The "Goldilocks" Isotope for Cancer Therapy

At-211 is often called the "perfect" or "Goldilocks" isotope because it can deliver just the right amount of radiation to destroy cancer cells while leaving the surrounding tissue unharmed. This breakthrough isotope has demonstrated strong potential against blood cancers, ovarian tumors, and certain brain cancers. Within the Texas A&M Cyclotron Institute, scientists are producing At-211 using the K150 cyclotron with support from the U.S. Department of Energy (DOE) Isotope Program. Since 2023, Texas A&M has been one of only two national suppliers of astatine for targeted cancer therapy through the National Isotope Development Center (NIDC) and its University Isotope Network.

"Targeted alpha therapy is a potentially transformative cancer therapeutic of great interest due to its ability to cause large amounts of damage near a tumor cell while keeping the healthy surrounding tissue and organs intact," said Texas A&M Distinguished Professor and Regents Professor of Chemistry Dr. Sherry J. Yennello, director of the Cyclotron Institute. "We are one of a handful of U.S. centers capable of routinely producing astatine in medically relevant quantities and delivering it to nearby facilities."

Harnessing the Power of Alpha Particles

When astatine decays, it emits alpha particles -- tiny clusters made of two protons and two neutrons -- that can release powerful, localized bursts of energy. These alpha particles are highly effective in destroying cancer cells because they travel only a short distance before releasing their energy, minimizing damage to healthy tissue. When At-211 is positioned within or near tumors, its alpha emissions penetrate just deep enough to eliminate cancerous cells while sparing surrounding organs.

At-211's short half-life also means it quickly loses its radioactivity, making it less toxic than longer-lived radiopharmaceuticals. Unlike many other isotopes, At-211 does not produce harmful secondary alpha decay, ensuring that its energy is used efficiently for therapy. This combination of precision and safety has drawn attention from researchers and pharmaceutical developers worldwide. It is already being tested in clinical trials for blood cancers and explored for potential use in treating Alzheimer's disease.

"Astatine-211's availability remains the biggest hurdle to harnessing its potential to transform the future of nuclear medicine," Yennello said. "Fortunately, the advances we're making here at Texas A&M will go a long way toward addressing that."

A Breakthrough in Isotope Production and Transport

One of Texas A&M's major achievements has been the creation of an automated system to separate and ship At-211. This patent-pending technology purifies the isotope by removing it from the bismuth target and then loads it onto a shipping column for incorporation into targeted alpha therapy drugs. According to Yennello, the new resin-column trapping technique allows for faster processing, enabling larger quantities of At-211 to be shipped with minimal decay and reduced risk compared with traditional methods. This improvement strengthens the case for At-211 as a viable next-generation cancer treatment.

Texas A&M has already delivered significant batches of At-211 to collaborators, including the University of Alabama at Birmingham and MD Anderson Cancer Center, which has received more than two dozen shipments. These partnerships are helping researchers refine At-211-based radiopharmaceuticals and deepen understanding of its chemical behavior.

Collaboration and Global Progress

Yennello and Dr. Federica Pisaneschi, a former MD Anderson radiochemist now at the University of Texas Health Science Center at Houston, are scheduled to present their findings at the 2025 World Astatine Community Meeting in New Orleans. Their talk, titled "The Texas Two-Step," will highlight their combined experience producing, shipping, and applying At-211 for therapeutic use. This first U.S.-based meeting will bring together researchers and commercial groups dedicated to expanding At-211's role in cancer treatment worldwide.

Yennello recently shared Texas A&M's progress at another major event -- the 26th International Symposium on Radiopharmaceutical Sciences, held in Queensland -- where she emphasized growing international interest in At-211 research.

"Although clinical trials in humans are in the early stages, there are initiatives currently looking at astatine-211's potential in Japan, several European countries and the United States," Yennello said. "I'm looking forward to sharing Texas A&M's success in producing and supplying astatine-211 while also learning more about global progress in our common efforts to better understand its chemical properties and possible therapeutic advancement in oncology."

This pioneering research is supported by the DOE Office of Science through the DOE Isotope Program, by Texas A&M through the Bright Chair in Nuclear Science, and by The Texas A&M University System Nuclear Security Office in partnership with Los Alamos National Laboratory.