Phase II Study of Pazopanib in Patients with Von Hippel-Lindau Disease.

4516 Background: Von Hippel-Lindau disease (VHL) is an autosomal dominant inherited disorder. Affected individuals develop vascular neoplastic lesions in multiple sites including eye, brain, pancreas, adrenal and kidney. Standards of care include surveillance imaging and surgical intervention. We hypothesized that treatment of VHL related lesions with an antiangiogenic agent would result in shrinkage of all lesion types. We chose the multikinase inhibitor pazopanib to test this hypothesis. Methods: After obtaining IRB approval, patients with clinical features or genetic confirmation of VHL disease and with measurable lesions were treated with pazopanib 800mg PO daily for two 12-week cycles. Efficacy was determined by RECIST after two cycles. Patients had the option to continue therapy if considered in patient’s best interest. Continuous monitoring for any lesion progression and drug discontinuation due to toxicity during the whole period of the treatment was planned. Results: Patients were enrolled (N=32) and treated (N=31) between 1/2012 and 6/2016. Median age was 37 (range 19-67). 23 patients had genomically confirmed VHL disease; four had family and personal history but had not undergone genetic testing, and five patients had clinical features of VHL disease and negative genetic testing. A median of two cycles (range 1-12) of therapy was administered. Of 31 evaluable patients, 13 (42%) showed a response, 18 patients had stable disease and no patients had PD as best response. Responses were seen in renal (2 CR and 29 PR/59 total), pancreatic (9 PR/17 total) and CNS 2 PR/49 total) target lesions. The most common side effect was diarrhea (grades 1 and 2) experienced in 14 patients. Twelve patients dose reduced to 600 mg and 6 to 400 mg pazopanib PO daily. Eight patients discontinued therapy due to adverse events of whom 4 experienced transaminitis. One patient experienced a grade V CNS hemorrhage. Conclusions: This is the largest prospective VHL disease specific therapeutic study performed to date. Pazopanib resulted in significant and sustained disease control for the majority of VHL patients enrolled on the study, with an acceptable safety profile. This agent may be considered as an alternative to surgical intervention in patients with VHL disease. Clinical trial information: NCT01436227.