(Agencies)
Updated: 2008-02-23 16:04

Shares of Genentech Inc. rose $5.76, or 8 percent, Friday to $77.36 in after hours trading.

FDA approval for drugs targeted at cancer patients who have never been treated before is usually contingent upon data showing a drug extended, or improved the quality of, patients' lives. Avastin showed neither in a study submitted by Genentech, though the drug did slow tumor growth.

Wall Street analysts believe FDA's Avastin decision opens the door for more cancer drugs to be approved for their tumor-shrinking capabilities — a trend that worries some health experts.

"If FDA sets a precedent of approving a drug based on progression free survival, people are afraid they may stop looking at survival as the most important endpoint," said Dr. Kay Dickersin, director of the Center for Clinical Trials at Johns Hopkins University.

In December, a panel of outside FDA advisers voted 5 to 4 against Genentech's application, indicating the drug's benefits did not outweigh toxic side effects. Nevertheless, US doctors continued prescribing it "off-label," or without a federal endorsement.

Some insurers are reluctant to pay for Avastin's use among breast-cancer patients, which can cost $100,000 for a year's supply.

Dr. Joseph Sparano of Montefiore Medical Center in New York said he prescribes Avastin because it has shown better results at slowing breast cancer growth than any other drug on the market.

The Y-ME National Breast Cancer Organization said the approval gives patients an important new option.

"The benefits we're looking at here matter because they give patients hope," said Margaret C. Kirk, the group's chief executive. "Without disease progression they may survive to see a discovery that can help them." they may survive to see a discovery that can help them."

But the president of the National Breast Cancer Coalition said the decision marked a lowering of standards for FDA. She argued that the drug's effectiveness should not have outweighed safety risks, pointing to six deaths attributed to the drug in the study submitted to FDA.

"All they had was progression-free survival in one trial, no increase in quality of life and patient deaths in the Avastin group," said Fran Visco. "We're very confused why FDA made this decision."

First approved in the US to treat colon cancer in 2004, Avastin was the first drug to fight cancer by blocking nutrients from reaching tumors.

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