Similar to our result, it has been reported that IDO1 overexpression was linked to the reduction of apoptosis of endometrial stromal or breast cancer cells35, 36 and IDO1 inhibitor Incyte markedly promoted apoptosis of oral squamous cell carcinoma or colon cancer cells both in vitro and in vivo.37, 38. This evidence concerns the gene IDO1 and oral cavity squamous cell carcinoma.