The purpose of the study is to evaluate the efficacy, safety & patient-reported outcomes of peptide receptor radionuclide therapy (PRRT) with 177Lu-Edotreotide as 1st or 2nd line of treatment compared to best standard of care in patients with well-differentiated aggressive grade 2 and grade 3, somatostatin receptor-positive (SSTR+), neuroendocrine tumours of gastroenteric or pancreatic origin.

Inclusion Criteria:

• Patients aged ≥ 18 years.
• Histologically confirmed diagnosis of unresectable, well-differentiated GastroEnteroPancreatic NeuroEndocrine Tumors (GEP-NETs). measurable site of disease per RECIST v1.1 (Response evaluation criteria in solid tumors) using contrast computed tomography (CT) / magnetic resonance imaging (MRI).
• Somatostatin receptor-positive (SSTR+) disease.

Exclusion Criteria:

• Known hypersensitivity to Lutetium 177Lu, edotreotide, DOTA (dodecane tetraacetic acid), any of the comparators, or any excipient or derivative (e.g. rapamycin).
• Prior (Peptide Receptor Radionuclide Therapy) PRRT.
• Any major surgery within 4 weeks prior to randomization in the trial.
• Therapy with an investigational compound and/or medical device within 30 days or 7 half-life periods (whichever is longer) prior to randomization.
• Other known malignancies.
• Serious non-malignant disease.
• Renal, hepatic, cardiovascular, or hematological organ dysfunction, potentially interfering with the safety of the trial treatments.
• Pregnant or breastfeeding women.
• Patients not able to declare meaningful informed consent on their own or any other vulnerable population to that.