The purpose of this Phase 1 study is to evaluate the safety and potential efficacy of Gene Mediated Cytotoxic Immunotherapy for pancreatic cancer. The approach uses an adenoviral vector (disabled virus) engineered to express the Herpes thymidine kinase gene (AdV-tk), followed by an antiherpetic prodrug, valacyclovir.

The AdV-tk vector is injected into the tumor or tumor bed at the time of biopsy or standard tumor surgery after which valacyclovir pills are taken for 14 days. Two courses of AdV-tk, each followed by valacyclovir, are given as adjuvant to standard of care therapies (surgery and/or chemoradiation) which have been shown to work cooperatively with AdV-tk to kill tumor cells. Arm A is for resectable tumors in which the first course is given prior to surgery and the second is at the time of surgery. Arm B is for locally advanced disease in which both AdV-tk injections are administered by needle injection into the tumor before and during chemoradiation. The hypothesis is that this combination therapy can be safely delivered and will lead to improvement in the clinical outcome for patients with pancreatic cancer.

Inclusion Criteria:

• Must have presumed pancreatic adenocarcinoma based on clinical and radiologic evaluation with identifiable tumor accessible for injection (pathologic diagnosis of pancreatic adenocarcinoma must be made prior to AdV-tk injection
• For Arm A, resectable disease. Arm B for locally advanced disease has completed accrual.
• Performance status must be ECOG 0-2
• SGOT (AST)<3x upper limit of normal
• Serum creatinine<2mg/dl and calculated creatinine clearance >10ml/min
• Platelets>100,000/mm3 and WBC>3000/mm3 and ANC>1500/mm3
• Must give study specific informed consent prior to enrollment

Exclusion Criteria:

• Primary hepatic dysfunction including active hepatitis but not to exclude patients due to obstructive jaundice. If obstructive jaundice is clinically significant, bilirubin should be stable or decreasing prior to enrollment.
• Evidence of clinically significant pancreatitis as determined by the investigator.
• Patients on corticosteroids or other immunosuppressive drugs
• Known HIV+ patients
• Patients with acute infections (viral, bacterial or fungal infections requiring therapy)
• Pregnant or breast-feeding patients. Female patients of childbearing age must have negative serum or urine pregnancy test within 1 week of beginning therapy
• Evidence of distant metastatic disease at the time of enrollment or other malignancy (except squamous or basal cell skin cancers) and no prior abdominal radiation therapy or prior treatment for pancreatic cancer
• Other serious co-morbid illness or compromised organ function