Prognostic and therapeutic implications of immune classification by CD8+ tumor-infiltrating lymphocytes and PD-L1 expression in sinonasal squamous cell carcinoma

Abstract

Sinonasal squamous cell carcinoma (SNSCC) is an aggressive tumor predominantly aris-ing in the maxillary sinus and nasal cavities. Advances in imaging, surgical and radiotherapeutic techniques have reduced complications and morbidity; however, the prognosis generally remains poor, with an overall 5-year survival rate of 30–50%. As immunotherapy may be a new therapeutic option, we analyzed CD8+ tumor-infiltrating lymphocytes (TILs) and the tumor microenvironment immune type (TMIT, combining CD8+ TILs and PD-L1) in a series of 57 SNSCCs. Using immunohis-tochemistry, tissue samples of 57 SNSCCs were analyzed for expression of CD8 on TILs and of PD-L1 on tumor cells. The results were correlated to the clinical and survival data. In total, 88% (50/57) of the tumors had intratumoral CD8+ TILs; 19% (11/57)—CD8high (>10%); and 39/57 (68%)—CD8low (1–10%). PD-L1 positivity (>5%) was observed in 46% (26/57) of the SNSCCs and significantly co-occurred with CD8+ TILs (p = 0.000). Using univariate analysis, high intratumoral CD8+ TILs and TMIT I (CD8high/PD-L1pos ) correlated with a worse survival rate. These results indicate that SNSCCs are immunogenic tumors, similar to head and neck squamous cell carcinomas. Nineteen percent of the cases were both CD8high and PD-L1pos and this subgroup may benefit from therapy with immune checkpoint inhibitors.