T-cell Immunoglobulin and Mucin-Domain-Containing Molecule-3 (TIM3) is present on T-helper type 1 lymphocytes and other immune cells including dendritic cells and natural killer cells. TIM3 is overexpressed in CD4+ tumor-infiltrating lymphocytes, including those with non-small cell lung cancer associated with poor prognoses. TIM3 has recently emerged as a potential target for cancer immunotherapy.