Bevacizumab May Increase Blood Clot Risk
"Bevacizumab (Avastin), the first FDA-approved drug designed to inhibit the growth of new blood vessels to tumors, significantly increases the risk of venous thromboembolism (VTE) in cancer patients, according to a meta-analysis in the November 19 Journal of the American Medical Association.
Pooled results from nearly 8,000 patients with a variety of advanced solid tumors in 15 randomized trials published since 2003 showed that patients taking bevacizumab were
33 percent more likely to develop VTE than those who did not. Incidence among those taking bevacizumab was 11.9 percent for VTE of all grades, and 6.3 percent for high-grade VTE. Those taking the drug had a 38 percent greater risk of developing high-grade VTE.
A dosage as small as 2.5 mg/kg per week was enough to pose a risk, which the authors believe "suggests that the so-called low dose of bevacizumab may already be reaching the saturation level to induce thrombosis." Based on the greater risk found in patients with mesothelioma and aerodigestive malignancies such as non-small cell lung cancer, the authors advised that patients with these conditions receive concurrent prevention for VTE."It may be appropriate to add a black box warning [to the package insert currently required by the FDA]," noted the study authors, led by Dr. Shobha Rani Nalluri and colleagues at Stony Brook University. Other angiogenesis inhibitors such as thalidomide and lenalidomide have also been shown to increase risk of VTE, and the authors warned that combining them with bevacizumab could compound the increased risk."
Avastin is not yet approved by the FDA for OC, but it is in use in a number of clinical trials.