Bill Gates-backed TerraPower Isotopes produces rare, radioactive ingredient sought for cancer drugs

Nearly a decade ago, radio chemists at the nuclear power startup TerraPower saw a promising opportunity in radioactive waste from Cold War weapons. And when you work for a company backed by Bill Gates and his resources, you get some leeway for running with outside-the-box ideas.

TerraPower Isotopes this week announced a milestone, becoming the first commercial-scale producer of a promising and rare isotope for cancer therapies, which is extracted from weapons waste.

“We are so excited, we can hardly stand it. We’re honored and humbled,” said Scott Claunch, president of TerraPower Isotopes, a TerraPower subsidiary. “I really believe that in the future, we will utilize targeted radiotherapy as a pillar for how we treat disease.”

Others seem to agree. News headlines this year have highlighted the billions of dollars of investments and acquisitions going to radiopharmaceutical manufacturers.

At its facility in Everett, Wash., TerraPower Isotopes is producing radioactive actinium-225. The isotope is a great candidate for cancer treatments because its radiation zaps only the cells that are very close to its target and lasts a short time, creating a precise therapy that should have limited collateral damage.

Its sources, however, are few.

The isotope is most easily produced from uranium-233 in weapons waste that has decayed for decades. A fraction of that material turns into thorium-229, which can be harvested for the actinium.

TerraPower has a public-private partnership with the U.S. Department of Energy’s Oak Ridge Office to use the recovered thorium for medical applications.

Terra Power Isotopes’ supply of thorium-229 sounds tiny — an amount equivalent to the weight of 17 U.S. pennies. But with the process developed by the company, it should be able to produce enough actinium-225 to use in up to 400,000 doses of cancer therapies every year, for many years to come.

“We’re really excited that we’ve reached this scale,” Claunch told GeekWire.

The DOE is also producing actinium-225 for medical purposes, but in more limited supplies. There is a company in Germany using thorium to extract the isotope, and Russia could potentially do so as well, Claunch said. Other ventures are seeking alternate methods for producing actinium isotopes starting from different elements.

Scientists almost a decade ago did initial tests showing that actinium-225 containing therapies could treat prostate cancer that resisted other solutions.

The strategy is part of a broader field of cancer care using antibodies that recognize cancerous cells and bind to them while carrying isotopes or chemical poisons that destroy the diseased cell. Actinium-225 can be that isotope, creating a radiopharmaceutical that kills the target cells.

Actinium-225 could be applied to therapies for all of the solid tumor cancers, including breast, colon, liver and other cancers.

“The demand for [actinium-225] is growing daily with researchers, physicians, and patients around the world waiting for shipments of the radionuclide,” states a DOE website on the isotope.

In January, TerraPower Isotopes began shipping samples of its product to two pharmaceutical companies. It is now serving more than 10 customers on a weekly basis.

There are fewer than 20 drug developers in this space, including big names in pharma such as Novartis, Janssen, AstraZeneca and Eli Lilly, as well as startups including Alpha-9 Oncology, Aktis Oncology and Abdera Therapeutics.

Claunch declined to say which are among its customers.

None of the actinium-225 cancer therapies are approved for clinical use by the U.S. Food and Drug Administration, but they are being tested in Phase 1, Phase 2 and Phase 3 trials.

In the meantime, work continues with parent-company TerraPower’s efforts to build a small modular nuclear reactor in Wyoming. TerraPower launched in 2006 with support from Microsoft co-founder Gates and others. As the company was working on its next-gen nuclear power plant, a few of its researchers became interested in actinium-225 and realized their expertise could help in producing it. That led to the creation of the subsidiary.

The progress on actinium has been cause for celebration.

“We haven’t made our first electron yet in reactors. That’ll happen in 2030,” said Chris Levesque, CEO and president of TerraPower.

“But when our actinium was used in human trials for the first time, that was the beginning of realizing the mission to innovate in nuclear science and have an impact,” he added. “So it was really an emotional event for us.”