Safety and pharmacokinetics of the dual action Raf kinase and vascular endothelial growth factor receptor inhibitor, BAY 43-9006, in patients with advanced, refractory solid tumors

Purpose: BAY 43-9006, a novel multikinase inhibitor, prevents tumor growth by combining two antitumor activities: inhibition of both tumor cell proliferation and tumor angiogenesis. This phase 1, open-label, nonrandomized, noncontrolled, single-arm, dose escalation study was done to determine the maximum tolerated dose (MTD), safety profile, pharmacokinetic variables, effect on biomarkers, and tumor response with BAY 43-9006 in 19 patients with advanced, refractory solid tumors. Experimental Design: BAY 43-9006 was given orally in repeated cycles of 1-week on/1-week off. The study comprised five dose levels, ranging from 100 mg twice daily (bid) to 800 mg bid. Treatment of each patient continued until unacceptable toxicity, tumor progression, or death. Results: Rash and hypertension were the dose-limiting toxicities at the 800 mg bid dose requiring study drug discontinuation; therefore, the MTD of BAY 43-9006 in this study was determined to be 600 mg bid. BAY 43-9006 was generally well tolerated, with mild to moderate toxicities. Pharmacokinetic analysis showed early absorption followed by delayed secondary peaks and slow terminal elimination. Stable disease was achieved in five patients: one patient showed reduced tumor activity (positron emission tomography scan) and reduced mitogen-activated protein kinase signaling (lower phospho-ERK); one patient remained on treatment until study end point. Conclusions: The results confirm the favorable safety profile of BAY 43-9006 and support the development of this compound for the treatment of solid tumors.