Inclusion Criteria:

          -  Pathological diagnosis of pancreatic adenocarcinoma adequately treated with induction
             chemotherapy for at least 2 months such that they are a candidate for localized
             therapy with chemoradiation followed by surgery with or without major vascular
             resection.

          -  Patients must be deemed to be in adequate health to undergo major surgery
             (pancreaticoduodenectomy)

          -  Tumor accessible for injection that is classified as borderline-resectable or locally
             advanced but considered potentially resectable after central review by surgical
             investigators (based upon pre-induction chemotherapy imaging). Resection may include
             major vascular resection with reconstruction as needed.

          -  Age 18-76 years

          -  Performance status ECOG 0-1

          -  SGOT (AST)<3x upper limit of normal

          -  Total bilirubin ≤2mg/dl

          -  Creatinine<2mg/dl

          -  Calculated creatinine clearance >30ml/m

          -  WBC>3000/mm3

          -  Absolute neutrophil count (ANC)>1500/mm3

          -  Platelets>100,000/mm3

          -  Hemoglobin > 9 g/dL.

          -  Patients must give study specific informed consent prior to enrollment

        Exclusion Criteria:

          -  Primary hepatic dysfunction including known cirrhosis or active hepatitis. Patients
             with biliary obstruction must be stented prior to initiating treatment.

          -  Evidence of clinically significant pancreatitis as determined by the investigator

          -  Evidence of significant ascites as determined by the investigator

          -  Patients on systemic corticosteroids (>10 mg prednisone per day or equivalent) or
             other systemic immunosuppressive drugs

          -  Known to be HIV+

          -  Pregnant or breast-feeding. Female patients of childbearing age must have negative
             serum or urine pregnancy test within 1 week of beginning therapy.

          -  Other current malignancy (except squamous or basal cell skin cancers)

          -  Other serious co-morbid illness or compromised organ function

          -  Known sensitivity or allergic reactions to acyclovir or valacyclovir