Inclusion Criteria:

• All patients who have biopsy proven T3 or T4 rectal cancer which is confined to the primary tumor site with or without regional lymph node involvement
• Patients must be willing to return for follow-up
• Patients must be able to give and sign informed consent
• Patients must be suitable candidates for surgical resection post-chemoradiation, i.e. no history of severe congestive heart failure or severe pulmonary disease
• Life expectancy > 6 months

Exclusion Criteria:

• Patients with evidence of distant metastatic disease
• Any of the following hematologic abnormalities: hemoglobin (HGB) < 8.0 gm/dL unable to be corrected with a transfusion; absolute neutrophil count (ANC) < 1500 cells/mm3; platelets < 100,000/mm3; activated partial thromboplastin time (APTT) ratio or International Normalized Ratio (INR) > 1.5 (except in patients who are therapeutically anticoagulated for non-related medical conditions such as atrial fibrillation and whose anti-thrombotic treatment cannot be withheld for vector injection or surgery).
• A history of hepatic cirrhosis or present hepatic dysfunction with total bilirubin > 2.0 mg/dL except for patients with Gilbert's syndrome who must have a direct bilirubin </= 1.0 mg/dL; AST/ALT >/= 2.5 times upper limit of normal.
• Renal insufficiency as determined by a serum creatinine > 2.0 mg/dL
• Patients may not have received prior therapy with chemotherapy, biologic therapy or radiation therapy for rectal cancer
• Significant history of a medical problem that would preclude the patient from undergoing an operative procedure such as a history of severe congestive heart failure or active ischemic heart disease
• Concurrent second malignancy requiring systemic therapy
• Pregnant or lactating women
• Chronic systemic corticosteroid use
• Prior surgery for rectal cancer
• Patients with history of deep venous thrombosis or pulmonary embolism
• Patients with Doppler evidence of deep venous thrombosis at screening
• Known history of documented coagulopathy or thrombophilic disorders
• Hormone replacement therapy within one month prior to Day 1
• Known history of documented cerebrovascular disease, stroke or transient ischemic attack (TIA)
• Surgery within the last one month, excluding diverting colostomy or ileostomy for obstruction