Intraductal papillary mucinous neoplasms (IPMNs) are precancerous lesions that can progress to invasive pancreatic cancer and a key system in which to study early pancreatic tumorigenesis. We used a combination of multi-region and single-cell targeted next generation sequencing to assess the diversity of somatic driver gene mutations in IPMNs. The resulting data, combined with evolutionary modeling, whole exome sequencing, and in situ mutation detection, show that the earliest stages of pancreatic tumorigenesis are characterized by independent clones with distinct early driver gene mutations, thus revealing the polyclonal origin of precancerous pancreatic neoplasms. In addition, multiple mutations in later-occurring driver genes were also common and were frequently localized to unique tumor clones, raising the possibility of convergent evolution of these genetic events in pancreatic tumorigenesis. Collectively, our data demonstrate substantial genetic heterogeneity within IPMN, predominately in IPMNs with low-grade dysplasia. These data also challenge traditional monoclonal tumor origin models and transform our understanding of the evolutionary history of pancreatic neoplasia. Understanding the mechanism underlying polyclonal precancers may reveal new strategies to identify patients at increased risk of developing invasive pancreatic cancer
