Schultz, Sydney

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, >105% of baseline; (2) constant edema, 75%-105% of baseline; (3) slight decrease of edema, 25%-75% of baseline; (4) large decrease of edema, <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 < 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.

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.