Neoadjuvant CAN-2409 in Combination With Chemoradiation or SBRT for Borderline Resectable Pancreatic Adenocarcinoma

Inclusion Criteria: 1. Pathological diagnosis of pancreatic adenocarcinoma adequately treated with a FOLFIRINOX based induction chemotherapy for at least 4 months such that they are a candidate for localized therapy with CR or SBRT followed by surgery with or without major vascular resection. 2. Subjects must be deemed to be in adequate health to undergo major surgery (e.g., pancreaticoduodenectomy). 3. Tumor accessible for injection by EUS or CT-guidance, considered potentially resectable at time of diagnosis, and classified as borderline resectable based on central radiologic review of CT scans performed following completion of FOLFIRINOX based induction chemotherapy. Resection may include major vascular resection with reconstruction as needed. Criteria for borderline resectable disease status: * No distant metastasis or lymph node involvement outside the planned resection field. * Venous involvement of the superior mesenteric vein (SMV) or portal view (PV) with distortion or narrowing of the vein or occlusion of the vein with suitable vessel proximal and distal, allowing for safe resection and replacement * Gastroduodenal artery encasement up to the hepatic artery with either short segment encasement or direct tumor abutment of the hepatic artery, without extension to the celiac axis * Tumor abutment of the superior mesenteric artery (SMA) not to exceed \> 180 degrees of the circumference of the vessel wall 4. Age \> 18 years at the time of consent 5. Performance status ECOG 0 or 1 6. SGOT (AST) \<3x upper limit normal 7. Total bilirubin \<2mg/dl * Subjects with biliary obstruction can be enrolled if AST and bilirubin do not meet criteria but must meet the criteria after stenting before starting treatment 8. Creatinine \<2mg/dl 9. Calculated creatinine clearance \> 30ml/min 10. WBC \> 3000/mm\^3 11. Absolute neutrophil count (ANC) \> 1000/mm\^3 12. Platelets \> 100,000/mm\^3 13. Hemoglobin \> 9g/dl 14. Signed, written informed consent Exclusion Criteria: 1. Primary hepatic dysfunction including known cirrhosis or active hepatitis. Subjects with biliary obstruction must be stented prior to initiating treatment 2. Evidence of clinically significant pancreatitis as determined by the investigator 3. Evidence of significant ascites as determined by investigator 4. Subjects on systemic corticosteroid (\>10 mg prednisone per day or equivalent), systemic immunomodulators, or other systemic immunosuppressive drugs 5. Known to be HIV+ 6. Pregnant or breast-feeding. Female subjects of childbearing age must have negative serum or urine pregnancy test within 2 weeks of beginning protocol therapy 7. Other current malignancy (except squamous or basal cell skill cancers) 8. Other serious co-morbid illnesses or compromised organ function 9. Known sensitivity or allergic reactions to acyclovir or valacyclovir