IDO1 and neoplasm: Finally, we demonstrate that combined blockade of signalling ligands PD-L1 and TGFβ1 together with inhibition of indoleamine 2,3-dioxygenase 1 (IDO1) was able to reverse, in part, the suppressive effects of peritumoral CD90+CD73+ cells on tumor-infiltrating lymphocytes (TILs).