5. Patients enrolling onto Arm C (FOLFIRI) or Arm D (MM-398 with 5-FU and leucovorin) must have failed one prior line of gemcitabine-based therapy with or without BBI608 in the metastatic setting. No additional lines of therapy in the metastatic setting are allowed. Prior adjuvant therapy with gemcitabine is allowed as long as disease recurrence occurred > 6 months of last dose of therapy. Toxicities related to prior therapy must have completely resolved (except for alopecia and anemia), or be deemed irreversible. Prior treatment with radiotherapy is allowed.