A Study Evaluating Lanreotide as Maintenance Therapy in Patients With Non-Resectable Duodeno-Pancreatic Neuroendocrine Tumors (REMINET)

Inclusion Criteria: * Metastatic (synchronous or metachronous) or locally advanced, non-resectable, well-differentiated duodeno-pancreatic neuroendocrine tumour, of grade 1 or 2 (WHO 2010 classification; Ki-67 ≤ 20%) * Progressive before first-line treatment * Histologically confirmed (either on primary tumour or metastases) * Pathological diagnosis validated by the NET consulting pathologist * Documented stable disease or objective response after first-line treatment, within 4 weeks (28 days) prior to randomisation * The first-line treatment will consist of either a chemotherapy or biotherapy (everolimus or sunitinib) as referred to TNCD or ENETS guidelines. Treatment must have been administered for 3 to 6 months for chemotherapy and for 6 months for biotherapy * Non-functional tumour or gastrinoma controlled by PPIs * Age \> or = 18 years * WHO 0, 1 or 2 * Effective contraception for male or female patients of childbearing age, defined as: oral contraceptives, intra-uterine devices, barrier contraceptive methods along with a spermicide gel, or surgical sterilisation. Female patients should use this contraception throughout the treatment period and for 6 months after the last treatment administration. Male patients should use contraception throughout the treatment period and for 3 months after the last treatment administration. * Signed informed consent prior to initiation of any study-specific procedures or treatment. Exclusion Criteria: * History of haematological malignancy or other cancer, except those treated for more than 5 years and considered as cured, carcinoma in situ of the cervix and treated skin cancer (excluding melanoma) * Poorly differentiated neuroendocrine carcinoma or NET grade 3 ENETS (Ki-67 \> 20%) * If primary resected, bone metastasis exclusively * Pre-treatment by somatostatin long-acting analogue * Total bilirubin ≥ 60 µmol/L * Uncontrolled diabetes * Contraindication to product used in the study or its components * Tumour arising in the context of a genetic disease * Pregnancy or lactation * Patients unable to undergo medical follow-up due to geographical, social, psychological or legal reasons * Concomitant participation in another clinical trial investigating a treatment during the treatment phase and within 30 days prior to the start of the study treatment.