Correlation of PD-L1 with VEGF and KI-67 index in patients with primary glioma.
94 Background: The treatment strategies for glioma, especially glioblastoma multiforme, are not effective. The programmed death ligand 1 (PD-L1) immune escape and increased angiogenesis may be two of the underlying sources of treatment resistance. However, the relationship between these pathways in human glioma is still unknown. Methods: Data for 64 patients with primary glioma recorded from June 2007 to December 2013 in Shan Dong Cancer Hospital were immunohistochemically evaluated for the expressions of PD-L1, VEGF, MMP-9 and KI-67 index. Image ProPlus software was used to quantify the mean optical density (MOD) of the immunohistochemical image. Results: PD-L1 expression was observed in 65.22% of low-grade glioma and 90.24% of high-grade glioma, respectively. The whole expression rate of PD-L1 in glioma was 81.25%. The expression of PD-L1 is significantly related to pathological grade ( p <0.001), VEGF ( p= 0.017) and KI-67 index ( p= 0.009). The mean of PD-L1 MOD in High-grade group was 0.1144±0.02754, higher than that in low-grade group, 0.005129±0.001441 ( p= 0.004). In addition, Expression of VEGF, MMP-9 and KI-67 was significantly different between low-grade and high-grade gliomas ( p= 0.008, 0.04, 0.004 for VEGF, MMP-9 and KI-67, respectively). When analyzed as a continuous variable, the expressions of PD-L1 was positively correlated with VEGF (r = 0.392, p= 0.001) and KI-67 (r = 0.388, p= 0.001). Conclusions: These data suggest, for the first time, that PD-L1 play an important role in glioma angiogenesis and proliferation potential, providing the possibility for considering additional combinations of targeted VEGF therapies and anti-PD-L1 immunotherapy for the treatment of human brain glioma.