Inclusion Criteria:  Male or female patient ≥18 years old Histologically confirmed, advanced (unresectable and/or metastatic), and well-differentiated NET of GEP or presumed GEP origin At least 1 measurable, somatostatin receptor-positive lesion according to RECIST 1.1 determined by multiphasic CT or MRI (performed within 28 days before randomization) ECOG performance status of 0 to 2  Exclusion Criteria:  Documented evidence of disease progression while on treatment (including SSAs) for locally advanced unresectable or metastatic disease Known central nervous system metastases Consecutive treatment with long-acting SSAs for more than 6 months before randomization Carcinoid symptoms that are refractory to treatment (according to the Investigator's judgement) with conventional doses of octreotide LAR or lanreotide ATG and/or to treatment with daily doses of ≤600 µg of octreotide IR Previous treatment with more than 1 cycle of targeted therapies such as mTOR inhibitors or vascular endothelial growth factor inhibitors, or more than 1 cycle of chemotherapy or interferon for GEP-NET Treatment of GEP-NET with trans-arterial chemoembolization or trans-arterial embolization within 12 months before screening Previously received radioligand therapy (PRRT) at any time