Reduction in the cerebrospinal fluid protein level after bevacizumab treatment in patients with optic pathway low-grade gliomas.

Optic pathway gliomas (OPG) can cause elevated cerebrospinal fluid (CSF) protein concentrations. We report on two patients with suprasellar low-grade gliomas and high CSF protein levels (590 and 551 mg/dl) that precluded shunt implantation. After two and three doses of bevacizumab, respectively, the levels dropped dramatically to 191 and 178 mg/dl, respectively. Bevacizumab treatment was associated with a decrease in CSF protein level, allowing successful shunt placement. Our results are consistent with the pharmacological mechanism of bevacizumab, which decreases protein leakage from blood vessels to the ventricles.