CD4 and neoplasm: Several biomarkers are under investigation including PD-L1, PD-L2, FAS, HLA class I and HLA class II antigen expression, immune checkpoints LAG-3, TIM-3, IDO, OX40, CD137 and CD40 expression, tumor infiltrating lymphocytes (TIL), CD4+, CD8+, granzyme B+, CD56+ and FOXP3+ cells, secreted molecules IL-2, IFN-γ, IL-10, IL-4, CXCL9, CXCL10, CCL5, cancer cell mutational load, antigenic peptide expression, gene expression and TCR signaling analysis.