Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically or cytologically proven solid malignancy for which
no curative therapy exists Glioblastoma eligible if following criteria are met: Stable
performance status Stable symptoms At least 4 weeks on stable dose of dexamethasone CNS
metastases allowed if no progression or no new edema present Measurable or evaluable
disease No acute or chronic leukemia or multiple myeloma No known bone marrow involvement
with tumor

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy:
Not specified Hematopoietic: Absolute neutrophil count greater than 1500/mm3 Platelet
count at least 100,000/mm3 Hemoglobin at least 9 g/dL Hepatic: Bilirubin no greater than
2.0 mg/dL SGOT or SGPT no greater than 3 times upper limit of normal (ULN) (5 times ULN if
due to liver metastases) Renal: Creatinine no greater than 1.5 mg/dL Other: No
malabsorption syndrome due to prior surgery, gastrointestinal disease, or other unknown
reason No concurrent nonmalignant systemic disease No active uncontrolled infection No
frequent vomiting or medical condition that could interfere with oral medication uptake
(e.g., partial bowel obstruction, bowel resection, partial intestinal bypass, external
biliary diversion) No prior or concurrent malignancies at other sites except carcinoma in
situ of the cervix or adequately treated basal or squamous cell skin cancer HIV negative
No AIDS-related illness Not pregnant or nursing Fertile patients must use effective
contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: At least 4 weeks since prior biologic therapy
and recovered No prior allogeneic, syngeneic, or autologous bone marrow transplantation No
prior peripheral blood stem cell transplantation No concurrent biologic therapy
Chemotherapy: At least 4 weeks since prior chemotherapy (6 weeks for nitrosourea or
mitomycin) and recovered No concurrent chemotherapy Endocrine therapy: See Disease
Characteristics Radiotherapy: At least 4 weeks since prior radiotherapy to at least 25% of
bone marrow (including pelvic irradiation) and recovered No concurrent radiotherapy
Surgery: Prior major gastrointestinal surgery allowed (e.g., Whipple procedure) Other: At
least 4 weeks since any prior investigational therapy At least 24 hours since prior
alcohol consumption