DISEASE CHARACTERISTICS:

• Histologically confirmed solid tumor

  • Metastatic or unresectable disease
  • Progressive disease after prior standard therapy OR no standard therapy exists
• Hypoxia inducible factor-1α (HIF-1α)-expressing tumor by immunohistochemistry, defined as > 10% of cells staining positive for HIF-1α
• Tumor accessible by biopsy with minimal or small amount of risk to the patient

• No known brain metastases

  • Previously treated brain metastases that have remained stable for ≥ 4 months without steroids or antiseizure medication allowed at the discretion of the investigator

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2 OR
• Karnofsky 60-100%

Life expectancy

• More than 3 months

Hematopoietic

• WBC ≥ 3,000/mm^3
• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3

Hepatic

• AST and ALT ≤ 2.5 times upper limit of normal (ULN)
• Bilirubin ≤ 1.5 times ULN
• PT and PTT ≤ 1.5 times ULN

Renal

• Creatinine ≤ 1.5 mg/dL OR
• Creatinine clearance ≥ 50 mL/min

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No known HIV positivity
• No known immune deficiency syndrome
• No history of allergic reaction attributed to compounds of similar chemical or biologic composition to topotecan or to any component of the topotecan formulation
• No active peptic ulcer or gastrointestinal condition that could alter absorption or motility
• No other unstable medical illness

PRIOR CONCURRENT THERAPY:

Biologic therapy

• More than 4 weeks since prior anticancer vaccines

Chemotherapy

• More than 4 weeks since prior anticancer chemotherapy (6 weeks for nitrosoureas, mitomycin, or UCN-01)
• No concurrent chemotherapy

Endocrine therapy

• More than 4 weeks since prior anticancer hormonal therapy except gonadotropin-releasing hormone agonists
• Concurrent androgen suppression for the treatment of prostate cancer allowed

Radiotherapy

• More than 4 weeks since prior anticancer radiotherapy

Surgery

• Not specified

Other

• Recovered from prior therapy
• No prior topotecan
• At least 2 weeks since prior and no other concurrent investigational agents administered as part of a phase 0 study
• No concurrent herbal or alternative medications except a single daily multivitamin