Abstract 1767: Molecular subclassification of gastrointestinal stromal tumors by genomic backgrounds

Abstract

Abstract Gastrointestinal stromal tumors (GISTs) are the most common gastrointestinal mesenchymal tumors. While about 10% of GISTs are known to be developed from the KIT or PDGFRA gain-of-function mutations, the rest, which is the majority of GISTs, is so-called as wild-type GISTs. There are attempts to make subclassification of wild-type GISTs in syndromic or non-syndromic group as promising for understanding of heterogeneity or treatment strategy. Genomic states of succinate dehydrogenase B (SDHB) and neurofibromatosis type 1 (NF1) have been raised as candidates for subclassification of wild-type GISTs. In this presentation, we will discuss our recent three cases of wild-type GISTs, carrying germline pathogenic variants in SDHB or NF1. Two cases with SDHB germline pathogenic variants showed stomach GISTs with good clinical course, the maintained performance status and long survival nevertheless of the recurrence. The other case with an NF1 germline pathogenic variant showed multiple GISTs in small intestine which was controlled surgically and the late onset of other clinical symptoms of NF1. These cases might clinically suggest potential prognostic and predictive markers in genomic alterations of SDHB or NF1 for the cases with wild-type GISTs. Citation Format: Hideki Yamamoto, Eiji Nakada, Seiji Kawano, Fumino Kato, Chika Fukano, Mashu Futagawa, Yusaku Urakawa, Risa Ohsumi, Sayaka Ueno, Hiroyuki Yanai, Akira Hirasawa. Molecular subclassification of gastrointestinal stromal tumors by genomic backgrounds [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1767.