The safety and efficacy of pazopanib prior to planned nephrectomy in metastatic clear cell renal cancer.

Abstract

427 Background: The safety and efficacy of upfront pazopanib, prior to nephrectomy in metastatic clear cell renal cancer (mCRC), has not been prospectively evaluated. The toxicity profile of pazopanib potentially makes it an attractive agent in this setting. Methods: A single arm phase II study (PANTHER 2009-016675-29) evaluated 12–14 weeks of pazopanib prior to planned nephrectomy in untreated patients with metastatic clear cell renal cancer. Patients had MSKCC intermediate and poor risk disease. Pazopanibwas stopped for a minimum of 16 days during nephrectomy. FDG-PET and DCEMRI were performed on a subgroup of patients. The study follows a Simon 2 stage design and we present the results of the initial stage(n=34). Results: Overall 30 (88%) of patients obtained clinical benefit (by RECIST) prior to surgery. The partial response rate of the primary tumor was 21% by RECIST. No patients became inoperable due to local progression of disease. A nephrectomy was performed in 25 (74%) of patients. The reasons for not having surgery were patient choice (n=5) and progression of disease (n=4). Delayed wound healing, a post operative bleed and a post operative death occurred in 1patient each (4%). The median blood loss, hospital stay and surgical time were 350mls, 7 days and 180mins respectively. FDG-PET and DCE MRI responses were reported. Conclusions: This interim analysis suggest nephrectomy after upfront pazopanib can be performed safely in mRCC and obtains control of disease in the majority of patients.