Discovery unlocking the secrets of leukemia

The discovery of different types of leukemia stem cells by a Canadian Cancer Society researcher may unlock the secrets of why this blood-borne cancer can recur so often in patients after treatment.

The study, led by Dr John Dick of Toronto’s University Health Network, is an important advancement in understanding how leukemia develops and points to the need for new cancer therapies that target these stem cells as well as the regular leukemia cells.

“For the first time, we know where we should be focusing our research in order to end this deadly cancer,” says Dr Dick. “We’ve painted a target on these specific cancer stem cells, and now we need to know how best to eradicate them.”

Dr Dick’s study is published in the July 2004 issue of Nature Immunology.

Like ordinary blood stem cells, the leukemia stem cells are very rare and act as the originator of all the other leukemia cells that develop and end up killing more than 2,000 Canadians every year. The researchers discovered that there are several types of leukemia stem cells – some fast acting, and others that may lay dormant for long periods of time before bursting into activity.

This research may explain why there is such a high rate of recurrence, typically between 60-90%, in cases of acute myeloid leukemia (the specific type involved in this study). The high recurrence may be due to the fact that chemotherapy treatments are designed to target leukemia cells that are dividing – potentially missing dormant leukemia stem cells that created the disease in the first place.

This discovery builds on the Dr Dick’s pioneering method of studying human stem cells by transplanting them into immunodeficient mice which will not reject the human cells. The findings may also predict that similar cancer stem cells will be found for solid tumors such as breast cancer, he says.

Dr Dick has received more than $2 million in funding for cancer research from the Canadian Cancer Society over the last 15 years. In 2003, he discovered a new class of stem cells that could reduce the time it takes to rebuild cancer patients’ depleted blood systems following chemotherapy and radiation treatment.

Last modified on: 07 February 2012