Outcomes with bevacizumab for radiation induced-brain necrosis.

Abstract

e14006 Background: Radiation necrosis (RN) is post-radiation complication that leads to increased permeability and disruption of the blood brain barrier (BBB). This in turn leads to a pro-inflammatory state and an increased production of vascular-endothelial growth factor (VEGF). Bevacizumab is a monoclonal antibody against VEGF and is a potential treatment for RN. The objective of the study is to assess effectiveness of bevacizumab (BEV) for the treatment of brain RN in adults. Methods: Retrospective chart review of 22 patients with various solid malignancies including non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), metastatic melanoma and breast cancer with clinical or radiographic diagnosis of RN seen at Memorial Cancer Institute (MCI) in a 3-year period, from January 1st, 2019 to January 1st, 2023. Radiation doses ranged from 18-24 Gy (single fraction) or 24-27 Gy (3-fraction) for radiosurgery and 30-37.5 Gy for whole brain radiotherapy. Patients were identified that developed RN and VEGF inhibitors were subsequently given to assess effectiveness in the treatment of the condition. We evaluated the dose, frequency, number of treatments received, adverse effects and therapeutic benefits of BEV. Therapeutic benefit was defined as patients that received bevacizumab had a radiological and clinical improvement of the RN (clinical benefit). Brain imaging with MRI or PET/CT scan was completed both pre and post treatment to evaluate efficacy of treatment. Patients were initially given 4 cycles with a subsequent 4 more cycles if it was beneficial and tolerated treatment. Results: 22 patients were included in the study, 9 were males (41%) and median age 66 (range 31-81). 91% (20/22) had a diagnosis of lung cancer. 1 patient had a diagnosis of SCLC, while 19 were diagnosed with NSCLC. The study had a good representation of different races including Non-Hispanic Whites 7 (32%), Hispanics 10 (45%), Blacks 13% (3) and Asians 10% (2). Over 95% (21/22) of patients achieved a clinical benefit, while one patient did not (5%). Patients experienced improvement in cognitive function, headaches, dizziness, weakness, and other symptoms with BEV. MRIs showed improvement in edema and a reduction/stabilization of brain lesions. The most frequent dosing regimen used was BEV 10 mg/kg every two weeks. The median number of cycles given was 4 cycles (1-12). The most common adverse events were hypertension, minor nose bleeding, an occasional protein found in urine. There were no severe AEs or discontinuation of therapy with bevacizumab. Conclusions: This study demonstrated treatment with BEV 10 mg/kg every two weeks for a total of 12 cycles is well tolerated and has potential clinical benefit in RN in lung cancer patients with CNS metastasis. The therapeutic effects of VEGF inhibitors were seen in our small population study but warrants further investigation in a larger population study.