This single arm study will determine the maximum tolerated dose, and recommended dose for further development, of R547, in patients with advanced solid tumors. Groups of patients will receive ascending doses of R547 as weekly intravenous infusions administered over a) 90 minutes and b) 180 minutes, on days 1 and 8 of a 21 day cycle. In the absence of dose-limiting toxicity following the starting dose, incremental dose-escalations will be allowed in subsequent cohorts of patients until the maximum tolerated dose is reached. The anticipated time on study treatment is until disease progression or dose-limiting toxicity, and the target sample size is <100 individuals.