Mutations in BRCA1, BRCA2, and PALB2, and a panel of 50 cancer-associated genes in pancreatic ductal adenocarcinoma

Mutations in genes of the breast cancer susceptibility gene (BRCA) pathway, namely, BRCA1, BRCA2, and PALB2, can provide useful information for the efficacy of platinum-based or poly ADP-ribose polymerase inhibitors chemotherapeutic regimens. Pancreatic ductal adenocarcinoma (PDAC) is an important target for such precision chemotherapies because of its dismal prognosis. We analyzed mutations in the entire coding regions of the BRCA pathway genes, expression of breast cancer 2 (BRCA2), and mutations in hotspots of 50 cancer-associated genes in 42 surgically resected PDACs, and evaluated their associations with clinicopathological features. We identified 13 rare germline mutations in the BRCA pathway genes; 68 somatic mutations in KRAS, TP53, SMAD4, CDKN2A, GNAS, SMARCB1, and RB1; and 2 germline variations in MLH1. Among them, BRCA2(S2148fs) was known to be pathogenic. BRCA2(R18H) and BRCA2(G2044V) were enriched in tumor tissues. BRCA2(K799R) and BRCA2(R2964T) were novel germline variations. Patients harboring potentially deleterious mutations in the BRCA pathway genes showed significantly better prognosis than those with benign mutations or no mutation. These results indicate that rare germline variations in BRCA pathway genes could be found more frequently than previously anticipated and, more importantly, potentially deleterious mutations of them could be a favorable prognostic factor in patients with resectable PDACs.