IDO1 and neoplasm: Moreover, a correlation between a low intratumoral CD8+/FoxP3+ (forkhead box P3) cell ratio and BRAFV600E PTCs has been found; markers of tumor immune suppression, namely tumor PD-L1, HLA-G (human leukocyte antigen-G), and IDO1 expression, decreased intratumoral CD8+/FoxP3+cell ratio and increased ARG1+ tumor infiltrating leukocytes were together significant predictors of tumor BRAF status (49).