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
Menée à partir de l'analyse immunohistochimique de 59 échantillons de carcinomes épidermoïdes de la cavité buccale, cette étude évalue l'association entre la quantité de fluorodésoxyglucose (18F) consommée par les cellules cancéreuses (et mesurée avant l'opération chirurgicale à l'aide d'une tomographie numérique par émission de positrons), le statut immunitaire de la tumeur (défini par le niveau d'expression du ligand PD-L1 et la quantité de lymphocytes CD8+ ayant infiltré le tissu tumoral) et le niveau d'expression de quatre protéines (facteur HIF-1A, transporteur de glucose GLUC1, E-cadhérine et antigène Ki67)
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, 18F-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 18F-FDG-uptake, clinicopathological characteristics and prognosis.
Results : Low expression of PD-L1 in OSCC correlated with cancer aggressiveness, poor prognosis, high 18F-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 18F-FDG-uptake and E-cadherin suppression. Furthermore, the high level of preoperative 18F-FDG-uptake in OSCC was an independent predictor of the cold tumour immune status.
Conclusions : 18F-FDG-uptake is an independent predictor of cold tumour in OSCC. 18F-FDG-PET imaging could be a promising diagnostic tool to estimate tumour immune status.
British Journal of Cancer , article en libre accès, 2020