Tumor Immunity is Related to 18F-FDG Uptake in Thymic Epithelial Tumor

Abstract

Background2-Deoxy-2-[fluorine-18]-fluoro-d-glucose (18F-FDG) positron emission tomography (18F-FDG-PET) is a convenient modality to assess metabolic activity within tumor cells. However, there is no consensus regarding the relationship between 18F-FDG uptake and the immune environment in thymic epithelial tumors (TETs). We conducted a clinicopathological study to elucidate the relationship between 18F-FDG uptake and programmed death ligands 1 and 2 (PD-L1/PD-L2) expression in patients with TETs. MethodsA total of 108 patients with histologically confirmed TETs classified as thymomas or thymic carcinomas who underwent surgical resection or biopsy or needle biopsy and 18F-FDG PET before any treatment between August 2007 and March 2020 were enrolled in this study. Tumor specimens underwent immunohistochemical staining for PD-L1, PD-L2, GLUT1, HIF-1α, VEGFR2, VEGF-C and β2 adrenergic receptor. ResultsHigh uptakes of SUVmax, SUVmean, MTV and TLG were identified in 28 (25.9%), 61 (56.5%), 55 (50.9%) and 55 (50.9%) of 108 patients, respectively. High uptake of SUVmax significantly correlated with PS of 1-2, thymic carcinoma and advanced stage, and SUVmax on 18F-FDG uptake displayed a close association with PD-L1 and PD-L2 expression, but not MTV and TLG. Multivariate analysis revealed that SUVmax was identified as an independent predictor for positive PD-L1 /PD-L2 expression. GLUT1 was clarified as a significant marker for the expression of PD-L1/PD-L2 from the biological viewpoint. Conclusion18F-FDG accumulation was closely associated with the expression of PD-L1/PD-L2, which, in turn, was correlated with glucose metabolism and hypoxia. PD-L1/PD-L2 could affect glucose metabolism and hypoxia in thymic tumor cells.

Prognostic Potential of Metabolic Activity on 18F-FDG Accumulation in Advanced NSCLC Receiving Combining Chemotherapy Plus PD-1 Blockade

“…Therefore, tumor metabolic volume measured by TLG may be a potentially related to PS, nutrition, and inflammation related to resistance to ICI therapy. Although several previous studies have disclosed a close relationship between glycolysis by SUV max and PD-L1 expression,12–14 MTV or TLG seemed to be unrelated to PD-L1 expression, supported by a previous approach 26. Furthermore, the relevance of 18 F-FDG uptake within the tumor microenvironment determined by tumor infiltrative lymphocytes (TILs) has been reported; however, SUV max by 18 F-FDG uptake indicates to be unrelated to the cell counting of CD4, CD8, and Foxp3 in TILs 13,14.…”

Determination of diagnostic and predictive parameters for vertical mandibular invasion in patients with lower gingival squamous cell carcinoma: A retrospective study

“…First, PD-L1 did not show significant results to be a predictive factor in univariate analysis. There have been reports of PD-L1 and metabolic imaging parameters demonstrating correlation [52–55] and no correlation. [56,57] PET also provides information on the metabolic state of the tumor microenvironment (TME), as the glucose analogue 18 F-FDG is transported by cancer cells and active immune cells, such as tumor-infiltrating lymphocytes (TIA) and tumor-associated macrophages (TAM).…”