LG-72: CYST RESPONSE TO BEVACIZUMAB IN PILOCYTIC ASTROCYTOMA: A CASE SERIES

Pilocytic astrocytoma (PA) is one of the most common central nervous system (CNS) tumors in childhood, accounting for 21-23% of all pediatric CNS tumors. PA is a low grade glioma often characterized by solid and cystic components. Current treatment strategies include surgery, chemotherapy, and/or radiation. Although chemotherapy and radiation are effective against the solid component, they show limited activity on the cystic component. Management of cystic tumor progression often involves surgical intervention and can be problematic. Bevacizumab is a monoclonal antibody that binds vascular endothelial growth factor (VEGF) and prevents formation of new blood vessels. In this case series, we present three patients with PAs and cystic progression, who were treated with bevacizumab from 2012 to 2015. Patient 1 has an optic pathway glioma (OPG) treated with two chemotherapy regimens, multiple surgical procedures for cyst fenestration and placement of an Ommaya reservoir. Patient 2 has a midbrain PA treated with subtotal surgical resection, multiple chemotherapy regimens, and gamma knife radiation. Patient 3 has an OPG treated with two chemotherapy regimens, tumor debulking, and cyst fenestration. All three patients were treated with bevacizumab every two weeks with improvement in the cystic components of their tumors as shown by magnetic resonance imaging. In this case series, we report three patients with significant history of refractory disease in which bevacizumab was well-tolerated and showed substantial improvement in the cystic component of their tumor. We believe bevacizumab is a promising agent for cyst control in patients with pilocytic astrocytoma.