PEGPH20 is a PEGylated version of human recombinant PH20 hyaluronidase that, in preclinical studies, has been shown to remove HA from the extracellular matrix surrounding tumor cells by depolymerizing this substrate. 87% of pancreatic ductal adenocarcinomas (PDA) overexpress HA. PDA tumor tissue may be especially sensitive to the HA-degradation properties of PEGPH20 and thus more responsive to the cytotoxic effects of a given dose of gemcitabine. Modifying the extracellular environment to increase the penetration and efficacy of anti-cancer agents represents a novel approach to treating pancreatic cancer and may provide important therapeutic outcomes in patients with Stage IV Previously Untreated Pancreatic Cancer.