SAN ANTONIO — Cancer drugs and radiation target and kill fast-growing cancer cells. But a small number of noncancer cells in the tumor often survive. These, researchers believe, are "mother" cells — stem cells that eventually manufacture more cancer cells.
Houston researchers are examining the vulnerability of these mother cells, and in early studies have an experimental drug that seems to stop them in breast cancers.
"Cancer stem cells are present, we believe, in all cancers," said Dr. Jenny Chang, medical director of the breast center at Baylor College of Medicine. "So that 1 to 5 percent of the cancer contains cancer stem cells. And while chemotherapy kills 99 to 95 percent of the tumor, what's left behind is the 5 percent of cancer stem cells. Those will then regrow and regenerate."
Chang spoke Friday at the San Antonio Breast Cancer Symposium.
Chang first identified a vulnerable target on the breast stem cells called the Notch receptor and used an experimental drug, gamma-secretase inhibitor, along with a common anticancer drug, docetaxel — first on mice grafted with human tumors, and later in a few women with advanced breast cancer.
In one dramatic set of photos, Chang showed an inoperable egg-sized mass on one patient's breast that eventually shrank to the point where surgery was possible.
But it can be a slow process, which makes proving the effectiveness of these types of anti-stem-cell drugs challenging, researchers said.