title: The Impact of PD-L1 Expression in Patients with Metastatic GEP-NETs.
abstract: Programmed death-ligand 1 (PD-L1), which is expressed on many cancer cells, interacts with PD1 expressed on the surface of T cells, inhibiting the T cells and blocking the antitumor immune response. Expression of PD-L1 in gastroenteropancreatic neuroendocrine tumors (GEP-NETs) has not been studied. We investigated the impact of PD-L1 expression in 32 patients with metastatic GEP-NET. The expression of PD-L1 was evaluated using an anti-PD-L1 immunohistochemistry (IHC) antibody optimized for staining of formalin-fixed paraffin-embedded (FFPE) tissue samples. The correlation between PD-L1 and clinicopathological data including survival and response to systemic treatments was analyzed. Primary sites were 24 foregut-derived GEP-NETs, including stomach (n=1), duodenum (n=2), biliary tract (n=7), and pancreas (n=14), and 8 hindgut-derived GEP-NETs of the distal colon and rectum. Among the 32 patients with metastatic GEP-NET analyzed in this study, 7 (21.9%) had expression of PD-L1 in tumor tissues. Expression of PD-L1 was significantly associated with high-grade WHO classification (grade 3) (p=0.008) but not with gender, primary site, and number of metastatic sites (p>0.05). The status of PD-L1 expression was statistically associated with progression-free survival (PFS) for first-line systemic treatment (p=0.047). Moreover, the status of PD-L1 expression could significantly predict overall survival (p=0.037). The expression of PD-L1 was associated with higher WHO tumor grade (grade 3) in metastatic GEP-NETs. PD-L1 expression had both predictive and prognostic value for survival of patients with metastatic GEP-NETs.
authors.affiliation: 1. Division of Hematology-Oncology, Department of Medicine.
authors.forename: Seung Tae
authors.initials: ST
authors.lastname: Kim
authors.affiliation: 2. Department of Pathology & Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Sang Yun
authors.initials: SY
authors.lastname: Ha
authors.affiliation: 1. Division of Hematology-Oncology, Department of Medicine.
authors.forename: Sujin
authors.initials: S
authors.lastname: Lee
authors.affiliation: 2. Department of Pathology & Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Soomin
authors.initials: S
authors.lastname: Ahn
authors.affiliation: 1. Division of Hematology-Oncology, Department of Medicine.
authors.forename: Jeeyun
authors.initials: J
authors.lastname: Lee
authors.affiliation: 1. Division of Hematology-Oncology, Department of Medicine.
authors.forename: Se Hoon
authors.initials: SH
authors.lastname: Park
authors.affiliation: 1. Division of Hematology-Oncology, Department of Medicine.
authors.forename: Joon Oh
authors.initials: JO
authors.lastname: Park
authors.affiliation: 1. Division of Hematology-Oncology, Department of Medicine.
authors.forename: Ho Yeong
authors.initials: HY
authors.lastname: Lim
authors.affiliation: 1. Division of Hematology-Oncology, Department of Medicine.
authors.forename: Won Ki
authors.initials: WK
authors.lastname: Kang
authors.affiliation: 2. Department of Pathology & Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: Kyoung-Mee
authors.initials: KM
authors.lastname: Kim
authors.affiliation: 1. Division of Hematology-Oncology, Department of Medicine.
authors.forename: Young Suk
authors.initials: YS
authors.lastname: Park
keywords: Gastroenteropancreatic neuroendocrine tumor (GEP-NET); Programmed death-ligand 1 (PD-L1); WHO classification.