It is worth mentioning that PD-1/TIM-3 or PD-1/LAG-3 co-expression on CD4+ TILs were also observed in a recurrent mouse melanoma model.30, 32 These tumor-specific CD4+T cells expressed inhibitory receptors, such as PD-1, TIM-3 and LAG-3.49 However, whether the function of tumor-infiltrating CD4+T cells is decreased or whether these cells are also exhausted remains unknown. The gene discussed is PDCD1; the disease is melanoma.