Tumor PD-L1 expression is associated with improved survival and lower recurrence risk in young women with oral cavity squamous cell carcinoma

Young patients with oral cavity squamous cell carcinoma (OCSCC) are often recognized as a distinct epidemiological cohort. In this study, genomic and immune-based metrics were correlated with long-term outcomes for a young patient population treated at a single institution. A fully clinically annotated, retrospective cohort of 81 patients aged ≤45 years with OCSCC is described, and the impact of clinicopathological features on long-term survival outcomes is reported. Genomic and immune parameters were integrated utilizing a whole-exome sequencing and immunohistochemical approach among females in the cohort. It was found that young OCSCC patients had favorable outcomes (10-year disease-free survival 79.1%, overall survival 80.0%) regardless of sex, particularly if they presented with oral tongue primaries and early stage disease. While mutational analysis appeared similar to that of older patients with OCSCC who lack a smoking history, a comparatively high degree of PD-L1 expression and PD-1/L1 concordance (P=0.001) was found among young female OCSCC patients. Subjects with greater membranous PD-L1 positivity and the presence of tumor-infiltrating lymphocytes had a decreased risk of recurrence (P=0.01 and P=0.01, respectively) and improved survival (P=0.04 and P=0.03, respectively). These findings warrant further validation and support the investigation of immunotherapeutic approaches targeting PD-1/L1 interactions in young OCSCC patients.