A research study of a drug called clofarabine will be used for advanced cancer in persons in which drugs are no longer effective or no reliable effective treatment is available. Clofarabine is approved by the FDA for the treatment of pediatric patients 1 to 21 years old with relapsed acute lymphoblastic leukemia (ALL) who have had at least 2 prior treatment regimens. The purpose of this study is to find the answers to the following research questions:

• 1. What is the largest dose of clofarabine that can safely be given by a needle in the arm once a week for 3 weeks (days 1, 8 and 15) followed by 1 week of rest and repeated every 28 days?
• 2. What are the side effects of clofarabine when given on this schedule?
• 3. How much clofarabine is in the blood at specific times after administration and how does the body get rid of the drug?
• 4. Will clofarabine help treat a specific cancer?

Inclusion Criteria:

• Have a pathologic diagnosis of advanced solid tumors
• After MTD is established, patients must have a measurable disease per RECIST criteria
• Be greater than or equal to 18 years old
• Not eligible for therapy of higher curative potential
• Have a Karnofsky Performance Status (KPS) greater than or equal to 70
• Have an estimated life expectancy of greater than or equal to 12 weeks
• Have a negative serum or urine pregnancy test within 7 days of study enrollment (if patient is a female of childbearing potential)
• Male and female patienst who are fertile agree to use an effective barrier method of birth control (latex condom, diaphragm, cervical cap, etc) to avoid pregnancy
• Sign a written informed consent form
• Able to comply with study procedures and follow-up examinations
• Have adequate organ function as indicated by the following laboratory values, obtained within 2 weeks prior to registration:
• Inclusion Laboratory Values: ANC: greater than or equal to 1.5 × 10 9th/L; Platelets: greater than or equal to 100 × 10 9th/L; Serum bilirubin: less than 2.0 mg/dL; AST and ALT: less than 3 ULN* without liver involvement OR less than 5 ULN* with liver involvement; Serum creatinine: less than 2.0 mg/dL; Echocardiogram shortening fraction: greater than or equal to 28%** or Ejection fraction greater than or equal to 50%**

* ULN = Institutional Upper Limit of Normal. ** Not on pharmacologic support.

Exclusion Criteria: Patients who meet any of the following criteria will be excluded from study admission:

• Received previous treatment with clofarabine.
• Have an active, uncontrolled systemic infection considered opportunistic, life threatening, or clinically significant at the time of treatment.
• Prior malignancy with less than a 2-year disease-free interval, except for adequately treated basal cell or squamous cell skin cancer. Or in situ cancer of the cervix.
• Are pregnant or lactating.
• Have a psychiatric disorder(s) that would interfere with consent, study participation, or follow-up.
• Have received any chemotherapy, major surgery, or irradiation, whether conventional or investigational, < 4 weeks before enrollment in this study (6 weeks for mitomycin-C or nitrosourea) and/or have not recovered from acute toxicity of all previous therapy prior to enrollment.
• Have any other severe concurrent disease, which, in the judgment of the investigator, would make the patient inappropriate for entry into this study (eg, uncontrolled severe insulin-dependent diabetes, uncontrolled hypertension, transient ischemic attacks, uncontrolled symptomatic coronary artery disease, etc).
• Have received prior radiation therapy to 25% of the bone marrow (eg, no whole pelvic irradiation is allowed) and not have recovered from the acute side effects of radiotherapy.
• Have received prior radiation therapy to the mediastinal region.
• Have a broncho-alveolar pattern evident on chest x-ray.
• Have symptomatic or untreated CNS metastases.