MKI67 and melanoma: For example, an increase in the number of circulating cytotoxic (Ki67 + CD8 + PD-1+) lymphocytes [44], the ratio of central memory to effector T lymphocytes subtype [45] and the higher frequency of blood NK cells [46] and classical monocytes (CD14 + CD16 + HLA-DR+) at baseline [47] appear to correlate with improved survival in PD-1/PD-L1inhibitor treated lung cancer and melanoma patients.