The role of plasma GFAP as a biomarker for glioblastoma

2095 Background: Magnetic resonance imaging (MRI) of the brain primarily assesses blood brain barrier (BBB) dysfunction which provides indirect information regarding tumor size. The limitations of MRI have become evident with the use of temozolomide (pseudo-progression) and VEGF based therapies (pseudo-response). As a result, a blood-based marker to assess tumor burden is increasingly important. Previous studies suggested that plasma glial fibrillary acidic protein (GFAP) levels are sensitive and specific for glioblastoma (GBM). This pilot study examines the utility of GFAP as a biomarker in pre- and post-operative gliomas. Methods: Plasma samples were collected in patients pre-operatively (N=34) and 24-48 hours post-operatively (N=24) for what was post-operatively confirmed to be newly diagnosed glioma. Plasma GFAP was detected using an electrochemiluminescent immunoassay with a detection threshold of >0.04ng/ml. Presence or absence of contrast enhancement (CE) on the pre-op MRI was compared with the pre...