Bevacizumab Treatment in Glioblastoma Patients is Associated with an Increased Development of Secondary Gliosarcoma

Keywords: glioblastoma multiforme, Imaging, brain tumor, gliosarcoma, bevacizumab

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     Glioblastoma multiforme (GBM) is the most common primary malignant brain tumor with an overall survival around 14 months. Bevacizumab is an anti-angiogenic medication approved by the FDA for treatment of recurrent GBM. Gliosarcomas are a subset of GBM that may arise due to vascular changes imparted by malignant glial cells.
     In this novel study, we compared the overall rate of gliosarcomas in patients who received bevacizumab versus standard GBM therapy.
     351 patients met our inclusion criteria. The average age of the patients at primary resection was 51 years old (range: 5-80).
     A retrospective review of patients from 1995-2011 were analyzed with confirmed diagnosis of recurrent GBM and/or gliosarcoma treated at UCLA. Patient data, chemotherapy treatment regimens, and clinical follow up were aggregated. Inclusion criteria were: 1) GBM as the primary diagnosis, 2) confirmed histopathology reports, 3) repeat surgery for follow-up histopathology. Fisher exact test with non-Gaussian distribution was used for statistical analysis.
     A significantly greater number of GBM patients receiving bevacizumab developed gliosarcoma (15%) vs. the no bevacizumab group (1%, p<0.0001). In this subset, the average time (AT) on bevacizumab for those developing gliosarcoma was 3.7 months versus 6.4 months. This difference in AT was not statistically significant (p=0.2557).
     This is a retrospective study.
     Our results suggest that bevacizumab is correlated with an increased incidence of secondary gliosarcoma in GBM patients versus those who did not receive bevacizumab.
     This increase in gliosarcoma for bevacizumab GBM patients may suggest that bevacizumab plays an important role in the pathogenesis of secondary gliosarcoma.


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