DISEASE CHARACTERISTICS:

• Histologically confirmed recurrent primary malignant glioma

  • Anaplastic astrocytoma
  • Glioblastoma multiforme
  • Anaplastic oligodendroglioma
  • Gliosarcoma
  • Anaplastic mixed oligoastrocytoma
• Measurable disease by MRI or CT
• No immediate radiotherapy required
• Neurologically stable for at least 2 weeks prior to study

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• Karnofsky 60-100%

Life expectancy:

• Greater 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:

• Blood urea nitrogen and creatinine less than 1.5 times ULN

Other:

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• HIV negative
• No other nonmalignant systemic disease
• No acute infection treated with IV antibiotics
• No frequent vomiting or other condition that would preclude oral medication administration (e.g., partial bowel obstruction)
• No other prior malignancies except surgically cured carcinoma in situ of the cervix or basal or squamous cell skin cancer

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• No more than 1 prior biologic therapy regimen

Chemotherapy:

• No more than 1 prior chemotherapy regimen
• At least 6 weeks since prior chemotherapy, unless evidence of disease progression
• No prior failure of irinotecan or temozolomide

Endocrine therapy:

• Concurrent corticosteroids allowed

Radiotherapy:

• See Disease Characteristics
• At least 6 weeks since prior radiotherapy, unless evidence of disease progression

Surgery:

• At least 3 weeks since prior surgery, unless evidence of disease progression, and recovered

Other:

• No concurrent immunosuppressive agents