DISEASE CHARACTERISTICS:

• Histologically confirmed advanced malignancy
• No active brain metastases (as indicated by clinical symptoms, cerebral edema, or progressive tumor growth) that have been unstable for at least 8 weeks

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2

Life expectancy

• At least 12 weeks

Hematopoietic

• Absolute neutrophil count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3
• Hemoglobin at least 9 g/dL

Hepatic

• Bilirubin no greater than 1.5 times upper limit of normal (ULN)
• AST and ALT no greater than 2.5 times ULN (5 times ULN if liver metastases are present)

Renal

• Creatinine no greater than 1.5 times ULN
• No history of hemorrhagic cystitis
• No history of microscopic hematuria associated with drug therapy or radiotherapy or of unknown origin

Cardiovascular

• No significant cardiac disease

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• Able to comply with study schedule and assessments
• No other significant nonmalignant systemic disease
• No active infection
• No other condition that would in the investigator's opinion make the patient an inappropriate study candidate

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• No more than 3 prior chemotherapy regimens
• More than 4 weeks since prior chemotherapy

Endocrine therapy

• Not specified

Radiotherapy

• More than 4 weeks since prior definitive radiotherapy (except for palliative reasons to sites of nonmeasurable disease, in patients with measurable disease at baseline)
• Concurrent palliative radiotherapy allowed

Surgery

• More than 4 weeks since prior major thoracic or abdominal surgery

Other

• Recovered from prior therapy (except alopecia or stable grade 1 neuropathy)
• More than 4 weeks since prior investigational agents
• No prior myeloablative therapy