Slow Accrual.

Primary Endpoint:

To determine the maximum tolerated dose (MTD) of vorinostat + radiation therapy (RT) in patients with locally advanced pancreatic cancer (LAPC).

Secondary Endpoints:

1. To assess the efficacy of vorinostat + RT in patients with LAPC as estimated by median overall survival.
2. To determine the radiological response as assessed by regular computer tomography (CT) and/or dynamic contrast enhanced computer tomography (DCE-CT) among patients treated with vorinostat and RT.
3. To evaluate the occurrence of symptoms and correlate to disease progression and tolerance to treatment using the MD Anderson Symptom Inventory-Gastrointestinal Module (MDASI-GI) self-reporting tool.
4. To correlate serum cytokine levels with symptoms and treatment outcomes.

The Study Drugs:

Vorinostat is designed to interfere with the growth of cancer cells.

Study Drug Dose Level:

If you are found to be eligible to take part in the study, you will begin receiving vorinostat. The dose you receive will be based on how many participants have been enrolled before you, and on the safety data available. The first group of 3 enrolled participants will be given low doses of vorinostat. If no intolerable side effects occur, the next group of 3 will be enrolled at a higher dose level. The study doctor will tell you what dose you will be receiving and how it compares to the doses other participants have received. Up to 3 dose levels will be tested.

Study Drug Administration:

On each day that you receive radiation, you will take vorinostat (as a capsule taken by mouth) in the morning with food.

Radiation:

You will receive radiation once a day on Monday through Friday, except for holidays. This schedule will be continued for 5 1/2 weeks or 28 doses total. Each radiation treatment will usually last about 10-15 minutes.

Surgical Evaluation:

After completing radiation therapy, you will come back for a follow-up visit about 6-12 weeks later.

Length of Study:

You will remain on study for up to 5 1/2 weeks. You will be taken off-study early if the disease gets worse or intolerable side effects occur.

This is an investigational study. Vorinostat is FDA approved and commercially available. The use of vorinostat for pancreatic cancer and in combination with radiation is investigational. At this time, this combination is being used in research only.

Up to 37 patients will take part in the study. All will be enrolled at M. D. Anderson.

Inclusion Criteria:

1. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
2. Patients must be >/= 18 years of age. There will be no upper age restriction.
3. Cytologic or histologic proof of adenocarcinoma of the pancreas. Patients can have tumor originating in any part of the pancreas. Islet cell tumors are not eligible. Only patients with non- metastatic, unresectable disease (American Joint Committee on Cancer (AJCC) 2002 stage T4 NX M0) are eligible. Patients who cannot undergo resection because of underlying medical problems are also eligible. Patients with regional nodal disease are eligible.
4. All patients must be staged with a physical exam, chest x-ray/CXR, and contrast-enhanced helical thin-cut abdominal CT. Unresectability is defined by CT criteria: a) evidence of tumor extension to the celiac axis or superior mesenteric (SM) artery, or b) evidence on either CT or angiogram of occlusion of the SM vein or SM/ portal vein confluence. If a tumor does not meet this definition and is found to be unresectable at surgical exploration, then that tumor is considered unresectable.
5. Patients may have received prior chemotherapy but not prior radiation therapy to the upper abdomen.
6. Bone marrow function: absolute neutrophil count (ANC) >1,500/ul. Platelets >100,000/ul.
7. Hepatic function: Total bilirubin less than 1.5mg/dL. If the patient required an endobiliary stent and/or external biliary drain, the bilirubin level must have declined on consecutive measurements indicating adequate biliary decompression; alanine aminotransferase (ALT) \

2.5 months