J Cancer 2016; 7(5):484-489. doi:10.7150/jca.13711

Research Paper

The Impact of PD-L1 Expression in Patients with Metastatic GEP-NETs

Seung Tae Kim1*, Sang Yun Ha2*, Sujin Lee1, Soomin Ahn2, Jeeyun Lee1, Se Hoon Park1, Joon Oh Park1, Ho Yeong Lim1, Won Ki Kang1, Kyoung-Mee Kim2✉, Young Suk Park1✉

1. Division of Hematology-Oncology, Department of Medicine,
2. Department of Pathology & Translational Genomics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
*S.T.K and S.Y.H. contributed equally to this work.

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Kim ST, Ha SY, Lee S, Ahn S, Lee J, Park SH, Park JO, Lim HY, Kang WK, Kim KM, Park YS. The Impact of PD-L1 Expression in Patients with Metastatic GEP-NETs. J Cancer 2016; 7(5):484-489. doi:10.7150/jca.13711. Available from http://www.jcancer.org/v07p0484.htm

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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.

Keywords: Programmed death-ligand 1 (PD-L1), Gastroenteropancreatic neuroendocrine tumor (GEP-NET), WHO classification.