Phase II Study of Axitinib (AG-013736) With Evaluation of the VEGF-pathway in Metastatic, Recurrent or Primary Unresectable Pheochromocytoma/Paraganglioma

Background: * Most treatments for malignant pheochromocytomas/paragangliomas (PHEO/PGL) are palliative and multidisciplinary. Chemotherapy using the combination of cyclophosphamide, vincristine, and dacarbazine has been successfully utilized in the management of rapidly progressive metastatic PHEO, with more than 50% complete or partial tumor response and more than 70% complete or partial biochemical response. * Vascular endothelial growth factor (VEGF) expression and evidence of angiogenesis has been found in many PHEO/PGL, so it is plausible that interfering with VEGF signaling may result in anti-tumor activity in patients with PHEO/PGL. * Axitinib (AG-013736) is an oral, potent and selective inhibitor of vascular endothelial growth factor (VEGF) receptors 1, 2, and 3. Pre-clinical data suggests that the anti-tumor activity of axitinib may result from its anti-angiogenic activity and that this is reversible when treatment is discontinued. * Given the known clinical safety and efficacy of axitinib, an assessment of its activity in PHEO/PGL and its impact on the VEGF pathway in PHEO/PGL could provide valuable information. Objectives: * Determine the response rate of metastatic PHEO/PGL to axitinib (AG-013736). * Determine the progression-free survival of metastatic PHEO/PGL treated with axitinib (AG-013736). * Explore the relationship of potential biological markers of axitinib activity with clinical outcomes. * Perform pharmacogenomics analyses of drug metabolism and transport proteins through germline deoxyribonucleic acid (DNA) examination. Eligibility: * Adults with a confirmed pathologic diagnosis of PHEO/PGL by the Laboratory of Pathology, National Cancer Institute (NCI) * Biochemical evidence of PHEO/PGL * Imaging confirmation of metastatic, locally advanced or unresectable disease. * Measurable disease at presentation * Eastern Cooperative Oncology Group (ECOG) performance status less than or equal to 2 * Patients must not have received prior therapy wi