Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically confirmed supratentorial anaplastic
oligodendroglioma or anaplastic oligoastrocytoma not requiring immediate radiotherapy
Newly diagnosed, progressive, or recurrent disease Bidimensionally measurable disease At
least 1.5 cm2 by MRI

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 70-100% Life
expectancy: More than 12 weeks Hematopoietic: Neutrophil count at least 1,500/mm3 Platelet
count at least 100,000/mm3 Hemoglobin at least 10 g/dL Hepatic: Bilirubin less than 1.5
times upper limit of normal (ULN) SGOT/SGPT less than 2.5 times ULN Alkaline phosphatase
less than 2 times ULN Renal: BUN less than 1.5 times ULN Creatinine less than 1.5 times
ULN Other: Neurologically stable No nonmalignant systemic disease No acute infection
treated with intravenous antibiotics No frequent vomiting No medical condition (e.g.,
partial bowel obstruction) that would interfere with oral medication intake No other prior
or concurrent malignancy except surgically cured carcinoma in situ of the cervix or basal
cell or squamous cell carcinoma of the skin No AIDS-related illness HIV negative Not
pregnant or nursing Negative pregnancy test Fertile patients must use effective
contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: No more than 1 prior biologic therapy No
concurrent biologic therapy No concurrent growth factors (e.g., epoetin alfa)
Chemotherapy: No more than 1 prior chemotherapy regimen No other concurrent chemotherapy
Endocrine therapy: Must be on stable dose of steroids for at least 1 week prior to study
Concurrent steroids allowed Radiotherapy: See Disease Characteristics No concurrent
radiotherapy Surgery: At least 2 weeks since prior surgical resection (newly diagnosed
patients must be enrolled within 28 days of surgery or biopsy) Recovered from prior major
surgery Other: No other concurrent investigational drugs