KRAS and pancreatic ductal adenocarcinoma: NRG1 fusions occur in ~ 3% NSCLC, ~ 1.5% pancreatic cancer and less than 1% of other cancers, and are detected frequently in KRAS–wildtype pancreatic ductal adenocarcinomas (PDAC) providing a potential drug target for those patients who do not benefit from KRAS inhibitors.