Pancreatic Neuroendocrine Tumor With Liver Metastases

This prospective, non-randomized, concurrent parallel-controlled study will evaluate treatment response and resistance mechanisms in patients with pancreatic neuroendocrine tumors with liver metastases (pNET-LM) receiving second-line systemic therapy after failure of first-line treatment. Eligible patients will receive either lenvatinib combined with chemotherapy or chemotherapy alone according to the study protocol and clinical treatment strategy. The clinical efficacy and safety of the two treatment strategies will be evaluated using objective response rate (ORR), progression-free survival (PFS), overall survival (OS), and adverse events. Peripheral blood samples will be collected before treatment, during early treatment, and at disease progression. Circulating cell-free DNA (cfDNA) and peripheral blood mononuclear cells (PBMCs) will be analyzed to investigate molecular and immune changes associated with treatment response, primary resistance, and acquired resistance. The study aims to identify potential biomarkers for predicting treatment response and to improve understanding of resistance mechanisms in pNET-LM.