Adenoviral vector-mediated gene therapy for gliomas: coming of age

INTRODUCTION: Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults and it carries a dismal prognosis. Adenoviral vector (Ad)-mediated gene transfer is being developed as a promising therapeutic strategy for GBM. Preclinical studies have demonstrated safety and efficacy of adenovirus administration into the brain and tumor mass in rodents and into the non-human primates' brain. Importantly, Ads have been safely administered within the tumor resection cavity in humans. AREAS COVERED: This review gives background on GBM and Ads; we describe gene therapy strategies for GBM and discuss the value of combination approaches. Finally, we discuss the results of the human clinical trials for GBM that have used Ads. EXPERT OPINION: The transduction characteristics of Ads, and their safety profile, added to their capacity to achieve high levels of transgene expression have made them powerful vectors for the treatment of GBM. Recent gene therapy successes in the treatment of retinal diseases and systemic brain metabolic diseases encourage the development of gene therapy for malignant glioma. Exciting clinical trials are currently recruiting patients; although, it is the large randomized Phase III controlled clinical trials that will provide the final decision on the success of gene therapy for the treatment of GBM.Fil: Castro, María G.. University of Michigan; Estados UnidosFil: Candolfi, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Wilson, Thomas J.. University of Michigan; Estados UnidosFil: Calinescu, Alexandra. University of Michigan; Estados UnidosFil: Paran, Christopher. University of Michigan; Estados UnidosFil: Kamran, Neha. University of Michigan; Estados UnidosFil: Koschmann, Carl. University of Michigan; Estados UnidosFil: Moreno Ayala, Mariela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina; ArgentinaFil: Assi, Hikmat. University Of Michigan Medical School;Fil: Lowenstein, Pedro R.. University of Michigan; Estados Unido

HMGB1 Mediates Endogenous TLR2 Activation and Brain Tumor Regression

Maria Castro and colleagues use cell line and transgenic mouse approaches to study the mechanisms underlying the immune response to glioblastoma multiforme

STAT3 as a Therapeutic Target for the Treatment of Glioblastoma Multiforme

The STAT3 transcription factor is a central mediator of tumor growth and immune suppression. As a transcription factor, STAT3 promotes the expression of genes that allow tumor cells to proliferate, migrate and evade apoptosis. Activation of STAT3 in tumor infiltrating immune cells has also been demonstrated to be responsible for their immune-suppressive phenotype. As such, STAT3 is an attractive target for cancer therapy. In these set of studies, we evaluated the inhibition of STAT3 as a means of inducing tumor regression in mouse models of brain cancer. Inhibition of STAT3 was achieved using shRNA-mediated knockdown or small molecules (CPA-7, WP1066, or ML116) and was associated with an induction of growth arrest in glioma cells with a concomitant induction of apoptosis. Moreover, the targeting specificity of the small molecules appeared to be highly dependent on the cell line and drug concentration utilized in the assay. In addition to the in vitro studies, we evaluated the therapeutic efficacy of these compounds using peripheral and intracranial mouse glioma and melanoma models. Of these compounds CPA-7 appeared to be the most effective at inducing the regression of peripheral tumors. Furthermore, therapeutic efficacy of CPA-7 was not evident in intracranial tumors, as our data indicated limited diffusion into the CNS as a consequence of the blood-brain barrier.In addition, we evaluated whether DC-based immunotherapies would benefit from STAT3 suppression. Using a conditional hematopoietic knockout mouse model, we assessed the impact of STAT3 deletion on the differentiation and function of dendritic cells from bone marrow precursors. Our results indicated the following pleiotropic functions of STAT3: hematopoietic cells that lacked STAT3 were unresponsive to Flt3L and failed to differentiate as DCs. In contrast, STAT3 was not required for GM-CSF induced DC differentiation. However, STAT3 null GM-CSF derived DCs did express higher levels of MHC-II, IL-12p70, IL-10, and TNFα upon TLR stimulation. STAT3 deficient DCs were also better at presenting antigen to naïve T cells. While STAT3 deficient DCs displayed an enhanced activation phenotype in culture, they elicited an equivalent therapeutic response in vivo compared to their wild type counterparts when utilized as vaccines for mice bearing intracranial gliomas

Rodent Glioma Models: Intracranial Stereotactic Allografts and Xenografts

Modeling human disease in small animals has been fundamental in advancing our scientific knowledge and for the development of novel therapeutic strategies. In the case of brain cancer, implantable tumor models, both intracranial and also in the periphery, have been widely used and xtensively characterized. These models can be used to better understand certain aspects of tumor biology such as growth, neovascularization, response to potential therapies, and interaction with the immune system. Brain tumors from patients as well as rodents have been cultured in vitro, in an attempt to establish permanent cell lines. Human glioma tumors have also been maintained by serial passage in the flanks of immune-deficient animals, as it has been shown that it is not feasible to continuously passage them in culture. In this chapter, we describe various gliomas that have been isolated from mice, rats, and humans and subsequently used as syngeneic or xenograft tumor models in vivo. The majority of the models that we present in this chapter arose either spontaneously or by administration of chemical carcinogens. We compare and contrast the histopathological, genetic, and invasive features of the tumor lines as well as identify novel treatment modalities that have been developed. Finally, we present the procedures for intracranial implantation of tumor cells in rodents using stereotactic surgical techniques. The use of this technique enables the generation of large numbers of animals harboring intracranial tumors with relative ease and the survival of tumor-bearing animals is highly reproducible. These characteristics make the use of these in vivo models very attractive when aiming to develop and test the effectiveness of novel anticancer therapies.Fil: Assi, Hikmat. University of Michigan; Estados UnidosFil: Candolfi, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Lowenstein, Pedro R.. University of Michigan; Estados UnidosFil: Castro, Maria Gabriela. University of Michigan; Estados Unido

Treatment Strategies for Residual Disease following Neoadjuvant Chemotherapy in Patients with Early-Stage Breast Cancer

Breast cancer continues to be the most diagnosed cancer among women worldwide. Neoadjuvant chemotherapy is the standard of care for breast cancer patients with locally advanced disease and patients with poor pathological features, such as triple-negative (TN) or human epidermal growth factor receptor-2 (HER2)-positive subtypes. Neoadjuvant therapy offers several advantages, including better surgical outcomes, early systemic treatment for micro-metastases, and accurate tumor biology and chemosensitivity assessment. Multiple studies have shown that achieving pathological complete response (pCR) following neoadjuvant chemotherapy is associated with better prognosis and better treatment outcomes; almost half of such patients may fail to achieve pCR. Tumor proliferative index, hormone receptor (HR) status, and HER2 expression are the major predictors of pCR. Strategies to improve pCR have been dependent on augmenting neoadjuvant chemotherapy with the addition of taxanes and dual anti-HER2 targeted therapy in patients with HER2-positive tumor, and more recently, immunotherapy for patients with TN disease. The clinical management of patients with residual disease following neoadjuvant chemotherapy varies and depends mostly on the level of HR expression and HER2 status. Recent data have suggested that switching trastuzumab to trastuzumab-emtansine (T-DM1) in patients with HER2-positive disease and the addition of capecitabine for patients with HER2-negative and HR-negative subtype is associated with a better outcome; both strategies are incorporated into current clinical practice guidelines. This paper reviews available and ongoing studies addressing strategies to better manage patients who continue to have residual disease following neoadjuvant chemotherapy

Gene therapy for brain tumors: Basic developments and clinical implementation

Glioblastoma multiforme (GBM) is the most common and deadliest of adult primary brain tumors. Due to its invasive nature and sensitive location, complete resection remains virtually impossible. The resistance of GBM against chemotherapy and radiotherapy necessitate the development of novel therapies. Gene therapy is proposed for the treatment of brain tumors and has demonstrated pre-clinical efficacy in animal models. Here we review the various experimental therapies that have been developed for GBM including both cytotoxic and immune stimulatory approaches. We also review the combined conditional cytotoxic immune stimulatory therapy that our lab has developed which is dependent on the adenovirus mediated expression of the conditional cytotoxic gene, Herpes Simplex Type 1 Thymidine Kinase (TK) and the powerful DC growth factor Fms-like tyrosine kinase 3 ligand (Flt3L). Combined delivery of these vectors elicits tumor cell death and an anti-tumor adaptive immune response that requires TLR2 activation. The implications of our studies indicate that the combined cytotoxic and immunotherapeutic strategies are effective strategies to combat deadly brain tumors and warrant their implementation in human Phase I clinical trials for GBM. © 2012 Elsevier Ireland Ltd.Fil: Assi, Hikmat. University of Michigan; Estados Unidos. David Geffen School of Medicine; Estados UnidosFil: Candolfi, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Baker, Gregory. University of Michigan; Estados Unidos. David Geffen School of Medicine; Estados UnidosFil: Mineharu, Yohei. David Geffen School of Medicine; Estados UnidosFil: Lowenstein, Pedro R.. University of Michigan; Estados UnidosFil: Castro, Maria Gabriela. University of Michigan; Estados Unido

Assessing the role of STAT3 in DC differentiation and autologous DC immunotherapy in mouse models of GBM.

Cellular microenvironments, particularly those found in tumors, elicit a tolerogenic DC phenotype which can attenuate immune responses. Central to this process is the STAT3-mediated signaling cascade. As a transcription factor and oncogene, STAT3 promotes the expression of genes which allow tumor cells to proliferate, migrate and evade apoptosis. More importantly, activation of STAT3 in tumor infiltrating immune cells has been shown to be responsible, in part, for their immune-suppressed phenotype. The ability of STAT3 to orchestrate a diverse set of immunosuppressive instructions has made it an attractive target for cancer vaccines. Using a conditional hematopoietic knockout mouse model of STAT3, we evaluated the impact of STAT3 gene ablation on the differentiation of dendritic cells from bone marrow precursors. We also assessed the impact of STAT3 deletion on phagocytosis, maturation, cytokine secretion and antigen presentation by GM-CSF derived DCs in vitro. In addition to in vitro studies, we compared the therapeutic efficacy of DC vaccination using STAT3 deficient DCs to wild type counterparts in an intracranial mouse model of GBM. Our results indicated the following pleiotropic functions of STAT3: hematopoietic cells which lacked STAT3 were unresponsive to Flt3L and failed to differentiate as DCs. In contrast, STAT3 was not required for GM-CSF induced DC differentiation as both wild type and STAT3 null bone marrow cells gave rise to similar number of DCs. STAT3 also appeared to regulate the response of GM-CSF derived DCs to CpG. STAT3 null DCs expressed high levels of MHC-II, secreted more IL-12p70, IL-10, and TNFα were better antigen presenters in vitro. Although STAT3 deficient DCs displayed an enhanced activated phenotype in culture, they elicited comparable therapeutic efficacy in vivo compared to their wild type counterparts when utilized in vaccination paradigms in mice bearing intracranial glioma tumors

Effect of Caveolin-1 on Stat3-ptyr705 levels in breast and lung carcinoma cells

We recently demonstrated that Cav1 (caveolin-1) is a negative regulator of Stat3 (signal transducer and activator of transcription-3) activity in mouse fibroblasts and human lung carcinoma SHP77 cells. We now examined whether the cellular context may affect their levels as well as the relationship between them, by assessing Cav1 and Stat3-ptyr705 amounts in different cell lines. In MDA-MB-231, A549, and HaCat cells, Cav1 levels were high and Stat3-ptyr705 levels were low, consistent with the notion of a negative effect of endogenous Cav1 on Stat3-ptyr705 levels in these lines. In addition, manipulation of Cav1 levels revealed a negative effect in MCF7 and mouse fibroblast cells, while Cav1 upregulation induced apoptosis in MCF7 cells. In contrast, however, line MRC9 had high Cav1 and high Stat3-ptyr705 levels, indicating that high Cav1 is insufficient to reduce Stat3-ptyr705 levels in this line. MCF7 and LuCi6 cells had very low Cav1 and Stat3-ptyr705 levels, indicating that the low Stat3-ptyr705 can be independent from Cav1 levels altogether. Our results reveal a further level of complexity in the relationship between Cav1 and Stat3-ptyr705 than previously thought. In addition, we demonstrate that in a feedback loop, Stat3 inhibition upregulates Cav1 in HeLa cells but not in other lines tested.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Immunotherapies for brain cancer: from preclinical models to human trials

Glioblastoma Multiforme (GBM) is the most common and aggressive primary brain tumor. Every year ~22,000 patients are diagnosed with GBM in the US, and less than 5% survive 5 years post-diagnosis. Thus, novel therapeutic approaches are urgently needed to improve the outcome in these patients. Immunotherapy has the potential of stimulating the immune system to eliminate GBM cells that might have spread throughout the brain. Here we will discuss the latest advances in preclinical immunotherapy for glioma, which involve the local delivery of pro-inflammatory cytokines, such as Flt3L, Type I IFNs, IL-2, IL-4, and IL-12 using gene therapy vectors and neural stem cells, or the blockade of immune-suppressive mediators such as TGF-beta, FasL and phosphorylated STAT3. Novel immunotherapeutic approaches have also been assessed in clinical trials implemented in GBM patients. These involve the systemic or local adoptive transfer of autologous immune cells activated ex vivo back into the patient, and the administration of dendritic cell vaccines loaded with tumor peptides or cells, which induce active immunity against GBM. Preclinical and clinical findings so far indicate that immunotherapy improves anti-tumor immunity in preclinical GBM models and patients, which makes it a valuable adjuvant in the treatment of GBM.Fil: Wilson, Thomas J.. University of Michigan; Estados UnidosFil: Candolfi, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Assi, Hikmat. University of Michigan; Estados UnidosFil: Moreno Ayala, Mariela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Mineharu,Yohei. University of Michigan; Estados UnidosFil: Hervey-Jumper, Shawn L.. University of Michigan; Estados UnidosFil: Lowenstein, Pedro R.. University of Michigan; Estados UnidosFil: Castro, Maria Graciela. University of Michigan; Estados Unido