The U.S. Food and Drug Administration has granted accelerated approval for Roche Holding's Avastin drug for the most aggressive form of brain cancer, Roche said on Wednesday.

The approval comes after a U.S. advisory panel said in March that early data for Avastin showed enough promise to be considered for quick approval for patients with an especially aggressive tumor, glioblastoma multiforme.

Avastin, Roche's most important drug that is made by its recently acquired Genentech unit, is already used to treat lung, colon and breast cancers, and annual global sales have soared to $4.61 billion.

The U.S. panel said in March data from two early studies showed enough of a response in patients whose disease did not advance and some whose tumors decreased in size to warrant faster approval before the company finishes a larger trial.

Glioblastoma has seen renewed public attention since U.S. Senator Edward Kennedy was diagnosed with the malignant tumor last year. It is one of the deadliest types of cancer, with patients surviving six to 12 months after diagnosis on average, or six months without treatment.

About 10,000 patients are diagnosed with the disease each year in the United States, Roche said.

Given a treatment price of about $50,000 per patient per year, ZKB analysts said in a note the approval could yield additional revenue of $500 million for Roche.

Last month, Roche shares fell sharply when Avastin failed in a major study to prevent the recurrence of colon cancer in patients who have undergone surgery.

Analysts had estimated that Avastin sales could more than double if the drug was found to delay progression in early-stage colon cancer.

Despite the setback, Roche said Avastin could still sell 8 billion to 9 billion francs by 2011 treating advanced cancers.

ZKB analysts noted that studies on Avastin in ovarian and prostate cancer were still expected this year and predicted sales growth of 30-40 percent despite the failed colon cancer study.