Baseline assessment of programmed death-ligand 1 (PD-L1) expression by immunohistochemistry, tumor infiltration by CD8-positive T cells, evidence of an inflamed tumor microenvironment (TME) driven by active interferon gamma (IFNγ) signaling detected by gene expression profiling, or high tumor mutational burden (TMB) have shown limited predictive value when tested prospectively or have been challenging to implement in the clinic7–15. Here, CD8A is linked to neoplasm.