BackgroundNeuroblastoma is one of the most challenging malignancies of childhood, being associated with the highest death rate in paediatric oncology, underlining the need for novel therapeutic approaches. Typically, patients with high risk disease undergo an initial remission in response to treatment, followed by disease recurrence that has become refractory to further treatment. Here, we demonstrate the first silica nanoparticle-based targeted delivery of a tumor suppressive, pro-apoptotic microRNA, miR-34a, to neuroblastoma tumors in a murine orthotopic xenograft model. These tumors express high levels of the cell surface antigen disialoganglioside GD2 (GD2), providing a target for tumor-specific delivery.Principal FindingsNanoparticles encapsulating miR-34a and conjugated to a GD2 antibody facilitated tumor-specific delivery following systemic administration into tumor bearing mice, resulted in significantly decreased tumor growth, increased apoptosis and a reduction in vascularisation. We further demonstrate a novel, multi-step molecular mechanism by which miR-34a leads to increased levels of the tissue inhibitor metallopeptidase 2 precursor (TIMP2) protein, accounting for the highly reduced vascularisation noted in miR-34a-treated tumors.SignificanceThese novel findings highlight the potential of anti-GD2-nanoparticle-mediated targeted delivery of miR-34a for both the treatment of GD2-expressing tumors, and as a basic discovery tool for elucidating biological effects of novel miRNAs on tumor growth.

Grade C PF: (i) accounts for 15% of fistulae following PD and has an associated mortality rate of 35%; (ii) occurs most commonly in pathology associated with a soft remnant, and (iii) requires reoperation in approximately one half of patients. The published literature incompletely describes grade C PF.

Introduction The anti-tumor activity of angiogenesis inhibitors is often limited by the development of resistance to these drugs. Here we establish HIF-1α as a major factor in the development of this resistance in neuroblastoma xenografts. Methods Neuroblastoma xenografts were established by injecting unmodified SKNAS or NB-1691 cells (2×106 cells), or cells in which HIF-1α expression had been knocked down with shRNA, into the retroperitoneal space of SCID mice. Treatment of established tumors included bevacizumab (5mg/kg q2wk), sunitinib (40mg/kg qd), or topotecan (0.5mg/kg qd) alone or in combination for a total of two weeks. Results NB-1691 xenografts showed no difference in relative growth in HIF-1α knockdowns compared to control tumors (73.33±7.90 vs 79.94±6.15, p=0.528). However, HIF-1α knockdowns demonstrated relative final volumes that were significantly lower than unmodified tumors when both were treated with bevacizumab (35.88±4.24 vs 53.57±6.61, p=0.0544) or sunitinib (12.46±2.59 vs 36.36±4.82, p=0.0024). Monotherapy of unmodified xenografts with bevacizumab, sunitinib, or topotecan was largely ineffective. Relative final volumes of NB-1691 xenografts were significantly less in cohorts treated with sunitinib+topotecan (4.78±0.77 vs 39.17±2.44 [sunitinib alone], p=0.011) and bevacizumab+topotecan (13.63±1.55 vs 48.16±9.94 [bevacizumab alone], p=0.014). Conclusion Upregulation of HIF-1α appears to be a significant mechanism of resistance to antiangiogenic therapies in neuroblastoma. Suppressing HIF-1α with low-dose topotecan potentiates the effects of the antiangiogenic drugs in a mouse model.

The outcome for localized patients treated with extraosseous ESFT was similar to that reported for all ESFT patients treated on protocols at SJCRH. Patients with subcutaneous ESFT had a favorable prognosis when compared to their counterparts.

Introduction Ewing sarcoma (ES) is the most common chest wall malignancy in adolescents. Current therapy incorporates chemotherapy to treat systemic disease and radiation to assist with local control. We sought to evaluate the timing of surgery and role of adjuvant radiation. Methods We reviewed the SJCRH chest wall ES experience from 1979-2009. Patient demographics, tumor characteristics, treatment variables, and outcomes were analyzed with respect to timing of surgery and use of adjuvant radiation. Results Our cohort consisted of 36 patients with chest wall ES; median follow-up of 14.2 years and 15-year estimate of overall survival (OS) was 66%. In patients with localized disease, the timing of surgery (up-front versus delayed) did not impact margin negativity or the use of adjuvant radiation, but did decrease the extent of chest wall resection. When considering radiation in patients with localized disease, we found that patients who did not receive radiation had smaller tumor size (median, 6 versus 10cm) (p=0.04), and were more likely to have had negative margins (p=0.01) than patients who received adjuvant radiation. One patient in each group developed a locoregional recurrence. The 15-year estimated of OS for patients who received adjuvant radiation was 80% versus 100% for those who did not. Conclusion Delayed surgery decreased the extent of chest wall resection and helped define a patient population with favorable tumor biology. Patients with complete pathologic responses to chemotherapy, and those with tumors < 8cm and negative surgical margins may be spared adjuvant radiation without any decrement in OS.

Ionizing radiation (IR) is an essential component of therapy for alveolar rhabdomyosarcoma. Nuclear factor-kappaB (NF-κΒ) transcription factors are upregulated by IR and have been implicated in radioresistance. We evaluated the ability of curcumin, a putative NF-κΒ inhibitor, and cells expressing genetic NF- κΒ inhibitors (IκBα and p100 super-repressor constructs) to function as a radiosensitizer. Ionizing radiation induced NF-κΒ activity in the ARMS cells in vitro in a dose- and time-dependent manner, and upregulated expression of NF-κΒ target proteins. Pretreatment of the cells with curcumin inhibited radiation-induced NF-κΒ activity and target protein expression. In vivo, the combination of curcumin and IR had synergistic antitumor activity against Rh30 and Rh41 ARMS xenografts. The greatest effect occurred when tumor-bearing mice were treated with curcumin prior to IR. Immunohistochemistry revealed that combination therapy significantly decreased tumor cell proliferation and endothelial cell count, and increased tumor cell apoptosis. Stable expression of the super-repressor, SR-IκBα, that blocks the classical NF-κB pathway, increased sensitivity to IR, while expression of SR-p100, that blocks the alternative pathway, did not. Our results demonstrate that curcumin can potentiate the antitumor activity of IR in ARMS xenografts by suppressing a classical NF-κΒ activation pathway induced by ionizing radiation. These data support testing of curcumin as a radiosensitizer for the clinical treatment of alveolar rhabdomyosarcoma.Impact of workThe NF-κΒ protein complex has been linked to radioresistance in several cancers. In this study, we have demonstrated that inhibiting radiation-induced NF-κΒ activity by either pharmacologic (curcumin) or genetic (SR-IκBα) means significantly enhanced the efficacy of radiation therapy in the treatment of alveolar rhabdomyosarcoma cells and xenografts. These data suggest that preventing the radiation-induced activation of the NF-κΒ pathway is a promising way to improve the antitumor efficacy of ionizing radiation and warrants clinical trials.

Background High-grade glioblastomas have immature, leaky tumor blood vessels that impede the efficacy of adjuvant therapy. We assessed the ability of human interferon-beta (hIFN-β) delivered locally via gene transfer to effect vascular stabilization in an orthotopic glioblastoma xenograft resection model. Methods Xenografts were established by injecting three grade IV glioblastoma cell lines (GBM6-luc, MT330-luc, and SJG2-luc) into the cerebral cortex of nude rats. Tumors underwent subtotal resection, and then had gel foam containing an adeno-associated virus vector encoding either hIFN-β or green fluorescence protein (GFP, control) placed in the resection cavity. The primary end point was stabilization of tumor vasculature, as evidenced by CD34, αSMA, and CA IX staining. Overall survival was a secondary endpoint. Results hIFN-β treatment altered the tumor vasculature of GBM6-luc and SJG2-luc xenografts, decreasing the density of endothelial cells, stabilizing vessels with pericytes, and decreasing tumor hypoxia. The mean survival for rats with these tumors was not significantly improved, however. In rats with MT330-luc xenografts, hIFN-β resulted in tumor regression, with a 6-month survival of 55% (INF-β group) and 9% (control group). Conclusion The use of AAV hIFN-β in our orthotopic glioblastoma resection model stabilized tumor vasculature, and dramatically improved survival in rats with MT330 xenografts.

In the original publication, the first author's surname is captured incorrectly. The correct name is Orr, W. Shannon.