Immunochemoradiotherapy in Patients With Pancreatic Cancer

All study participants receive an initial 4 week course of intra-dermal vaccination with telomerase vaccine (GV1001) and immune adjuvant, granulocyte macrophage colony-stimulating factor (GM-CSF), along with a cycle of gemcitabine chemotherapy. This is followed by concurrent radiation therapy and low-dose intravenous (IV) gemcitabine chemotherapy given twice weekly followed by one additional dose of vaccine. About 4 weeks (as late as 8 weeks) after chemotherapy and radiation treatment, participants with disease that can be removed by surgery will proceed to surgery. After recovery, immunochemotherapy will resume. Participants with stable or responsive disease that is not able to be treated with surgery will proceed to immunochemotherapy. Immunochemotherapy will consist of 2 cycles of telomerase vaccine with GM-CSF along with gemcitabine chemotherapy. Participants with disease that is not able to be treated with surgery, or that has worsened following immunochemoradiotherapy phase of treatment may continue on study with transition to immunochemotherapy phase of treatment. Tadalafil will be administered orally on a daily basis from start of therapy (Day 1) through completion of therapy with doses held only when required in the immediate perioperative period in patients who proceed to surgery.