Endogenous angiogenesis inhibitors have shown promise in preclinical trials, but clinical use has been hindered by low half-life in circulation and high production costs. Here, we describe a strategy that targets the angiostatin receptor angiomotin (Amot) by DNA vaccination. The vaccination procedure generated antibodies that detected Amot on the endothelial cell surface. Purified Ig bound to the endothelial cell membrane and inhibited endothelial cell migration. In vivo, DNA vaccination blocked angiogenesis in the matrigel plug assay and prevented growth of transplanted tumors for up to 150 days. We further demonstrate that a combination of DNA vaccines encoding Amot and the extracellular and transmembrane domains of the human EGF receptor 2 (Her-2)͞neu oncogene inhibited breast cancer progression and impaired tumor vascularization in Her-2͞neu transgenic mice. No toxicity or impairment of normal blood vessels could be detected. This work shows that DNA vaccination targeting Amot may be used to mimic the effect of angiostatin.cancer vaccines ͉ neoplasia ͉ neovascularization ͉ breast cancer ͉ angiostatin

Tumor-associated inflammation is a driving force in several adult cancers and intake of low-dose aspirin has proven to reduce cancer incidence. Little is known about tumor-associated inflammation in pediatric neoplasms and no in vivo data exists on the effectiveness of low-dose aspirin on established tumors. The present study employs the transgenic TH-MYCN mouse model for neuroblastoma (NB) to evaluate inflammatory patterns paralleling tumor growth in vivo and low-dose aspirin as a therapeutic option for high-risk NB. Spontaneously arising abdominal tumors were monitored for tumor-associated inflammation ex vivo at various stages of disease and homozygous mice received daily low-dose aspirin (10mg/kg) using oral gavage or no treatment, from 4.5 to 6 weeks of age. Using flow cytometry, a transition from an adaptive immune response predominated by CD8(+) T cell in early neoplastic lesions, towards enrichment in immature cells of the innate immune system, including myeloid-derived suppressor cells, dendritic cells and tumor-associated macrophages, was detected during tumor progression. An M1 to M2 transition of tumor-associated macrophages was demonstrated, paralleled by a deterioration of dendritic cell status. Treatment with low-dose aspirin to mice homozygous for the TH-MYCN transgene significantly reduced the tumor burden (P < 0.01), the presence of tumor-associated cells of the innate immune system (P < 0.01), as well as the intratumoral expression of transforming growth factor-β, thromboxane A2 (P < 0.05) and prostaglandin D2 (P < 0.01). In conclusion, tumor-associated inflammation appears as a potential therapeutic target in NB and low-dose aspirin reduces tumor burden in the TH-MYCN transgenic mouse model of NB, hence warranting further studies on aspirin in high-risk NB.

Tumor infiltration by lymphocytes has been linked to improved clinical outcome in children with neuroblastoma (NB) but T-cell activation has never been demonstrated to occur within the NB microenvironment. Here we show that tumor-associated lymphocytes (TALs) obtained from lesions representing all genetic subsets of NB and autologous peripheral blood lymphocytes (PBLs) analyzed on the day of tumor excision differed in composition, phenotype and functional characteristics. The NB microenvironment appeared to promote the accumulation of CD3+CD8+ T cells and contained a larger proportion of T cells expressing the interleukin-2 receptor α chain (CD25) and manifesting an effector memory (CCR7−CD45RA−) phenotype. Accordingly, the stimulation of PBLs with autologous tumor cells in short-term cultures increased the proportion of effector memory T cells, upregulated CD25, stimulated the expression of the TH1 cytokines interferon γ and tumor necrosis factor α, and reduced the expression of transforming growth factor β. In situ proliferation as well as a characteristic pattern of T-cell receptor aggregation at the contact sites with malignant cells was revealed by the immunohistochemical staining of TALs in primary tumors, indicating that the NB milieu is compatible with the activation of the immune system. Our results are compatible with the hypothesis that CD8+ T cells are specifically activated within the NB microenvironment, which appears to be permissive for effector memory responses.

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The daily intake of low-dose aspirin lowers the risk of several cancers among the adults. The continuous administration of low-dose aspirin to TH-MYCN mice (a model of pediatric neuroblastoma) delays tumor outgrowth and decreases tumor-promoting inflammation by inhibiting regulatory cells of the innate immune system as well as immunosuppressive mediators such as transforming growth factor β (TGFβ) and thromboxane A2. These findings pave novel avenues for the clinical management of neuroblastoma.

Effective vaccination against heterologous influenza virus infection remains elusive. Immunization with plasmid DNA (pDNA) expressing conserved genes from influenza virus is a promising approach to achieve cross-variant protection. However, despite having been described for more than a decade, pDNA vaccination still requires further optimization to be applied clinically as a standard vaccination approach. We have recently described a simple and efficient approach to enhance pDNA immunization, based on the use of tucaresol, a Schiff base-forming drug. In this report we have tested the ability of this drug to increase the protection conferred by pDNA vaccination against influenza virus infection. Our results demonstrate that a significant protection was achieved in two strains of mice by using the combination of pDNA and tucaresol. This protection was associated with an elevated humoral and cellular response and a switch in the type of the T helper cell (Th) immune response from type 2 to type 1. This vaccine combination represents a promising strategy for designing a clinical study for the protection from influenza and similar infections.

Tumor-associated inflammation is a driving force in several adult cancers, and low doses of non-steroidal anti-inflammatory drugs (NSAIDs) such as aspirin have proven to reduce cancer incidence. Little is known about tumor-associated inflammation in pediatric neoplasms and no in vivo data exists on the effectiveness of low-dose aspirin on established tumors. Our study evaluates inflammatory patterns paralleling neuroblastoma (NB) tumor growth in vivo and low-dose aspirin as a therapeutic option for high-risk NB. Using the TH-MYCN mouse model of NB, this study demonstrates the presence and progression of tumor-associated inflammation during NB tumor growth. Ex vivo analysis of tumors revealed a transition from an adaptive immune response predominated by CD8+ T-cells in neoplastic lesions from 5 week old homozygous mice, towards an enrichment in immature cells of the innate immune system, including myeloid-derived suppressor cells (MDSCs), immature dendritic cells (DCs) and M2 tumor-associated macrophages (TAMs) during tumor progression. An ongoing M1 to M2 transition of TAMs was demonstrated, which was paralleled by a gradual deterioration of DC status. Ten days of consecutive anti-inflammatory treatment with low-dose aspirin significantly reduced tumor burden (p&lt;0.01) and the presence of tumor-associated cells of the innate immune system (p&lt;0.01) in homozygous mice. In conclusion, our study depicts how inflammatory pathways assist tumor progression through sculpturing of the tumor microenvironment, and for the first time demonstrates an in vivo effect of low-dose aspirin on established MYCN amplified NB tumors in a transgenic mouse model, suggesting a potential new treatment option for high-risk NB patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr LB-496. doi:1538-7445.AM2012-LB-496

Medulloblastoma is the most common paediatric high-grade brain tumour, which comprises four different molecular subtypes (SHH, Wnt, Group 3, and Group 4), each defined by different molecular characteristics, genomic aberrations, and prognosis. High levels of inter- and intra-tumoural heterogeneity, together with the detrimental side effects caused by the current medulloblastoma treatments, need to be addressed in order to develop more personalised treatments and improve the quality of life of these patients. In this study, we analysed single-cell RNA sequencing data from 14 medulloblastoma patients, comprising all four molecular subtypes. We found that these tumours exhibit great levels of heterogeneity with regard to their copy number variation (CNV) profiles analysed using Numbat, as well as immune cell infiltration and composition within these tumours. Tumour-infiltrating immune cells represented a heterogeneous population comprised of monocytes, M1- and M2-like macrophages, dendritic cells, and microglia. Our ligand-receptor analysis also identified a subset of immune cells that send EGF signals to the tumour clusters, potentially contributing to the tumour growth. In addition, we showed that the tissue of origin of the immune cells found within the tumour microenvironment and their medulloblastoma subgroup specificity greatly influence their clustering when projected onto a UMAP. We also found that the clustering of tumour cells is influenced by their CNV levels. Finally, we performed RNA velocity analysis and identified subgroup-specific cell trajectories for each medulloblastoma subtype. As predicted, identified cell trajectories demonstrated that cells move in a direction of increasing CNV levels, making it possible to visualise and track the tumour progression and identify genetic markers specific to either earlier or later tumour stages. Overall, our study underlines high levels of inter-tumoural heterogeneity in medulloblastoma. It also provides opportunities for the identification of subgroup-specific biomarkers for the early stages of medulloblastoma, potentially contributing to the discovery of novel drug targets.