Sunitinib achieved fast and sustained control of VIPoma symptoms

VIPomas are rare-functioning neuroendocrine tumors (NETs). Overproduction of vasointestinal peptide (VIP) leads to the Verner-Morrison syndrome, whose management is challenging when refractory to somatostatin analogs. Two patients with progressive metastatic pancreatic NETs and refractory VIPoma symptoms were treated with sunitinib. This led to fast and sustained total relief of VIPoma symptoms, enabling earlier discharge from hospital and improvement in their quality of life. In both cases, sunitinib discontinuation led to the quick recurrence of watery diarrhea, which resolved within a few days after reintroducing sunitinib. The anti-secretory effect of sunitinib on VIPoma syndrome was probably not related to any anti-tumor effect. These observations agree with the rare reported cases of anti-secretory effects with targeted therapies. The sunitinib-driven inhibition of multiple-tyrosine kinase receptors might act on secretory pathways and describe sunitinib's ability to improve VIPoma symptoms. Sunitinib could be a therapeutic option to control refractory VIPoma symptoms in patients with NETs.