Cancer patients with liver or renal dysfunction will be treated with rubitecan capsules to define the maximum tolerated dose and the dose-limiting toxicity in this patient population, and to perform pharmacokinetic studies of rubitecan in this patient population.

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.