Feb. 1, 2011 -- Patients treated with Avastin, a top-selling cancer medication, appear to have a 50% increased risk of dying from treatment-related adverse events compared to the use of chemotherapy alone, a new research review finds.
What’s more, the risk of fatal problems like bleeding, blood clots, and bowel perforations may more than triple when the biologic therapy Avastin is used with certain kinds of chemotherapy drugs, particularly taxanes or platinum medications.
But Avastin’s manufacturer found fault with the study. Genentech, the maker of Avastin, says the study includes data in which Avastin was a treatment for types of cancer that are not on the FDA-approved list of uses for Avastin.
The review, which will be published in the Feb. 2 issue of the Journal of the American Medical Association, pools the results of 16 studies of 5,589 patients who were taking Avastin for solid tumors of the colon, lung, breast, prostate, kidney, or pancreas.
Overall, patients who took Avastin, which is an antibody that is given by intravenous infusion, had about 50% more fatal adverse events compared to those on chemotherapy alone.
About 2.5% of people who took Avastin died from drug-related adverse events compared to 1.7% on standard chemotherapy.
Those differences got larger, however, when Avastin was combined with certain kinds of chemotherapy medications, including taxanes and platinum agents. About 3.3% of people on these combined treatments experienced fatal events.
“It has an impact on how much people may use this drug, I think,” says study researcher Shenhong Wu, MD, PhD, an oncologist and assistant professor at the Stony Brook University School of Medicine in New York. “We used to think this drug was not very toxic, but I think now we understand more.”
Other experts disagree. "I'm not sure the risks with this drug are any different than any of the other cancer drugs," says Scott Kopetz, MD, who treats gastrointestinal cancers at the University of Texas M.D. Anderson Cancer Center in Houston.
In the case of stage IV colon cancer, "These are patients that have an average life expectancy due to their cancer of two years. These patients are living longer, by several months on [Avastin]," says Kopetz, who was not involved in the study.
"For patients with metastatic disease, we can shrink tumors and, in some cases, delay the growth of the cancer,” he says. “We can't cure it, but we can delay the progression of the disease."
Genentech takes issue with some of the study’s methods.
Particularly, the fact that the analysis includes results from trials of the drug in three advanced cancer types, including prostate, pancreatic, and squamous cell lung cancer, for which it is not FDA approved and “should not be used,” according to a statement.