Oktay E.Yalcin G.D.Ekmekci S.Kahraman D.S.Yalcin A.Degirmenci M.Dirican A.Altin Z.Ozdemir O.Surmeli Z.Diniz G.Ayhan S.Bulut G.Erdogan A.Uslu R.2024-07-222024-07-22201911070625http://akademikarsiv.cbu.edu.tr:4000/handle/123456789/14522Purpose: Gastroenteropancreatic tumors (GEPNETs) is a heterogeneous disease with variable clinical course. While promising therapeutic options exist for other adult cancers, there are no new molecular-based treatments developed for GEPNETs. One of the main targets of cancer immunotherapy is the Programmed Cell Death Ligand-1 (PD-L1) pathway. Our purpose was to investigate the profile of PD-L1 expression in different organs of GEPNETs and compare the conventional immunohistochemistry (IHC) with the RNA expression analysis via real time polymerase chain reaction (RT-PCR) in order to determine which patients might be appropriate for immune check point-targeted therapy. Methods: A total of 59 surgically or endoscopically resected GEPNET tissues were retrospectively collected. The expression of PD-L1 and mRNA was evaluated with IHC. Results: The expression of PD-L1 was significantly associated with the high-grade classification (p=0.012). PD-L1 mRNA expression in tumor samples appeared to be higher compared to the corresponding normal tissues. In appendix, stomach and small intestine, the expression of PD-L1 mRNA was higher in the tumor tissues compared to the respective controls. In pancreas and colon, control tissues tend to have a higher PD-L1 mRNA expression compared to tumor tissues. PD-L1 mRNA expression was higher in GEP carcinomas (p=0.0031). Conclusion: RT-PCR was found to be more sensitive in detecting PD-L1 expression than conventional IHC. This study may provide an important starting point and useful background information for future research about immunotherapy for appendix, stomach and small intestine neuroendocrine carcinomas. © 2019 Zerbinis Publications. All rights reserved.EnglishAdolescentAdultAgedAged, 80 and overApoptosisB7-H1 AntigenCarcinoma, NeuroendocrineColonFemaleGastric MucosaGene Expression Regulation, NeoplasticHumansImmunohistochemistryImmunotherapyIntestinal NeoplasmsIntestine, SmallMaleMiddle AgedNeuroendocrine TumorsPancreasPancreatic NeoplasmsRNA, MessengerStomach NeoplasmsYoung Adultactincomplementary DNAmessenger RNAprogrammed death 1 ligand 1RNACD274 protein, humanmessenger RNAprogrammed death 1 ligand 1adultagedappendix cancerArticleclinical classificationclinical evaluationcolon cancercomparative studycontrolled studydisease associationfemalegastroenteropancreatic neuroendocrine tumorgenetic associationhumanhuman tissueimmunohistochemistrymajor clinical studymalemolecularly targeted therapymRNA expression assayneuroendocrine carcinomapancreas cancerprotein expressionreal time polymerase chain reactionretrospective studysmall intestine cancerstomach cancervery elderlyadolescentapoptosiscarcinomacolongene expression regulationgeneticsimmunohistochemistryimmunologyimmunotherapyintestine tumormetabolismmiddle agedneuroendocrine tumorpancreaspancreas tumorpathologysmall intestinestomach mucosastomach tumoryoung adultArticle