CD274 and neoplasm: However, another in vivo study showed a depletion of tumour-associated macrophages from the tumour microenvironment and an upregulation of the immune checkpoint programmed death ligand-1 (PD-L1) by sevoflurane in melanomas, indicating a possible positive effect of sevoflurane in combination with the checkpoint inhibitor programmed death-1(PD-1) [11].