Multicenter retrospective cohort study of two bevacizumab doses for radiation necrosis

Bevacizumab is an effective treatment for radiation necrosis; however, dose-dependent radiographic and edema response data are lacking. A multicenter retrospective cohort study investigated edema response, assessed by a blinded neuro-oncologist, to doses of 7.5 mg/kg or 10 mg/kg every three weeks. A total of 104 patients were included (53 in the 7.5 mg/kg group and 51 in the 10 mg/kg group). Tumor type differed significantly between the groups (p<0.001), with more primary CNS tumors in the 10 mg/kg group. Edema response differed between dosing groups in unadjusted analyses (p=0.032), favoring the 7.5 mg/kg dose; however, this association was attenuated after adjustment for tumor type. Contrast enhancing disease response did not differ between the groups. Clinical response was higher in the 7.5 mg/kg group (65.2% versus 37.8%; p=0.013). Rates of adverse events, treatment discontinuation, and re-dosing were similar. The authors conclude that 7.5 mg/kg and 10 mg/kg dosing strategies achieved similar radiographic outccomes. Prospective, tumor-stratified studies are needed to better define optimal dosing strategies.