We’ve been told stem cells are supposed to be good: the Holy Grail for cures to cancer and any number of menacing diseases. Now scientists are learning that some stem cells actually give rise to cancer.
For leukemia patients, these cells can mean the difference between remission and relapse.
Fortunately, researchers such as Ravi Bhatia, M.D., director of City of Hope’s Department of Hematopoietic Stem Cell and Leukemia Research
, are working hard to eliminate this threat.
When Bhatia first started out as a hematologic oncologist — a blood cancer specialist — in the late 1980s, researchers already suspected leukemia stem cells were important, even if they didn’t know much about them yet.
“We didn’t call them stem cells, but we understood what they were,” Bhatia said. These stem cells are present in the marrow of leukemia patients; and just as healthy stem cells are “parents” to the various types of normal tissue cells in our bodies, cancer stem cells develop into mature malignant cells.
If treatment doesn’t eliminate these stem cells, the disease can, and often does, return.
These sleeping, early cancer cells bide their time until therapy subsides and they can emerge and develop into cancer once again. This can frustrate a physician-researcher who is doing all he can to rid his patients of the disease.
is a good example of this phenomenon. Although very effective in controlling chronic myelogenous leukemia, Gleevec and similar drugs only target mature leukemia cells, leaving the stem cells unaffected. Patients remain disease-free as long as they continue to take the drug. If they stop the drug, or if they develop resistance to it, the cancer invariably returns.
It’s this type of challenge that drives Bhatia. He is delving into the characteristics of leukemia stem cells — how they develop into cancer and how they survive therapy — to uncover targets for novel drugs and treatments. If he can eliminate the leukemia stem cells, patients will be free of the disease — for good.
The work reinforces why Bhatia got into leukemia research in the first place. “I recognized the need for improvements in treatments, and also that there was much opportunity in this field,” he said. “When we, as physicians, see survivors leading a healthy life many years after their therapy, we want to extend that experience to as many patients as possible.”