Abstract 3102: The Chilean gastric cancer task force: Final report

Background: Globally, gastric cancer (GC) ranks as the third cause of cancer related mortality. Like most malignancies, GC is characterized by its heterogeneity. In Chile, GC is the leading cause of cancer death claiming >3,000 deaths/year. Given its high heterogeneity an effective GC patient stratification may improve clinical outcomes. Here, we describe the results of the Chilean Gastric Cancer Task Force (GCTF) a descriptive cross sectional study (ClinicalTrials.gov identifier: NCT03158571, registered May 18, 2017) reporting clinical, genomic and protein expression data in a cohort of 224 patients. Methods: Demographic and basic information was obtained from 224 Chilean patients. We assessed p53, p16, HER2, and PDL1 expression and markers of Microsatellite Instability (MSI) by Tissue Microarray (TMA). We also assessed Epstein Barr Virus (EBV) status in a subset of 90 patients. Using Next Generation Sequencing (NGS), we profiled 143 cancer-related genes in a subset of 116 patients. Results: Patients were predominantly male (63.4%) staged III/IV (39.3 and 21.9%, respectively). Tumors were preferentially located at the stomach body (38.4%). Median overall survival (OS) was 39.0 months. By TMA analysis, 26.7% of patients were PDL1+, 13.3% were EBV+, and 13.3% MSI+. 36.7% were p16+, 13.3% HER2+3 and 56% possessed p53 overexpression. NGS confirmed TP53 as the most frequently mutated gene, followed by PI3KCA, VHL, PTEN and KRAS, together with alterations in numerous other actionable genes. Conclusions. Our data in Chilean GC patients demonstrate EBV+ is present at a higher proportion than reported in other geographical regions. In line with the published literature in South America, most patients were males staged III/IV. As anticipated, molecular analysis confirmed p53 as the most frequently altered gene in our cohort. A high number of further genomic alterations within actionable genes may allow the use of precision medicine within the Chilean population. Citation Format: Mauricio P. Pinto, Ignacio N. Retamal, Maria Loreto Bravo, Matias Munoz-Medel, Miguel Cordova-Delgado, Diego Romero, Maria Jose Maturana, Nathaly De La Jara, Javiera Torres, Manuel Espinoza, Carlos Balmaceda, Matias Freire, Valentina Garate-Calderon, Javier Caceres-Molina, Gonzalo Sepulveda-Hermosilla, Rodrigo Lizana, Liliana Ramos, Fernando Crovari, Ricardo Armisen, Alejandro Corvalan, Gareth I. Owen, Marcelo Garrido. The Chilean gastric cancer task force: Final report [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3102.