Comprehensive immunohistochemical studies have demonstrated significant IDO1 overexpression across diverse malignancies, with particularly high expression observed in triple-negative breast cancer (TNBC), glioblastoma multiforme (GBM), and microsatellite-stable colorectal carcinomas (CRC) (Muller et al., 2019). The gene discussed is IDO1; the disease is colorectal carcinoma.