Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically proven refractory or recurrent supratentorial
glioblastoma multiforme Bidimensionally measurable, enhancing residual disease by
T1-weighted gadolinium-enhanced MRI required within 15 days prior to treatment Stable dose
of corticosteroids required for at least 7 days prior to scan

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Karnofsky 60-100% Life
expectancy: Not specified Hematopoietic: Absolute neutrophil count at least 1,500/mm3
Platelet count at least 75,000/mm3 Hemoglobin at least 9 g/dL without blood transfusions
for 15 days prior to treatment Hepatic: AST/SGOT no greater than 3 times upper limit of
normal (ULN) Bilirubin less than 1.5 times ULN Renal: Creatinine no greater than 2 mg/dL
OR Creatinine clearance at least 40 mL/min Other: Not allergic to etoposide Effective
contraception required of fertile patients Negative serum pregnancy test required of
fertile women No other acute or chronic medical or psychiatric condition

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No prior
leflunomide (SU101) therapy No more than one prior single-agent or combination systemic
chemotherapy regimen for initial disease Radiosensitizer(s) concurrent with radiotherapy
allowed in addition to chemotherapy for primary disease At least 6 weeks since nitrosourea
or mitomycin At least 2 weeks since vincristine No prior single-agent procarbazine At
least 4 weeks since other chemotherapy No concurrent chemotherapy agents Endocrine
therapy: No concurrent hormone therapy (except medroxyprogesterone acetate for appetite
stimulation) Less than 4 weeks of prior hormonal therapy (tamoxifen or retinoids) if
failed one prior chemotherapy regimen Radiotherapy: Prior conventional radiotherapy for
initial disease required No more than one prior course of radiotherapy At least 8 weeks
since radiotherapy No prior interstitial radiotherapy No concurrent radiotherapy Surgery:
Maximally feasible resection for initial disease required No more than two resections
permitted At least 1 week since surgery and/or biopsy for disease No prior interstitial
radiotherapy or implanted BCNU-wafers No concurrent surgery (including resection,
stereotactic surgery or interstitial implants) Other: No concurrent investigational agent
At least 4 weeks since prior investigational agent At least 1 week since cholestyramine or
monoamine oxidase inhibitors