These neoantigens are recognized as non-self and elicit anti-tumor responses including higher tumor-infiltrating lymphocyte (TIL) grade and expression of type II interferon (IFN-γ)-related genes, such as those encoding programmed cell death 1 ligand 1 (PD-L1), cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), lymphocyte activation gene-3 (LAG-3) and indolamine-2,3-dioxygenase (IDO) [5, 6]. The gene discussed is IDO1; the disease is neoplasm.