IDO1 and acute lymphoblastic leukemia: The results indicated that ALL prognostic signature was significantly positive correlated to CD274 (r = 0.26; p = 0.00015), CTLA4 (r = 0.33; p = 1.3e − 06), HAVCR2 (r = 0.41; p = 1.4e − 09), IDO1 (r = 0.15; p = 0.03), PDCD1 (r = 0.16; p = 0.021) and PDCD1LG2 (r = 0.23; p = 0.001; Fig. 5b–g).