Recent developments in immuno-oncology permit classification of tumours according to their immunological contexture: inflamed cancer types, such as melanoma and lung cancer, are characterized by the presence of tumour infiltrating lymphocytes (TILs), high CD8+ T-cell density, and high programmed cell death receptor ligand 1 (PD-L1) positivity of tumour or immune cells, and immune signatures. The gene discussed is CD8A; the disease is neoplasm.