Phase II trial of pazopanib in advanced/progressive malignant pheochromocytoma and paraganglioma.

ABSTRACT

INTRODUCTION: Pheochromocytomas and paragangliomas (Pheo/PGL) are rare, vascular, sometimes malignant endocrine tumors. Case reports indicate the activity of vascular endothelium growth factor receptor-targeted kinase inhibitors in these cancers. OBJECTIVES: To assess the antitumor activity and tolerability of pazopanib in progressive malignant Pheo/PGL. PATIENTS AND METHODS: This multicenter Phase II trial (MC107C) enrolled individuals ≥18 years old with disease progression ≤ 6 months prior to registration, Eastern Cooperative Oncology Group PS 0-2, and measurable disease (response evaluation criteria in solid tumors 1.0). Pazopanib was administered in 28-day cycles, with the regimen ultimately being as follows cycle 1 400 mg daily on days 1-14, cycle 2 800 mg daily on days 1-14, and then cycle 2 + 800 mg daily on all days. RESULTS: The study was halted due to poor accrual. Seven patients were enrolled (05/2011-11/2014). One patient withdrew consent prior to treatment, leaving six evaluable patients. Treatment was discontinued, due to the following reasons disease progression (4); withdrawal (1); and grade 4 (Takotsubo) cardiomyopathy (1). The median number of cycles administered was 4 (range 2-29, total 49). Four patients had >1 dose reduction due to the following reasons fatigue (1), abnormal liver tests (2), hypertension and (Takotsubo) cardiomyopathy (1), and headaches (1). Common severe (Common Terminology Criteria for Adverse Events v3.0 grades 3-5) toxicities were as follows hypertension (3/6), (Takotsubo) cardiomyopathy (2/6), diarrhea (1/6), fatigue (1/6), headache (1/6), and hematuria (1/6). One confirmed partial response was observed in PGL (17%, duration 2.4 years); median progression-free survival and overall survival were 6.5 and 14.8 months, respectively. CONCLUSION: Pazopanib has activity in Pheo/PGL requiring more study; optimal alpha- and beta-blockade are imperative pre-therapy in patients with secretory tumors, as risk of hypertension and cardiomyopathy are potentially life threatening.