The purpose of this study is to determine whether SNS-595 given intravenously weekly for 3 weeks is safe.

Other objectives of this study include measuring pharmacokinetics (how long the drug can be measured in the blood) and determining the dose and dose schedule for the next phase of studies with SNS-595.

Inclusion Criteria:

• Must give written informed consent
• 18 years of age
• Advanced solid malignant tumors
• Tumor can be measured and evaluated
• Blood tests are within standard limits
• Normal blood coagulation
• ECOG Performance Status equal to 0 or 1
• Hemoglobin > or = to 9.0 g/dL
• Absolute Neutrophil Count > or = to 1,500
• Platelets > or = to 100,000
• Calculated or measured creatinine clearance < 50 mL/min
• Serum creatinine < or = 1.5 times the upper limit of normal (ULN)
• AST, ALT, Alkaline Phosphatase < 3 times ULN except if there is hepatic involvement then AST, ALT, and Alkaline Phosphatase < or = to 5 times ULN
• Total Bilirubin < or = to 2 mg/dL

Exclusion Criteria:

• Prior exposure to SNS-595
• Pregnant or breastfeeding.
• Women of childbearing potential unwilling to use an approved, effective means of contraception according to the institution's standards.
• Heart attack, stroke/TIA or other blood clotting event (deep vein thrombosis or pulmonary embolus) within 6 months before the screen visit.
• Requires kidney dialysis (hemodialysis or peritoneal).
• Known bleeding disorder (i.e., hemophilia, von Willebrand Disease, coagulopathy, etc.).
• Received an investigational agent or prior chemotherapy or immunotherapy within 28 days before first dose of SNS-595
• Receiving therapeutic anticoagulation therapy (coumadin, heparin, etc.).
• Currently receiving corticosteroids (inhaled steroids for breathing diseases are allowed) or seizure medications.
• Any medical, psychological, or social condition that, in the opinion of the Principal Investigator, would contraindicate the patient's participation in the clinical trial due to safety and or compliance with study procedures.