Barreto, Jasón

Abstract Purpose Bevacizumab is an effective treatment for radiation necrosis; dose dependent radiographic and edema response data are lacking. Methods Multicenter, retrospective cohort study of adult patients with primary central nervous system 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). 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). Tumor type differed significantly between cohorts (p < 0.001), with more primary CNS tumors in the 10 mg/kg group. Rates of adverse events, treatment discontinuation, and re-dosing were similar. Conclusions While lower-dose bevacizumab was associated with greater edema reduction in unadjusted analyses, this effect was attenuated after accounting for tumor type. Importantly, 7.5 mg/kg dosing appeared sufficient for achieving edema control and contrast enhancing disease response. These findings support an individualized approach to bevacizumab dosing in radiation necrosis and highlight the need for prospective, tumor-stratified studies.

Abstract Background Bevacizumab is a treatment for radiation necrosis; the optimal dosing remains inadequately studied. Methods Retrospective review of adult patients with primary central nervous system (CNS) tumors or brain metastasis treated with bevacizumab for radiation necrosis from 6/29/2021 to 7/31/2024. Primary outcome was to compare edema response with two different bevacizumab doses: 7.5 mg/kg and 10 mg/kg. Edema response was classified according to the following groups: (1) increase of edema, &gt;105% of baseline; (2) constant edema, 75%-105% of baseline; (3) slight decrease of edema, 25%-75% of baseline; (4) large decrease of edema, &lt;25% of baseline. Results 104 patients were evaluated (median age 59 years, 56% male); 53 patients in the 7.5 mg/kg group and 51 patients in the 10 mg/kg group. Tumor type varied significantly across dosing groups (p &lt; 0.001). In the 7.5 mg/kg group, tumor type was primary CNS (n = 23, 43%), lung (n = 14, 26%), breast (n = 8, 15%), melanoma (n = 4, 8%) and other (n = 4, 8%). In the 10 mg/kg group, tumor type was primary CNS (n = 43, 84%), lung (n = 2, 4%), melanoma (n = 2, 4%) and other (n = 4, 8%). Median number of bevacizumab doses administered was 4. There was a statistically significant difference in distribution of edema response across all response levels favoring bevacizumab 10 mg/kg (p = 0.032). When edema response was dichotomized (large decrease vs other), the difference remained statistically significant (p = 0.015). Conclusion Bevacizumab 10 mg/kg was more efficacious in terms of edema response; this result is impacted by the significantly higher incidence of primary CNS tumors in the 10 mg/kg dosing group.