Advanced phase I/II studies of targeted gene delivery in vivo: intravenous Rexin-G for gemcitabine-resistant metastatic pancreatic cancer

Advances in HIV Gene Therapy

Early gene therapy studies held great promise for the cure of heritable diseases, but the occurrence of various genotoxic events led to a pause in clinical trials and a more guarded approach to progress. Recent advances in genetic engineering technologies have reignited interest, leading to the approval of the first gene therapy product targeting genetic mutations in 2017. Gene therapy (GT) can be delivered either in vivo or ex vivo. An ex vivo approach to gene therapy is advantageous, as it allows for the characterization of the gene-modified cells and the selection of desired properties before patient administration. Autologous cells can also be used during this process which eliminates the possibility of immune rejection. This review highlights the various stages of ex vivo gene therapy, current research developments that have increased the efficiency and safety of this process, and a comprehensive summary of Human Immunodeficiency Virus (HIV) gene therapy studies, the majority of which have employed the ex vivo approach.

Innovative Genoceuticals in Human Gene Therapy Solutions: Challenges and Safe Clinical Trials of Orphan Gene Therapy Products

The success of gene therapy attempts is controversial and inconclusive. Currently, it is popular among the public, the scientific community, and manufacturers of Gene Therapy Medical Products. In the absence of any remedy or treatment options available for untreatable inborn metabolic orphan or genetic diseases, cancer, or brain diseases, gene therapy treatment by genoceuticals and T-cells for gene editing and recovery remains the preferred choice as the last hope. A new concept of "Genoceutical Gene Therapy" by using orphan 'nucleic acid-based therapy' aims to introduce scientific principles of treating acquired tissue damage and rare diseases. These Orphan Genoceuticals provide new scope for the 'genodrug' development and evaluation of genoceuticals and gene products for ideal 'gene therapy' use in humans with marketing authorization application (MAA). This perspective study focuses on the quality control, safety, and efficacy requirements of using 'nucleic acid-based and human cell-based new gene therapy' genoceutical products to set scientific advice on genoceutical-based 'orphan genodrug' design for clinical trials as per Western and European guidelines. The ethical Western FDA and European EMA guidelines suggest stringent legal and technical requirements on genoceutical medical products or orphan genodrug use for other countries to frame their own guidelines. The introduction section proposes lessknown 'orphan drug-like' properties of modified RNA/DNA, human cell origin gene therapy medical products, and their transgene products. The clinical trial section explores the genoceutical sources, FDA/EMA approvals for genoceutical efficacy criteria with challenges, and ethical guidelines relating to gene therapy of specific rare metabolic, cancer and neurological diseases. The safety evaluation of approved genoceuticals or orphan drugs is highlighted with basic principles and 'genovigilance' requirements (to observe any adverse effects, side effects, developed signs/symptoms) to establish their therapeutic use. Current European Union and Food and Drug Administration guidelines continuously administer fast-track regulatory legal framework from time to time, and they monitor the success of gene therapy medical product efficacy and safety. Moreover, new ethical guidelines on 'orphan drug-like genoceuticals' are updated for biodistribution of the vector, genokinetics studies of the transgene product, requirements for efficacy studies in industries for market authorization, and clinical safety endpoints with their specific concerns in clinical trials or public use.

Protection is not always a good thing: The immune system's impact on gene therapy

There are many clinical trials underway for the development of gene therapies, and some have resulted in gene therapy products being commercially approved already. Significant progress was made to develop safer and more effective strategies to deliver and regulate genetic products. An unsolved aspect is the immune system, which can affect the efficiency of gene therapy in different ways. Here we present an overview of approved gene therapy products and the immune response elicited by gene delivery systems. These include responses against the vector or its content after delivery and against the product of the corrected gene. Strategies to overcome the hurdles include hiding the vector or/and the transgene product from the immune system and hiding the immune system from the vector/transgene product. Combining different strategies, such as patient screening and intelligent vector design, gene therapy is set to make a difference in the life of patients with severe genetic diseases.

Targeting Engineered Nanoparticles for Breast Cancer Therapy

Breast cancer (BC) is the second most common cancer in women globally after lung cancer. Presently, the most important approach for BC treatment consists of surgery, followed by radiotherapy and chemotherapy. The latter therapeutic methods are often unsuccessful in the treatment of BC because of their various side effects and the damage incurred to healthy tissues and organs. Currently, numerous nanoparticles (NPs) have been identified and synthesized to selectively target BC cells without causing any impairments to the adjacent normal tissues or organs. Based on an exploratory study, this comprehensive review aims to provide information on engineered NPs and their payloads as promising tools in the treatment of BC. Therapeutic drugs or natural bioactive compounds generally incorporate engineered NPs of ideal sizes and shapes to enhance their solubility, circulatory half-life, and biodistribution, while reducing their side effects and immunogenicity. Furthermore, ligands such as peptides, antibodies, and nucleic acids on the surface of NPs precisely target BC cells. Studies on the synthesis of engineered NPs and their impact on BC were obtained from PubMed, Science Direct, and Google Scholar. This review provides insights on the importance of engineered NPs and their methodology for validation as a next-generation platform with preventive and therapeutic effects against BC.

Biomarkers in Pancreatic Cancer as Analytic Targets for Nanomediated Imaging and Therapy

As the increase in therapeutic and imaging technologies is swiftly improving survival chances for cancer patients, pancreatic cancer (PC) still has a grim prognosis and a rising incidence. Practically everything distinguishing for this type of malignancy makes it challenging to treat: no approved method for early detection, extended asymptomatic state, limited treatment options, poor chemotherapy response and dense tumor stroma that impedes drug delivery. We provide a narrative review of our main findings in the field of nanoparticle directed treatment for PC, with a focus on biomarker targeted delivery. By reducing drug toxicity, increasing their tumor accumulation, ability to modulate tumor microenvironment and even improve imaging contrast, it seems that nanotechnology may one day give hope for better outcome in pancreatic cancer. Further conjugating nanoparticles with biomarkers that are overexpressed amplifies the benefits mentioned, with potential increase in survival and treatment response.

The regulation of nanomaterials and nanomedicines for clinical application: current and future perspectives

Nanomedicine research has increased drastically over the past ten years, however, before clinical translation many regulatory factors must be considered.

Development and Clinical Translation of Approved Gene Therapy Products for Genetic Disorders

The field of gene therapy is striving more than ever to define a path to the clinic and the market. Twenty gene therapy products have already been approved and over two thousand human gene therapy clinical trials have been reported worldwide. These advances raise great hope to treat devastating rare and inherited diseases as well as incurable illnesses. Understanding of the precise pathomechanisms of diseases as well as the development of efficient and specific gene targeting and delivery tools are revolutionizing the global market. Currently, human cancers and monogenic disorders are indications number one. The elevated prevalence of genetic disorders and cancers, clear gene manipulation guidelines and increasing financial support for gene therapy in clinical trials are major trends. Gene therapy is presently starting to become commercially profitable as a number of gene and cell-based gene therapy products have entered the market and the clinic. This article reviews the history and development of twenty approved human gene and cell-based gene therapy products that have been approved up-to-now in clinic and markets of mainly North America, Europe and Asia.

Insights into Active Targeting of Nanoparticles in Drug Delivery: Advances in Clinical Studies and Design Considerations for Cancer Nanomedicine

Nanomedicine is a promising strategy for improving clinical outcomes for cancer therapies, by improving drug efficacy through enhanced delivery to disease sites. It is of importance for ultimate clinical success to consider the contributing factors to achieving this goal, such as size, chemistry, and functionality of nanoparticle delivery systems, and how these parameters influence tumor localization and uptake. This Topical Review will first discuss the evolution and progress of nanoparticles for cancer drug delivery and the current challenges that remain to be addressed. Strategies for overcoming the limitations of passive targeting through active targeting approaches, and the current state of such nanomedicines in the clinic will be highlighted. Finally, novel approaches toward the design of active targeted nanoparticles building on our growing understanding of nanobio interactions are considered, in order to shed light on future design considerations for accelerating clinical translation of nanomedicines.

A Phase I-II Study Using Rexin-G Tumor-Targeted Retrovector Encoding a Dominant-Negative Cyclin G1 Inhibitor for Advanced Pancreatic Cancer

Rexin-G is a replication-incompetent retroviral vector displaying a cryptic SIG-binding peptide for targeting abnormal Signature (SIG) proteins in tumors and encoding a dominant-negative human cyclin G1 construct. Herein we report on the safety and antitumor activity of escalating doses of Rexin-G in gemcitabine-refractory pancreatic adenocarcinoma, with one 10-year survivor. For the safety analysis (n = 20), treatment-related grade 1 adverse events included fatigue (n = 6), chills (n = 2), and headache (n = 1), with no organ damage and no DLT. No patient tested positive for vector-neutralizing antibodies, antibodies to gp70, replication-competent retrovirus (RCR), or vector integration into genomic DNA of peripheral blood lymphocytes (PBLs). For the efficacy analysis (n = 15), one patient achieved a complete response (CR), two patients had a partial response (PR), and 12 had stable disease (SD). Median progression-free survival (PFS) was 2.7, 4.0, and 5.6 months at doses 0–I, II, and III, respectively. Median overall survival (OS) and 1-year OS rate at dose 0–I were 4.3 months and 0%, and at dose II–III they were 9.2 months and 33.3%. To date, one patient is still alive with no evidence of cancer 10 years after the start of Rexin-G treatment. Taken together, these data suggest that Rexin-G, the first targeted gene delivery system, is uniquely safe and exhibits significant antitumor activity, for which the FDA granted fast-track designation.

Gene Therapy for Pancreatic Diseases: Current Status

The pancreas is a key organ involved in digestion and endocrine functions in the body. The major diseases of the pancreas include pancreatitis, pancreatic cancer, cystic diseases, pancreatic divisum, islet cell tumors, endocrine tumors, diabetes mellitus, and pancreatic pain induced by these diseases. While various therapeutic methodologies have been established to date, however, the improvement of conventional treatments and establishment of novel therapies are essential to improve the efficacy. For example, conventional therapeutic options, including chemotherapy, are not effective against pancreatic cancer, and despite improvements in the last decade, the mortality rate has not declined and is estimated to become the second cause of cancer-related deaths by 2030. Therefore, continuous efforts focus on the development of novel therapeutic options. In this review, we will summarize the progress toward the development of gene therapies for pancreatic diseases, with an emphasis on recent preclinical studies and clinical trials. We aim to identify new areas for improvement of the current methodologies and new strategies that will lead to safe and effective gene therapeutic approaches in pancreatic diseases.

Nanomedicine in cancer stem cell therapy: from fringe to forefront

Nanomedicine is the spin-off of modern medicine and nanotechnology and aims to prevent and treat diseases using nanoscale materials such as biocompatible nanoparticles and nanorobots. Targeted cellular and tissue-specific clinical applications with maximal therapeutic effects and insignificant side effects could be achieved by the pursuit of nanotechnology in medicine and healthcare regimen. The majority of conventional cancer therapies eliminate the cells of the tumor but not the cancer stem cells (CSCs). Conversely, the use of nanotechnology in CSC-based therapies is an emerging field of biomedical sciences. This article summarizes the recent trends and application of nanomedicine especially in CSC therapy along with its limitations.

Current status and dilemma of second-line treatment in advanced pancreatic cancer: is there a silver lining?

Pancreatic cancer remains one of the most lethal malignant diseases worldwide. The majority of patients present with advanced disease and, therefore, need palliative chemotherapy. Some chemotherapeutic regimens have been well established as first-line therapies and have been shown to increase survival; however, almost all patients with advanced pancreatic cancer will experience disease progression after first-line therapy. Nevertheless, many patients who retain good performance status after initial treatment remain good candidates for additional therapy. Historically, few studies have assessed second-line therapy, with most reports representing small phase II trials with variable findings; however, clinical research for second-line treatment has increased in the past decade, and several randomized controlled trials using different regimens have been published. The current literature shows varying results on treatment efficacy and tolerability. Thus, we reviewed the published data on the use of chemotherapy in the second-line setting for the treatment of advanced pancreatic cancer.

Cell cycle checkpoint control: The cyclin G1/Mdm2/p53 axis emerges as a strategic target for broad-spectrum cancer gene therapy - A review of molecular mechanisms for oncologists

Basic research in genetics, biochemistry and cell biology has identified the executive enzymes and protein kinase activities that regulate the cell division cycle of all eukaryotic organisms, thereby elucidating the importance of site-specific protein phosphorylation events that govern cell cycle progression. Research in cancer genomics and virology has provided meaningful links to mammalian checkpoint control elements with the characterization of growth-promoting proto-oncogenes encoding c-Myc, Mdm2, cyclins A, D1 and G1, and opposing tumor suppressor proteins, such as p53, pRb, p16^INK4A and p21^WAF1, which are commonly dysregulated in cancer. While progress has been made in identifying numerous enzymes and molecular interactions associated with cell cycle checkpoint control, the marked complexity, particularly the functional redundancy, of these cell cycle control enzymes in mammalian systems, presents a major challenge in discerning an optimal locus for therapeutic intervention in the clinical management of cancer. Recent advances in genetic engineering, functional genomics and clinical oncology converged in identifying cyclin G1 (CCNG1 gene) as a pivotal component of a commanding cyclin G1/Mdm2/p53 axis and a strategic locus for re-establishing cell cycle control by means of therapeutic gene transfer. The purpose of the present study is to provide a focused review of cycle checkpoint control as a practicum for clinical oncologists with an interest in applied molecular medicine. The aim is to present a unifying model that: i) clarifies the function of cyclin G1 in establishing proliferative competence, overriding p53 checkpoints and advancing cell cycle progression; ii) is supported by studies of inhibitory microRNAs linking CCNG1 expression to the mechanisms of carcinogenesis and viral subversion; and iii) provides a mechanistic basis for understanding the broad-spectrum anticancer activity and single-agent efficacy observed with dominant-negative cyclin G1, whose cytocidal mechanism of action triggers programmed cell death. Clinically, the utility of companion diagnostics for cyclin G1 pathways is anticipated in the staging, prognosis and treatment of cancers, including the potential for rational combinatorial therapies.

Efficacy and Safety of Pancreas-Targeted Hydrodynamic Gene Delivery in Rats

Development of an effective, safe, and convenient method for gene delivery to the pancreas is a critical step toward gene therapy for pancreatic diseases. Therefore, we tested the possibility of applying the principle of hydrodynamic gene delivery for successful gene transfer to pancreas using rats as a model. The established procedure involves the insertion of a catheter into the superior mesenteric vein with temporary blood flow occlusion at the portal vein and hydrodynamic injection of DNA solution. We demonstrated that our procedure achieved efficient pancreas-specific gene expression that was 2,000-fold higher than that seen in the pancreas after the systemic hydrodynamic gene delivery. In addition, the level of gene expression achieved in the pancreas by the pancreas-specific gene delivery was comparable to the level in the liver achieved by a liver-specific hydrodynamic gene delivery. The optimal level of reporter gene expression in the pancreas requires an injection volume equivalent to 2.0% body weight with flow rate of 1 mL/s and plasmid DNA concentration at 5 μg/mL. With the exception of transient expansion of intercellular spaces and elevation of serum amylase levels, which recovered within 3 days, no permanent tissue damage was observed. These results suggest that pancreas-targeted hydrodynamic gene delivery is an effective and safe method for gene delivery to the pancreas and clinically applicable.

Gene Therapy for Pancreatic Cancer: Specificity, Issues and Hopes

A recent death projection has placed pancreatic ductal adenocarcinoma as the second cause of death by cancer in 2030. The prognosis for pancreatic cancer is very poor and there is a great need for new treatments that can change this poor outcome. Developments of therapeutic innovations in combination with conventional chemotherapy are needed urgently. Among innovative treatments the gene therapy offers a promising avenue. The present review gives an overview of the general strategy of gene therapy as well as the limitations and stakes of the different experimental in vivo models, expression vectors (synthetic and viral), molecular tools (interference RNA, genome editing) and therapeutic genes (tumor suppressor genes, antiangiogenic and pro-apoptotic genes, suicide genes). The latest developments in pancreatic carcinoma gene therapy are described including gene-based tumor cell sensitization to chemotherapy, vaccination and adoptive immunotherapy (chimeric antigen receptor T-cells strategy). Nowadays, there is a specific development of oncolytic virus therapies including oncolytic adenoviruses, herpes virus, parvovirus or reovirus. A summary of all published and on-going phase-1 trials is given. Most of them associate gene therapy and chemotherapy or radiochemotherapy. The first results are encouraging for most of the trials but remain to be confirmed in phase 2 trials.

Rexin-G®, a tumor-targeted retrovector for malignant peripheral nerve sheath tumor: A case report

Soft tissue sarcoma is a rare neoplasm of mesenchymal origin, accounting for only ~1% of all adult cancers and consisting of 75 histological subtypes. In the present report, the unique case of a 14 year-old female with metastatic malignant peripheral nerve sheath tumor (formerly, malignant melanotic schwannoma) of the parotid gland, who experienced a durable response and sustained tumor control with Rexin-G^®, a tumor-targeted retroviral expression vector encoding an anti-cyclin G1 construct, is described. Post-parotidectomy, and prior to the administration of Rexin-G^®, the patient received various chemotherapy regimens, including doxorubicin, ifosfamide, temozolomide, sorafenib, and an immunological therapy with interleukin-2, which only resulted in the further progression of lung metastases. The patient subsequently participated in a Phase 1/2 gene therapy study, during which she received intravenous Rexin-G^® as monotherapy for two years with minimal drug-associated adverse events. Currently, the patient has no evidence of active disease 9 years after commencing the Rexin-G^® treatment, and with no additional anti-cancer therapy. In conclusion, Rexin-G^® may be a viable therapeutic option for malignant peripheral nerve sheath tumors, and should be further investigated in prospective histology-specific clinical trials for this type, and possibly other types, of chemotherapy-resistant sarcoma.

Clinical Outcomes of Specific Immunotherapy in Advanced Pancreatic Cancer: A Systematic Review and Meta-Analysis

Specific immunotherapies, including vaccines with autologous tumor cells and tumor antigen-specific monoclonal antibodies, are important treatments for PC patients. To evaluate the clinical outcomes of PC-specific immunotherapy, we performed a systematic review and meta-analysis of the relevant published clinical trials. The effects of specific immunotherapy were compared with those of nonspecific immunotherapy and the meta-analysis was executed with results regarding the overall survival (OS), immune responses data, and serum cancer markers data. The pooled analysis was performed by using the random-effects model. We found that significantly improved OS was noted for PC patients utilizing specific immunotherapy and an improved immune response was also observed. In conclusion, specific immunotherapy was superior in prolonging the survival time and enhancing immunological responses in PC patients.

The Promise of Gene Therapy for Pancreatic Cancer

Unlike for other digestive cancer entities, chemotherapy, radiotherapy, and targeted therapies have, so far, largely failed to improve patient survival in pancreatic adenocarcinoma (PDAC), which remains the fourth leading cause of cancer-related death in Europe and the United States. In this context, gene therapy may offer a new avenue for patients with PDAC. In this review, we explore the research currently ongoing in French laboratories aimed at defeating PDAC using nonviral therapeutic gene delivery, targeted transgene expression, or oncolytic virotherapy that recently or will soon bridge the gap between experimental models of cancer and clinical trials. These studies are likely to change clinical practice or thinking about PDAC management, as they represent a major advance not only for PDAC but may also significantly influence the field of gene-based molecular treatment of cancer.

Nanovectors for anti-cancer drug delivery in the treatment of advanced pancreatic adenocarcinoma

Liposome, albumin and polymer polyethylene glycol are nanovector formulations successfully developed for anti-cancer drug delivery. There are significant differences in pharmacokinetics, efficacy and toxicity between pre- and post-nanovector modification. The alteration in clinical pharmacology is instrumental for the future development of nanovector-based anticancer therapeutics. We have reviewed the results of clinical studies and translational research in nanovector-based anti-cancer therapeutics in advanced pancreatic adenocarcinoma, including nanoparticle albumin-bound paclitaxel and nanoliposomal irinotecan. Furthermore, we have appraised the ongoing studies incorporating novel agents with nanomedicines in the treatment of pancreatic adenocarcinoma.

Emerging Therapeutic Potential of Nanoparticles in Pancreatic Cancer: A Systematic Review of Clinical Trials

Pancreatic cancer is an aggressive disease with a five year survival rate of less than 5%, which is associated with late presentation. In recent years, research into nanomedicine and the use of nanoparticles as therapeutic agents for cancers has increased. This article describes the latest developments in the use of nanoparticles, and evaluates the risks and benefits of nanoparticles as an emerging therapy for pancreatic cancer. The Preferred Reporting Items of Systematic Reviews and Meta-Analyses checklist was used. Studies were extracted by searching the Embase, MEDLINE, SCOPUS, Web of Science, and Cochrane Library databases from inception to 18 March 2016 with no language restrictions. Clinical trials involving the use of nanoparticles as a therapeutic or prognostic option in patients with pancreatic cancer were considered. Selected studies were evaluated using the Jadad score for randomised control trials and the Therapy CA Worksheet for intervention studies. Of the 210 articles found, 10 clinical trials including one randomised control trial and nine phase I/II clinical trials met the inclusion criteria and were analysed. These studies demonstrated that nanoparticles can be used in conjunction with chemotherapeutic agents increasing their efficacy whilst reducing their toxicity. Increased efficacy of treatment with nanoparticles may improve the clinical outcomes and quality of life in patients with pancreatic cancer, although the long-term side effects are yet to be defined. The study registration number is CRD42015020009.

Interventional Nanotheranostics of Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for over 90% of all pancreatic cancer. Nanoparticles (NPs) offer new opportunities for image-guided therapy owing to the unique physicochemical properties of the nanoscale effect and the multifunctional capabilities of NPs. However, major obstacles exist for NP-mediated cancer theranostics, especially in PDAC. The hypovascular nature of PDAC may impede the deposition of NPs into the tumor after systemic administration, and most NPs localize predominantly in the mononuclear phagocytic system, leading to a relatively poor tumor-to-surrounding-organ uptake ratio. Image guidance combined with minimally invasive interventional procedures may help circumvent these barriers to poor drug delivery of NPs in PDAC. Interventional treatments allow regional drug delivery, targeted vascular embolization, direct tumor ablation, and the possibility of disrupting the stromal barrier of PDAC. Interventional treatments also have potentially fewer complications, faster recovery, and lower cost compared with conventional therapies. This work is an overview of current image-guided interventional cancer nanotheranostics with specific attention given to their applications for the management of PDAC.

Recent Advances and Prospects for Multimodality Therapy in Pancreatic Cancer

The outcomes for treatment of pancreatic cancer have not improved dramatically in many decades. However, the recent promising results with combination chemotherapy regimens for metastatic disease increase optimism for future treatments. With greater control of overt or occult metastatic disease, there will likely be an expanding role for local treatment modalities, especially given that nearly a third of pancreatic cancer patients have locally destructive disease without distant metastatic disease at the time of death. Technical advances have allowed for the safe delivery of dose-escalated radiation therapy, which can then be combined with chemotherapy, targeted agents, immunotherapy, and nanoparticulate drug delivery techniques to produce novel and improved synergistic effects. Here we discuss recent advances and future directions for multimodality therapy in pancreatic cancer.

Gene and cell therapy for pancreatic cancer

INTRODUCTION

The clinical outcomes of patients with pancreatic cancer are poor, and the limited success of classical chemotherapy underscores the need for new, targeted approaches for this disease. The delivery of genetic material to cells allows for a variety of therapeutic concepts. Engineered agents based on synthetic biology are under clinical investigation in various cancers, including pancreatic cancer.

AREAS COVERED

This review focuses on Phase I - III clinical trials of gene and cell therapy for pancreatic cancer and on future implications of recent translational research. Trials available in the US National Library of Medicine (www.clinicaltrials.gov) until February 2014 were reviewed and relevant published results of preclinical and clinical studies were retrieved from www.pubmed.gov .

EXPERT OPINION

In pancreatic cancer, gene and cell therapies are feasible and may have synergistic antitumor activity with standard treatment and/or immunotherapy. Challenges are related to application safety, manufacturing costs, and a new spectrum of adverse events. Further studies are needed to evaluate available agents in carefully designed protocols and combination regimens. Enabling personalized cancer therapy, insights from molecular diagnostic technologies will guide the development and selection of new gene-based drugs. The evolving preclinical and clinical data on gene-based therapies can lay the foundation for future avenues improving patient care in pancreatic cancer.

Engineered nanoparticles for drug delivery in cancer therapy

In medicine, nanotechnology has sparked a rapidly growing interest as it promises to solve a number of issues associated with conventional therapeutic agents, including their poor water solubility (at least, for most anticancer drugs), lack of targeting capability, nonspecific distribution, systemic toxicity, and low therapeutic index. Over the past several decades, remarkable progress has been made in the development and application of engineered nanoparticles to treat cancer more effectively. For example, therapeutic agents have been integrated with nanoparticles engineered with optimal sizes, shapes, and surface properties to increase their solubility, prolong their circulation half-life, improve their biodistribution, and reduce their immunogenicity. Nanoparticles and their payloads have also been favorably delivered into tumors by taking advantage of the pathophysiological conditions, such as the enhanced permeability and retention effect, and the spatial variations in the pH value. Additionally, targeting ligands (e.g., small organic molecules, peptides, antibodies, and nucleic acids) have been added to the surface of nanoparticles to specifically target cancerous cells through selective binding to the receptors overexpressed on their surface. Furthermore, it has been demonstrated that multiple types of therapeutic drugs and/or diagnostic agents (e.g., contrast agents) could be delivered through the same carrier to enable combination therapy with a potential to overcome multidrug resistance, and real-time readout on the treatment efficacy. It is anticipated that precisely engineered nanoparticles will emerge as the next-generation platform for cancer therapy and many other biomedical applications.

Immunotherapeutic and oncolytic viral therapeutic strategies in pancreatic cancer

Pancreatic adenocarcinoma is an aggressive disease with dismal outcomes despite recent advances using combination chemotherapeutic regimens. The lack of an adequate immune response to malignant cells has been identified as a factor associated with tumor aggressiveness and refractoriness to systemic treatment. Preclinical and early clinical studies have identified numerous immunotherapeutic and oncolytic viral therapeutic strategies aimed towards amplifying the immune reaction to pancreatic cancer and have established encouraging results. Promising antitumor efficacy has been observed both in vitro and in vivo with many of these approaches. These novel applications have also led to improved understanding of the process of pancreatic tumor growth and invasion, knowledge of the tumor microenvironment and have pioneered further investigations of similar therapies. Here we review both immunotherapeutic and oncolytic viral therapeutic strategies in pancreatic cancer.

Cancer nanotechnology: the impact of passive and active targeting in the era of modern cancer biology

Cancer nanotherapeutics are progressing at a steady rate; research and development in the field has experienced an exponential growth since early 2000's. The path to the commercialization of oncology drugs is long and carries significant risk; however, there is considerable excitement that nanoparticle technologies may contribute to the success of cancer drug development. The pace at which pharmaceutical companies have formed partnerships to use proprietary nanoparticle technologies has considerably accelerated. It is now recognized that by enhancing the efficacy and/or tolerability of new drug candidates, nanotechnology can meaningfully contribute to create differentiated products and improve clinical outcome. This review describes the lessons learned since the commercialization of the first-generation nanomedicines including DOXIL® and Abraxane®. It explores our current understanding of targeted and non-targeted nanoparticles that are under various stages of development, including BIND-014 and MM-398. It highlights the opportunities and challenges faced by nanomedicines in contemporary oncology, where personalized medicine is increasingly the mainstay of cancer therapy. We revisit the fundamental concepts of enhanced permeability and retention effect (EPR) and explore the mechanisms proposed to enhance preferential "retention" in the tumor, whether using active targeting of nanoparticles, binding of drugs to their tumoral targets or the presence of tumor associated macrophages. The overall objective of this review is to enhance our understanding in the design and development of therapeutic nanoparticles for treatment of cancers.

Genetic and molecular alterations in pancreatic cancer: implications for personalized medicine

Recent advances in human genomics and biotechnologies have profound impacts on medical research and clinical practice. Individual genomic information, including DNA sequences and gene expression profiles, can be used for prediction, prevention, diagnosis, and treatment for many complex diseases. Personalized medicine attempts to tailor medical care to individual patients by incorporating their genomic information. In a case of pancreatic cancer, the fourth leading cause of cancer death in the United States, alteration in many genes as well as molecular profiles in blood, pancreas tissue, and pancreas juice has recently been discovered to be closely associated with tumorigenesis or prognosis of the cancer. This review aims to summarize recent advances of important genes, proteins, and microRNAs that play a critical role in the pathogenesis of pancreatic cancer, and to provide implications for personalized medicine in pancreatic cancer.

Ligand-targeted particulate nanomedicines undergoing clinical evaluation: current status

Since the introduction of Doxil® on the market nearly 20years ago, a number of nanomedicines have become part of treatment regimens in the clinic. With the exception of antibody-drug conjugates, these nanomedicines are all devoid of targeting ligands and rely solely on their physicochemical properties and the (patho)physiological processes in the body for their biodistribution and targeting capability. At the same time, many preclinical studies have reported on nanomedicines exposing targeting ligands, or ligand-targeted nanomedicines, yet none of these have been approved at this moment. In the present review, we provide a concise overview of 13 ligand-targeted particulate nanomedicines (ligand-targeted PNMs) that have progressed into clinical trials. The progress of each ligand-targeted PNM is discussed based on available (pre)clinical data. Main conclusions of these analyses are that (a) ligand-targeted PNMs have proven to be safe and efficacious in preclinical models; (b) the vast majority of ligand-targeted PNMs is generated for the treatment of cancer; (c) contribution of targeting ligands to the PNM efficacy is not unambiguously proven; and (d) targeting ligands do not cause localization of the PNM within the target tissue, but rather provide benefits in terms of target cell internalization and target tissue retention once the PNM has arrived at the target site. Increased understanding of the in vivo fate and interactions of the ligand-targeted PNMs with proteins and cells in the human body is mandatory to rationally advance the clinical translation of ligand-targeted PNMs. Future perspectives for ligand-targeted PNM approaches include the delivery of drugs that are unable or inefficient in passing cellular membranes, treatment of drug resistant tumors, targeting of the tumor blood supply, the generation of targeted vaccines and nanomedicines that are able to cross the blood-brain barrier.

Library screening and receptor-directed targeting of gammaretroviral vectors

Gene- and cell-based therapies hold great potential for the advancement of the personalized medicine movement. Gene therapy vectors have made dramatic leaps forward since their inception. Retroviral-based vectors were the first to gain clinical attention and still offer the best hope for the long-term correction of many disorders. The fear of nonspecific transduction makes targeting a necessary feature for most clinical applications. However, this remains a difficult feature to optimize, with specificity often coming at the expense of efficiency. The aim of this article is to discuss the various methods employed to retarget retroviral entry. Our focus will lie on the modification of gammaretroviral envelope proteins with an in-depth discussion of the creation and screening of envelope libraries.

Antitumoral activity of parvovirus-mediated IL-2 and MCP-3/CCL7 delivery into human pancreatic cancer: implication of leucocyte recruitment

Pancreatic ductal adenocarcinoma (PDAC) represents the fourth leading cause of cancer-related death in western countries. The patients are often diagnosed in advanced metastatic stages, and the prognosis remains extremely poor with an overall 5-year survival rate less than 5 %. Currently, novel therapeutic strategies are being pursued to combat PDAC, including oncolytic viruses, either in their natural forms or armed with immunostimulatory molecules. Natural killer cells are critical players against tumours and infected cells. Recently, we showed that IL-2-activated human NK cells displayed killing activity against PDAC cells, which could further be enhanced through the infection of PDAC cells with the rodent parvovirus H-1PV. In this study, the therapeutic efficacy of parvovirus-mediated delivery of three distinct cyto/chemokines (Il-2, MCP-3/CCL7 and IP-10/CXCL10) was evaluated in xenograft models of human PDAC. We show here that activated NK and monocytic cells were found to be recruited by PDAC tumours upon infection with parvoviruses armed with IL-2 or the chemokine MCP-3/CCL7, resulting in a strong anti-tumour response.

Emerging inorganic nanomaterials for pancreatic cancer diagnosis and treatment

Pancreatic cancer is a devastating disease with incidence increasing at an alarming rate and survival not improved substantially during the past three decades. Although enormous efforts have been made in early detection and comprehensive treatment for this disease, little or no survival improvement was obtained, which necessitates the development of novel strategies. Emerging inorganic nanomaterials, such as carbon nanotubes, quantum dots, mesoporous silica/gold/supermagnetic nanoparticles, have been widely used in biomedical research with great optimism for cancer diagnosis and therapy. Such nanoparticles possess unique optical, electrical, magnetic and/or electrochemical properties. With such properties along with their impressive nano-size, these particles can be targeted to cancer cells, tissues, and ligands efficiently and monitored with extreme precision in real-time. In additional to liposome, dendrimer, and polymeric nanoparticles, they are considered the most promising nanomaterials with the capability of both cancer detection and multimodality treatment. Emerging approaches to harness nanotechnology to optimize the existing diagnostic and therapeutic tools for pancreatic cancer have been extensively explored during the recent years. Future options for early detection, individual therapy and monitoring responses of pancreatic cancer are focused on multifunctional nanomedicine. In this review, we present the recent development of clinically applicable inorganic nanoparticles, with focus on the diagnosis and treatment of pancreatic cancer. Furthermore, their advantages in theranostic nanomedicine, and challenges of translation to clinical practice, are discussed.

Nanoparticle delivery systems for cancer therapy: advances in clinical and preclinical research

Conventional anticancer drugs display significant shortcomings which limit their use in cancer therapy. For this reason, important progress has been achieved in the field of nanotechnology to solve these problems and offer a promising and effective alternative for cancer treatment. Nanoparticle drug delivery systems exploit the abnormal characteristics of tumour tissues to selectively target their payloads to cancer cells, either by passive, active or triggered targeting. Additionally, nanoparticles can be easily tuned to improve their properties, thereby increasing the therapeutic index of the drug. Liposomes, polymeric nanoparticles, polymeric micelles and polymer- or lipid-drug conjugate nanoparticles incorporating cytotoxic therapeutics have been developed; some of them are already on the market and others are under clinical and preclinical research. However, there is still much research to be done to be able to defeat the limitations of traditional anticancer therapy. This review focuses on the potential of nanoparticle delivery systems in cancer treatment and the current advances achieved.

A short perspective on gene therapy: Clinical experience on gene therapy of gliomablastoma multiforme

More than two decades have passed since the first gene therapy clinical trial was conducted. During this time, we have gained much knowledge regarding gene therapy in general, but also learned to understand the fear that persists in society. We have experienced drawbacks and successes. More than 1700 clinical trials have been conducted where gene therapy is used as a means for therapy. In the very first trial, patients with advanced melanoma were treated with tumor infiltrating lymphocytes genetically modified ex-vivo to express tumor necrosis factor. Around the same time the first gene therapy trial was conducted, the ethical aspects of performing gene therapy on humans was intensively discussed. What are the risks involved with gene therapy? Can we control the technology? What is ethically acceptable and what are the indications gene therapy can be used for? Initially, gene therapy was thought to be implemented mainly for the treatment of monogenetic diseases, such as adenosine deaminase deficiency. However, other therapeutic areas have become of interest and currently cancer is the most studied therapeutic area for gene therapy based medicines. In this review I will be giving a short introduction into gene therapy and will direct the discussion to where we should go from here. Furthermore, I will focus on the use of the Herpes simplex virus-thymidine kinase for gene therapy of malignant gliomas and highlight the efficacy of gene therapy for the treatment of malignant gliomas, but other strategies will also be mentioned.

Combinational therapy: new hope for pancreatic cancer?

Pancreatic cancer is a devastating disease with a low overall survival rate. Chemotherapy is the most common treatment for patients presenting with advanced pancreatic cancer. Gemcitabine achieves a modest improvement in overall survival and is the gold standard for advanced pancreatic cancer treatment. Capecitabine and S-1, derivatives of 5-fluorouracil (5-FU), offers minimal clinical benefits. Folfirinox represents a new and aggressive regimen that might benefit patients of metastatic pancreatic cancer with good performance status. Other chemotherapy drugs such as platinums and irinotecan do not provide significant improvement in overall survival, but have been used as part of combinational therapies. Comparing to systemically delivered chemotherapy, regional intra-arterial chemotherapy achieves higher local drug concentration in tumors with lower systemic drug toxicity, and may serve as a better treatment regimen. Although there have been progress made in chemotherapeutic strategies against pancreatic cancer, the overall survival is not significantly improved in the last decade. Recently, development of chemotherapy in combination with molecular targeted therapies holds great promise in pancreatic cancer treatment, especially in patients with metastatic disease. Growing bodies of preclinical and clinical evidences indicate that the combination of conventional modalities with specific molecular targeted therapy increase the efficacy of the monotherapy without an increase in toxicity. In this review, we summarized the current regimens of chemotherapy and molecular targeted therapy for advanced pancreatic cancer and highlighted the novel combinational treatments tested in recent clinical trials.

Nanovector-based therapies in advanced pancreatic cancer

Systemic therapy for advanced pancreatic cancer has been largely disappointing owing to the unfavorable pharmacokinetic profile and poor penetration of current chemotherapeutic agents ,as well as the fragile patient population with compromised tolerance to toxic chemotherapies. Nanovectors can provide passive drug delivery through abnormal tumor neo-vasculature microanatomy or active targeting via binding to receptors or macromolecules associated with the tumor. In such a manner, nanovector-based therapy may not only modulate the pharmacokinetics and therapeutic index of chemotherapeutic agents but also provide new treatment options in patients with advanced pancreatic cancer. In this article, we present the rationale and currently available clinical results of nanovector-based therapies to highlight the potential use of this class of agent in patients with advanced pancreatic cancer.

Current advances in retroviral gene therapy

There have been major changes since the incidents of leukemia development in X-SCID patients after the treatments using retroviral gene therapy. Due to the risk of oncogenesis caused by retroviral insertional activation of host genes, most of the efforts focused on the lentiviral therapies. However, a relative clonal dominance was detected in a patient with β-thalassemia Major, two years after the subject received genetically modified hematopoietic stem cells using lentiviral vectors. This disappointing result of the recent clinical trial using lentiviral vector tells us that the current and most advanced vector systems does not have enough safety. In this review, various safety features that have been tried for the retroviral gene therapy are introduced and the possible new ways of improvements are discussed. Additional feature of chromatin insulators, co-transduction of a suicidal gene under the control of an inducible promoter, conditional expression of the transgene only in appropriate target cells, targeted transduction, cell type-specific expression, targeted local administration, splitting of the viral genome, and site specific insertion of retroviral vector are discussed here.

Overcoming drug resistance in pancreatic cancer

INTRODUCTION

Pancreatic cancer has the worst survival rate of all cancers. The current standard care for metastatic pancreatic cancer is gemcitabine, however, the success of this treatment is poor and overall survival has not improved for decades. Drug resistance (both intrinsic and acquired) is thought to be a major reason for the limited benefit of most pancreatic cancer therapies.

AREAS COVERED

Previous studies have indicated various mechanisms of drug resistance in pancreatic cancer, including changes in individual genes or signaling pathways, the influence of the tumor microenvironment, and the presence of highly resistant stem cells. This review summarizes recent advances in the mechanisms of drug resistance in pancreatic cancer and potential strategies to overcome this.

EXPERT OPINION

Increasing drug delivery efficiency and decreasing drug resistance is the current aim in pancreatic cancer treatment, and will also benefit the treatment of other cancers. Understanding the molecular and cellular basis of drug resistance in pancreatic cancer will lead to the development of novel therapeutic strategies with the potential to sensitize pancreatic cancer to chemotherapy, and to increase the efficacy of current treatments in a wide variety of human cancers.

Gammaretroviral vectors: biology, technology and application

Retroviruses are evolutionary optimized gene carriers that have naturally adapted to their hosts to efficiently deliver their nucleic acids into the target cell chromatin, thereby overcoming natural cellular barriers. Here we will review—starting with a deeper look into retroviral biology—how Murine Leukemia Virus (MLV), a simple gammaretrovirus, can be converted into an efficient vehicle of genetic therapeutics. Furthermore, we will describe how more rational vector backbones can be designed and how these so-called self-inactivating vectors can be pseudotyped and produced. Finally, we will provide an overview on existing clinical trials and how biosafety can be improved.

Pancreatic cancer gene therapy: from molecular targets to delivery systems

The continuous identification of molecular changes deregulating critical pathways in pancreatic tumor cells provides us with a large number of novel candidates to engineer gene-targeted approaches for pancreatic cancer treatment. Targets—both protein coding and non-coding—are being exploited in gene therapy to influence the deregulated pathways to facilitate cytotoxicity, enhance the immune response or sensitize to current treatments. Delivery vehicles based on viral or non-viral systems as well as cellular vectors with tumor homing characteristics are a critical part of the design of gene therapy strategies. The different behavior of tumoral versus non-tumoral cells inspires vector engineering with the generation of tumor selective products that can prevent potential toxic-associated effects. In the current review, a detailed analysis of the different targets, the delivery vectors, the preclinical approaches and a descriptive update on the conducted clinical trials are presented. Moreover, future possibilities in pancreatic cancer treatment by gene therapy strategies are discussed.

Rexin-G, a targeted genetic medicine for cancer

IMPORTANCE OF THE FIELD

Rexin-G, a tumor-targeted retrovector bearing a cytocidal cyclin G1 construct, is the first targeted gene therapy vector to gain fast track designation and orphan drug priorities for multiple cancer indications in the US.

AREAS COVERED IN THIS REVIEW

This review describes the major milestones in the clinical development of Rexin-G: from the molecular cloning and characterization of the human cyclin G1 proto-oncogene in 1994, to the design of the first knockout constructs and genetic engineering of the targeted delivery system from 1995 to 1997, through the initial proofs-of-concept, molecular pharmacology and toxicology studies of Rexin-G in preclinical cancer models from 1997 to 2001, to the pioneering clinical studies in humans from 2002 to 2004, which--together with the advancements in bioprocess development of high-potency clinical grade vectors circa 2005 - 2006--led to the accelerated approval of Rexin-G for all solid tumors by the Philippine FDA in 2007 and the rapid progression of clinical studies from 2007 to 2009 to the cusp of pivotal Phase III trials in the US.

WHAT THE READER WILL GAIN

In recording the development of Rexin-G as a novel form of targeted biological therapy, this review also highlights important aspects of vector design engineering which served to overcome the physiological barriers to gene delivery as it addresses the key regulatory issues involved in the development of a targeted gene therapy product.

TAKE HOME MESSAGE

Progressive clinical development of Rexin-G demonstrates the potential safety and efficacy of targeted genetic medicine, while validating the design engineering of the molecular biotechnology platform.