Prognostic and predictive significance of VEGF, CD31, and Ang-1 in patients with metastatic clear cell renal cell carcinoma treated with first-line sunitinib

Abstract

The most common type of renal cell carcinoma (RCC) is clear cell renal cell carcinoma (ccRCC), which has a high metastatic potential. Even though the International Metastatic RCC Database Consortium (IMDC) risk model is conventionally utilized for selection and stratification of patients with metastatic RCC (mRCC), there remains an unmet demand for novel prognostic and predictive markers. The goal of this study was to analyze the expression of Vascular endothelial growth factor (VEGF), Cluster of Differentiation 31 (CD31) to determine microvessel density, and Angiopoietin-1 (Ang-1) in primary kidney tumors, as well as their predictive and prognostic value in patients with metastatic ccRCC (mccRCC) who were treated with first-line sunitinib. The study included 35 mccRCC patients who were treated with first-line sunitinib in period between 2009 and 2019. Immunofluorescence was used to examine biomarker expression in tissue specimens of the primary tumor and surrounding normal kidney tissue. Median disease-free survival (DFS) was longer in patients with negative and low tumor VEGF score than in patients with medium tumor VEGF score (p=0.02). Those with low tumor CD31 expression had a longer median DFS than patients with high tumor CD31 expression (p=0.019). There was no correlation between Ang-1 expression and DFS. The expression of biomarkers in normal kidney tissue was significantly lower than in tumor tissue (p<0.001). In conclusion, higher VEGF scores and greater CD31 expression were associated with longer DFS, but neither of these biomarkers correlated with progression-free survival or overall survival.

Figure 1.

VEGF (H) score in normal kidney tissue compared to tumor tissue. Wilcoxon signed-rank test identified significantly lower values of VEGF (H) score in normal kidney tissue compared to tumor tissue, z ═−3.85, p < 0.001. Median VEGF score (interquartile range) in normal kidney tissue was 1.156 (0–16.644) and in tumor tissue 50.256 (8.949–84.315).

Figure 2.

Double immunofluorescence staining revealed no coexpression of CD31 and VEGF markers in blood vessels of renal cell carcinoma (arrows) (D and H). Tumor VEGF H score in tumor tissue (B and F) was higher than in normal kidney tissue (J and N). Double immunofluorescence staining showed higher values of expression of CD31 stained blood vessels of tumor tissue (A and E) than in normal kidney tissue (I and M). Magnification ×400. Scale bar ═ 25 µm. (Wilcoxon signed-rank test, p < 0.001).

Figure 3.

Coexpression of CD31 and Ang-1 markers in blood vessels of renal cell carcinoma (A-H). Double immunofluorescence staining showed higher expression of Ang-1 in blood vessels of tumor tissue (B and F). Merge A+B and E+F with DAPI showing coexpression of CD31 and Ang-1 (arrows) (D and H). Double immunofluorescence staining showed higher values of expression of CD31 stained blood vessels of tumor tissue (A and E) than in the normal kidney tissue (I and M). Magnification ×400. Scale bar ═ 25 µm. (Wilcoxon signed-rank test, p < 0.001).

Figure 4.

Kaplan–Meier curves showing distant-free survival (DFS), stratified by tumor VEGF score. Median DFS in patients with negative, low, and medium tumor VEGF score was 7.0 (0–33.0), 8.0 (1–92.0), and 2.0 (0–22.0) months, respectively (p ═ 0.02).

Figure 5.

Kaplan–Meier curves showing distant-free survival (DFS), stratified by tumor CD31 score. Median DFS in patients with low and high tumor CD31 expression was 17.5 (0–92.0) and 2.0 (0–45.0) months (p ═ 0.019).