Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed glioblastoma

- Presence of oligodendroglial elements allowed provided they make up < 25% of
tumor

- Measurable disease, defined as ≥ 1 bidimensionally measurable target lesion with a
largest diameter of ≥ 2 cm by MRI within the past 2 weeks

- Recurrent disease

- Documented by MRI after failing prior therapy (usually standard radiotherapy
with concurrent and maintenance temozolomide)

- Subsequent histologic confirmation of recurrence required for patients who
received prior high-dose radiotherapy (> 65 Gy), stereotactic radiosurgery, or
internal radiotherapy

- Multifocal disease that is not amenable to radiotherapy allowed provided the patient
received no more than 1 line of prior chemotherapy

PATIENT CHARACTERISTICS:

- WHO performance status 0-2

- Absolute neutrophil count ≥ 1,500/mm³

- Platelet count ≥ 100,000/mm³

- Bilirubin < 1.5 times upper limit of normal (ULN)

- AST and ALT < 2.5 times ULN

- Alkaline phosphatase < 2.5 times ULN

- Creatinine < 1.5 times ULN

- Clinically normal cardiac function

- No ischemic heart disease within the past 12 months

- Stable ischemic heart disease (e.g., treated angina that is stable under
appropriate therapy) allowed

- No New York Heart Association class III or IV cardiac insufficiency

- No unstable angina

- No arrhythmia

- No psychological, familial, sociological, or geographical factors that would preclude
study compliance

- No other malignancy except cone-biopsied carcinoma of the cervix or adequately
treated basal cell or squamous cell skin cancer

- Not pregnant or nursing

- Negative pregnancy test

- Fertile female patients must use effective contraception during and for 3 months
after completion of study treatment

- Fertile male patients must use effective contraception during and for 6 months after
completion of study treatment

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

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

- More than 3 months since prior radiotherapy to the brain

- More than 3 months since prior surgery for recurrent primary brain tumor unless 1 of
the following criteria are met:

- Measurable residual disease documented by immediate (within 72 hours)
postoperative imaging

- Evidence of a progressive and measurable target lesion found at postoperative
follow-up

- Presence of a second measurable target lesion outside the surgical area

- Prior adjuvant temozolomide as first-line therapy allowed

- No prior chemotherapy for recurrent glioblastoma

- One prior chemotherapy regimen given as adjuvant therapy allowed

- Concurrent corticosteroids allowed provided dose is stable or decreasing for ≥ 1 week

- No concurrent phenytoin, carbamazepine, or phenobarbital

- No concurrent Hypericum perforatum (St. John's wort)

- No concurrent enzyme-inducing antiepileptic drugs (EIAEDs)

- Patients on EIAEDs should have been switched to non-EIAEDs with a wash-out
period of ≥ 1 month

- No other concurrent anticancer agents (except alternative or homeopathic medicine)

- No other concurrent investigational treatment