Breit, Jeff

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 Peritumoral brain edema (PTBE) is a frequent complication of CNS tumors and radiation therapy (RT). PTBE is primarily treated with corticosteroids, but prolonged use is associated with severe toxicities including myopathy and immunosuppression. Bevacizumab, an alternative treatment, is not recommended in patients with thromboembolic events and intracerebral hemorrhage. Plasma kallikrein is a key driver of tumor-related edema. By targeting this pathogenic enzyme, the orally delivered inhibitor, RZ402, may provide therapeutic value by controlling edema and decreasing corticosteroid use. Methods In this single-patient investigational new drug protocol, we report results from use of RZ402 for treatment of cerebral edema related to metastatic melanoma and RT. Results A 74-year-old man with BRAF-wildtype melanoma had a right frontal and basal ganglia hemorrhagic metastasis not amenable to resection, treated with stereotactic RT (30 Gy, 5 fractions), followed by ipilimumab and nivolumab. MRI obtained 5 months after RT showed increased edema associated with midline shift. After 12 weeks of treatment with high-dose dexamethasone (16 mg daily), edema remained persistent and patient was unable to tolerate dose reduction below 4 mg daily. Course was complicated by a pulmonary embolus prompting initiation of anticoagulation, leading to deferral of bevacizumab. Patient was treated with RZ402, which was tolerated well with no reported toxicities. Dexamethasone was discontinued over 4 weeks. Follow up imaging 6 weeks after RZ402 initiation and off dexamethasone demonstrated stability without rebound edema. Patient did experience adrenal insufficiency characterized by severe fatigue, managed with low-dose prednisone. RZ402 was discontinued after 8 weeks of treatment with patient remaining clinically stable. Conclusion Despite persistent edema after prolonged use of corticosteroids, the selective plasma kallikrein inhibitor RZ402 was associated with radiographic stabilization and discontinuation of dexamethasone for this patient. These findings support prospective evaluation of RZ402 in treatment of symptomatic cerebral edema related to CNS tumors.