PRIOR CONCURRENT THERAPY: Biologic therapy: No prior immunotherapy for glioblastoma multiforme No prior immunotoxins, immunoconjugates, antisense, peptide receptor antagonists, interferons, interleukins, tumor infiltrating lymphocytes, lymphokine activated killer cells, or gene therapy for glioblastoma multiforme Chemotherapy: No prior chemotherapy for glioblastoma multiforme Endocrine therapy: No prior hormonal therapy for glioblastoma multiforme Stable corticosteroid regimen for at least 5 days prior to study Radiotherapy: No prior radiotherapy for glioblastoma multiforme Surgery: Recovered from postoperative complications Other: No other concurrent investigational agents