Combined Tumor Infiltrating Lymphocytes and PD-L1 Status in Recurrent/Metastatic Head and Neck Squamous Cell Carcinoma.

Abstract

To determine if the assessment of CD8+ tumor-infiltrating lymphocytes (TILs) adds prognostic information to the PD-L1 combined positive score (CPS) in recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC). A retrospective case series was performed of 77 patients with R/M HNSCC between 2003 and 2019. From pre-treatment biopsies, CD8+ TILs and PD-L1 CPS were quantified on a tissue microarray. Associations of biomarkers with overall survival and immune checkpoint inhibition (ICI) response were assessed. Neither CD8+ TIL counts nor PD-L1 CPS alone were associated with overall survival; however, combined high TILs and CPS ≥ 1 were associated with improved survival compared to low TILS and CPS < 1 (18.5 vs. 10.0 months, p = 0.058). For patients treated with ICI (n = 28), PD-L1 CPS predicted ICI response more strongly than CD8+ TILs. In R/M HNSCC, the combination of PD-L1 CPS and CD8+ TILs is a stronger prognostic biomarker for overall survival compared with either biomarker alone.