IDO2 and neoplasm: Other promising candidate predictive biomarkers are currently under investigation [17], particularly cells or molecules related to immune response in tumor microenvironment such as tumor infiltrating lymphocytes (TILs) [18], indoleamine 2,3-dioxygenase (IDO) [19], BCL-2 interacting mediator of cell death-Bim [20], and interferon-gamma [21].