It significantly upregulates PD-L1 (Falcinelli et al., 2023[31], Wu et al., 2024[125]) and indoleamine 2,3-dioxygenase (IDO) expressions (Schalper et al., 2017[98]) in tumor cells, and drives malignant transformation (Choi et al., 2022[21]). This evidence concerns the gene IDO1 and neoplasm.