Scientists a step closer to tailored cancer therapy

Response to new drug suggests breakthrough

April 30, 2004|By Thomas H. Maugh II | Thomas H. Maugh II,LOS ANGELES TIMES

Researchers stepped closer toward the long-sought goal of tailoring cancer therapy to individuals, identifying a genetic defect that predicts response to a new drug called Iressa.

Two studies reported today indicate that about 15 percent of the 170,000 Americans who develop lung cancer each year have a specific genetic mutation that correlates with a potent, life-prolonging response to Iressa.

Those without the mutation receive no benefit from the drug and can be spared the $2,000 to $3,000 per month cost of treatment.

"This is something very exciting that we have long hoped for, that we would have a way of predicting who would respond to a therapy and who would not," said Dr. Ronald Blum, director of the Cancer Center at Beth Israel Hospital in New York City.

For every 100 patients being treated with Iressa, only 10 are receiving a benefit, he said. "This way, you would benefit all that you treat," he added.

"This will be very important for physicians considering giving Iressa to patients in the future," predicted Dr. Harmon Eyre, chief medical officer of the American Cancer Society. After the tumor is initially removed from the lung, he said, its "gene mutation profile can be assessed, and the potential for Iressa to be effective can be evaluated."

Therapy could also be started much earlier in the course of the disease, which would improve survival and quality of life, Blum said. Iressa is approved only for use after two other chemotherapy agents have failed.

Experts cautioned that there is not a simple test available to determine if the mutation is present, but researchers are racing to develop one, and it should be available within a year.

Similar mutations are also present in some patients with other cancers, including head and neck cancer and a brain tumor called glioblastoma. Researchers are trying to learn whether the drugs will work in those patients as well.

The findings might change the way clinical trials of cancer drugs are conducted, Eyre said. By using genetic markers to identify patients who are most likely to benefit from new drugs, clinical trials could be conducted with fewer patients and new drugs could reach the market more quickly, he said.

The Los Angeles Times is a Tribune Publishing newspaper.

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