1. A single-arm, open-label, international multicenter clinical study investigating the efficacy and safety of sunitinib malate in patients with advanced metastatic highly differentiated unresectable pancreatic neuroendocrine tumors (phase IV) Primary enrollment criteria: For highly differentiated pancreatic neuroendocrine tumors that are metastatic or locally advanced and unresectable by surgery, with at least one measurable lesion and essentially normal organ function. Have not received targeted therapy. Will receive free sunitinib treatment and free imaging after enrollment 2. Phase I clinical study of sofantinib for malignant solid tumors Sofantinib is a novel structured pyrimidine small molecule antitumor drug that inhibits VEGFR1, 2, 3 and FGFR kinase activity and inhibits VEGFR2 phosphorylation and its downstream signaling, leading to inhibition of tumor vasculature. Previous studies have confirmed its efficacy in neuroendocrine tumors, and the trial is now enrolling only patients with neuroendocrine tumors. Major criteria for enrollment: Currently, we are enrolling patients with highly differentiated neuroendocrine tumors (G1/G2), at least one measurable lesion, and normal liver and kidney function and blood picture. Enrollment is free of charge for treatment with sovalteinib and for some tests and examinations.