This is an open-label, non-randomized, sequentially enrolling single arm phase II trial to evaluate the activity of TAS-102 in previously treated metastatic and locally advanced unresectable pancreatic cancer after progression through or intolerance to first line chemotherapy. Trial therapy will consist of TAS-102 (Lonsurf®) 35 mg/m2 to be given orally twice daily on days 1-5 and 8-12 with cycles repeating every 28 days. The primary endpoint is to determine the progression free survival (PFS) in subjects with unresectable pancreatic adenocarcinoma.