Inclusion Criteria:

- Have a pathologically confirmed diagnosis of a solid tumor malignancy that is
refractory to conventional therapy or for which no therapy exists. Patients must
have measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST)
criteria.

- Be greater than or equal to 18 years old.

- Must not be eligible for therapy of higher curative potential. (NB: Where an
alternative therapy has been shown to prolong survival in an analogous population,
that therapy will be offered to the patient prior to discussing this study.)

- Have a Karnofsky Performance Status (KPS) of greater than or equal to 70.

- Have an estimated life expectancy of greater than or equal to 12 weeks.

- Be male or a non-pregnant, non-lactating female. Patients who are fertile must agree
to use an effective barrier method of birth control (ie, latex condom, diaphragm,
cervical cap, etc.) to avoid pregnancy.

- Have a negative serum or urine pregnancy test within 10 days of study treatment (if
patient is a female of childbearing potential).

- Sign a written informed consent form.

- Have adequate organ function as indicated by the following laboratory values,
obtained within 2 weeks prior to registration: A. ANC: greater than or equal to 1.5 ×
10 ^9th/L; B. Platelets: greater than or equal to 100 × 10 ^9th/L; C.Serum bilirubin:
less than 2.0 mg/dL; D. AST and ALT: less than 3 x ULN* without liver involvement OR
less than 5 x ULN with liver involvement; E. Serum creatinine: less than or equal to
2.0 mg/dL. NOTE: ULN = Institutional Upper Limit of Normal.

Exclusion Criteria:

- Have received previous treatment with clofarabine.

- Have an active, uncontrolled systemic infection considered opportunistic, life
threatening, or clinically significant at the time of treatment.

- 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, 28 days before treatment in this study (42 days for mitomycin-C
or nitrosourea).

- Have not recovered from acute toxicities 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). Patients with
abnormal cardiac function who are in consideration for study participation should be
discussed with the Medical Monitor prior to enrollment.

- Have received prior radiation therapy to greater than or equal to 25% of the bone
marrow (eg, no whole pelvic irradiation is allowed) and have not recovered from the
acute side effects of radiotherapy.

- Have symptomatic or untreated central nervous system (CNS) metastases.