4544 Background: BAY 43–9006 (BAY) is a Raf kinase and VEGFR inhibitor with effects on both tumor proliferation and angiogenesis. This Phase II RDT determined the effects of BAY on tumor growth in patients (pts) with stable disease (SD) after 12 wks treatment. Methods: 202 pts with advanced RCC (ECOG 1–2) entered a 12-wk induction phase (BAY 400 mg po bid). Pts with bidimensional tumor measurements remaining within 25% of baseline (SD) were then randomized (double-blind) to BAY 400 mg bid or placebo (Pb), and the progression-free rate [percentage of pts with SD or response] at 24 wks compared. Results: 65 pts with SD at 12 wks were randomized to BAY (n=32) or Pb (n=33); pt characteristics were well matched between groups. After 24 wks, 6 pts (18%) on Pb were progression-free compared with 16 pts (50%) on BAY (p=0.0077). Median progression-free survival (PFS) after randomization was greater with BAY vs Pb (23 vs 6 wks, p=0.0001, hazard ratio 0.29). BAY was restarted in 25 pts who progressed on Pb after a m...