Clinicopathological features of tumor mutation burden, Epstein-Barr virus infection, microsatellite instability and PD-L1 status in Chinese patients with gastric cancer

Abstract Objectives: Gastric cancer (GC) is the 4th most common type of cancer worldwide. Different GC subtypes exhibit unique molecular features that may potentially guide therapeutic decisions. The aim of the present study was to investigate Epstein-Barr virus (EBV) infection, microsatellite instability (MSI) status, the expression of programmed death-ligand 1 (PD-L1) and gene mutations in patients with surgically-treated GC. Methods: The data of 2,504 GC patients, who underwent potentially curative gastrectomy with lymphadenectomy at Peking University Cancer Hospital between 2013 and 2018, were reviewed from a prospectively collected medical database. We also analyzed the clinicopathological factors associated with the immunohistochemistry (IHC) profiles of these patients, and genetic alterations were analyzed using next generation sequencing (NGS). Results: Mismatch repair-deficient (d-MMR) GC patients were found to have a higher probability of expressing PD-L1 (p<0.001, PD-L1 cutoff value = 1%). In addition, 4 and 6.9% of the 2,504 gastric cancer patients were EBV-positive and d-MMR, respectively. The number of MLH1/PMS2-negative cases was 126 (6%), and the number of MSH2/MSH6-negative cases was 14 (0.9%). d-MMR status was associated with a diffuse/mixed group (p<0.05), but not with tumor differentiation. Furthermore, MSI and d-MMR GC status (detected by NGS and IHC, respectively) were consistently high, and the rate of MSI was higher in patients with d-MMR GC. A number of genes associated with DNA damage repair were detected in GC patients with MSI, including POLE, ETV6, BRCA and RNF43. In patients with a high tumor mutation burden, the most significantly mutated genes were LRP1B (79.07%), ARID1A (74.42%), RNF43 (69.77%), ZFHX3 (65.12%), TP53 (58.14%), GANS (51.16%), BRCA2 (51.16%), PIK3CA (51.16%), NOTCH1 (51.16%), SMARCA4 (48.84%), ATR (46.51%), POLE (41.86%) and ATM (39.53%). Conclusions: Using IHC and NGS, MSI status, protein expression, TMB and genetic alterations were identified in patients with GC, which provides a theoretical basis for the future clinical treatment of GC.

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Clinicopathological features of Epstein-Barr virus infection, microsatellite instability, tumor mutation burden and PD-L1 status in Chinese patients with gastric cancer

10.21203/rs.3.rs-48875/v2 ◽

2020 ◽

Author(s):

Li Zhang ◽

Aiwen Wu ◽

Zhongwu Li

Keyword(s):

Gastric Cancer ◽

Microsatellite Instability ◽

Epstein Barr Virus ◽

Genetic Alterations ◽

Epstein Barr Virus Infection ◽

Tumor Mutation Burden ◽

Barr Virus ◽

Mutation Burden ◽

Therapeutic Decisions ◽

Epstein Barr

Abstract Objectives: Gastric cancer (GC) is the 4th most common type of cancer worldwide. Different GC subtypes exhibit unique molecular features that may potentially guide therapeutic decisions. The aim of the present study was to investigate Epstein-Barr virus (EBV) infection, microsatellite instability (MSI) status, the expression of programmed death-ligand 1 (PD-L1) and gene mutations in patients with surgically-treated GC. Methods: The data of 2,504 GC patients, who underwent potentially curative gastrectomy with lymphadenectomy at Peking University Cancer Hospital between 2013 and 2018, were reviewed from a prospectively collected medical database. We also analyzed the clinicopathological factors associated with the immunohistochemistry (IHC) profiles of these patients, and genetic alterations were analyzed using next generation sequencing (NGS). Results: Mismatch repair-deficient (d-MMR) GC patients were found to have a higher probability of expressing PD-L1 (p<0.001, PD-L1 cutoff value = 1%). In addition, 4 and 6.9% of the 2,504 gastric cancer patients were EBV-positive and d-MMR, respectively. The number of MLH1/PMS2-negative cases was 126 (6%), and the number of MSH2/MSH6-negative cases was 14 (0.9%). d-MMR status was associated with a diffuse/mixed group (p<0.05), but not with tumor differentiation. Furthermore, MSI and d-MMR GC status (detected by NGS and IHC, respectively) were consistently high, and the rate of MSI was higher in patients with d-MMR GC. A number of genes associated with DNA damage repair were detected in GC patients with MSI, including POLE, ETV6, BRCA and RNF43. In patients with a high tumor mutation burden, the most significantly mutated genes were LRP1B (79.07%), ARID1A (74.42%), RNF43 (69.77%), ZFHX3 (65.12%), TP53 (58.14%), GANS (51.16%), BRCA2 (51.16%), PIK3CA (51.16%), NOTCH1 (51.16%), SMARCA4 (48.84%), ATR (46.51%), POLE (41.86%) and ATM (39.53%). Conclusions: Using IHC and NGS, MSI status, protein expression, TMB and genetic alterations were identified in patients with GC, which provides a theoretical basis for the future clinical treatment of GC.

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