Genentech halts Avastin ovarian cancer trial (Reuters)

NEW YORK (Reuters) - Genentech Inc. halted a mid-stage test to determine if its colon cancer drug Avastin could treat ovarian cancer after 11 percent of patients developed dangerous holes in their stomach and intestines, the company said on Friday.

"Enrollment was discontinued following reports of five gastrointestinal perforations observed in the first 44 patients enrolled in the proposed 53-patient study," said Genentech, whose shares fell as much as 4.2 percent.

Perforations are potentially fatal holes that develop in the walls of the stomach or in the small or large intestine, thereby allowing leakage of waste into the abdomen.

The trial involved patients with ovarian cancer whose tumors had spread to other parts of the body, and who had all previously failed to benefit from at least three rounds of chemotherapy, Genentech said.

"This news means very little" for Avastin, said SG Cowen analyst Eric Schmidt. He said the drug still has potential to garner peak annual sales of $5 billion for various types of cancer, including less-advanced ovarian cancer.

Annual sales for very seriously ill patients like those in the halted trial would only have amounted "to several hundred million dollars," he said.

The company said gastrointestinal perforations are already a known side effect of the drug, but that the rate of their occurrence in the Phase II study was higher than that seen in other trials of Avastin in ovarian cancer and other types of cancer.

"Our hypothesis is that these patients with more-advanced ovarian cancer developed a higher incidence of perforations because their tumors tend to move to the bowel," thereby weakening it, Genentech spokesman Neil Cohen told Reuters.

Cohen said perforations were not a major problem in two other Phase II ovarian cancer trials that have been completed, each of which involved 62 patients whose tumors were not so advanced.

In one of those trials, no perforations were seen. In the other trial, two perforations were seen.

Moreover, tumors shrank in 20 percent of patients taking Avastin in the earlier trials, and the disease stabilized in 60 percent of patients in one of the studies.

Given the favorable findings seen in those and other ovarian cancer trials, Genentech said it plans to press on with trials among patients with earlier-stage ovarian cancer, including a larger Phase III trial of patients who have never previously undergone chemotherapy. It also plans to continue testing the drug in other types of tumors.

Genentech developed Avastin with Swiss drugmaaker Roche Holding AG, which owns a majority of its shares. The drug, approved for colorectal cancer early last year with great fanfare, had second-quarter U.S. sales of $246 million.

Asked if Friday's Avastin setback would affect Roche's internal sales expectations for the company's fastest-growing medicine, Roche official Peter Wenner said: "No, definitely not."

Genentech next year plans to also seek approval of the drug for breast and lung cancer, based on successful completed trials.

The injectable drug prevents creation of blood vessels that feed tumors by blocking a protein called Vascular Endothelial Growth Factor. Genentech has said Avastin has the potential to have annual sales of up to $1.6 billion for treatment of colon cancer alone.

Genentech was down $2.91, or 3.31 percent, to $85.09, in afternoon trading on the Nasdaq, after having touched as low as $84.25. Shares of Roche closed down 1.3 percent in Switzerland.