Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed malignant glioma

- Glioblastoma

- Gliosarcoma

- High-grade glioma

- Anaplastic astrocytoma

- Anaplastic mixed oligoastrocytoma

- Anaplastic oligodendroglioma

- Anaplastic ependymoma

- Must have completed radiotherapy

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- Karnofsky 60-100%

Life expectancy:

- More than 3 months

Hematopoietic:

- Absolute neutrophil count at least 1,500/mm^3

- Platelet count at least 100,000/mm^3

- Hemoglobin at least 10 g/dL

Hepatic:

- Bilirubin less than 1.5 times upper limit of normal (ULN)

- SGOT/SGPT less than 3 times ULN

- Alkaline phosphatase less than 2 times ULN

Renal:

- BUN less than 1.5 times ULN

- Creatinine less than 1.5 times ULN

Pulmonary:

- Pulmonary function test with diffusion greater than 50 OR

- Clearance by the pulmonary service

Other:

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- HIV negative

- No AIDS-related illness

- No nonmalignant systemic disease that would preclude study

- No acute infection requiring IV antibiotics

- No psychiatric condition that would preclude study compliance

- No frequent vomiting or medical condition that would interfere with oral medication
intake (e.g., partial bowel obstruction)

- No other prior or concurrent malignancy except surgically cured carcinoma in situ of
the cervix or basal cell or squamous cell skin cancer

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- No prior immunotherapy

- No prior biologic therapy

Chemotherapy:

- No prior chemotherapy

Endocrine therapy:

- Not specified

Radiotherapy:

- See Disease Characteristics

- At least 2 weeks since prior radiotherapy

Surgery:

- Not specified