The study agent is Saltikva, an attenuated Salmonella Typhimurium containing the gene for human IL-2 (Salmonella-IL2). Salmonella is a human pathogen typically spread via contaminated water supplies or foodstuffs. After ingestion, these bacteria invade the intestinal mucosa and colonize the gut associated lymphoid tissues, the liver, and the spleen. If pathogenic, symptoms persist for 7 to 14 days. These organisms are thought to be facultative intracellular parasites, which can persistently infect the endothelium, kupfer cells, and parenchymal cells of the liver for up to 12 weeks. The liver is considered a 'safe-site' for Salmonella as the preferred organ of residence after infection. The carrier state is eventually eradicated by the stimulation of cell-mediated and secretory immunity. Saltikva is a Salmonella based cancer therapeutic that has been genetically altered so it is incapable of causing any disease and is unable to mutate to a wild-type form of Salmonella, thus can never become pathogenic or harm anyone. Furthermore, Saltikva has been shown to preferentially invade and colonize within solid tumor tissues at a ratio of 1,000-10,000:1 over the normal 'safe-sites' of the liver. In addition, the Salmonella of Saltikva carries the gene for a powerful anti-cancer immune stimulant, Interleukin-2. Thus, Saltikva's mode of action is to invade and colonize solid tumors after oral ingestion, release a powerful immune stimulant directly within the tumor microenvironment thus avoiding systemic side effects, and imparts an immunologic mediated cancer cell kill.~Hypothesis: The addition of Saltikva to the standard of care regimen for Stage IV metastatic pancreatic cancer will significantly prolong the overall survival and prolong the time to disease progression.~Rationale for study design Two standard of care chemotherapeutic regimens are used for pancreatic cancer, namely, FOLFIRINOX and a Gemcitabine-based regimen. Despite these regimens, the median survival from Stage 4 metastatic pancreas cancer is 11.1 and 6.8 months, respectively. Oncologists choose these regimens based on the assessment of which regimen will be tolerated by the individual patients the FOLFIRINOX regimen is significantly more toxic and not as well tolerated as a gemcitabine based regimen.~Because of the significant lethality of metastatic pancreatic cancer and numerous studies conducted world wide with the two chemotherapeutic strategies that will be used in this trial, the investigators will use historical controls as comparison to the study arms in this trial. Furthermore, because the outcomes of chemotherapy only in patients with metastatic pancreatic cancer has been well documented, the investigators do not see the need for a control arm in this study. Lastly, although the patient numbers are small, the preliminary data is quite promising, and it would be considered unethical to have a control arm in this study.
Objectives: Assess the efficacy of multiple dose oral administration of Saltikva, an attenuated strain of Salmonella Typhimurium expressing IL-2, in patients with metastatic pancreatic cancer on standard chemotherapy (either FOLFIRINOX or Gemcitabine/Abraxane and Saltikva).~Study Rationale: The addition of Saltikva to the standard of care regimen for Stage IV metastatic pancreatic cancer will significantly prolong the overall survival and prolong the time to disease progression.~Patient Population: unresectable, metastatic pancreatic cancer patients 18 years of age or older