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Cancer 'Wonder Drug' Still Shows Promise

But some patients become resistant to Gleevec

TUESDAY, Dec. 11, 2001 (HealthDayNews) -- Researchers are learning more about the leukemia wonder drug with the funny name, and their findings confirm that Gleevec can be a godsend for blood cancer patients. But it won't work for everyone.

A small number of patients become resistant to the drug one year after starting to take it daily, says a new study. The research suggests that Gleevec may have to be combined with other medications to do the most good, says Alan Kinniburgh, vice president of research for the Leukemia and Lymphoma Society.

Even considering that limitation, he says, "I would guess that Gleevec is going to be highly effective for the majority of patients for several years."

Scientists released the results of two new Gleevec research projects at the annual meeting of the American Society of Hematology, whose members work with blood disorders. The conference in Orlando, Fla., ends today.

Federal officials approved Gleevec last May after a quick review.

Gleevec treats chronic myeloid leukemia (CML) one of four major types of the blood cancer known as leukemia. CML, which causes unnaturally rapid growth of white blood cells, strikes about 4,400 Americans a year and eventually kills half of them.

The white blood cells, part of the immune system, eventually lose their ability to fight invaders. In the most serious cases, the crowd of ineffective cells overwhelms the circulatory system.

"The blood fills up with cells that don't function, clogging the arteries," Kinniburgh says. Death often follows, even before infections get a chance to take advantage of the weakened immune system.

Unlike chemotherapy drugs like interferon, which target both healthy and cancerous cells, Gleevec appears to stop growth only in the deadly cells. Because it doesn't poison the body, the number of side effects is low. With conventional chemotherapy, side effects can range from flu-like symptoms to mood changes that can include suicidal thoughts.

In one study released at the conference, Texas researchers looked at more than 500 patients, each treated with 400 milligrams of Gleevec per day. All had chronic cases of CML and didn't respond to interferon.

Blood counts returned to normal in 90 percent of the patients; in 85 percent of patients the drug either vanquished or largely eliminated cancerous cells in the bone marrow, where blood is created.

On the negative side, after one year, 10 percent of the patients in the M.D. Anderson Cancer Center study became resistant to Gleevec, and 3 percent of these died.

By contrast, however, 15 percent to 20 percent of CML patients who don't respond to interferon typically die within a year, according to the American Society of Hematology.

The second study involved 50 CML patients who became resistant to Gleevec. After taking only that drug, they wound up with certain mutations in their genes that weren't present before. The findings suggest that combining the drug with other medications may be helpful.

So-called combination therapy "will delay the time until resistance occurs," says Dr. Andreas Hochhaus of Germany's University of Heidelberg, who presented the study findings. "It's the same as with antibiotics and [treatments for] HIV. The combinations will overcome resistance."

The germs that cause viral diseases such as AIDS and many bacterial infections can mutate into new forms that resist medication. Some experts fear the rise of "superbugs" that will be resistant to many drugs.

Doctors have learned to combat some of these illnesses by giving a variety of drugs to patients, so that if one doesn't work, the others will pick up the slack.

Gleevec is made by Novartis Pharmaceuticals Corporation, which is based in East Hanover, N.J.

What To Do

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

Curious about Gleevec? Novartis provides an extensive site on the drug.

SOURCES: Interviews with Alan Kinniburgh, Ph.D., vice president of research, Leukemia and Lymphoma Society, White Plains, N.Y.; Andreas Hochhaus, M.D., University of Heidelberg, Germany; Dec. 7, 2001, presentation at the 43rd Annual Meeting of the American Society of Hematology, Orlando, Fla.
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