An open-labelled, uncontrolled, single-center Phase I/IIa clinical study to evaluate the safety of repeated infusions of AdVince into the hepatic artery in patients with metastatic neuroendocrine tumors (NETs), and if possible determination of maximum tolerated dose. Secondary objectives include to evaluate the anti-tumoral efficacy of AdVince infusions on metastatic neuroendocrine tumors, to determine the replication profile of AdVince and to determine the humoral (antibody) and cytokine-mediated immune response to AdVince. Minimum 12 and maximum 35 patients will be included, the number is based on the toxicity observed.