DISEASE CHARACTERISTICS:

• Histologically confirmed diagnosis of 1 of the following:

  • Glioblastoma multiforme (GBM) (phase I only)

    • Progressive disease despite standard therapy

    • Progressive disease based on 1 of the following:

      • New or progressive (25% bidimensional increase) soft tissue masses on CT scan or MRI
      • New or prior lesions that have increased in size by physical examination
    • Patients who had prior interstitial brachytherapy or stereotactic radiosurgery must have confirmation of true disease progression (rather than radiation necrosis) by positron-emission tomography scan, thallium scanning, magnetic resonance spectroscopy, or surgical documentation

  • Castrate metastatic prostate cancer (closed to accrual as of 10/19/2006) (phase I and II)

    • Progressive disease despite standard therapy AND castrate levels < 50 ng/dL of testosterone

    • Progressive disease based on 1 or more of the following:

      • A minimum of 3 rising levels of prostate-specific antigen (PSA) that are obtained 1 or more weeks apart OR 2 rising PSA values obtained more than 1 month apart with at least a 25% increase over the range of values
      • New or progressive (25% bidimensional increase) soft tissue masses on CT scan or MRI
      • New metastatic lesions
    • Patients on an antiandrogen as part of initial therapy must show disease progression after discontinuation of the antiandrogen
    • Patients who have not undergone surgical orchiectomy must continue with medical therapy (e.g., gonadotropin-releasing hormone analogs) to maintain castrate levels of serum testosterone
• No brain metastases

PATIENT CHARACTERISTICS:

Age

• Over 18

Performance status

• Karnofsky 70-100%

Life expectancy

• More than 3 months

Hematopoietic

• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3
• WBC ≥ 3,000/mm^3

Hepatic

• ALT and AST ≤ 2.5 times upper limit of normal (ULN)
• Bilirubin ≤ 1.5 mg/dL

Renal

• Creatinine within 1.5 times ULN (< 1.95 mg/dL at MSKCC)

Cardiovascular

• No significant cardiovascular disease
• No congestive heart failure
• No New York Heart Association class III or IV cardiac disease
• No active angina pectoris
• No myocardial infarction within the past 6 months

Other

• Not pregnant
• Negative pregnancy test
• Fertile patients must use effective contraception
• No serious medical illness
• No severe infection
• No severe malnutrition

• No other active malignancy except non-melanoma skin cancer

  • Patients are not considered to have an active malignancy if they have completed prior therapy and currently have a < 30% risk for relapse

PRIOR CONCURRENT THERAPY:

Biologic therapy

• No concurrent biological therapy
• No concurrent immunotherapy

Chemotherapy

• No concurrent chemotherapy

Endocrine therapy

• See Disease Characteristics

Radiotherapy

• See Disease Characteristics
• More than 4 weeks since prior radiotherapy
• No concurrent radiotherapy

Surgery

• See Disease Characteristics
• Prior recent resection of recurrent or progressive GBM allowed provided patient has recovered
• More than 4 weeks since prior major surgery

Other

• Recovered from all prior therapy
• More than 4 weeks since prior investigational anticancer drugs
• No concurrent anticonvulsant that interacts with CYP3A4 (e.g., phenytoin, carbamazepine, or phenobarbital)
• No other concurrent cytotoxic therapy
• No other concurrent investigational or commercial agents or therapies for the malignancy