Killing cancer cells with alpha particles could be the next frontier in treatment

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Canadian cancer researchers are part of global efforts to test targeted alpha therapy, a new form of treatment that some oncologists believe will become the next frontier in attacking cancer at the cellular level.

Targeted alpha therapy shreds the DNA of cancer cells by using radioactive alpha particles, which researchers say are more powerful at killing cancerous tumours than comparable existing treatments and less damaging to healthy tissue.

While no targeted alpha therapy has been approved for use outside a clinical trial, several are in the final stages of testing and could be ready for consideration by Health Canada and international regulators within the next few years.

Researchers see its potential in treating pancreatic, prostate and breast cancer, as well as the rarer neuroendocrine cancer, which affects the cells that regulate hormone production throughout the body.

Targeted alpha therapy "is another line of treatment that adds more hope for cancer patients," said Dr. François Bénard, a professor in the department of radiology at the University of British Columbia in Vancouver and a distinguished scientist at the B.C. Cancer Research Institute.

"It can prolong life, reduce symptoms, improve the well-being of people who are affected by cancers," said Bénard in an interview.  

Targeted alpha therapy falls within the same general category of the cutting-edge cancer treatment known as radioligand therapy, in which specially designed molecules that bond only to cancer cells are injected into the body and release radioactive particles that kill the tumours. 

The approved treatments in this category use isotopes that emit beta particles. What makes targeted alpha therapy a potential advance is that alpha particles emit more powerful radiation over a shorter range.

Bénard likens the existing radiopharmaceutical treatments that emit beta particles to throwing golf balls inside a glass house: they can travel quite a distance and cause various bits of damage along the way. 

In contrast, says Bénard, targeted alpha therapy "is like throwing a bowling ball. So it will cause a lot more damage, but in a much more limited area." 

Dr. Gerald Batist, director of the Segal Cancer Centre at Montreal's Jewish General Hospital, is participating in several clinical trials on treating various cancers with targeted alpha therapy. 

"The dimensions of their potential impact are just now being explored," said Batist in an interview.

One of Batist's clinical trials is testing a method of treating prostate cancer by embedding beads laden with alpha particles at the site of pancreatic cancer.