The prognostic value of TMB and the relationship between TMB and immune infiltration in head and neck squamous cell carcinoma: A gene expression-based study

Objective: Whether tumor mutation burden (TMB) affects prognosis and immune infiltration of tumor patients is controversial. We designed and conducted a multi-omics study with the aim of investigating the prognostic value of TMB and the relationship between TMB and immune infiltration in head and neck squamous cell carcinoma (HNSCC). Methods: TMB scores were calculated from the mutation data of 506 HNSCC samples from The Cancer Genome Atlas (TCGA), and the patients were divided into low- and high-TMB groups according to the TMB score quartiles. Differentially expressed genes (DEGs) between the low-TMB and high-TMB groups were identified. Immune cell infiltration and survival analyses were conducted between groups. Results: High TMB in HNSCC patients was associated with a poor prognosis, large primary tumor size, advanced clinical stage and a human papillomavirus (HPV)-negative status. A total of 576 DEGs were identified, and gene set enrichment analysis (GSEA) revealed that the DEGs in the low-TMB group were enriched in immune-related pathways. Four hub genes were significantly associated with prognosis, and mutations in these genes affected immune infiltration. The estimated fractions of B memory cells and CD4 + memory resting cells were higher in the low-TMB group than in the high-TMB group, and B cell and CD4 + T cell infiltration was positively correlated with prognosis in HNSCC patients. Conclusions: HNSCC patients with low TMB have better prognoses than those with high TMB, and TMB might affect B cell and CD4 + T cell infiltration.