Physics lab targets cancer with ‘rarest drug on Earth’
A small quantity of a radioactive isotope called the “rarest drug on Earth” has been produced by Vancouver-based TRIUMF and an Ontario nuclear science laboratory.
In medicine, radioactive isotopes are often used in imaging, to visualize what’s going on inside the body — in organs, bones, tumours, and blood flow, for example. But the scarce radioactive isotope called actinium-225 has unique properties that scientists believe could eradicate cancer cells.
On Wednesday, the UBC-based TRIUMF, the world’s largest cyclotron particle accelerator, and Canadian Nuclear Laboratories said they have completed their first production run of actinium-225.
When injected into the bloodstream, actinium-225 emits radiation that can kill cancer cells. It can be paired with a cancer-seeking drug so it zeros in on cancer cells, while ignoring healthy tissue.
However, there is so little actinium-225 available that only a handful of patients can be treated in the world each year.
TRIUMF announced its intention to become a world leader in the production of the isotope last year after largely anecdotal reports of cancer-arresting experimental treatments using actinium-225 — mostly in Germany — on patients with metastatic cancer.
“This accomplishment is a major milestone in making high-purity actinium-225, which is produced using TRIUMF’s high-energy cyclotron in Vancouver and processed at CNL’s Chalk River Laboratories in Ontario,” TRIUMF said in a statement.
Sean Lee, a spokesman for TRIUMF, said the first production run is “tangible” proof of the concept that demonstrates the feasibility and the next steps to take.
“Now, we have to refine the technology, increase capacity, and address technical challenges,” he said adding that it could be five to 10 years before the material is used on patients.
Small amounts of actinium-225 have been derived from American radioactive waste.
But a more sustainable, cleaner source — not reliant on nuclear weapon waste — is imperative if the substance is to become a medical tool.
Paul Schaffer, associate lab director at TRIUMF, said they’re deriving actinium-225 from thorium-232, a metallic chemical that can be mined around the world.
“While actinium-225 may be extracted as a natural decay product from thorium-229, derived from stocks of aging nuclear weapons material and spent nuclear fuel, TRIUMF intends to continue producing actinium-225 by irradiating a different isotope, thorium-232.
“Thorium-232 is a natural resource that can be mined, alongside uranium and other rare earth metals, at various sites across the world. Thorium-232 is mined and processed into targets, which can then be irradiated to produce actinium-225.”
The product is then shipped on special trucks to Ontario, where it goes through various chemical refining processes.
“With a short half-life of just 10 days, the actinium decays without accumulating in a patient’s body,” the TRIUMF statement said.
“This form of treatment has shown exciting potential in early studies with prostate cancer patients for whom conventional cancer therapies have not worked. Researchers are eager to try this targeted alpha therapy approach with a wide range of cancers.”
Jonathan Bagger, the director of TRIUMF, said its cyclotron is capable of producing actinium-225 “at a level of purity not possible with smaller cyclotrons.”
Mark Lesinski, CEO of CNL, said the collaboration may eventually enable “hundreds of thousands of medical treatments every year across Canada and around the world.
“This achievement is a major leap forward in the availability of one of the rarest medical isotopes in the world.”