Prolonged survival in adult neurofibromatosis type I patients with recurrent high-grade gliomas treated with bevacizumab

Astrocytic tumors, especially optic pathway pilocytic astrocytomas, are common in pediatric NF1 patients. High-grade gliomas (HGGs) appear to be rare in adult and pediatric NF1 patients. This is a series of five consecutive, adult NF1 patients with recurrent HGGs treated at The University of Texas MD Anderson Cancer Center. Four patients met consensus clinical criteria for NF1 and one patient had presumed segmental NF1. Three patients had glioblastomas, one gliosarcoma, and one progressive, enhancing optic pathway glioma which was not biopsied. Two tumors had molecular testing performed; both were IDH wild type and activating oncogene mutations (1 BRAFV600E and 1 PIK3CA mutation) were found in these tumors. All five patients received bevacizumab-containing regimens at tumor recurrence. The median number of 4-week cycles of bevacizumab was 20. All five patients experienced prolonged post-recurrence survival following bevacizumab treatment ranging from ten to 72 months. The median overall survival from HGG diagnosis was 72.6 months with three patients alive and progression free at last follow-up. Three out of five patients developed vascular complications leading to bevacizumab discontinuation. In this case series, adult NF1 patients with recurrent HGGs had prolonged, post-recurrence survival after treatment with bevacizumab-containing regimens. Based on these results, further study of antiangiogenic therapy in NF1 patients with HGGs and bevacizumab-response in sporadic HGG patients with NF1-mutated tumors is warranted.