IDO1 and AIDS dementia complex: The most predominant immune checkpoint expressed in malignant cells from ADC and SCC was B7-H3 (median, 307.79 cells/mm2), followed by PD-L1 (median, 77.265 cells/mm2), OX40 (median 25.38 cells/mm2), B7-H4 (median, 19.17 cells/mm2), and IDO-1 (median, 7.08 cells/mm2), and significantly higher densities of B7-H3 and B7-H4 were observed in SCC than in ADC (P < 0.001 for both immune checkpoints), whereas significantly higher densities of IDO-1 were observed in ADC than in SCC (P = 0.015; Supplementary Table 2).