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Michael A. Vogelbaum, Jianxin X. Tong, Ryuji Higashikubo, David H. Gutmann and Keith M. Rich

Object. Genes known to be involved in the regulation of apoptosis include members of the bcl-2 gene family, such as inhibitors of apoptosis (bcl-2 and bcl-xl) and promoters of apoptosis (bax). The authors investigated a potential approach for the treatment of malignant gliomas by using a gene transfection technique to manipulate the level of an intracellular protein involved in the control of apoptosis.

Methods. The authors transfected the murine bax gene, which had been cloned into a mammalian expression vector, into the C6 rat glioma cell line. Overexpression of the bax gene resulted in a decreased growth rate (average doubling time of 32.96 hours compared with 22.49 hours for untransfected C6, and 23.11 hours for clones transfected with pcDNA3 only), which may be caused, in part, by an increased rate of spontaneous apoptosis (0.77 ± 0.15% compared with 0.42 ± 0.08% for the vector-only transfected C6 cell line; p = 0.038, two-tailed Student's t-test). Treatment with 1 µM cytosine arabinoside (ara-C) resulted in significantly more cells undergoing apoptosis in the cell line overexpressing bax than in the vector-only control cell line (23.57 ± 2.6% compared with 5.3 ± 0.7% terminal deoxynucleotidyl transferase—mediated biotinylated—deoxyuridine triphosphate nick-end labeling technique—positive cells; p = 0.007). Furthermore, measurements of growth curves obtained immediately after treatment with 0.5 µM ara-C demonstrated a prolonged growth arrest of at least 6 days in the cell line overexpressing bax.

Conclusions. These results can be used collectively to argue that overexpression of bax results in increased sensitivity of C6 cells to ara-C and that increasing bax expression may be a useful strategy, in general, for increasing the sensitivity of gliomas to antineoplastic treatments.

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Michael A. Vogelbaum, Jianxin X. Tong, Ryuji Higashikubo, David H. Gutmann and Keith M. Rich

Genes known to be involved in the regulation of apoptosis include members of the bcl-2 gene family, such as inhibitors of apoptosis (bcl-2 and bcl-xl) and promotors of apoptosis (bax). The authors investigated a potential approach for the treatment of malignant gliomas by using a gene transfection technique to manipulate the level of an intracellular protein involved in the control of apoptosis.

The authors transfected the murine bax gene, which had been cloned into a mammalian expression vector, into the C6 rat glioma cell line. Overexpression of the bax gene resulted in a decreased growth rate (average doubling time of 32.96 hours compared with 22.49 hours for untransfected C6, and 23.11 hours for clones transfected with pcDNA3 only), which may be caused, in part, by an increased rate of spontaneous apoptosis (0.77 ± 0.15% compared with 0.42 ± 0.08% for the vector-only transfected C6 cell line; p = 0.038, two-tailed Student's t-test). Treatment with 1 μM of cytosine arabinoside (ara-C) resulted in significantly more cells undergoing apoptosis in the cell line overexpressing bax than in the vector-only control cell line (23.57 ± 2.6% compared with 5.3 ± 0.7% terminal deoxynucleotidyl transferase-mediated biotinylated-deoxyuridine triphosphate nick-end labeling technique-positive cells; p = 0.007). Furthermore, measurements of growth curves obtained immediately after treatment with 0.5 μM ara-C demonstrated a prolonged growth arrest of at least 6 days in the cell line overexpressing bax.

These results can be used collectively to argue that overexpression of bax results in increased sensitivity of C6 cells to ara-C and that increasing bax expression may be a useful strategy, in general, for increasing the sensitivity of gliomas to antineoplastic treatments.

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Leland Rogers, Peixin Zhang, Michael A. Vogelbaum, Minesh P. Mehta and on behalf of the authors

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Michael A. Vogelbaum, Jianxin X. Tong, Rajashri Perugu, David H. Gutmann and Keith M. Rich

Object. Cells that lose their ability to undergo apoptosis may promote the development of neoplasms and result in resistance to clinical treatment with DNA-damaging modalities such as radio- and chemotherapy. Four established human glioma cell lines that are resistant to apoptosis were transfected with the proapoptotic gene bax and assessed for their sensitivity to a proapoptotic stimulus.

Methods. Two cell lines had a wild-type p53 genotype (U87 and D247MG) and two had mutant p53 genotypes (U138 and U373). Constitutive overexpression of murine bax was achieved in U138 and U373 only, which resulted in an increased sensitivity of these lines to the apoptosis-inducing effect of cytosine arabinoside (ara-C). Multiple attempts to produce constitutive overexpression of bax in U87 and D247MG cells resulted in spontaneous, near-complete cell loss. Vector-only control transfections were successful in all four cell lines. Inducible overexpression of bax was achieved in the U87 cells and elevated levels of BAX were observed as early as 6 hours after gene induction. This overexpression of BAX resulted in the spontaneous induction of apoptosis in these cells.

Conclusions. Overexpression of BAX in four human glioma cell lines resulted in increased sensitivity to apoptosis. In the two lines that had a wild-type p53 genotype, overexpression of BAX produced spontaneous apoptosis. In contrast, the lines that had mutant, nonfunctional P53 did not undergo spontaneous apoptosis, but they were rendered more sensitive to the apoptosis-inducing effect of ara-C. Modulation of BAX expression may be a useful therapeutic modality for gliomas, regardless of p53 genotype.

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Andrew A. Kanner, Michael A. Vogelbaum, Marc R. Mayberg, Joseph P. Weisenberger and Gene H. Barnett

Object. Intracranial navigation by using intraoperative magnetic resonance (iMR) imaging allows the surgeon to reassess anatomical relationships in near—real time during brain tumor surgery. The authors report their initial experience with a novel neuronavigation system coupled to a low-field iMR imaging system.

Methods. Between October 2000 and December 2001, 70 neurosurgical procedures were performed using the mobile 0.12-tesla PoleStar N-10 iMR imaging system. The cases included 38 craniotomies, 15 brain biopsies, nine transsphenoidal approaches, and one drainage of a subdural hematoma. Tumor resection was performed using the awake method in seven of 38 cases.

Of the craniotomies, image-confirmed complete or radical tumor resection was achieved in 28 cases, subtotal resection in eight cases, and open biopsies in two cases. Tumor resection was controlled with the use of image guidance until the final intraoperative images demonstrated that there was no residual tumor or that no critical brain tissue was at risk of compromise. In each stereotactic biopsy the location of the biopsy needle could be verified by intraoperative imaging and diagnostic tissue was obtained. Complications included a case of aseptic meningitis after a biopsy and one case of temporary intraoperative failure of the anesthesia machine. Awake craniotomies were performed successfully with no permanent neurological complications.

Conclusions. Intraoperative MR image—based neuronavigation is feasible when using the Odin PoleStar N-10 system for tumor resections that require multiple other surgical adjuncts including awake procedures, cortical mapping, monitoring of somatosensory evoked potentials, or electrocorticography. Use of the system for brain biopsies offers the opportunity of immediate verification of the needle tip location. Standard neurosurgical drills, microscopes, and other equipment can be used safely in conjunction with this iMR imaging system.

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Michael A. Vogelbaum, Cathy Brewer, Gene H. Barnett, Alireza M. Mohammadi, David M. Peereboom, Manmeet S. Ahluwalia and Shenqiang Gao

OBJECTIVE

Progress in management of high-grade gliomas (HGGs) has been hampered by poor access of potential therapeutics to the CNS. The Cleveland Multiport Catheter (CMC), which deploys 4 independent delivery microcatheters, was developed to be a reliable, high-volume delivery device for delivery of therapeutic agents to the brain and other solid organs. The authors undertook this first-in-human clinical trial effort to evaluate the delivery characteristics of the CMC in patients with HGGs.

METHODS

A series of pilot studies were launched after approval of a sponsor-investigator IND (investigational new drug) application to evaluate the delivery of topotecan and gadolinium-DTPA (Gd-DTPA) via the CMC in patients with recurrent HGG. The first pilot trial evaluated delivery into enhancing tumor and nonenhancing, tumor-infiltrated brain. Two catheters were placed with the use of a conventional frameless stereotactic technique following a biopsy to confirm tumor recurrence, and drug infusion was performed both intraoperatively and postoperatively for a total of 96 hours with the same rate for all microcatheters. Delivery was assessed by intermittent MRI.

RESULTS

Three patients were enrolled in the first pilot study. MRI demonstrated delivery from all 6 catheters (24 microcatheters). The volume of distribution (Vd) of Gd-DTPA was heavily dependent upon CMC location (enhancing vs nonenhancing) with an approximately 10-fold difference in Vd observed (p = 0.005). There were no hemorrhages related to catheter placement or removal, and all 3 patients completed the protocol-defined treatment.

CONCLUSIONS

The CMC is capable of providing backflow-resistant drug delivery to the brain and brain tumors. The volume of distribution is heavily dependent upon the integrity of the blood-brain barrier. Assessment of delivery is essential for development of loco-regionally applied therapeutics in the CNS.

Clinical trial registration no.: NCT02278510 (clinicaltrials.gov)

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Michael A. Vogelbaum, Lilyana Angelov, Shih-Yuan Lee, Liang Li, Gene H. Barnett and John H. Suh

Object

The maximal tolerated dose (MTD) for stereotactic radiosurgery (SRS) for brain tumors was established by the Radiation Therapy Oncology Group (RTOG) in protocol 90-05, which defined three dose groups based on the maximal tumor diameter. The goal in this retrospective study was to determine whether differences in doses to the margins of brain metastases affect the ability of SRS to achieve local control.

Methods

Between 1997 and 2003, 202 patients harboring 375 tumors that met study entry criteria underwent SRS for treatment of one or multiple brain metastases. The median overall follow-up duration was 10.7 months (range 3–83 months). A dose of 24 Gy to the tumor margin had a significantly lower risk of local failure than 15 or 18 Gy (p = 0.0005; hazard ratio 0.277, confidence interval [CI] 0.134–0.573), whereas the 15- and 18-Gy groups were not significantly different from each other (p = 0.82) in this regard. The 1-year local control rate was 85% (95% CI 78–92%) in tumors treated with 24 Gy, compared with 49% (CI 30–68%) in tumors treated with 18 Gy and 45% (CI 23–67%) in tumors treated with 15 Gy. Overall patient survival was independent of dose to the tumor margin.

Conclusions

Use of the RTOG 90-05 dosing scheme for brain metastases is associated with a variable local control rate. Tumors larger than 2 cm are less effectively controlled than smaller lesions, which can be safely treated with 24 Gy. Prospective evaluations of the relationship between dose to the tumor margin and local control should be performed to confirm these observations.

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Michael A. Vogelbaum, Cathy Brewer, Gene H. Barnett, Alireza M. Mohammadi, David M. Peereboom, Manmeet S. Ahluwalia and Shenqiang Gao

OBJECTIVE

Progress in management of high-grade gliomas (HGGs) has been hampered by poor access of potential therapeutics to the CNS. The Cleveland Multiport Catheter (CMC), which deploys 4 independent delivery microcatheters, was developed to be a reliable, high-volume delivery device for delivery of therapeutic agents to the brain and other solid organs. The authors undertook this first-in-human clinical trial effort to evaluate the delivery characteristics of the CMC in patients with HGGs.

METHODS

A series of pilot studies were launched after approval of a sponsor-investigator IND (investigational new drug) application to evaluate the delivery of topotecan and gadolinium-DTPA (Gd-DTPA) via the CMC in patients with recurrent HGG. The first pilot trial evaluated delivery into enhancing tumor and nonenhancing, tumor-infiltrated brain. Two catheters were placed with the use of a conventional frameless stereotactic technique following a biopsy to confirm tumor recurrence, and drug infusion was performed both intraoperatively and postoperatively for a total of 96 hours with the same rate for all microcatheters. Delivery was assessed by intermittent MRI.

RESULTS

Three patients were enrolled in the first pilot study. MRI demonstrated delivery from all 6 catheters (24 microcatheters). The volume of distribution (Vd) of Gd-DTPA was heavily dependent upon CMC location (enhancing vs nonenhancing) with an approximately 10-fold difference in Vd observed (p = 0.005). There were no hemorrhages related to catheter placement or removal, and all 3 patients completed the protocol-defined treatment.

CONCLUSIONS

The CMC is capable of providing backflow-resistant drug delivery to the brain and brain tumors. The volume of distribution is heavily dependent upon the integrity of the blood-brain barrier. Assessment of delivery is essential for development of loco-regionally applied therapeutics in the CNS.

Clinical trial registration no.: NCT02278510 (clinicaltrials.gov)

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Leland Rogers, Igor Barani, Marc Chamberlain, Thomas J. Kaley, Michael McDermott, Jeffrey Raizer, David Schiff, Damien C. Weber, Patrick Y. Wen and Michael A. Vogelbaum

Evolving interest in meningioma, the most common primary brain tumor, has refined contemporary management of these tumors. Problematic, however, is the paucity of prospective clinical trials that provide an evidence-based algorithm for managing meningioma. This review summarizes the published literature regarding the treatment of newly diagnosed and recurrent meningioma, with an emphasis on outcomes stratified by WHO tumor grade. Specifically, this review focuses on patient outcomes following treatment (either adjuvant or at recurrence) with surgery or radiation therapy inclusive of radiosurgery and fractionated radiation therapy. Phase II trials for patients with meningioma have recently completed accrual within the Radiation Therapy Oncology Group and the European Organisation for Research and Treatment of Cancer consortia, and Phase III studies are being developed. However, at present, there are no completed prospective, randomized trials assessing the role of either surgery or radiation therapy. Successful completion of future studies will require a multidisciplinary effort, dissemination of the current knowledge base, improved implementation of WHO grading criteria, standardization of response criteria and other outcome end points, and concerted efforts to address weaknesses in present treatment paradigms, particularly for patients with progressive or recurrent low-grade meningioma or with high-grade meningioma. In parallel efforts, Response Assessment in Neuro-Oncology (RANO) subcommittees are developing a paper on systemic therapies for meningioma and a separate article proposing standardized end point and response criteria for meningioma.