Comparative dosing of bevacizumab for radiation necrosis: impact of tumor type on edema response.

PURPOSE: Bevacizumab is an effective treatment for radiation necrosis; however, dose -dependent radiographic and edema response data are lacking.

METHODS

Multicenter, retrospective cohort study of adult patients with primary central nervous system (CNS) tumors or brain metastases who received bevacizumab for radiation necrosis between June 2021 and July 2024. Patients were grouped by bevacizumab dose (7.5 mg/kg vs. 10 mg/kg administered every three weeks). Primary outcome was edema response, assessed by a blinded neuro-oncologist. Secondary outcomes included contrast enhancing disease response, clinical response, adverse events, treatment discontinuation, and re-dosing for recurrent radiation necrosis. Analyses were performed with and without adjustment for tumor type.

RESULTS

104 patients were included (7.5 mg/kg, n = 53; 10 mg/kg, n = 51). Tumor type differed significantly between cohorts (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 cohort; however, this association was attenuated after adjustment for tumor type. Contrast enhancing disease response did not differ between groups in either unadjusted or adjusted analyses (p = 0.43). Clinical response was higher in the 7.5 mg/kg group (65.2% vs. 37.8%, p = 0.013). Rates of adverse events, treatment discontinuation, and re-dosing were similar.

CONCLUSIONS

Taken together, both 7.5 mg/kg and 10 mg/kg dosing strategies achieved similar radiographic outcomes. Prospective, tumor-stratified studies incorporating edema-focused and patient-centered endpoints are needed to better define optimal dosing strategies in this heterogeneous population. These findings support an individualized approach to bevacizumab dosing in radiation necrosis and highlight the need for prospective, tumor-stratified studies.