Abstract 5463: The PD-L1 protein expression in Chinese patients with recurrent or metastatic head and neck squamous cell carcinoma: A multi-center retrospective study

Programmed death-ligand 1 (PD-L1) is a trans-membrane protein and co-inhibitory factor of the immune response. PD-L1 can combine with its receptor (PD-1) to reduce the proliferation of PD-1-positive cells and induce apoptosis. Therefore, PD-L1 was employed as a prognostic marker and a target for anti-cancer immunotherapy in blocking the PD-1 and PD-L1 checkpoints. PD-L1 is highly expressed in various malignancies, including head and neck squamous cell carcinoma (HNSCC). HNSCC is the sixth most common cancer worldwide, with high incidence and mortality rates in China. Although PD-L1 expression has been widely investigated, the PD-L1 expression status in Chinese HNSCC patients (pts) is largely unrevealed. The primary objective of this study was to determine the prevalence of PD-L1 expression with the Combined Positive Score (CPS) ≥20 in Chinese pts with recurrent or metastatic (R/M) HNSCC. The secondary objectives were to determine the prevalence of CPS≥1 in pts with R/M HNSCC and to study the difference in the demographic characteristics, clinicopathological parameters, treatment status, and other available biomarkers between the PD-L1 CPS≥20 group and the PD-L1 CPS