Abstract 1191: Differences in gene mutation characteristics of gastric, intestinal and colorectal stromal tumors

Abstract

Abstract Background: Gastrointestinal stromal tumors (GIST), which were thought to originate from interstitial cells of Cajal,is the most common malignant mesenchymal neoplasm, and account for 1%-3% of digestive tract tumors. Drug development in GIST has successfully utilized the KIT/PDGFRA oncogenic mutation. At the same time, drug sensitivity and resistance, such as imatinib resistance, is a problem should be paid more attention. We analyzed features of kit/pdgfra mutation in different region GIST of Chinese patients, which will provide reference information for the use of targeted drugs among patients with gastric, intestinal or colorectal stromal tumors. Methods: Tumor samples of 201 HCC patients were consecutively collected in China from January 2018 to June 2020, next generation sequencing (NGS) was performed to detect gene mutation by 3D Medicines, a laboratory accredited by College of American Pathologists (CAP) and Clinical Laboratory Improvement Amendments (CLIA. Results: All these tissue samples were divided as stomach (n=109), small intestine (n=79), colon and the rectum (n=13). The average age of three group were 57, 55 and 50, the proportion of males in gastric, intestinal and colorectal stromal tumor were 64.2% (79/109), 60.8% (48/79) and 61.5%(8/13), respectively. NGS analysis showed that, frequency of kit were 71.5% (78/109), 83.5% (66/79) and 61.5% (8/13), among witch, mutation of exon 9 were 1.8%(2/109), 27.8% (22/79), 30.7% (4/13), and exon 11 were 66.1%(72/109), 53.2%(42/79), 30.8%(4/13); frequency of pdgfra were 14.7%(16/109), 3.8%(3/79) and 7.7%(1/13), and mutation frequency of pdgfra exon 18 were 11.9% (13/109), 1.3%(1/79), 7.7%(1/13). Conclusions: GIST is more inclined to occur in male. kit was the main mutation in GIST, however, only 1.8% of gastric GIST carry exon 9 mutations, a large proportion (66.1% and 53.2%) of gastric and intestinal GISTs carry exon 11 mutations. Besides, more mutation of pdgfra happened in gastric GIST than intestinal and colorectal GISTs. These results demonstrate that GIST occurred in different location may show different sensitivity or resistance to drugs targeting KIT/PDGFRA signals. Citation Format: Qian Wang, Hushan Zhang, Sihui Zhao, Jianxun Wang, Ning Ma, Jun Zhu. Differences in gene mutation characteristics of gastric, intestinal and colorectal stromal tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1191.