Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed meningioma

- Recurrent or progressive disease after prior surgical resection

- Measurable disease by contrast-enhanced MRI

- Multifocal disease allowed

- No evidence of intratumor hemorrhage on pretreatment diagnostic imaging

- Stable postoperative grade 1 hemorrhage allowed

- No peripheral edema or central or systemic fluid collections ≥ grade 2 (e.g.,
pericardial effusion, pulmonary effusion, ascites)

PATIENT CHARACTERISTICS:

- Karnofsky performance status 70-100%

- Absolute neutrophil count > 1,500/mm³

- Hemoglobin > 9 g/dL

- Platelet count > 100,000/mm³

- Potassium normal*

- Calcium normal*

- Magnesium normal*

- Phosphorus normal*

- alanine aminotransferase (AST) and alanine aminotransferase (ALT) < 2.5 times upper
limit of normal (ULN)

- Bilirubin < 1.5 times ULN

- Creatinine < 1.5 times ULN OR creatinine clearance > 50 mL/min

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No excessive risk of bleeding, as defined by stroke within the past 6 months

- No active systemic bleeding (i.e., gastrointestinal bleeding or gross hematuria)

- No history of central nervous system (CNS) or intraocular bleeding or septic
endocarditis

- No concurrent severe and/or uncontrolled medical disease, including any of the
following:

- Uncontrolled diabetes

- Congestive cardiac failure

- Myocardial infarction within the past 6 months

- Poorly controlled hypertension

- History of labile hypertension

- History of poor compliance with antihypertensive regimen

- Chronic renal disease

- Active uncontrolled infection requiring intravenous antibiotics

- No acute or chronic liver disease (i.e., hepatitis, cirrhosis)

- No HIV positivity

- No impairment of gastrointestinal function or disease that may significantly alter
the absorption of imatinib mesylate, including any of the following:

- Ulcerative disease

- Uncontrolled nausea

- Vomiting

- Diarrhea

- Malabsorption syndrome

- Bowel obstruction

- Inability to swallow tablets

- No other malignancy within the past 5 years except basal cell skin cancer or cervical
carcinoma in situ NOTE: *Unless correctable with supplements

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- Recovered from prior therapy

- More than 1 week since prior tumor biopsy

- More than 2 weeks since prior surgical resection

- Prior hydroxyurea allowed provided patient has not had progressive disease or
toxicity > grade 3

- No prior imatinib mesylate or other platelet-derived growth factor-directed therapy

- At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas)*

- Chemotherapeutic agents such as etoposide that are normally given at shorter
intervals allowed even if < 4 weeks from last prior dose of chemotherapy

- At least 4 weeks since prior radiotherapy*

- At least 1 week since prior biological, immunotherapeutic, or cytostatic drugs

- At least 2 weeks since prior investigational drugs

- No concurrent warfarin NOTE: *Unless there is unequivocal evidence of tumor
progression