Nine months after the FDA approved Genentech’s cancer-fighter Avastin for advanced breast cancer, scientists reported that it increases the risk of venous thromboembolism (VTE), a potentially serious side-effect.
Shobha Nalluri and her group at Stony Brook University combined results from 15 randomized controlled trials of 7,956 patients that were treated for advanced solid tumors. Overall, 7.3% of the patients developed VTE, and those treated with Avastin had a 33% higher risk.
Last year, an FDA advisory panel voted 5-4 against approving Avastin for advanced breast cancer because the drug’s beneficial effects in slowing disease progression did not, in its opinion, outweigh its potential for causing cardiovascular complications and VTE. Approval was granted anyway.
The FDA had approved Avastin for colon and lung cancer in 2004. The drug works by choking off the blood supply to a tumor rather than killing tumor cells directly. Scientists had hoped Avastin could replace traditional cancer drugs which are debilitating and increase the risk of serious infections, but this has not turned out to be the case. Avastin is typically used in conjunction with old-school cancer fighters.
Annual treatment costs for Avastin can exceed $50,000 per year. Its 2007 sales were $2.3 billion.
Previous studies were too small to detect the adverse effect found in the present study.
Avastin’s label already warns about the risk of VTE, but the Stony Brook scientists suggest in their publication that a tougher, “black box” warning should be affixed.