The prometastatic relevance of tumor‐infiltrating B lymphocytes in laryngeal squamous cell carcinoma

OBJECTIVES: Laryngeal squamous cell carcinomas (LSCCs) typically have an excellent prognosis for stage I tumors but a significant risk of locoregional and distant recurrence for intermediate to advanced disease. This study will investigate the clinical relevance of the tumor microenvironment in a large cohort of treatment‐naïve patients affected by stage II–IV LSCC. METHODS: Whole slide‐based digital pathology analysis was applied to measure six immune cell populations identified by immunohistochemistry (IHC) staining for CD3, CD8, CD20, CD66b, CD163 and CD38. Survival analysis was performed by Cox proportional hazards models and unsupervised hierarchical clustering using the k‐means method. Double IHC staining and in‐situ hybridisation by RNAscope allowed further analysis of a protumoral B cell population. RESULTS: A cohort of 98 patients was enrolled and analysed. The cluster of immune‐infiltrated LSCCs demonstrated a significantly worse disease‐specific survival rate. We also discovered a new association between high CD20(+) B cells and a greater risk of distant recurrence. The phenotypic analysis of infiltrating CD20(+) B cells showed a naïve (BCL6(−)CD27(−)Mum1(−)) regulatory phenotype, producing TGFβ but not IL10, according to an active TGFβ pathway, as proved by positive pSMAD2 staining. CONCLUSION: The identification of regulatory B cells in the context of LSCC, along with the activation of the TGFβ pathway, could provide the basis for new trials investigating the efficacy of already available molecules targeting the TGFβ pathway in the treatment of LSCC.