IDO1 and sarcoma: In human sarcoma cells, exposure to axitinib and HDAC inhibitors rapidly increased the expression of MHCA and reduced the levels of PD-L1, PD-L2, ornithine decarboxylase (ODC) and indoleamine 2, 3-dioxygenase 1 (IDO1) (Supplemental Figures 12A, B).