Actinium-225: A breakthrough in cancer treatment
Scientists at CNL are working hard on the development of advanced life-saving treatments that harness the power of nuclear science and radioisotopes to achieve unprecedented levels of precision in beating cancer. This work includes the production of a promising new weapon in the fight against cancer—Actinium-225—a radioisotope so rare that the annual global production is less than a grain of sand.
Cancer can be treated by exposing the cancerous cells to radiation (alpha, beta or gamma). Gamma radiation travels through most materials, beta radiation through fewer, and alpha radiation through very little. In the context of TAT, it means that if alpha radiation can be delivered directly to the cancer cells, it will kill the cancerous cells without also damaging close-by healthy tissue. It sounds simple enough, but the challenge lies in getting an alpha-emitting substance very close to (or inside) the cancerous cells without it also going to other parts of the body.
The field of targeted alpha therapy research aims to solve this problem.
There are only a few alpha-emitting radioactive isotopes that have suitable half-lives and decay properties to be used in the human body for medical applications. (Half-life is the amount of time it takes for 50 per cent of the radioactive particles to decay by emitting some combination of alpha, beta and gamma radiation). For the purposes of medical treatment, a shorter half-life is generally better. CNL works with the isotope Actinium 225 which has a half-life of 10 days. This is long enough for researchers to incorporate it into a radiopharmaceutical which has time to circulate in the body, collect in target areas and emit high energy alpha particles to cells immediately surrounding it, but short enough that it decays to stable products without adverse dose consequences.
Actinium-225: The rarest drug
One of the challenges in conducting clinical trials or even basic research in targeted alpha therapy is the limited availability of the isotopes, in particular, actinium-225. There are only a few locations globally with thorium generators to produce this material in research-scale quantities. CNL’s Chalk River Laboratories is one of them.
Through our generators, we are able to make a significant amount of pure actinium-225 which we use in our research and share with other collaborators across Canada and around the world.
Targeting cancer cells
In targeted alpha therapies, the Actinium 225 isotope is attached to a targeting molecule, like an antibody, which then locks on a specific antigen on the cancer cell. When the isotope decays, it emits high-energy alpha particles that kill the cancer cell by causing irreparable damage, like shattering its DNA. The healthy cells nearby are unharmed by this process.
Research capabilities
In addition to radioisotope production, CNL also maintains the capabilities to conduct biological research to explore the possibilities of TAT. Our first TAT pre-clinical (in vivo) research study was initiated in the Biological Research Facility (BRF) to examine the targeting efficiency and anti-tumour efficacy of specific actinium-225 labelled targeting vectors on human breast cancer cells.
Experienced and Capable
CNL’s Biological Research Facility (BRF) is a unique facility which holds the necessary capabilities to conduct TAT-related research. The BRF is currently pursuing Good Laboratory Practice (GLP) recognition, has ISO 9001 certification, Good Animal Practice (GAP) certification from the Canadian Council on Animal Care (CCAC) and is staffed by a team with significant experience in radiobiology and radiochemistry.
CNL has made extensive contributions in supply, pre-clinical research, shipping and logistics, and waste management for previous radioisotopes as they made their way to market. We are excited to apply these strengths and experience to the field of targeted alpha therapy.