GVAX Pancreas Vaccine (With CY) and CRS-207 With or Without Nivolumab

Inclusion Criteria: * Age ≥18 years. * Have histologically- or cytologically-proven adenocarcinoma of the pancreas. Patients with mixed histology will be excluded. * Have metastatic disease. * Have failed only 1 prior chemotherapy regimen for metastatic pancreatic cancer. * Patients with the presence of at least one measurable lesion. * Patients acceptance to have a tumor biopsy of an accessible lesion at baseline and on treatment if the lesion can be biopsied with acceptable clinical risk (as judged by the investigator). * ECOG performance status 0 or 1. * Life expectancy of greater than 3 months. * Patients must have adequate organ and marrow function defined by study-specified laboratory tests. * Must use acceptable form of birth control while on study. * Ability to understand and willingness to sign a written informed consent document. Exclusion Criteria: * known history or evidence of brain metastases. * Had surgery within the last 28 days * Have received any non-oncology vaccine therapy used for prevention of infectious diseases including seasonal vaccinations within 28 days of study treatment. * Prior treatment with anti-PD-1, anti-PD-L1, anti-PD-L2, anti-CTLA4, GVAX or CRS-207 * Systemic steroids within the last 14 days * Use more than 3 g/day of acetaminophen. * Patients on immunosuppressive agents. * Patients receiving growth factors within the last 14 days * Known allergy to both penicillin and sulfa. * Severe hypersensitivity reaction to any monoclonal antibody. * Have artificial joints or implants that cannot be easily removed * Have any evidence of hepatic cirrhosis or clinical or radiographic ascites. * Have significant and/or malignant pleural effusion * Infection with HIV or hepatitis B or C at screening * Significant heart disease * Conditions, including alcohol or drug dependence, intercurrent illness, or lack of sufficient peripheral venous access, that would affect the patient's ability to comply with study visits and procedures * Unable to avoid intimate contact with another individual known to be at high risk of listeriosis (e.g., newborn infant, pregnant woman, HIV-positive individual) during the course of CRS-207 treatment until completion of antibiotic regimen. * Are pregnant or breastfeeding. * Have rapidly progressing disease