Results from a phase 2 trial of bortezomib (B) and sorafenib (S) in unresectable or metastatic renal cell cancer.

Abstract

495 Background: B is a small molecule proteasome inhibitor that affects multiple signaling pathways. S is an orally active multikinase inhibitor with known activity in renal cell cancer. In vitro data has shown that S and B interact synergistically in a number of neoplastic cell lines to cause apoptosis. A phase 1 trial of S and B demonstrated no unexpected toxicities. We now report the results of this phase 2 efficacy trial. Methods: Eligibility included cytologically confirmed clear cell cancer with no prior chemotherapy, PS 0-1, Cr < 1.5 mg/dl, normal LFTs. Regimen: S 200 mg PO BID and B 1mg/m2 IV days 1,4,8, & 11 every 21 days. Patients were treated until disease progression or unacceptable toxicity. The primary objective of the study was to achieve a PFS of 70 weeks. Results: Seventeen patients were enrolled between April of 2011 and January of 2013. Median age was 62y (range 44-75). Four of 17 patients had known brain metastasis on entry to the trial. Median number of cycles = 4 (range 1-45+). Response: CR/PR/SD/PD =0/1/12/4 (RR: 6%, 95% CI = 0%, 29%) Median progression free survival was 13.7 weeks; median overall survival was 110 weeks Toxicity: See table. Only 1 pts. treatment was stopped due to an AE of pancreatitis. There were no toxic deaths. The study was halted for futility. Conclusions: 1.The combination of S and B was well tolerated. 2. The RR of 6% and PFS of 13.7 weeks is not superior to S as a single agent. 3. The combination of SB is not recommended for further development. Clinical trial information: NCT 01100242.