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Venous thromboembolic complications in patients with malignant glioma treated on a bevacizumab clinical trial.

9090 Background: Although the prognosis for malignant glioma remains poor, the introduction of bevacizumab has improved survival for patients with this devastating illness. Bevacizumab is a humanized monoclonal antibody to vascular endothelial growth factor (VEGF). Patients with malignant gliomas are felt to have an incidence of thromboembolism in 20-30%. As patients with malignant gliomas are at increased risk for venous thrombosis by nature of their diagnosis, one worries about potentially increasing this risk with the addition of bevacizumab. Previous reports have shown an incidence of approximately 25% of venous thromboembolic disease in cancer patients receiving concurrent chemotherapy and bevacizumab.


METHODS
We performed a retrospective analysis of all clinical trial participants receiving bevacizumab for malignant glioma from April 2005 to January 2011. 617 patients with malignant glioma were included: 529 with glioblastoma (GBM) and 88 with anaplastic glioma (AG). Of those, 204 patients were newly diagnosed. This group was treated with standard temozolomide and radiation, combined with bevacizumab and a topoisomerase I inhibitor. 413 patients with recurrent tumors were included. Their treatment regimens varied, but all had progressed on standard therapy. After being diagnosed with a venous thromboembolic complication, patients were started on anticoagulation with heparin, low molecular weight heparin, or warfarin. They were followed until death or progression of disease.


RESULTS
The incidence of venous thrombosis was 7% (n=43), and incidence of pulmonary embolism was 2.9% (n=18). Of those, 1.3% (n=8) were patients with anaplastic glioma. Newly diagnosed patients represented only 2.3% (n=14). Of those patients, 0.6% (n=4) had a history of previous venous thrombosis but were no longer on anticoagulation. The mean time on treatment prior to diagnosis of the venous thromboembolic complication was 105.8 days; and a median time of 87 days. Of the patients treated for thromboembolic disease, 0.5% (n=3) had intracranial hemorrhage.


CONCLUSIONS
Use of bevacizumab does not increase the risk of venous thromboembolic complications in patients with malignant gliomas.