Immunotherapy and SBRT Study in Borderline Resectable Pancreatic Cancer

Inclusion Criteria: * A histological diagnosis of adenocarcinoma of the pancreas confirmed by pathology. * Patients must have borderline resectable pancreatic cancer with no metastatic spread as determined by a baseline diagnostic CT scan with intravenous contrast (or MRI). CT should be performed according to a defined pancreas protocol such as triphasic cross-sectional imaging with thin slices. Optimal multi-phase technique including a non-contrast phase plus arterial, pancreatic parenchymal and portal venous phase of contrast enhancement with thin cuts (3mm) throughout the abdomen is preferred. Studies must be evaluated by a radiologist and/or surgeon and deemed borderline resectable as defined below: 1. Borderline resectable- Tumors considered borderline resectable are defined as follows: 2. Venous involvement of the SMV/portal vein demonstrating tumor abutment with impingement and narrowing of the lumen, encasement of the SMV/portal vein but without encasement of the nearby arteries, or short-segment venous occlusion resulting from either tumor thrombus or encasement but with suitable vessel proximal and distal to the area of vessel involvement, allowing for safe resection and reconstruction 3. Gastroduodenal artery encasement up to the hepatic artery with either short segment encasement or direct abutment of the hepatic artery without extension to the celiac axis. 4. Tumor abutment of the SMA not to exceed greater than 180 degrees of the circumference of the vessel wall. * Tumors considered to be unresectable due to local advancement include an absence of distant metastases as well as: 1. Head: Greater than 180 degrees SMA encasement or any celiac abutment or unreconstructible SMV/portal occlusion or aortic invasion or encasement. 2. Body: Greater than 180 degrees SMA or celiac encasement or unreconstructible SMV/portal occlusion or aortic invasion. 3. Tail: SMA or celiac encasement greater than 180 degrees. 4. Nodal status: Involvement of lymph nodes beyond the field of resection should be considered unresectable due to distant spread and therefore not eligible for this protocol. * Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 1. * Serum albumin ≥ 2.0 gm/dL. * Expected survival ≥ 6 months. * Adequate organ function including: 1. Marrow: WBC ≥3000/mm\^3 and platelets ≥100,000/mm\^3. 2. Hepatic: serum total bilirubin ≤ 1.5 mg/dL, ALT (SGPT) and AST (SGOT) ≤3 x upper limit of normal (ULN) at time of enrollment. If a patient has elevated liver function tests at the time of initial presentation or develops them during work-up and they are the result of a mechanical obstruction of biliary drainage by tumor compression or invasion, a biliary drain may be placed as described in NCCN Practice Guidelines in Oncology V2.2012. If drainage allows for the liver function tests to come within inclusion criteria, the patient may be enrolled. 3. Renal: serum creatinine (sCr) ≤2.0 x ULN, or creatinine clearance (Ccr) ≥30 mL/min. * Patients must have the ability to understand the study, its inherent risks, side effects and potential benefits and be able to give written informed consent to participate. Patients may not be consented by a durable power of attorney (DPA). * All subjects of child producing potential must agree to use contraception or avoidance of pregnancy measures while enrolled on study and receiving the experimental product, and for one month after the last immunization. Exclusion Criteria: * Age \<18-years-old. * Active metastases. * Other malignancy within five years, unless the probability of recurrence of the prior malignancy is \<5% as determined by the Principal Investigator based on available information. Patient's curatively treated for squamous and basal cell carcinoma of the skin or patients with a history of malignant tumor in the past that have been disease free for at least five years are also eligible for this study. * History of organ transplant. * Current, active immunosuppressive therapy such as cyclosporine, tacrolimus, etc. * Subjects taking chronic systemic corticosteroid therapy for any reason are not eligible. Subjects may receive steroids as prophylactic anti-emetics per the mFOLFIRINOX regimen. Subjects receiving inhaled or topical corticosteroids are eligible. Subjects who require chronic systemic corticosteroids after beginning treatment, will be removed from study. * Significant or uncontrolled congestive heart failure (CHF), myocardial infarction or significant ventricular arrhythmias within the last six months. * Patient has active, uncontrolled bacterial, viral, or fungal infection(s) requiring systemic therapy. * Autoimmune disease (e.g., systemic lupus erythematosis (SLE), rheumatoid arthritis (RA), etc.). Patients with a remote history of asthma or mild active asthma are eligible. * Other serious medical conditions that may be expected to limit life expectancy to less than 2 years (e.g., active liver cirrhosis) or a serious illness in medical opinion of the clinical investigator. * Any condition, psychiatric or otherwise, that would preclude informed consent, consistent follow-up or compliance with any aspect of the study (e.g., untreated schizophrenia or other significant cognitive impairment, etc.). * A known history of allergy or hypersensitivity to any of the study drugs or any of their excipients. * Pregnant or nursing women due to the unknown effects of immunization on the developing fetus or newborn infant. (For patients with child bearing potential, a βHCG must be completed within 14 days of first treatment). * Known HIV positive. * Prior treatment with chemotherapy or radiation for pancreatic cancer or prior treatment with radiation for other diagnoses to expected pancreatic cancer treatment fields. * Current grade II or higher peripheral neuropathy.