Safety of TAS-102 in Combination With Temozolomide for Metastatic Pancreatic NETs

Inclusion Criteria: * Part 1: Patients with histologically or cytologically confirmed metastatic or locally advanced NETs of any origin and grade * Part 1: Presence of evaluable OR measurable disease * Part 2: Patients with histologically confirmed unresectable or metastatic pNETs of grade 1 or 2. * Part 2: Presence of measurable disease by RECIST 1.1 criteria * Concurrent somatostatin analogues are allowed provided that the dose has been stable (+/- 10mg) for at least 8 weeks * Prior chemoembolization or radiation therapy (including Y90) must be performed at least 2 weeks before study enrollment * ECOG performance status 0-2 * Life expectancy more than 3 months * Absolute neutrophil count (ANC) ≥ 1.5 x 10\^9/L * Hemoglobin ≥ 9 g/dL * Platelets ≥ 100 x 10\^9/L * AST/ALT ≤ 3 x ULN (≤5 x ULN in case of liver metastases) * Total serum bilirubin of ≤ x institutional ULN (except for Grade 1 hyperbilirubinemia solely due to a medical diagnosis of Gilbert's syndrome) * Serum creatinine ≤ 1.5 x institutional ULN (Cockcroft and Gault formula) * Ability to take oral medication (i.e. no feeding tube) * Female patients of childbearing potential must have a negative pregnancy test (urine or serum) within 14 days prior to the start of the study drug treatment and must agree to use adequate birth control if conception is possible during the study and up to 6 months after discontinuation of study drug treatment * Male patients must agree to use adequate birth control during the study and up to 6 months after discontinuation of study drug treatment * Women who are nursing must discontinue breast feeding prior to the enrollment in the trial * Patient must be able and willing to comply with study procedures as per protocol * Patient able to understand and willing to sign and date the written voluntary informed consent form (ICF) at screening visit prior to any protocol-specific procedures Exclusion Criteria: * Part 2: Grade 3 tumors or tumors with small cell histology will be excluded * Previous treatment with TAS-102 or TMZ * History of partial or total gastrectomy * Symptomatic CNS metastases requiring treatment * Prior radiation therapy irradiating more than 10% of total bone marrow * Other active malignancy requiring treatment within the last 2 years (except for non-melanoma skin cancer, a non-invasive/in situ cancer, or indolent nonmetastatic Gleason 6 prostate cancer) * Pregnancy or breast feeding * Active infection requiring treatment * Known chronic infection with human immunodeficiency virus, hepatitis B, or hepatitis C * Major surgery within prior 4 weeks (the surgical incision should be fully healed prior to drug administration) * Any anticancer therapy treatments, including other investigational agents within prior 2 weeks * History of allergic reactions attributed to compounds of similar chemical or biologic composition to TAS-102 or TMZ * Extended field radiation within prior 4 weeks or limited field radiation within prior 2 weeks * Psychological, familial, or sociological condition potentially hampering compliance with the study protocol and follow-up schedule * Ascites, pleural effusion or pericardial fluid requiring drainage in the last 4 weeks * Uncontrolled diabetes mellitus * Intestinal obstruction * Pulmonary fibrosis * Myocardial infarction within the last 12 months, severe/unstable angina, symptomatic congestive heart failure NYHA class III or IV * Gastrointestinal hemorrhage