Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed progressive, primary, intracranial, supratentorial,
low-grade glioma including:

- Astrocytoma

- Oligodendroglioma

- Mixed glioma

- Optic pathway glioma*

- Pontine glioma* NOTE: *Biopsy not required

- Patients with optic pathway glioma must also meet the following criteria:

- Progressive loss of vision as defined by doubling of octaves

- Visual acuity loss not explained by other causes

- Increase in proptosis of greater than 3 mm

- Increase in diameter of optic nerve of at least 2 mm on neuroimaging

- Increase in distribution of tumor involving optic tracts or optic radiations as
indicated by CT scan or MRI

PATIENT CHARACTERISTICS:

Age:

- 4 and over

Performance status:

- Karnofsky 70-100%

Life expectancy:

- More than 12 weeks

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 and SGPT less than 2.5 times ULN

- Alkaline phosphatase less than 2 times ULN

Renal:

- Creatinine less than 1.5 times ULN

- BUN less than 1.5 times ULN

Other:

- Must be neurologically stable

- No systemic disease

- No acute infection requiring IV antibiotics

- No frequent vomiting

- No other medical condition that would interfere with oral medication (e.g., partial
bowel obstruction)

- No other prior or concurrent malignancies except:

- Surgically cured carcinoma in situ of the cervix

- 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:

- No concurrent biologic therapy (growth factors or epoetin alfa)

Chemotherapy:

- At least 6 weeks since prior chemotherapy unless evidence of disease progression

- No other concurrent chemotherapy

Endocrine therapy:

- Not specified

Radiotherapy:

- At least 6 weeks since prior radiotherapy unless evidence of disease progression

- No concurrent radiotherapy

Surgery:

- At least 3 weeks since prior surgery unless evidence of disease progression

- Recovered from all prior surgery

Other:

- No other concurrent investigational drugs