Inclusion Criteria:

- The patient is at least 18 years of age.

- The patient has histologically or cytologically proven malignancy recurrent or
refractory to standard treatment or for which there is no standard therapy.

- The patient has measurable disease.

- The patient has sufficiently recovered from the acute toxic effects of previous
chemotherapy, radiotherapy (no less than 3 weeks prior to randomization), and/or
immunotherapy.

- The patient's estimated life expectancy is at least 8 weeks.

- The patient has a National Cancer Institute Common Toxicity Criteria (NCI CTC)
Performance Status between 0 and 2.

- The patient has adequate bone marrow function.

- The patient must not have active central nervous system (CNS) metastases.

Exclusion Criteria:

- The patient has any serious, uncontrolled intercurrent illness or infection.

- The patient is receiving anti-retroviral therapy (HAART) for HIV infection.

- The patient is pregnant or nursing.