Firstly, patients with lung cancer treated with PD-1 inhibitors have a highly specific subset of proliferating CD8+ T cells in the peripheral blood, expressing effector-like phenotypes (HLA-DR+, CD38+, Bcl-2lo), costimulatory molecules (CD28, CD27, ICOS), and high levels of PD-1. The gene discussed is CD27; the disease is lung cancer.