While beta-particle treatments are currently used for cancer patients, there is no FDA-approved alpha-particle cancer treatment. An Alpha-particle is a particle composed of two protons and two neutrons, whereas a beta-particle is an electron or a positron. Alpha-particles have low penetration abilities, but their impact is much stronger than that of beta particles. In fact, the impact of alpha-particles is more than 4,000 times stronger than that of beta-particles. It takes thousands of beta-particles to kill a single cell, while a direct hit of just one alpha-particle is sufficient. Alpha-particles can thus be used to specifically target single cancer cells.
Producing alpha-particles is not easy, and the team of UW scientists used the element astatine for this purpose. Astatine is one of the rarest elements on Earth and in this research was created in a UW cyclotron. Since the half life of astatine is short, the alpha-particle treatment must be conducted shortly after the element is generated. After is is generated, the astatine is encapsulated in carbon nanotubes and is then delivered to the cancerous cells.
The specific targeting method uses antibodies to specifically locate cancerous cells and then to binds on to them. The different proteins that every cell expresses on its outer membrane can help other cells or pathogens recognize the specific cell (for instance, recognition of T-cells by HIV was mentioned in a recent TFOT article). A lone cancer cell must express certain proteins in order to leave its original tissue and enter the blood stream. Antibodies are proteins, originally generated by our immune system, which have the ability to bind other specific proteins. In this case, the antibodies bind the proteins surrounding the cancerous cell.
This new method, of combining massive radioactive power and specific targeting of the cancerous cells, has yet to be tested. The researchers, headed by Professor Lon Wilson, are planning an actual test in a follow-up research. If the overall treatment will prove to be effective, the main obstacle will be the astatine’s brief half-life, only 7.5 hours (meaning that every 7.5 hours or so, the element looses half its radioactive power). This research may help create new therapeutic pathways for effectively killing cancer cells and preventing metastases.
