In particular, single-cell proteomics data from mass cytometry (CyTOF) have been used extensively to profile the tumor immune landscape (37, 48), to monitor how ICBs shape the population of immune cells and their function in responders and non-responders (49, 50), and to predict response to anti-PD-1 treatment from peripheral blood mononuclear cells (PBMCs) (49). Here, PDCD1 is linked to neoplasm.