BI-16 * CIRCULATING PROTEIN ANALYSIS OF POTENTIAL BRAIN TUMOR BIOMARKERS

Abstract

BACKGROUND: Blood-based, circulating biomarkers play an important role in the detection and care for many cancer types. Such a biomarker is not clinically available for gliomas, even though there is pressing need for improved assessment of disease response and progression. The objective of this study was to explore eight potential biomarkers in their ability to discriminate among glioblastomas (WHO Grade IV), low grade gliomas (WHO Grade II), and healthy controls. METHODS: We collected pre-operative plasma from 34 patients with gliomas (WHO grade IV, n = 23; WHO grade II, n = 11), and we collected plasma from healthy subjects as controls (n = 15). Using enzyme-linked immunosorbent assays, we measured plasma concentrations of glial fibrillary acidic protein (GFAP), neurogranin, brain derived neurotrophic factor (BDNF), intracellular adhesion molecule 5 (ICAM-5), metallothionein-3 (MT3), beta-synuclein, S100B, and neuron specific enolase (NSE). RESULTS: The distributions of plasma protein concentrations demonstrated a high degree of overlap among WHO grade IV, WHO grade II, and healthy subjects. We found statistically significant differences between WHO grade IV tumors and healthy controls for ICAM-5 (p < 0.05, increased in grade IV) and BDNF (p < 0.05 decreased in grade IV), however not for the other markers tested. Whether blood was collected pre- or post-anesthesia affected some protein levels significantly (p < 0.05). We noticed that gliosarcomas (WHO Grade IV, n = 2) had substantially elevated levels of several biomarkers compared to glioblastomas and healthy subjects. CONCLUSIONS: Our analysis concludes that the eight circulating proteins are not glioma-specific biomarkers. Anesthesia may have an effect on plasma protein levels in plasma that future circulating biomarker studies should take into account. Gliosarcomas were under-represented in our sample, but they appear to have markedly higher levels of some of the studied proteins which deserves further evaluation.