RATIONALE: Vaccines made from gene-modified tumor cells may help the body build an effective immune response to kill pancreatic cancer cells. Drugs used in chemotherapy, such as cyclophosphamide, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving vaccine therapy together with cyclophosphamide may kill more tumor cells. It is not yet known whether vaccine therapy is more effective with or without cyclophosphamide in treating patients with pancreatic cancer.