Henry Brem

Johns Hopkins University, Baltimore, Maryland, United States

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Publications (283)1259.09 Total impact

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    ABSTRACT: We examined the relationship between the O(6)-methylguanine-methyltransferase (MGMT) methylation status and clinical outcomes in newly diagnosed glioblastoma multiforme (GBM) patients who were treated with Gliadel wafers (Eisai, Tokyo, Japan). MGMT promoter methylation has been associated with increased survival among patients with GBM who are treated with various alkylating agents. MGMT promoter methylation, in DNA from 122 of 160 newly diagnosed GBM patients treated with Gliadel, was determined by a quantitative methylation-specific polymerase chain reaction, and was correlated with overall survival (OS) and recurrence-free survival (RFS). The MGMT promoter was methylated in 40 (32.7%) of 122 patients. The median OS was 13.5 months (95% confidence interval [CI] 11.0-14.5) and RFS was 9.4 months (95% CI 7.8-10.2). After adjusting for age, Karnofsky performance score, extent of resection, temozolomide (TMZ) and radiation therapy (RT), the newly diagnosed GBM patients with MGMT methylation had a 15% reduced mortality risk, compared to patients with unmethylated MGMT (hazard ratio 0.85; 95% CI 0.56-1.31; p=0.46). The patients aged over 70years with MGMT methylation had a significantly longer median OS of 13.5months, compared to 7.6months in patients with unmethylated MGMT (p=0.027). A significant difference was also found in older patients, with a median RFS of 13.1 versus 7.6months for methylated and unmethylated MGMT groups, respectively (p=0.01). Methylation of the MGMT promoter in newly diagnosed GBM patients treated with Gliadel, RT and TMZ, was associated with significantly improved OS compared to the unmethylated population. In elderly patients, methylation of the MGMT promoter was associated with significantly better OS and RFS. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Journal of Clinical Neuroscience 08/2015; DOI:10.1016/j.jocn.2015.07.003 · 1.32 Impact Factor
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    ABSTRACT: Checkpoint molecules like programmed death-1 (PD-1) and T-cell immunoglobulin mucin-3 (TIM-3) act as negative regulators of the immune system and can be upregulated in the setting of glioblastoma multiforme (GBM). Combined PD-1 blockade and stereotactic radiosurgery (SRS) have been shown to improve antitumor immunity and produce long-term survivors in a murine glioma model. However, tumor-infiltrating lymphocytes can express multiple checkpoints (including TIM-3), and expression of 2 or more checkpoints corresponds to a more exhausted T-cell phenotype. Here, we hypothesized that the addition of a second checkpoint-blocking antibody could achieve additive or synergistic antitumor effects. C57BL/6 mice were implanted with mouse glioma cell line GL261 transfected with luciferase and randomized into 8 treatment arms: (1) control, (2) SRS, (3) anti-PD-1 antibody, (4) anti-TIM-3 antibody, (5) anti-PD-1 + SRS, (6) anti-TIM-3 + SRS, (7) anti-PD-1 + anti-TIM-3, and (8) anti-PD-1 + anti-TIM-3 + SRS. Overall survival was measured. Brain, cervical lymph nodes, and peripheral blood were harvested on day 21 to assess immune activation. Survival benefits were demonstrated with combined anti-TIM-3 antibody + SRS compared with anti-TIM-3 antibody alone with a median survival (MS) of 92 vs 25 days and overall survival (OS) of 50% vs 0%, respectively (P < .001 by log-rank Mantel-Cox). Dual blockade with anti-TIM-3 + anti-PD-1 antibody also improved survival compared with TIM-3 blockade alone (MS of 146 vs 25 days, OS 60% vs 0%, respectively, P < .05). Notably, the triple-modality treatment (anti-PD-1 + anti-TIM-3 + SRS) provided a significant improvement in survival compared with all other treatment arms with an OS of 100% by day 146 (P < .05). Flow cytometry of organs harvested on day 21 showed that, compared with dual-therapy groups, mice treated with the triple-modality treatment had increased tumor infiltration by interferon-gamma+ (IFN-γ) and tumor necrosis factor-alpha+ (TNF-α)-producing CD4 T cells, as well as IFN-γ+ CD8 lymphocytes. Combining anti-TIM-3 with anti-PD-1 and radiation was synergistic and conferred a significant survival benefit.
    Neurosurgery 08/2015; 62 Suppl 1, CLINICAL NEUROSURGERY:212. DOI:10.1227/01.neu.0000467105.60300.04 · 3.03 Impact Factor
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    ABSTRACT: Craniectomy defects following resection of calvarial lesions are most often reconstructed using on-table manufacturing. With the advent of computer-aided design/manufacturing and customized craniofacial implants (CCIs), there seems to be more suited alternatives. In this study, the authors report their institutional experience and outcome using immediate, single-stage, CCI-based reconstruction for benign and malignant skull neoplasm defects. A retrospective review of a prospectively maintained database of all implant cranioplasties performed between 2011 and 2014, by a single craniofacial surgeon at a tertiary academic medical institution was performed. Preoperative and postoperative computed tomography scans with 3D reconstruction were performed for the purpose of assessing adequate resection and reconstructive outcomes. Primary endpoints included length of surgery, predicted defect versus postoperative implant surface area, contour irregularities, and complications. Of the 108 patients with cranioplasty identified, 7 patients were found to undergo immediate CCI-based reconstruction for calvarial neoplasms; 4 patients (4/7, 57%) presented with malignant pathology. All defects were >5 cm. As compared with their original size, all implants were modified intraoperatively between 0.2% and 40.8%, with a mean of 13.8%. With follow-up ranging between 1 and 16 months, there were no implant-related complications identified. The immediate and long-term aesthetic results, as well as patient satisfaction, were ideal. With this preliminary experience, the authors have successfully demonstrated that immediate customized implant reconstructive techniques, by way of intraoperative modification, are both safe and feasible for benign and malignant skull neoplasms. The authors believe that with wider acceptance of this multidisciplinary approach and increased surgeon familiarity, this technique will soon become the reconstructive standard of care.
    The Journal of craniofacial surgery 07/2015; 26(5):1456-1462. DOI:10.1097/SCS.0000000000001816 · 0.68 Impact Factor
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    ABSTRACT: Effective blood-brain tumor barrier penetration and uniform solid tumor distribution can significantly enhance therapeutic delivery to brain tumors. Hydroxyl-functionalized, generation-4 poly(amidoamine) (PAMAM) dendrimers, with their small size, near-neutral surface charge, and the ability to selectively localize in cells associated with neuroinflammation may offer new opportunities to address these challenges. In this study we characterized the intracranial tumor biodistribution of systemically delivered PAMAM dendrimers in an intracranial rodent gliosarcoma model using fluorescence-based quantification methods and high resolution confocal microscopy. We observed selective and homogeneous distribution of dendrimer throughout the solid tumor (∼6 mm) and peritumoral area within fifteen minutes after systemic administration, with subsequent accumulation and retention in tumor associated microglia/macrophages (TAMs). Neuroinflammation and TAMs have important growth promoting and pro-invasive effects in brain tumors. The rapid clearance of systemically administered dendrimers from major organs promises minimal off-target adverse effects of conjugated drugs. Therefore, selective delivery of immunomodulatory molecules to TAM, using hydroxyl PAMAM dendrimers, may hold promise for therapy of glioblastoma. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Biomaterials 06/2015; 52:507-16. DOI:10.1016/j.biomaterials.2015.02.053 · 8.31 Impact Factor
  • Plastic and Reconstructive Surgery 05/2015; 135(5S Suppl):36-37. DOI:10.1097/01.prs.0000465489.84283.e6 · 3.33 Impact Factor
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    ABSTRACT: Patients with glioblastoma (GBM) have an inherently shortened survival because of their disease. It has been recently shown that carmustine wafers in addition to other therapies (surgery, temozolomide, and radiation) can further extend survival. There is concern, however, that these therapies may increase infection risk. The goals of this study were to calculate the incidence of postoperative infection, evaluate if carmustine wafers changes the risk of infection and identify factors independently associated with an infection following GBM surgery. All patients who underwent non-biopsy, surgical resection of an intracranial GBM from 2007 to 2011 at a single institution were retrospectively reviewed. Stepwise multivariate proportional hazards regression analysis was used to identify factors associated with infection, including the use of carmustine wafers. Variables with P < 0.05 were considered statistically significant. Four hundred and one patients underwent resection of an intracranial GBM during the reviewed period, and 21 (5%) patients developed an infection at a median time of 40 [28-286] days following surgery. The incidence of infection was not higher in patients who had carmustine wafers, and this remained true in multivariate analyses to account for differences in treatment cohorts. The factors that remained significantly associated with an increased risk of infection were prior surgery [RR (95% CI); 2.026 (1.473-4.428), P = 0.01], diabetes mellitus [RR (95% CI); 6.090 (1.380-9.354)], P = 0.02], and increasing duration of hospital stay [RR (95% CI); 1.048 (1.006-1.078); P = 0.02], where the greatest risk occurred with hospital stays >5 days [RR (95% CI); 3.904 (1.003-11.620), P = 0.05]. These findings may help guide treatment regimens aimed at minimizing infection for patients with GBM.
    Neurological Research 04/2015; DOI:10.1179/1743132815Y.0000000042 · 1.45 Impact Factor
  • Neuro-Oncology 04/2015; 17(suppl 3):iii38-iii38. DOI:10.1093/neuonc/nov061.154 · 5.29 Impact Factor
  • PLoS ONE 04/2015; 10(4):e0123721. DOI:10.1371/journal.pone.0123721 · 3.23 Impact Factor
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    ABSTRACT: Malignant gliomas, including glioblastoma and anaplastic astrocytomas, are characterized by their propensity to invade surrounding brain parenchyma, making curative resection difficult. These tumors typically recur within two centimeters of the resection cavity even after gross total removal. As a result, there has been an emphasis on developing therapeutics aimed at achieving local disease control. In this review, we will summarize the current developments in the delivery of local therapeutics, namely direct injection, convection-enhanced delivery and implantation of drug-loaded polymers, as well as the application of these therapeutics in future methods including microchip drug delivery and local gene therapy.
    Therapeutic delivery 04/2015; 6(3):353-69. DOI:10.4155/tde.14.114
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    ABSTRACT: The advent of interstitial chemotherapy has significantly increased therapeutic options for patients with malignant glioma. Interstitial chemotherapy can deliver high concentrations of chemotherapeutic agents, directly at the site of the brain tumor while bypassing systemic toxicities. Gliadel, a locally implanted polymer that releases the alkylating agent carmustine, given alone and in combination with various other antitumor and resistance modifying therapies, has significantly increased the median survival for patients with malignant glioma. Convection enhanced delivery, a technique used to directly infuse drugs into brain tissue, has shown promise for the delivery of immunotoxins, monoclonal antibodies, and chemotherapeutic agents. Preclinical studies include delivery of chemotherapeutic and immunomodulating agents by polymer and microchips. Interstitial chemotherapy was shown to maximize local efficacy and is an important strategy for the efficacy of any multimodal approach.
    Surgical Neurology International 02/2015; 6(Suppl 1):S78-84. DOI:10.4103/2152-7806.151345 · 1.18 Impact Factor
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    ABSTRACT: Biodegradable polymeric nanoparticles have the potential to be safer alternatives to viruses for gene delivery; however, their use has been limited by poor efficacy in vivo. In this work, we synthesize and characterize polymeric gene delivery nanoparticles and evaluate their efficacy for DNA delivery of herpes simplex virus type I thymidine kinase (HSVtk) combined with the prodrug ganciclovir (GCV) in a malignant glioma model. We investigated polymer structure for gene delivery in two rat glioma cell lines, 9L and F98, to discover nanoparticle formulations more effective than the leading commercial reagent Lipofectamine 2000. The lead polymer structure, poly(1,4-butanediol diacrylate-co-4-amino-1-butanol) end-modified with 1-(3-aminopropyl)-4-methylpiperazine, is a poly(beta-amino ester) (PBAE) and formed nanoparticles with HSVtk DNA that were 138 ± 4 nm in size and 13 ± 1 mV in zeta potential. These nanoparticles containing HSVtk DNA showed 100% cancer cell killing in vitro in the two glioma cell lines when combined with GCV exposure, while control nanoparticles encoding GFP maintained robust cell viability. For in vivo evaluation, tumor-bearing rats were treated with PBAE/HSVtk infusion via convection-enhanced delivery (CED) in combination with systemic administration of GCV. These treated animals showed a significant benefit in survival (p=0.0012 vs. control). Moreover, following a single CED infusion, labeled PBAE nanoparticles spread completely throughout the tumor. This study highlights a nanomedicine approach that is highly promising for the treatment of malignant glioma.
    ACS Nano 02/2015; 9(2). DOI:10.1021/nn504905q · 12.88 Impact Factor
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    ABSTRACT: We assessed the antiangiogenic effects of subconjunctival injection of Fc-endostatin (FcE) using a human vascular endothelial growth factor-induced rabbit corneal neovascularization model. Angiogenesis was induced in rabbit corneas through intrastromal implantations of VEGF polymer implanted 2 mm from the limbus. NZW rabbits were separated into groups receiving twice weekly subconjunctival injections of either saline; 25 mg/mL bevacizumab; 2 mg/mL FcE; or 20 mg/mL FcE. Corneas were digitally imaged at 5 time points. An angiogenesis index (AI) was calculated (vessel length (mm) × vessel number score) for each observation. All treatment groups showed a significant decrease in the vessel length and AI compared to saline on all observation days (í µí±ƒ < 0.001). By day 15, FcE 2 inhibited angiogenesis significantly better than FcE 20 (í µí±ƒ < 0.01). There was no significant difference between FcE 2 and BV, although the values trended towards significantly increased inhibition by BV. BV was a significantly better inhibitor than FcE 20 by day 8 (í µí±ƒ < 0.01). FcE was safe and significantly inhibited new vessel growth in a rabbit corneal neovascularization model. Lower concentration FcE 2 exhibited better inhibition than FcE 20, consistent with previous FcE studies referencing a biphasic dose-response curve. Additional studies are necessary to further elucidate the efficacy and clinical potential of this novel angiogenesis inhibitor.
    Journal of Ophthalmology 01/2015; In Press(Article ID 137136). · 1.94 Impact Factor
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    ABSTRACT: The NCCN Guidelines for Central Nervous System Cancers provide multidisciplinary recommendations for the clinical management of patients with cancers of the central nervous system. These NCCN Guidelines Insights highlight recent updates regarding the management of metastatic brain tumors using radiation therapy. Use of stereotactic radiosurgery (SRS) is no longer limited to patients with 3 or fewer lesions, because data suggest that total disease burden, rather than number of lesions, is predictive of survival benefits associated with the technique. SRS is increasingly becoming an integral part of management of patients with controlled, low-volume brain metastases.
    Journal of the National Comprehensive Cancer Network: JNCCN 11/2014; 12(11):1517-23. · 4.24 Impact Factor
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    ABSTRACT: Metastases represent the most common brain tumors in adults. Surgical resection alone results in 45% recurrence and is usually accompanied by radiation and chemotherapy. Adequate chemotherapy delivery to the CNS is hindered by the blood-brain barrier. Efforts at delivering chemotherapy locally to gliomas have shown modest increases in survival, likely limited by the infiltrative nature of the tumor. Temozolomide (TMZ) is first-line treatment for gliomas and recurrent brain metastases. Doxorubicin (DOX) is used in treating many types of breast cancer, although its use is limited by severe cardiac toxicity. Intracranially implanted DOX and TMZ microcapsules are compared with systemic administration of the same treatments in a rodent model of breast adenocarcinoma brain metastases. Outcomes were animal survival, quantified drug exposure, and distribution of cleaved caspase 3. Intracranial delivery of TMZ and systemic DOX administration prolong survival more than intracranial DOX or systemic TMZ. Intracranial TMZ generates the more robust induction of apoptotic pathways. We postulate that these differences may be explained by distribution profiles of each drug when administered intracranially: TMZ displays a broader distribution profile than DOX. These microcapsule devices provide a safe, reliable vehicle for intracranial chemotherapy delivery and have the capacity to be efficacious and superior to systemic delivery of chemotherapy. Future work should include strategies to improve the distribution profile. These findings also have broader implications in localized drug delivery to all tissue, because the efficacy of a drug will always be limited by its ability to diffuse into surrounding tissue past its delivery source.
    Proceedings of the National Academy of Sciences 10/2014; 111(45). DOI:10.1073/pnas.1313420110 · 9.81 Impact Factor
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    ABSTRACT: Background 3-bromopyruvate (3-BrPA) and dichloroacetate (DCA) are inhibitors of cancer-cell specific aerobic glycolysis. Their application in glioma is limited by 3-BrPA's inability to cross the blood-brain-barrier and DCA's dose-limiting toxicity. The safety and efficacy of intracranial delivery of these compounds were assessed.
    Neuro-Oncology 07/2014; 17(1). DOI:10.1093/neuonc/nou143 · 5.29 Impact Factor
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    ABSTRACT: There is great promise that ongoing advances in the delivery of therapeutics to the central nervous system (CNS) combined with rapidly expanding knowledge of brain tumor patho-biology will provide new, more effective therapies. Brain tumors that form from brain cells, as opposed to those that come from other parts of the body, rarely metastasize outside of the CNS. Instead, the tumor cells invade deep into the brain itself, causing disruption in brain circuits, blood vessel and blood flow changes, and tissue swelling. Patients with the most common and deadly form, glioblastoma (GBM) rarely live more than 2 years even with the most aggressive treatments and often with devastating neurological consequences. Current treatments include maximal safe surgical removal or biopsy followed by radiation and chemotherapy to address the residual tumor mass and invading tumor cells. However, delivering effective and sustained treatments to these invading cells without damaging healthy brain tissue is a major challenge and focus of the emerging fields of nanomedicine and viral and cell-based therapies. New treatment strategies, particularly those directed against the invasive component of this devastating CNS disease, are sorely needed. In this review, we (1) discuss the history and evolution of treatments for GBM, (2) define and explore three critical barriers to improving therapeutic delivery to invasive brain tumors, specifically, the neuro-vascular unit as it relates to the blood brain barrier, the extra-cellular space in regard to the brain penetration barrier, and the tumor genetic heterogeneity and instability in association with the treatment efficacy barrier, and (3) identify promising new therapeutic delivery approaches that have the potential to address these barriers and create sustained, meaningful efficacy against GBM.
    Frontiers in Oncology 07/2014; 4:126. DOI:10.3389/fonc.2014.00126
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    ABSTRACT: Background Glioblastoma (GBM) is the most common malignant brain tumor in adults and is associated with a poor prognosis. Cytotoxic T lymphocyte antigen -4 (CTLA-4) blocking antibodies have demonstrated an ability to generate robust antitumor immune responses against a variety of solid tumors. 4-1BB (CD137) is expressed by activated T lymphocytes and served as a co-stimulatory signal, which promotes cytotoxic function. Here, we evaluate a combination immunotherapy regimen involving 4-1BB activation, CTLA-4 blockade, and focal radiation therapy in an immune-competent intracranial GBM model. Methods GL261-luciferace cells were stereotactically implanted in the striatum of C57BL/6 mice. Mice were treated with a triple therapy regimen consisted of 4-1BB agonist antibodies, CTLA-4 blocking antibodies, and focal radiation therapy using a small animal radiation research platform and mice were followed for survival. Numbers of brain-infiltrating lymphocytes were analyzed by FACS analysis. CD4 or CD8 depleting antibodies were administered to determine the relative contribution of T helper and cytotoxic T cells in this regimen. To evaluate the ability of this immunotherapy to generate an antigen-specific memory response, long-term survivors were re-challenged with GL261 glioma en B16 melanoma flank tumors. Results Mice treated with triple therapy had increased survival compared to mice treated with focal radiation therapy and immunotherapy with 4-1BB activation and CTLA-4 blockade. Animals treated with triple therapy exhibited at least 50% long-term tumor free survival. Treatment with triple therapy resulted in a higher density of CD4+ and CD8+ tumor infiltrating lymphocytes. Mechanistically, depletion of CD4+ T cells abrogated the antitumor efficacy of triple therapy, while depletion of CD8+ T cells had no effect on the treatment response. Conclusion Combination therapy with 4-1BB activation and CTLA-4 blockade in the setting of focal radiation therapy improves survival in an orthotopic mouse model of glioma by a CD4+ T cell dependent mechanism and generates antigen-specific memory.
    PLoS ONE 07/2014; 9(7). DOI:10.1371/journal.pone.0101764. · 3.23 Impact Factor
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    ABSTRACT: Extravascular optical coherence tomography (OCT), as a noninvasive imaging methodology with micrometer resolution, was evaluated in a murine model of carotid atherosclerosis by way of assessing the efficacy of pravastatin therapy. An OCT device was engineered for extravascular plaque imaging. Wild-type mice and apolipoprotein E-deficient (ApoE(-/-)) mice were randomized to 3 treatment groups: (1) wild-type on a diet of standard rodent chow (n=13); (2) ApoE(-/-) on a high-fat, atherosclerotic diet (HFD; n=13); and (3) ApoE(-/-) on a HFD given daily pravastatin (n=13). Mice were anesthetized and the left common carotid was surgically exposed. Three-dimensional (3D; 2 spatial dimensions+time) and 4D (3 spatial dimensions+time) OCT images of the vessel lumen patency were evaluated. After perfusion, in situ OCT imaging was performed for statistical comparison with the in vivo results and final histology. Intraoperative OCT imaging positively identified carotid plaque in 100% of ApoE(-/-) mice on HFD. ApoE(-/-) mice on HFD had a significantly decreased lumen patency when compared with that in wild-type mice (P<0.001). Pravastatin therapy was found to increase lumen patency significantly in ApoE(-/-) mice on HFD (P<0.01; compared with ApoE(-/-) on HFD). The findings were confirmed with OCT imaging after perfusion and histology. OCT imaging offers the potential for real-time, detailed vessel lumen evaluation, potentially improving surgical accuracy and outcomes during cerebrovascular neurosurgical procedures. Pravastatin significantly increases vessel lumen patency in the ApoE(-/-) mouse on HFD.
    Stroke 03/2014; 45(4). DOI:10.1161/STROKEAHA.113.002970 · 6.02 Impact Factor
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    ABSTRACT: Object The aim of this study was to demonstrate that paclitaxel could function as a radiosensitizer for malignant glioma in vitro and in vivo. Methods The radiosensitizing effect of paclitaxel was tested in vitro using the human U373MG and rat 9L glioma cell lines. Cell cycle arrest in response to paclitaxel exposure was quantified by flow cytometry. Cells were subsequently irradiated, and toxicity was measured using the clonogenic assay. In vivo studies were performed in Fischer 344 rats implanted with intracranial 9L gliosarcoma. Rats were treated with control polymer implants, paclitaxel controlled-release polymers, radiotherapy, or a combination of the 2 treatments. The study end point was survival. Results Flow cytometry demonstrated G2-M arrest in both U373MG and 9L cells following 6-12 hours of paclitaxel exposure. The order in which the combination treatment was administered was significant. Exposure to radiation treatment (XRT) during the 6-12 hours after paclitaxel treatment resulted in a synergistic reduction in colony formation. This effect was greater than the effect from either treatment alone and was also greater than the effect of radiation exposure followed by paclitaxel. Rats bearing 9L gliosarcoma tumors treated with paclitaxel polymer administration followed by single-fraction radiotherapy demonstrated a synergistic improvement in survival compared with any other treatment, including radiotherapy followed by paclitaxel treatment. Median survival for control animals was 13 days; for those treated with paclitaxel alone, 21 days; for those treated with XRT alone, 21 days; for those treated with XRT followed by paclitaxel, 45 days; and for those treated with paclitaxel followed by XRT, more than 150 days (p < 0.0001). Conclusions These results indicate that paclitaxel is an effective radiosensitizer for malignant gliomas because it renders glioma cells more sensitive to ionizing radiation by causing G2-M arrest, and induces a synergistic response to chemoradiotherapy.
    Journal of Neurosurgery 03/2014; 120(5). DOI:10.3171/2014.1.JNS13235 · 3.15 Impact Factor
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    ABSTRACT: The development of noninvasive methods to detect and monitor tumors continues to be a major challenge in oncology. We used digital polymerase chain reaction-based technologies to evaluate the ability of circulating tumor DNA (ctDNA) to detect tumors in 640 patients with various cancer types. We found that ctDNA was detectable in >75% of patients with advanced pancreatic, ovarian, colorectal, bladder, gastroesophageal, breast, melanoma, hepatocellular, and head and neck cancers, but in less than 50% of primary brain, renal, prostate, or thyroid cancers. In patients with localized tumors, ctDNA was detected in 73, 57, 48, and 50% of patients with colorectal cancer, gastroesophageal cancer, pancreatic cancer, and breast adenocarcinoma, respectively. ctDNA was often present in patients without detectable circulating tumor cells, suggesting that these two biomarkers are distinct entities. In a separate panel of 206 patients with metastatic colorectal cancers, we showed that the sensitivity of ctDNA for detection of clinically relevant KRAS gene mutations was 87.2% and its specificity was 99.2%. Finally, we assessed whether ctDNA could provide clues into the mechanisms underlying resistance to epidermal growth factor receptor blockade in 24 patients who objectively responded to therapy but subsequently relapsed. Twenty-three (96%) of these patients developed one or more mutations in genes involved in the mitogen-activated protein kinase pathway. Together, these data suggest that ctDNA is a broadly applicable, sensitive, and specific biomarker that can be used for a variety of clinical and research purposes in patients with multiple different types of cancer.
    Science translational medicine 02/2014; 6(224):224ra24. DOI:10.1126/scitranslmed.3007094 · 14.41 Impact Factor

Publication Stats

11k Citations
1,259.09 Total Impact Points


  • 1990–2015
    • Johns Hopkins University
      • • Department of Neurosurgery
      • • Department of Biomedical Engineering
      • • Department of Medicine
      Baltimore, Maryland, United States
  • 2014
    • University of Maryland, Baltimore
      Baltimore, Maryland, United States
  • 1988–2014
    • Johns Hopkins Medicine
      • • Department of Neurosurgery
      • • Division of General Surgery and Surgical Oncology
      • • Department of Pathology
      Baltimore, Maryland, United States
  • 2004
    • The University of Chicago Medical Center
      Chicago, Illinois, United States
  • 2003
    • University of San Francisco
      San Francisco, California, United States
  • 2002
    • Texas A&M University - Galveston
      Galveston, Texas, United States
  • 1998
    • University of North Carolina at Chapel Hill
      North Carolina, United States
    • University of South Florida
      • Morsani College of Medicine
      Tampa, FL, United States
  • 1994
    • The Children's Hospital of Philadelphia
      • Department of Neurology
      Philadelphia, PA, United States
  • 1991–1994
    • Massachusetts Institute of Technology
      • Department of Chemical Engineering
      Cambridge, Massachusetts, United States