CX3CR1 and neoplasm: So far, in addition to PD-L1, various biomarkers have been proved to be related to a better response rate in anti-PD-1/PD-L1 therapies, including tumor mutation burden, high microsatellite instability, neutrophil-to-lymphocyte ratio, deficient mismatch repair, TILs, tumor inflammation signature (TIS), T cell CX3C chemokine receptor 1 (CX3CR1) expression, etc. (132–137).