Serum Neurofilament Light, Glial Fibrillary Acidic Protein and Tau Are Possible Serum Biomarkers for Activity of Brain Metastases and Gliomas

Background: Primary central nervous system (CNS) tumors and brain metastases (BMs) are major causes of morbidity and mortality, accompanied by low survival rates. Efforts to early discovery of CNS malignancies are critical. However, to date, there are no biomarkers approved for detection of cancer activity in the brain. Blood levels of neurofilament light (NfL) and tau, as well as glial fibrillary acidic protein (GFAp), show promise as biomarkers for brain injury in previous studies. Therefore, we performed a cross-sectional study to investigate correlations of those biomarkers with CNS activity of gliomas and BMs. Methods: Serum samples of 36 participants of a single centered institution were tested for NfL, GFAp and tau with Simoa immunoassay, and correlated with clinical and radiological data. Results: NfL and GFAp levels were significantly associated with the state of intracranial disease (analysis of variance (ANOVA), P-sNfL 0.03; ANOVA, P-GFAp = 0.03). Although statistically significant (P = 0.04), differences in concentrations were not clinically meaningful for tau levels. Serum NfL (sNfL) and GFAp concentrations were higher in the group of patients with CNS tumors with disease in progression versus CNS with stable disease (P = 0.03 and P = 0.01, respectively). In addition, sNfL were higher in patients with metastatic solid tumors with known BMs than in those with metastatic tumors with no BM (P = 0.0004). Conclusion: sNfL and GFAp both apparently vary closely with presence and activity of gliomas and BMs. Further studies in larger populations are needed to expand these findings.