Diagnostic value of 18F-FDG-PET to predict the tumour immune status defined by tumoural PD-L1 and CD8+tumour-infiltrating lymphocytes in oral squamous cell carcinoma
Maria Togo, Takehiko Yokobori, Kimihiro Shimizu, Tadashi Handa, Kyoichi Kaira, Takaaki Sano, Mariko Tsukagoshi, Tetsuya Higuchi, Satoshi Yokoo, Ken Shirabe, Tetsunari Oyama
Abstract
Abstract Background Lately, immune checkpoint proteins, such as programmed death 1 (PD-1) and its ligand-1 (PD-L1), have garnered attention as a new target in oral squamous cell carcinoma (OSCC). Reportedly, fluoro- d -glucose (FDG)-uptake alteration by anti-PD-1 antibody treatment depicts the response in patients with lung cancer. This study aims to elucidate the correlations between tumour immune status, clinicopathological factors, 18 F-FDG-uptake and cold tumour phenotypes as low PD-L1 expression/low CD8 + tumour-infiltrating lymphocytes (TILs) in OSCC. Methods We performed immunohistochemical analysis of PD-L1, hypoxia-inducible factor 1 A (HIF-1A), glucose transporter type 1 (GLUT1), CD8, E-cadherin and Ki-67 on 59 operable OSCC samples. We assessed the correlations between these factors and preoperative 18 F-FDG-uptake, clinicopathological characteristics and prognosis. Results Low expression of PD-L1 in OSCC correlated with cancer aggressiveness, poor prognosis, high 18 F-FDG-uptake with HIF-1A/GLUT1 and low E-cadherin expression and low CD8. Cold tumour phenotypes as low PD-L1 tumour cells and low stromal CD8 correlated with the poor prognosis, high 18 F-FDG-uptake and E-cadherin suppression. Furthermore, the high level of preoperative 18 F-FDG-uptake in OSCC was an independent predictor of the cold tumour immune status. Conclusions 18 F-FDG-uptake is an independent predictor of cold tumour in OSCC. 18 F-FDG-PET imaging could be a promising diagnostic tool to estimate tumour immune status.