The purpose of this study is to compare two capsules of topotecan made by slightly different methods. This will be done by giving the drug made by the two different methods to patients orally and testing blood levels.

Inclusion Criteria:

• Written informed consent
• Patients with confirmed advanced solid tumors.
• No prior chemotherapy within 5 years of the diagnosis of SCLC (small cell lung cancer).
• At least 4 weeks since last chemotherapy, radiotherapy, biologic therapy or surgery.
• Laboratory criteria: Patients must have adequate bone marrow reserve and adequate kidney and liver function.

Exclusion criteria:

• Women who are pregnant or lactating.
• Patients of child bearing potential refusing to practice adequate contraception.
• Patients with uncontrolled vomiting.
• Active infection.
• Patients with clinical evidence of any gastrointestinal (GI) conditions which would alter GI absorption or GI motility.
• Patients requiring treatment with cyclosporin A.
• Severe medical problems other than the cancer, that would limit the ability of the patient to follow study guidelines or expose the patient to extreme risk.
• Ongoing or planned chemotherapy, immunotherapy, radiotherapy, or investigational therapy for cancer treatment.
• Use of investigational drug within 30 days prior to the first dose of study medication.