Table 4 Literature review of IDO1 in human lung cancer

Schalper et al. [21]

Non-small cell lung cancer

Resection specimens: Cohort #1 (202) Cohort #2 (350)

IDO1 (1:250, 1F8.2, Millipore)

Determined by a quantitative immunofluorescence assay^a

78/183 (43%) of cohort #1167/335 (50%) of cohort #2

IDO1 and PD-L1 were co-expressed in 7 and 11% of cohort #1 and #2, respectively; PD-L1 and IDO1 expression were associated with increased CD3+ and CD8+ tumor-infiltrating lymphocytes and IFNγ stimulation

Tang et al. [37]

Non-small cell lung cancer

Resection specimens (64)

Rabbit anti-IDO1 mAb (1:50, Abnova) with BioGenex i6000 automated stainer

Absent (0), weak (1), moderate (2), strong (3)

Reported median expression levels for different comparison groups

IDO1 expression was increased in lung cancer compared to corresponding non-tumor tissues; upregulation of IDO1 was significantly associated with higher stage and lymph node metastasis

Volaric et al. [34]

Non-small cell lung cancer

Resection specimens (102): 51 adenocarcinomas; 42 squamous cell carcinomas; 9 adenosquamous carcinomas

IDO1 (1:2000, HPA 023072, Sigma Prestige)

Cytoplasmic staining in ≥1% of tumor cells

21/51 (42%) adenocarcinomas18/42 (43%) squamous cell carcinomas4/9 (44%) adenosquamous carcinomas

IDO1 was frequently co-expressed with PD-L1 (27% of adenocarcinomas); IDO1 expression was not significantly associated with clinicopathologic factors or survival

Kozuma et al. [35]

Lung adenocarcinoma

Resection specimens (427)

Mouse anti-IDO1 mAb (1:200, UMAB126, Origene Technologies)

Cytoplasmic and membranous staining in ≥1% of tumor cells

260/427 (61%) using 1% cutoff63/427 (15%) using 50% cutoff

IDO1 and PD-L1 were co-expressed in 29% of tumors; IDO1 expression was significantly associated with aggressive clinicopathologic features (e.g., higher stage, higher grade, lymphovascular invasion, perineural invasion); IDO1 expression was significantly associated with shorter disease-free and overall survival