Changes in PD-L1 expression on microvessel endothelial cells during melanoma tumor growth and the regulation by anlotinib

Abstract

Abstract To evaluate the expression of PD-L1 on MEC in tumor and normal tissues, IF was used to detect the expression of PD-L1+CD31+ VECs and PD-L1+ Podoplanin + LECs in tumor, ear and kidney tissues. We found that the MEC PD-L1 in tumor showed an upward trend with tumor progression. The expression of PD-L1 in MEC in normal tissues is associated with the type of microvessels and tumor progression. The MEC PD-L1 expression in tumor is significantly down-regulated at 22th day in An5-9 group. In the early treatment group (An5-9), anlotinib increased the LEC PD-L1 but had no significant effect on VEC PD-L1 of ear, while decreased the LEC PD-L1 in kidney. In conclusion, the MEC-PD-L1 in melanoma increased with tumor growth and was downregulated significantly by early treatment of anlotinib, which proposes a potentiality of its enhancement on the therapeutic efficacy of anti-PD-L1 antibody. Anlotinib had no significant effect on the MEC PD-L1 of ear excepting the upregulation of LEC PD-L1 in early treatment group, while decreased such expression in kidney, hence the risk of possible renal damage by CD8 + T cells in the treatment of anlotinib should be bewared.