A Prospective Single Institution Study of Optic Neuropathy in 10 Patients with Glioblastoma Receiving Bevacizumab (P06.011)

Objective: Our research will focus on patients prior to them beginning treatment with bevacizumab (Avastin), by undergoing a baseline visual examination with Visual Evoked Potentials (VEP) testing. This will allow testing of the patient9s optic nerve function bilaterally so that we can obtain a baseline measurement of optic nerve function. Patients will then begin their normally scheduled treatment with avastin, and other chemotherapeutic agents, as well any radiation treatments scheduled. Once patients have completed their treatment with avastin for 6-8 weeks, they will then undergo their second Visual Evoked Potential testing. These results will be compared to the baseline results, looking for any changes within the optic nerves. Our patients will also be recommended to have stringent follow up with an Ophthalmologist to include confrontational visual field testing, external and anterior segment examination, and dilated fundus examination. Our main aim, objective and goal is to assess whether or not bevacizumab causes a direct toxic effect on patient9s optic nerves leading to an acute/subacute optic neuropathy. Background Review of the literature has revealed few proposed mechanisms leading to bevacizumab induced optic neuropathy. Proposed mechanisms in the literature have include arterial thrombosis, bevacizumab causing decreased optic nerve tolerance to radiation therapy as well as up regulation of VEGF receptors with ensuing neovascularization following radiation leading to optic ischemia. Although a rarely reported side effect, optic neuropathy while being treated with bevacizumab is a considerable issue treating physicians should be aware of. Design/Methods: 10 patients will be involved in the study. The patient population will be patients diagnosed with glioblastoma (WHO Grade IV) who are scheduled to begin chemo radiotherapy with bevacizumab. Results: Study is ongoing, results to be collected prior to conference. Conclusions: Study conclusions to be formulated once results are obtained. Supported by: Allegheny General Neuro-Oncology department. Disclosure: Dr. Fishman has nothing to disclose. Dr. Kunschner has nothing to disclose.