Clinical role of serum programmed death ligand 1 in patients with hepatocellular carcinoma: Where does it come from?

PURPOSES: Programmed death ligand 1 (PD-L1) is a key target for the treatment of several malignancies. The present study was conducted to clarify the role of serum PD-L1 in hepatocellular carcinoma (HCC). METHODS: Serum PD-L1 (sPD-L1) was examined by an enzyme-linked immunosorbent assay in 153 patients with HCC who underwent curative hepatectomy at Kumamoto University in 2011-2016. The expression of PD-L1 in tissue (tPD-L1) was investigated by immunohistochemistry. The clinical roles of the PD-L1 expression in both serum and tissue were examined. RESULTS: The sPD-L1 was significantly elevated in HCC patients compared to patients without any malignant or inflammatory disease (234 vs. 93 pg/mL, p < 0.0001). The percentage of the tPD-L1-positive area (%tPD-L1) in the background liver was significantly higher than in the tumor (1.52% vs. 0.48%, p < 0.0001). The %tPD-L1 in the background liver but not in the tumor was significantly correlated with the sPD-L1 level (p = 0.0079). The sPD-L1, %tPD-L1 in the tumor, and %tPD-L1 in the background liver were not correlated with the overall survival after surgery. CONCLUSION: PD-L1-expressing cells in the background liver, but not in the tumor tissue, appeared to contribute to the sPD-L1 level. The sPD-L1 level may thus not indicate the tumor burden in patients with HCC.

Clinical role of fludeoxyglucose (18F) positron emission tomography/computed tomography (18F-FDG PET/CT) in patients with pancreatic neuroendocrine tumors.

PURPOSES: Clinical predictive markers for the malignant potential of pancreatic neuroendocrine tumors (PNETs) are limited without histological investigation. We reported previously that a loss of the regular enhancement pattern in preoperative computed tomography (CT) was correlated with the malignant tumor phenotype. This study aimed to establish whether the metabolic aspect of the tumor evaluated by fludeoxyglucose (18F) positron emission tomography/computed tomography 18F-FDG PET/CT is associated with the tumor imaging characteristics and postoperative oncological outcome. METHODS: Among 77 patients who underwent surgery with curative intent for a PNET at our institution between 2001 and 2017, 24 who received 18F-FDG PET/CT before surgery were enrolled in this study. The clinical importance of the standardized uptake value (SUVmax) was investigated with regard to tumor progression and prognosis after curative surgery. RESULTS: There were four (16%) patients with insulinoma. The mean tumor size was 17 mm and when the median value of the SUVmax (= 2.0) was measured as the cut-off value, the SUVmax ≥ 2.0 group (n = 12) was associated with large tumor size (p = 0.021), high tumor grade (p = 0.015), and irregular pattern on CT (p = 0.0055). The SUVmax was not correlated with age, gender, whether the tumor was functioning or non-functioning, or lymph node metastasis. The SUVmax ≥ 2.0 group had significantly poorer disease-free survival (median, 3.5 vs 16.2 months; p = 0.023) and poorer overall survival (median, 8.8 vs 16.2 months; p = 0.042). CONCLUSION: An SUVmax ≥ 2.0 on 18F-FDG PET/CT might be associated with higher malignant potential of PNETs.