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. This evidence concerns the gene PDCD1 and cancer.