Assessment of vascularity in glioblastoma and its implications on patient outcomes

Abstract

There is little data on why glioblastomas (GBM) hemorrhage and how it may affect patient outcomes. The aim of this study was to investigate the mechanisms of hemorrhage in glioblastoma by examining molecular and genetic features by immunohistochemistry (IHC) and mRNA expression profiles in association with imaging and clinical outcomes. An observational retrospective cohort analysis was performed on 43 FFPE GBM tissue samples. MR images were assessed for the presence of hemorrhage and extent of resection. Specimens were examined for CD34 and CD105 expression using IHC. Tumor mRNA expression profiles were analyzed for 92 genes related to angiogenesis and vascularity. Forty-three specimens were analyzed, and 20 showed signs of hemorrhage, 23 did not. The average OS for patients with GBM with hemorrhage was 19.12 months (95% CI 10.39-27.84), versus 13.85 months (95% CI 8.85-18.85) in those without hemorrhage (p > 0.05). Tumors that hemorrhaged had higher IHC staining for CD34 and CD105. mRNA expression analysis revealed tumor hemorrhage was associated with increased expression of HIF1α and MDK, and decreased expression of F3. Hemorrhage in GBM was not associated with worsened OS. Increased expression of angiogenic factors and increased CD34 and CD105 IHC staining in tumors with hemorrhage suggests that increased hypoxia-induced angiogenesis and vessel density may play a role in glioblastoma hemorrhage. Characterizing tumors that are prone to hemorrhage and mechanisms behind the development of these hemorrhages may provide insights that can lead to the development of targeted, individualized therapies for glioblastoma.

Keywords: Gene analysis; Glioblastoma; HIF1α; Hemorrhage; Vascularity.

Figure 1

A) Overall survival of patients that achieved gross total resection compared to those with subtotal resection (excluding the excisional biopsy and unknown resection status). B) Overall survival and C) progression free survival comparing glioblastomas that hemorrhaged to those that did not. PFS data not available in all patients.

Figure 2

The relationship of A) CD105- and B) CD34-staining in GBM with hemorrhage (N=17), without hemorrhage (N=22), and controls (N=4).

Figure 3

mRNA expression of A) HIF1α, B) MDK, and C) F3 in glioblastomas with hemorrhage (N=17), without hemorrhage (N=22), and normal brain controls (N=4). There is increased expression of HIF1α and MDK and decreased F3 in in tumors that hemorrhaged.

Figure 4

The relationships between HIF1α with A) ANPEP, B) THBS1, C) COL18A1, and D) ITGAV mRNA expression comparing glioblastoma with hemorrhage, without hemorrhage, and normal brain controls. ANPEP, THBS1, and COL18A1 mRNA expression demonstrated a positive association with hemorrhage particularly in tumors with lower levels of HIF1α expression. ITGAV mRNA expression was inversely related to hemorrhage risk.