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Wong, Eric

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Wong, Eric
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    Tumor Treating Fields Perturb the Localization of Septins and Cause Aberrant Mitotic Exit
    (Public Library of Science, 2015) Gera, Nidhi; Yang, Aaron; Holtzman, Talia S.; Lee, Sze Xian; Wong, Eric; Swanson, Kenneth
    The anti-tumor effects of chemotherapy and radiation are thought to be mediated by triggering G1/S or G2/M cell cycle checkpoints, while spindle poisons, such as paclitaxel, block metaphase exit by initiating the spindle assembly checkpoint. In contrast, we have found that 150 kilohertz (kHz) alternating electric fields, also known as Tumor Treating Fields (TTFields), perturbed cells at the transition from metaphase to anaphase. Cells exposed to the TTFields during mitosis showed normal progression to this point, but exhibited uncontrolled membrane blebbing that coincided with metaphase exit. The ability of such alternating electric fields to affect cellular physiology is likely to be dependent on their interactions with proteins possessing high dipole moments. The mitotic Septin complex consisting of Septin 2, 6 and 7, possesses a high calculated dipole moment of 2711 Debyes (D) and plays a central role in positioning the cytokinetic cleavage furrow, and governing its contraction during ingression. We showed that during anaphase, TTFields inhibited Septin localization to the anaphase spindle midline and cytokinetic furrow, as well as its association with microtubules during cell attachment and spreading on fibronectin. After aberrant metaphase exit as a consequence of TTFields exposure, cells exhibited aberrant nuclear architecture and signs of cellular stress including an overall decrease in cellular proliferation, followed by apoptosis that was strongly influenced by the p53 mutational status. Thus, TTFields are able to diminish cell proliferation by specifically perturbing key proteins involved in cell division, leading to mitotic catastrophe and subsequent cell death.
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    An Evidence-Based Review of Alternating Electric Fields Therapy for Malignant Gliomas
    (Springer US, 2015) Wong, Eric; Lok, Edwin; Swanson, Kenneth
    Opinion statement Glioblastoma is a deadly disease and even aggressive neurosurgical resection followed by radiation and chemotherapy only extends patient survival to a median of 1.5 years. The challenge in treating this type of tumor stems from the rapid proliferation of the malignant glioma cells, the diffuse infiltrative nature of the disease, multiple activated signal transduction pathways within the tumor, development of resistant clones during treatment, the blood brain barrier that limits the delivery of drugs into the central nervous system, and the sensitivity of the brain to treatment effect. Therefore, new therapies that possess a unique mechanism of action are needed to treat this tumor. Recently, alternating electric fields, also known as tumor treating fields (TTFields), have been developed for the treatment of glioblastoma. TTFields use electromagnetic energy at an intermediate frequency of 200 kHz as a locoregional intervention and act to disrupt tumor cells as they undergo mitosis. In a phase III clinical trial for recurrent glioblastoma, TTFields were shown to have equivalent efficacy when compared to conventional chemotherapies, while lacking the typical side effects associated with chemotherapies. Furthermore, an interim analysis of a recent clinical trial in the upfront setting demonstrated superiority to standard of care cytotoxic chemotherapy, most likely because the subjects’ tumors were at an earlier stage of clonal evolution, possessed less tumor-induced immunosuppression, or both. Therefore, it is likely that the efficacy of TTFields can be increased by combining it with other anti-cancer treatment modalities.
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    Injection of Syngeneic Murine Melanoma Cells to Determine Their Metastatic Potential in the Lungs
    (MyJove Corporation, 2016) Timmons, Joshua J.; Cohessy, Sean; Wong, Eric
    Approximately 90% of human cancer deaths are linked to metastasis. Despite the prevalence and relative harm of metastasis, therapeutics for treatment or prevention are lacking. We report a method for the establishment of pulmonary metastases in mice, useful for the study of this phenomenon. Tail vein injection of B57BL/6J mice with B16-BL6 is among the most used models for melanoma metastases. Some of the circulating tumor cells establish themselves in the lungs of the mouse, creating "experimental" metastatic foci. With this model it is possible to measure the relative effects of therapeutic agents on the development of cancer metastasis. The difference in enumerated lung foci between treated and untreated mice indicates the efficacy of metastases neutralization. However, prior to the investigation of a therapeutic agent, it is necessary to determine an optimal number of injected B16-BL6 cells for the quantitative analysis of metastatic foci. Injection of too many cells may result in an overabundance of metastatic foci, impairing proper quantification and overwhelming the effects of anti-cancer therapies, while injection of too few cells will hinder the comparison between treated and controls.
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    Phase I study of low-dose metronomic temozolomide for recurrent malignant gliomas
    (BioMed Central, 2016) Wong, Eric; Timmons, Joshua; Callahan, Amy; O’Loughlin, Lauren; Giarusso, Bridget; Alsop, David
    Background: The treatment goal for recurrent malignant gliomas centers on disease stabilization while minimizing therapy-related side effects. Metronomic dosing of cytotoxic chemotherapy has emerged as a promising option to achieve this objective. Methods: This phase I study was performed using metronomic temozolomide (mTMZ) at 25 or 50 mg/m2/day continuously in 42-day cycles. Correlative studies were incorporated using arterial spin labeling MRI to assess tumor blood flow, analysis of matrix metalloproteinase-2 (MMP-2) and MMP-9 activities in the cerebrospinal fluid (CSF) as surrogates for tumor angiogenesis and invasion, as well as determination of CSF soluble interleukin-2 receptor alpha (sIL-2Rα) levels as a marker of immune modulation. Results: Nine subjects were enrolled and toxicity consisted of primarily grade 1 or 2 hematological and gastrointestinal side effects; only one patient had a grade 3 elevated liver enzyme level that was reversible. Tumor blood flow was variable across subjects and time, with two experiencing a transient increase before a decrease to below baseline level while one exhibited a gradual drop in blood flow over time. MMP-2 activity correlated with overall survival but not with progression free survival, while MMP-9 activity did not correlate with either outcome parameters. Baseline CSF sIL-2Rα level was inversely correlated with time from initial diagnosis to first progression, suggesting that subjects with higher sIL-2Rα may have more aggressive disease. But they lived longer when treated with mTMZ, probably due to drug-related changes in T-cell constituency. Conclusions: mTMZ possesses efficacy against recurrent malignant gliomas by altering blood flow, slowing invasion and modulating antitumor immune function.
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    Stereotactic radiosurgery for brain metastasis from gynecological malignancies
    (D.A. Spandidos, 2017) Kasper, Ekkehard; Ippen, Franziska; Wong, Eric; Uhlmann, Eric; Floyd, Scott; Mahadevan, Anand
    Brain metastases are relatively uncommon in gynecological malignancies, and there is limited available data on their management. The present study reports the outcomes of patients with brain metastasis from gynecological malignancies who were treated with stereotactic radiosurgery (SRS). Patients with brain metastasis from a gynecological primary site were treated with SRS using the Cyberknife™ frameless SRS system. Primary lesions were treated with a single fraction of 16–22 Gy. A total of 3 resection cavities were treated with 8 Gy 3 times, meaning a total of 24 Gy, and 1 recurrent lesion was re-irradiated with 5 Gy 5 times, meaning a total of 25 Gy. All patients were followed up with regular magnetic resonance imaging and clinical examinations 1 month after treatment and every 2 months thereafter. A total of 20 lesions in 8 patients were included in this study; 1 patient presented with metastatic endometrial cancer and the remaining 7 presented with metastatic ovarian cancer. The median age was 61 years (range, 48–78 years). All patients had received systemic therapy prior to developing brain metastasis. A total of 3 patients underwent surgical resection and 1 patient was administered re-irradiation for recurrence. There were 3 local failures in 2 patients. The actuarial 1-, 2- and 3-year local control rates were 91, 91 and 76%, respectively. The median overall survival time was 29 months. No SRS-associated toxicities or neurological mortalities were observed. In conclusion, brain metastasis from gynecological malignancies is uncommon, however, SRS is a safe and effective treatment modality for local control as a primary or adjuvant treatment in patients with this disease.
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    A microRNA-1280/JAG2 network comprises a novel biological target in high-risk medulloblastoma
    (Impact Journals LLC, 2015) Wang, Fengfei; Remke, Marc; Bhat, Kruttika; Wong, Eric; Zhou, Shuang; Ramaswamy, Vijay; Dubuc, Adrian; Fonkem, Ekokobe; Salem, Saeed; Zhang, Hongbing; Hsieh, Tze-chen; O'Rourke, Stephen T.; Wu, Lizi; Li, David W.; Hawkins, Cynthia; Kohane, Isaac; Wu, Joseph M.; Wu, Min; Taylor, Michael D.; Wu, Erxi
    Over-expression of PDGF receptors (PDGFRs) has been previously implicated in high-risk medulloblastoma (MB) pathogenesis. However, the exact biological functions of PDGFRα and PDGFRβ signaling in MB biology remain poorly understood. Here, we report the subgroup specific expression of PDGFRα and PDGFRβ and their associated biological pathways in MB tumors. c-MYC, a downstream target of PDGFRβ but not PDGFRα, is involved in PDGFRβ signaling associated with cell proliferation, cell death, and invasion. Concurrent inhibition of PDGFRβ and c-MYC blocks MB cell proliferation and migration synergistically. Integrated analysis of miRNA and miRNA targets regulated by both PDGFRβ and c-MYC reveals that increased expression of JAG2, a target of miR-1280, is associated with high metastatic dissemination at diagnosis and a poor outcome in MB patients. Our study may resolve the controversy on the role of PDGFRs in MB and unveils JAG2 as a key downstream effector of a PDGFRβ-driven signaling cascade and a potential therapeutic target.
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    An Overview of Alternating Electric Fields Therapy (NovoTTF Therapy) for the Treatment of Malignant Glioma
    (Springer US, 2016) Swanson, Kenneth; Lok, Edwin; Wong, Eric
    As with many cancer treatments, tumor treating fields (TTFields) target rapidly dividing tumor cells. During mitosis, TTFields-exposed cells exhibit uncontrolled membrane blebbing at the onset of anaphase, resulting in aberrant mitotic exit. Based on these criteria, at least two protein complexes have been proposed as TTFields’ molecular targets, including α/β-tubulin and the septin 2, 6, 7 heterotrimer. After aberrant mitotic exit, cells exhibited abnormal nuclei and signs of cellular stress, including decreased cellular proliferation and p53 dependence, and exhibit the hallmarks of immunogenic cell death, suggesting that TTFields treatment may induce an antitumor immune response. Clinical trials lead to Food and Drug Administration approval for their treatment of recurrent glioblastoma. Detailed modeling of TTFields within the brain suggests that the location of the tumor may affect treatment efficacy. These observations have a profound impact on the use of TTFields in the clinic, including what co-therapies may be best applied to boost its efficacy.
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    Stereotactic Radiosurgery for Renal Cancer Brain Metastasis: Prognostic Factors and the Role of Whole-Brain Radiation and Surgical Resection
    (Hindawi Publishing Corporation, 2015) Ippen, Franziska M.; Mahadevan, Anand; Wong, Eric; Uhlmann, Erik; Sengupta, Soma; Kasper, Ekkehard
    Background:. Renal cell carcinoma is a frequent source of brain metastasis. We present our consecutive series of patients treated with Stereotactic Radiosurgery (SRS) and analyse prognostic factors and the interplay of WBRT and surgical resection. Methods. This is a retrospective study of 66 patients with 207 lesions treated with the Cyberknife radiosurgery system in our institution. The patients were followed up with imaging and clinical examination 1 month and 2-3 months thereafter for the brain metastasis. Patient, treatment, and outcomes characteristics were analysed. Results. 51 male (77.3%) and 15 female (22.7%) patients, with a mean age of 58.9 years (range of 31–85 years) and a median Karnofsky Performance Status (KPS) of 90 (range of 60–100), were included in the study. The overall survival was 13.9 months, 21.9 months, and 5.9 months for the patients treated with SRS only, additional surgery, and WBRT, respectively. The actuarial 1-year Local Control rates were 84%, 94%, and 88% for SRS only, for surgery and SRS, and for WBRT and additional SRS, respectively. Conclusions. Stereotactic radiosurgery is a safe and effective treatment option in patients with brain metastases from RCC. In case of a limited number of brain metastases, surgery and SRS might be appropriate.
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    Computed modeling of alternating electric fields therapy for recurrent glioblastoma
    (John Wiley & Sons, Ltd, 2015) Lok, Edwin; Hua, Van; Wong, Eric
    Tumor treating fields (TTFields) are alternating electric fields frequency tuned to 200 kHz for the treatment of recurrent glioblastoma. We report a patient treated with TTFields and determined the distribution of TTFields intracranially by computerized simulation using co-registered postgadolinium T1-weighted, T2, and MP RAGE images together with pre-specified conductivity and relative permittivity values for various cerebral structures. The distribution of the electric fields within the brain is inhomogeneous. Higher field intensities were aggregated near the ventricles, particularly at the frontal and occipital horns. The recurred tumor was found distant from the primary glioblastoma and it was located at a site of relatively lower electric field intensity. Future improvement in TTFields treatment may need to take into account the inhomogeneity of the electric field distribution within the brain.