BEVACIZUMAB FOR SYMPTOMATIC RADIATION NECROSIS IN BRAIN METASTASES: OUTCOMES FROM A SINGLE-CENTER RETROSPECTIVE ANALYSIS

Radiation necrosis is a late complication after radiotherapy and can be treated with bevacizumab, however predictors of response are not well established. We performed a single-institution retrospective chart review of patients with previously irradiated brain metastases who developed radiation necrosis and were treated with bevacizumab. 19 patients (86% female, median age of 62 years) were included. 50% had metastatic lung cancer, 37% had breast cancer and 11 % had melanoma. 18 had perfusion imaging, 9 had chemical exchange saturation transfer (CEST) imaging to increase diagnostic confidence. 6 cases were tissue-confirmed, 3 before treatment, and 3 upon recurrence after bevacizumab. All patients received a dose of 7.5 mg/kg per infusion every 3 weeks and 63% received 4 infusions. All were symptomatic before treatment. Clinical response was seen in 89% while radiographic response was achieved in 95% of patients. Dexamethasone was successfully discontinued in 71% of steroid-dependent patients. The median duration of response (interval between first infusion and recurrence) was 7.2 months (range: 2.3 to 43.2). Of the nine diagnosed using perfusion and CEST imaging, 89% had clinical response, 100% had a reduction in T2/FLAIR volume and 89% in T1 post-gadolinium enhancement, 83% discontinued dexamethasone. Grade 1/2 adverse events occurred in 8 patients (hypertension, fatigue, rash, joint pain, intracranial hemorrhage). One patient developed a grade 3 bowel perforation requiring surgery. Bevacizumab resulted in significant and prolonged clinical and radiographic improvement in a series of carefully selected patients. CEST imaging helped select responders to bevacizumab in our cohort.