Among tumor cells, IDO1 (7.4% vs. 0.7%; p = 0.008) and HLA-DR (11.3% vs. 1.8%; p = 0.003) were significantly elevated in HPV-positive tumors, whereas CD44 was enriched in HPV-negative tumors (16.5% vs. 59.6%; p = 0.005) across both the TC and TSI (Fig. 3C–D, Suppl. This evidence concerns the gene IDO1 and neoplasm.