Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically proven advanced cancer (except hematological cancers)
for which there is no standard therapy or have failed standard therapies

- Measurable or evaluable disease

- Clinically controlled brain metastases allowed

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- SWOG 0-2

Life expectancy:

- At least 3 months

Hematopoietic:

- Hemoglobin at least 8.0 g/dL

- Absolute neutrophil count at least 1,500/mm^3

- Platelet count at least 100,000/mm^3

Hepatic:

- Bilirubin no greater than 1.5 times upper limit of normal (ULN) (elevated bilirubin
due to Gilbert's syndrome allowed if direct bilirubin normal)

- AST less than 2.5 times ULN

Renal:

- Creatinine normal

Cardiovascular:

- No active cardiac disease

Other:

- Not pregnant or nursing

- Fertile patients must use effective contraception

- No concurrent bacterial infection requiring antibiotics

- No serious concurrent medical condition

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- No concurrent immunotherapy

Chemotherapy:

- At least 3 weeks since systemic cytotoxic chemotherapy (including gemcitabine) and
recovered

- No other concurrent chemotherapy

Endocrine therapy:

- Prior hormonal therapy allowed

- No concurrent hormonal therapy (excluding contraceptives, appetite stimulants, or
replacement steroids)

Radiotherapy:

- At least 3 weeks since radiotherapy to large areas of active bone marrow and
recovered

- No concurrent radiotherapy

Surgery:

- Recovered from prior major surgery

Other:

- No concurrent antiviral nucleosides

- At least 1 month since prior investigational agents

- No other concurrent experimental medications