The initial dose level of STA 5312 will be 6 mg/m2. The starting dose level was chosen based on preclinical animal studies that used alternate day dosing x 3/week on alternate weeks. The dose level of 6 mg/m2 represents less than 1/10 the weekly dose (3 mg/m2 x 3) that demonstrated severe toxicity. Subsequent dose escalations will follow an accelerated titration design once the 8 mg/m2 cohort is completed No fewer than 3 patients will be enrolled at each dose level. Once a DLT is observed the cohort will be expanded to at least six subjects. If one-third of at least 6 subjects treated at a dose level experience a DLT, dose escalation will terminate. The dose below this will be considered the MTD and will be expanded to at least 12 subjects to collect additional safety and pharmacokinetic data. No intrasubject dose escalations will occur.