Targeted Therapy May Fight Leukemia

Study centers on stem cells that trigger cancerous growth

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HealthDay Reporter

WEDNESDAY, Aug. 11, 2004 (HealthDayNews) -- A new discovery on cancer stem cells could eventually lead to better treatment options for people with an often-fatal type of leukemia, scientists say.

At issue is the hard-to-control runaway growth of cancer cells in the blood of people who have chronic myeloid leukemia (CML). A new study suggests that targeting certain cells could stop a cascade of cancerous growth, just like killing a queen bee will devastate a hive by eliminating offspring.

"It opens a second line of investigation that we believe will lead to new therapies, whether they're pharmaceutical or immune-based," said study co-author Dr. Irving Weissman, a professor of cancer biology at Stanford University.

CML, one of four major types of the blood cancer known as leukemia, strikes about 4,400 Americans a year and eventually kills half of them. The cancer disrupts white blood cells, a vital part of the immune system, and the cells eventually lose their ability to fight invaders. In the most serious cases, the ineffective cells overwhelm the circulatory system.

While the new drug called Gleevec helps patients in the early, "smoldering" stages of the disease, doctors are still trying to find ways to effectively treat those in the later, deadly stages, Weissman said.

Weissman and his colleagues have been exploring so-called "stem cells" that normally play a routine role in the creation of blood cells. When leukemia strikes, cancerous stem cells help spread the disease.

In the new study, published in the Aug. 12 issue of the New England Journal of Medicine, the researchers describe their discovery of the stem cells, which have been found in a handful of other types of cancer. Among other things, they discovered that the cancerous stem cells are created when normal cells mutate. They're not, as some had suspected, the product of renegade stem cells.

The next step is to ask drug companies to develop medications that inhibit the genetic process that produces the deadly cancer stem cells, Weissman said. Combined with the use of Gleevec, "then you could think of a one-two punch for treating this disease," he added.

The findings suggest that "it's time to start looking for the cancer stem cell in other cancers and leukemias to see if the same kind of information can be obtained and new targets for therapies developed," he said.

The new research holds promise for future patients with chronic myeloid leukemia, according to Alan Kinniburgh, senior vice president of research at the Leukemia and Lymphoma Society.

"We've further defined how to treat leukemia" by learning which cancerous cells are most dangerous, he said.

More information

The Leukemia and Lymphoma Society has more information on forms of leukemia.

SOURCES: Irving Weissman, M.D., professor of cancer biology, Stanford University, Palo Alto, Calif.; Alan Kinniburgh, Ph.D., senior vice president of research, Leukemia and Lymphoma Society, White Plains, N.Y.; Aug. 12, 2004, New England Journal of Medicine

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