DISEASE CHARACTERISTICS:

• Histologically confirmed malignant tumors deemed to be incurable or refractory to therapy

  • Advanced, recurrent, or metastatic disease
• Previously treated with at least 1 chemotherapy regimen
• Brain metastases allowed if asymptomatic and controlled (e.g., after prior surgical resection or radiotherapy/radiosurgery) and not on steroids or anticonvulsants

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Karnofsky 60-100%

Life expectancy:

• Not specified

Hematopoietic:

• WBC at least 3,500/mm3
• Absolute granulocyte count at least 1,500/mm3
• Platelet count at least 75,000/mm3

Hepatic:

• Bilirubin no greater than 2.5 times upper limit of normal (ULN)
• SGOT no greater than 2.5 times ULN

Renal:

• Creatinine clearance at least 60 mL/min OR
• Creatinine no greater than 1.6 mg/dL

Other:

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 3 months after study

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No concurrent biologic therapy

Chemotherapy:

• See Disease Characteristics
• At least 4 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosourea)

Endocrine therapy:

• See Disease Characteristics
• No concurrent hormonal therapy

Radiotherapy:

• See Disease Characteristics
• At least 4 weeks since prior radiotherapy and recovered
• No prior radiotherapy to a field containing a measurable target lesion unless there is evidence of progression or a new lesion is present
• No concurrent radiotherapy to measurable lesions

Surgery:

• See Disease Characteristics
• At least 3 weeks since prior major surgery and recovered

Other:

• At least 2 weeks since prior proton pump inhibitors (e.g., omeprazole)
• Concurrent H2 blockers (e.g., cimetidine or related drugs) or antacids are allowed if there is an interval of at least 2 hours between H2 blocker/antacid intake and R115777 dosing