“…Candidate pathogenic mutations in untranslated regions (UTRs) and BC-relevant genes regions [18,19], including oncogenes (i.e., KRAS, ERBB3, PIK3C2G) and tumor suppressor genes (i.e., FANCC, ATR, SMAD2), were found in organoids, and the majority of them were conserved within the tumor-organoid pair ( Figure 3b, Table S5). In a few cases, mutations in driver genes comprising ATRX, BRCA2, and NF1 were found in primary tumors, but not in the derived organoids (Table S5), likely because of the selection in culture of less aberrant cell subpopulations and/or the presence of cell subpopulations at low frequencies in the originating tumors [12]. Next, we interrogated WES data for the presence of BC distinctive mutational signatures [20,21].…”