Inclusion Criteria

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