Finally, an analysis of public data sets of head and neck squamous cell carcinoma (HNSCC) and pan-cancer cohorts showed that SEMA6D was mainly expressed by nonhematopoietic cells such as cancer cells, fibroblasts, and endothelial cells, and SEMA6D expression was significantly negatively correlated with the expression of CD8A, PDCD1, IFNG, and GZMB. The gene discussed is PDCD1; the disease is head and neck squamous cell carcinoma.