188 for cancer studies, including a prostate cancer experiment at Vanderbilt University.

The mechanism is compact but useful. Tungsten-188 is made by irradiating tungsten-186 in Oak Ridge’s High Flux Isotope Reactor; as the tungsten decays, it produces rhenium-188. A few-inch-tall column captures the tungsten while allowing the rhenium to pass through for collection, so a customer can elute — separate and draw out — the isotope without rebuilding the chemistry each time.

That access is already being put to work. Vanderbilt graduate student Haswitha Sabbineni is testing a treatment strategy based on the sodium/iodide symporter, a protein first linked to targeted radioactive iodine therapy for thyroid cancer. A modified version is being studied in mice to see whether it can carry radioactive perrhenate, which contains rhenium-188, to prostate cancer cells without harming the thyroid.

Rhenium-188 is not confined to that experiment. A noninvasive skin cancer treatment using it is approved overseas, and the isotope is being investigated for multiple other cancers. Oak Ridge says the generator design used in the past relied on complicated, expensive custom components; Hoerres replaced them with a simpler connection that costs less and is easier for outside researchers to use.

So what changes in practice? A generator could last about a year to 18 months, because tungsten-188 has a half-life of about 60 days, and it can be shipped essentially anywhere in the world. That gives laboratories and clinical researchers a more practical route to a U.S.-produced isotope, rather than requiring them to manage the full generator-building process themselves. Oak Ridge is still studying how to scale up higher-activity versions and expects to ramp up production only as customers find new uses for rhenium-188.