Assessment of Systemically Administered Torisel Delivery to Brain Tumors by Intratumoral Microdialysis

Inclusion Criteria: 1. Patients must be at least 18 years of age. 2. Patients must have histologically confirmed supratentorial grade III or IV astrocytoma (anaplastic astrocytoma, anaplastic oligodendroglioma, glioblastoma multiforme) and require a stereotactic biopsy for confirmation of tumor progression or differentiation of tumor progression from treatment induced effects following radiation therapy ± chemotherapy. Patients with previous low-grade glioma who progressed after radiotherapy ± chemotherapy and are in need of a stereotactic biopsy to confirm the presence of a high-grade glioma, and this is accomplished at the time of biopsy, are eligible. 3. Patients must have a Karnofsky performance status ≥ 50% (i.e. the patient must be able to care for himself/herself with occasional help from others). 4. Patients must have had prior radiation therapy. 5. The patient is a candidate for temsirolimus as the next therapy for their tumor and the treating physician and the patient must be planning to continue temsirolimus chemotherapy after receiving the one dose required for this study. 6. Patients must have recovered from the toxicity of prior therapy. An interval of at least 3 months must have elapsed the since the completion of the most recent course of radiation therapy while at least 3 weeks must have elapsed since the completion of a non-nitrosourea containing chemotherapy regimen and at least six weeks since the completion of a nitrosourea containing chemotherapy regimen. 7. Patients must have adequate bone marrow function (defined as an absolute neutrophil count of \>1500 cells/mm3 and platelet count \>100,000 cells/mm3), liver function with Total bilirubin \<2.0 mg/dl and SGOT \<4 times upper limit of normal, and adequate renal function with serum creatinine ≤ 2 mg/dl, creatinine clearance (24 hour collection) \>50 cc/min. (Required labs must be within -7 days of catheter placement) 8. Patients must be able to provide written informed consent. 9. Patients with the potential for pregnancy or impregnating their partner must agree to follow acceptable birth control methods to avoid conception. Women of child bearing potential must have negative pregnancy test. The anti-proliferative activity of temsirolimus may be harmful to the developing fetus or nursing infant. 10. Patients must not be allergic to temsirolimus or rapamycin. Exclusion Criteria: 1. Patients with serious concurrent infection or medical illness, which would jeopardize the ability of the patient to receive the chemotherapy outlined in this protocol with reasonable safety. 2. Patients who are pregnant or breast-feeding. 3. Patients without MRI or CT evidence of measurable, contrast-enhancing residual disease are not eligible. 4. Patients receiving concurrent chemotherapeutic or investigational agents.