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Species and Cell Types / Virus / Adenovirus


State-Of-The-Art Human Gene Therapy: Part I. Gene Delivery Technologies

Abstract: Safe and effective gene delivery is a prerequisite for successful gene therapy. In the early age of human gene therapy, setbacks due to problematic gene delivery vehicles plagued the exciting therapeutic outcome. However, gene delivery technologies rapidly evolved ever since. With the advancement of gene delivery techniques, gene therapy clinical trials surged during the past decade. As the first gene therapy product (Glybera) has obtained regulatory approval and reached clinic, human gene therapy finally realized the promise that genes can be medicines. The diverse gene delivery techniques available today have laid the foundation for gene therapy applications in treating a wide range of human diseases. Some of the most urgent unmet medical needs, such as cancer and pandemic infectious diseases, have been tackled by gene therapy strategies with promising results. Furthermore, combining gene transfer with other breakthroughs in biomedical research and novel biotechnologies opened new avenues for gene therapy. Such innovative therapeutic strategies are unthinkable until now, and are expected to be revolutionary. In part I of this review, we introduced recent development of non-viral and viral gene delivery technology platforms. As cell-based gene therapy blossomed, we also summarized the diverse types of cells and vectors employed in ex vivo gene transfer. Finally, challenges in current gene delivery technologies for human use were discussed. ... Read more

Innovative Approaches for Enhancing Cancer Gene Therapy

Abstract: Gene therapy provides a novel platform for therapeutic intervention of several genetic and non-genetic disorders. With the recent developments in the field, a wide variety of viral and non-viral vectors have emerged that can deliver genetic payloads to target cells. However, non-targeted delivery of transgenes often results in undesirable effects, low tumor transduction, and reduced therapeutic index. In this review, we focus on some of the novel approaches that can be used to meet the present challenges in the field and translate the potential of cancer gene therapy from 'bench to bedside' in the near future. ... Read more

Recent Gene Therapy Advancements for Neurological Diseases

Abstract: The past few years have seen rapid advancements in vector-mediated gene transfer to the nervous system and modest successes in human gene therapy trials. The purpose of this review is to describe commonly-used viral gene transfer vectors and recent advancements towards producing meaningful gene-based treatments for central nervous system (CNS) disorders. Gene therapy trials for Canavan disease, Batten disease, adrenoleukodystrophy, and Parkinson's disease are discussed to illustrate the current state of clinical gene transfer to the CNS. Preclinical studies are under way for a number of diseases, primarily lysosomal storage disorders, using a newer generation of vectors and delivery strategies. Relevant studies in animal models are highlighted for Mucopolysaccharidosis IIIB and Krabbe disease to provide a prelude for what can be expected in the coming years for human gene transfer trials, using recent advancements in gene transfer technology. In conclusion, recent improvements in CNS gene transfer technology are expected to significantly increase the degree of disease rescue in future CNS-directed clinical trials, exceeding the modest clinical successes that have been observed so far. ... Read more

Developing an Effective Gene Therapy for Prostate Cancer: New Technologies with Potential to Translate from the Laboratory into the Clinic

Abstract: Prostate cancer is the second leading cause of cancer-related deaths in men in the U.S. At present, no single or combination therapy has shown efficacy in decreasing disease progression in patients with metastatic disease. A potentially viable approach for treating late-stage prostate cancer is gene therapy. Adenoviruses (Ad) are the most commonly used mode of gene delivery, but progress using this vector has been hampered by concerns over the safety and practicality of viruses including conditionally replicating Ads (CRAds), particularly for intravenous delivery, and the inefficiency of non-viral transfection techniques. Major challenges for effective gene therapy using Ads are the limited infectivity of regular Ad serotype 5 (Ad5) and the inability to specifically deliver the therapeutic directly into diseased tissue without trapping in the liver or elimination by the immune system. The shortcoming in using Ad5 is mostly attributed to a reduction in Coxsackie-adenovirus receptors (CAR) on the surface of cancer cells, which can be mitigated by generating tropism-modified Ads permitting CAR-independent infection of tumor cells. The limitations of systemic gene delivery can now be overcome by using a novel targeted-delivery approach such as ultrasound (US) contrast agents (microbubbles) to deliver effective therapeutic reagents, Ads, or recombinant proteins, combined with ultrasound-targeted microbubble destruction (UTMD), to develop a site-specific therapy in immune competent transgenic mouse models. These unique strategies for enhancing the efficacy of gene therapy provide a direct path to translation from the laboratory into the clinic for developing an effective gene therapy of prostate cancer. ... Read more

Oncolytic Virotherapy for Neuroblastoma

Abstract: Metastatic neuroblastoma (NB) remains a clinical challenge for pediatric oncologists. Overall survival rates stay less than 40% despite intensive multimodal therapy, with the toll of toxicity being related to high-dose chemotherapy. These rates have shown minor improvements over the last years, and the development of newer therapeutic strategies is necessary. Oncolytic viruses bear the promise of killing cancer cells with low toxicities to healthy tissues. Acting through mechanisms different from chemo- and radiotherapies, a growing arsenal of genetically engineered viruses is being tested in preclinical models of human cancers. Viral infection and selective replication inside tumor cells are achieved by modification of the virus genome in order to target specific molecules or signal transduction pathways of cancer. Cell death may also activate antitumor immune responses to further amplify the beneficial effects. Clinical trials in humans have been conducted and initial results have been reported, giving the first glance of information on safety and efficacy in patients. In this review we will summarize information about how oncolytic virotherapy is being evaluated against NB in preclinical models and recent reports on the use of this new therapy in sporadic cases of children with refractory NB. ... Read more

Gene Therapy and Virotherapy: Novel Therapeutic Approaches for Brain Tumors

Abstract: Glioblastoma multiforme (GBM) is a deadly primary brain tumor in adults, with a median survival of ~12-18 months post-diagnosis. Despite recent advances in conventional therapeutic approaches, only modest improvements in median survival have been achieved; GBM usually recurs within 12 months post-resection, with poor prognosis. Thus, novel therapeutic strategies to target and kill GBM cells are desperately needed. Our group and others are pursuing virotherapy and gene therapy strategies for the treatment of GBM. In this review, we will discuss various virotherapy and gene therapy approaches for GBM currently under pre-clinical and clinical evaluation including direct or conditional cytotoxic, and/or immunostimulatory approaches. We also discuss cutting-edge technologies for drug/gene delivery and targeting brain tumors, including the use of stem cells as delivery platforms, the use of targeted immunotoxins, and the therapeutic potential of using GBM microvesicles to deliver therapeutic siRNAs or virotherapies. Finally, various animal models available to test novel GBM therapies are discussed. ... Read more

Eradication of Brain Tumor Stem Cells with an Oncolytic Adenovirus

Abstract: Malignant gliomas, the most common type of primary brain tumors, are one of the most deadly cancers. Even when given the best available treatment, patients with these tumors face a poor prognosis, a situation that has changed little in the past several decades. Recently, researchers identified brain tumor stem cells that are responsible for tumors' resistance to therapy and recurrence. Since conventional radiotherapy and chemotherapy have had limited success in the treatment of malignant gliomas, we developed an oncolytic adenovirus, Delta-24-RGD, that is able to efficiently eradicate both brain tumor bulk and stem cells, indicating its potential to induce complete tumor remission in patients with malignant gliomas. Currently, this novel agent is being tested in a phase I clinical trial at the Brain Tumor Center, The University of Texas MD Anderson Cancer Center. ... Read more

Development of Gene Therapy for Neurological Disorders

Abstract: Given improvements in viral vector design, production and efficiency of transduction in the central nervous system (CNS), as well as increased knowledge of neuropathological mechanisms in neurological disorders, success in treating a CNS disorder with gene transfer seems inevitable. Several different vector systems have been studied extensively and the adeno-associated viral vector system has been utilized in most early stage clinical trials in neurological disorders. Other vector systems, such as lentivirus, adenovirus, and herpes simplex virus are also viable vector platforms that should fill significant clinical niches based on their specific characteristics. In addition to the choice of the appropriate vector, the proper choice of transgene for the appropriate strategy to treat a neurological disorder is also critical. The example of glial cell line-derived neurotrophic factor ligands to treat Parkinson's disease is used to illustrate the importance of the interface between interpretation of pre-clinical data and consideration of the natural history of the disorder. This interface dictates the proper design of clinical trials that are capable of testing whether the treatment is actually successful. ... Read more

MicroManipulating Viral-based Therapeutics

Abstract: Despite the social stigma and manufacturing hurdles that come with using viruses as therapeutic tools, the molecular specificity offered by these bugs makes them too attractive to ignore. Still largely based on vaccines, viral vectors offer exciting tools to treat cancer or deliver specific genetic payloads to a desired tissue. Unfortunately, early clinical trials utilizing such vectors have been plagued with poor performance or even clinical toxicity most commonly associated with spurious genetic regulation and/or replication of the vector. Past efforts to control for unwanted toxicity have focused on modification of the receptor or use of tissue-specific genetic elements that added specificity to the transcriptional induction of the gene(s) of interest. While this has had some success, engineering receptors to control viral tropism often fails or results in a loss of replicative fitness. In addition, the use of tissue-specific promoter elements not only restricts the vector that can be used, bona fide small promoter elements are often not available for the desired target. With the caveats of viral vector-based therapeutics largely centered on a lack of in vivo control, the recent success of exploiting microRNA expression to limit viral tropism may breathe new life into the field. ... Read more

Gene therapy makes islets from liver, treats diabetes

Exploring a “wild” idea, Lawrence Chan and colleagues at the Baylor College of Medicine, Houston, Texas and Shiga University of Medical Science, Otsu, Japan harnessed liver cells in vivo into pancreatic islet cells capable of secreting insulin, glucagons, and somatostatin (Kojima, H. et al. Nat. Med. 9:596-603, May 2003). The discovery is a windfall for gene therapy research and potentially the type 1 diabetes patients.

The researchers used helper-dependent adenovirus (HDAD, devoid of genes encoding for viral proteins) to deliver NeuroD and betacellulin genes to diabetic mice and completely reversed the diabetes for more than 120 days. Serum glucose level was ... Read more

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