This molecular tumor board (MTB) discussion focuses on a 46-year-old man with metastatic GI stromal tumor (GIST) who underwent an institutional review board-approved research autopsy study at our institution for patients with advanced cancer. For WES, we selected four biopsy samples (biopsy 1-4, Fig 1A) and 9 unique autopsy tumors with tumor cell content > 80% (Fig 1B). GIST is a tumor type characterized by low tumor mutational burden, consistent with the average tumor mutational burden of only 1.5 mut/Mb in this patient's tumors (Data Supplement). In our patient with GIST, who underwent research autopsy in addition to genomic evaluation of his biopsy and autopsy tumor tissues, we evaluated five ctDNA samples using targeted sequencing (Fig 1A). [Extracted from the article]