Drug extends lung cancer patients' survival

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http://www.usatoday.com/news/health/200 ... drug_x.htm

Posted 7/13/2005 10:04 PM

Drug extends lung cancer patients' survival

By Liz Szabo, USA TODAY

A study in Thursday's New England Journal of Medicine shows that the drug Tarceva helps lung cancer patients live longer. Experts say they don't yet completely understand how the drug works, however, and doctors disagree about the best way to predict which patients it will benefit most.

Researchers announced the discovery last year of genetic mutations, found in about 10% of patients, that make these people more likely to respond to Tarceva and a similar drug, Iressa. In these patients, tumors shrunk by about half. Doctors quickly developed tests to predict the patients for whom Tarceva and Iressa would work best.

The new study suggests that the tests are of little use.

In an international study of 731 patients led by the National Cancer Institute of Canada, researchers found that genetic mutations don't help them predict which Tarceva patients will survive longer.

Patients were more likely to respond to Tarceva if their tumors contained a certain protein or had lots of copies of a particular gene, says Frances Shepherd, a professor of medicine at Princess Margaret Hospital and a lead author of the article. But a careful analysis showed that these traits didn't improve survival.

The study did confirm that patients most likely to benefit from the drug include women, non-smokers, Asians and those with a type of tumor called adenocarcinoma.

Shepherd says doctors could consider Tarceva for all eligible patients without waiting for results of genetic tests. Tarceva was approved to treat people with advanced non-small-cell lung cancer who already have gone through chemotherapy. Lung cancer kills more than 160,000 Americans every year.

Some cancer experts say the new study has a number of weaknesses. Because taking slices of lung tumors is invasive, the study's authors were able to examine tissue from fewer than half of patients. They analyzed mutations in only about one-quarter, Shepherd says.

Vincent Miller, a lung cancer specialist at New York's Memorial Sloan-Kettering Cancer Center, says that small sample size might have skewed the results. Researchers also may have obtained different results because their study methods differed from those used by other doctors.

Some doctors note that patients' responses to Tarceva could be affected by other genes and proteins, which might not yet have been identified. Roy Herbst, chief of thoracic medical oncology at M.D. Anderson Cancer Center in Houston, says doctors must learn to better target cancer therapy.

Patients have several treatment options and can't afford to waste time on ineffective, expensive drugs, he says. Tarceva costs about $2,300 a month; Iressa costs $1,800 a month. Another drug, Taxotere, costs $2,100 for three weeks.

The study's findings could benefit the companies that make and distribute Tarceva, Herbst says, by helping them maintain a wide market for their drug. Tarceva is distributed by Genentech and made by OSI Pharmaceuticals, which helped pay for the study.

Herbst says that researchers need to perform additional research to shed more light on the debate and that by learning more about how the drugs operate, researchers might be able to create even better therapies.