Ilhami Kovanlikaya
Glioblastoma (GBM) is the most common aggressive primary brain tumor. Despite an aggressive multimodal treatment approach that includes surgical resection and chemoradiation, median survival is limited to approximately 14 months.1
Until recently, there was no standard treatment for recurrent disease after combined chemotherapy and radiation treatment. Between 1998 and 2014, there were 78 investigational brain tumor drugs that entered the clinical trial evaluation process and, unfortunately, 75 of them failed. That is a 25:1 failure ratio in developing new brain tumor treatments over the past 2 decades.2 One of these FDA-approved drugs was bevacizumab (BV), a monoclonal antibody (immunoglobulin G) to vascular endothelial growth factor, which has been used with safety and some clinical success in recurrent GBM. Despite the limited success with IV usage of BV, all patients progress and require salvage therapy.3
Our group has initiated a trial using superselective intra-arterial cerebral infusion (SIACI), a novel delivery technique of bevacizumab that may provide a more targeted treatment strategy.4 While treatment with bevacizumab produces dramatic decreases in contrast enhancement on MR imaging, the degree to which this imaging finding reflects an actual tumoricidal effect remains unclear. The inability of routine contrast-enhanced MR imaging to differentiate between response, progression, and/or treatment effects has led us to use MR perfusion (MRP) and other advanced molecular techniques in this trial.
In our study, by using DSC MRP, we sought to determine exactly how effective intra-arterial bevacizumab was in treating patients with recurrent GBM and whether it had tumoricidal effects. We found that there was a significant decrease in tumor perfusion metrics such as CBV and CBF within recurrent gliomas in response to SIACI of BV.
The results of our study have changed our practice here at Weill Cornell Medicine, and MRP sequences were added to our standard brain tumor imaging protocol specifically to assess the response to treatment.