ARID1A and neoplasm: We found that 27 of 28 samples (13 original tumor and 15 tumor organoids) (96.4%) exhibited somatic mutations, including mutations in tumor protein 53 (TP53; 71%), BRCA1-associated protein 1 (BAP1; 25%), the proto-oncogene GTPase KRAS (17%), AT-rich interaction domain 1A (ARID1A; 17%), and isocitrate dehydrogenase (IDH)-1/2 (7%) (Fig. 3a).