PT - JOURNAL ARTICLE AU - Bingxin Hu TI - Correlation of PD-L1 expression on tumor cells and tumor-infiltrating immune cells with <sup>18</sup>F-FDG uptake on PET/CT in surgically resected pulmonary adenocarcinoma DP - 2019 May 01 TA - Journal of Nuclear Medicine PG - 80--80 VI - 60 IP - supplement 1 4099 - http://jnm.snmjournals.org/content/60/supplement_1/80.short 4100 - http://jnm.snmjournals.org/content/60/supplement_1/80.full SO - J Nucl Med2019 May 01; 60 AB - 80Objectives: 18 F-fluorodeoxyglucose positron-emission tomography/ computed tomography ( 18 F-FDG-PET/CT) is a clinically useful modality for cancer evaluation. Programmed cell death-ligand 1 (PD-L1) is expressed on tumor cells (TC) and tumor-infiltrating immune cells (IC), and the latter is more related to the immunotherapeutic response. The uptake of 18 F-FDG within cancer cells is known to be linked to PD-L1 expression on TC. However, the association between PD-L1 expression on IC and 18 F-FDG accumulation is still unclear. Here, we conducted a clinicopathological study to investigate the relationship between PD-L1 expression on IC and 18 F-FDG uptake in patients with surgically resected pulmonary adenocarcinoma (ADC). Materials and Methods: Total 524 ADC patients (226 men and 297 women) who underwent preoperative 18F-FDG-PET/CT imaging were analyzed retrospectively. Patients who had accepted any anti-tumor therapy were excluded. Immunohistochemistry analysis was performed for PD-L1 expression on TC and IC in ADC specimens with two antibodies( 28-8 and SP142), also for Ki67 index and PD-1 expression on IC. The cut-off value of 5% for defining PD-L1 positivity was determined according to previously trails. The association between PD-L1 expression with SUVmax and clinicopathological variables were analyzed,including age, gender, smoking status, location, tumor diameter, histological subtype, differentiation, lymph node metastasis, stage, Ki-67, PD-1 expression on IC and epidermal growth factor receptor (EGFR) mutation status. Statistical methods include χ 2 test, mann-whitney U test and binary logistic regression. Results: PD-L1 positive expression was 63.9% (335/524) in ADC specimens. Its expression on TC and IC were 25.8% (135/524) and 55.9% (293/524) respectively. The maximum standardized uptake value (SUVmax) was significantly higher in patients with PD-L1 positive compared to those with PD-L1 negative tumors (7.2±5.6 vs 5.3±5.5, P=0.000). When compared with PD-L1 positive and negative expression lesions, SUVmax with PD-L1 expression on TC (positive 9.2±5.6 vs negative 5.6±5.4, P=0.000) and IC ((positive 7.1±5.7 vs negative 5.7±5.5, P=0.000) were also significantly higher. Multivariate analysis demonstrated that PD-L1 expression were correlated with Ki-67 and PD-1 expression on IC. PD-L1 expression on TC was associated with Ki-67 and histological subtypes. PD-L1 expression on IC was associated with Ki-67 and SUVmax. The best cut-off value of SUVmax for PD-L1 expression was 5.1 (AUC=0.632, 95% CI=0.582-0.682, P=0.000, sensitivity 58.2%, specificity 64.6%) determined by ROC curve. Furthermore, the best cut-off value of SUVmax for PD-L1≥50% on TC was 7.9 (AUC=0.748, 95% CI=0.709-0.785, P=0.000, sensitivity 70.2%, specificity 71.9%). Conclusions: High SUVmax is associated with PD-L1 expression on TC and IC in our population of surgically resected pulmonary adenocarcinoma. 18 F-FDG-PET/CT imaging may be a potential tool to evaluate PD-L1 expression in pulmonary adenocarcinoma.