IDO1 and colorectal carcinoma: We set median value of PD-L1 or IDO1 as cutoff value, and stratified them into four groups: PD-L1(−)/IDO1(−) (GC: n = 13, CRC: n = 19), PD-L1(−)/IDO1(+) (GC: n = 6, CRC: n = 11), PD-L1(+)/IDO1(−) (GC: n = 6, CRC: n = 12) and PD-L1(+)/IDO1(+) (GC: n = 13, CRC: n = 19).