Concrete examples include upregulation of programmed death-ligand 1 (PD-L1) on leukemia cells, and programmed death-1 (PD-1) on donor-derived T cells at the time of post-alloHSCT relapse, as well as deletion of human leukocyte antigen alleles in some leukemia patients relapsing after haploidentical alloHSCT [4, 5]. The gene discussed is CD274; the disease is leukemia.