Regorafenib in Treating Patients With Advanced or Metastatic Neuroendocrine Tumors

Inclusion Criteria: * Advanced metastatic, progressing carcinoid or pancreatic islet cell cancers * No prior targeted treatment (tx) or anti-angiogenic therapy; patients may have received one line of prior therapy with octreotide, locoregional therapy; continuation of concurrent octreotide is allowed; patients will be maintained on octreotide (sandostatin) for the duration of their treatment * Life expectancy of at least 12 weeks (3 months) * Subjects must be able to understand and be willing to sign the written informed consent form (ICF); a signed ICF must be appropriately obtained prior to the conduct of any trial-specific procedure * All acute toxic effects of any prior treatment have resolved to National Cancer Institute-Common Terminology Criteria for Adverse Events (NCI-CTCAE) version (v)4.0 grade 1 or less at the time of signing the informed consent form (ICF); exceptions to this include alopecia * Total bilirubin =\< 1.5 x the upper limits of normal (ULN) * Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) =\< 2.5 x ULN (=\< 5 x ULN for subjects with liver involvement of their cancer) * Alkaline phosphastase limit =\< 2.5 x ULN (=\< 5 x ULN for subjects with liver involvement of their cancer) * Lipase =\< 1.5 x the ULN * Amylase =\< 1.5 x the ULN * Serum creatinine =\< 1.5 x the ULN * International normalized ratio (INR)/ partial thromboplastin time (PTT) \< 1.5 x ULN; (subjects who are treated with an agent such as warfarin or heparin will be allo…