Treatment of VHL patients with sunitinib: Clinical observations and translational studies

e22047 Background: Von Hippel Lindau (VHL) disease induces vascular lesions in multiple organs. Surgical intervention is the treatment of choice. Effective, safe systemic therapy will greatly improve the quality of life of these individuals. Methods: Patients with genetically confirmed VHL were enrolled on an IRB approved trial. Eligibility criteria included retinal angiomas, hemangioblastomas (HBs) measuring at least 5mm, renal cell carcinoma (RCC) 1 to 3 cm and pancreatic neuroendocrine tumors (NETs) 1 to 3 cm. Patients received sunitinib 50mg/day for 28 days/14 days off for four cycles. Scans were performed at baseline, and after cycles two and four. A separate set of 20 formalin-fixed paraffin embedded HBs and 20 RCCs were used for laser scanning cytometry (LSC) analysis of total and phospho vascular endothelial growth factor receptor (pVEGFR) and phospho platelet derived growth factor receptor (pPDGFR) levels in tumor endothelium. Results: Twelve patients were evaluable for response and toxicity. Eig...