Immunogene therapy of recurrent glioblastoma multiforme with a liposomally encapsulated replication-incompetent Semliki forest virus vector carrying the human interleukin-12 gene--a phase I/II clinical protocol

Advances in Glioblastoma Therapy: An Update on Current Approaches

Glioblastoma multiforme (GBM) is a primary malignant brain tumor characterized by a high grade of malignancy and an extremely unfavorable prognosis. The current efficacy of established treatments for GBM is insufficient, necessitating the prompt development of novel therapeutic approaches. The progress made in the fundamental scientific understanding of GBM is swiftly translated into more advanced stages of therapeutic studies. Despite extensive efforts to identify new therapeutic approaches, GBM exhibits a high mortality rate. The current efficacy of treatments for GBM patients is insufficient due to factors such as tumor heterogeneity, the blood-brain barrier, glioma stem cells, drug efflux pumps, and DNA damage repair mechanisms. Considering this, pharmacological cocktail therapy has demonstrated a growing efficacy in addressing these challenges. Towards this, various forms of immunotherapy, including the immune checkpoint blockade, chimeric antigen receptor T (CAR T) cell therapy, oncolytic virotherapy, and vaccine therapy have emerged as potential strategies for enhancing the prognosis of GBM. Current investigations are focused on exploring combination therapies to mitigate undesirable side effects and enhance immune responses against tumors. Furthermore, clinical trials are underway to evaluate the efficacy of several strategies to circumvent the blood-brain barrier (BBB) to achieve targeted delivery in patients suffering from recurrent GBM. In this review, we have described the biological and molecular targets for GBM therapy, pharmacologic therapy status, prominent resistance mechanisms, and new treatment approaches. We also discuss these promising therapeutic approaches to assess prospective innovative therapeutic agents and evaluated the present state of preclinical and clinical studies in GBM treatment. Overall, this review attempts to provide comprehensive information on the current status of GBM therapy.

Engineering Non-Human RNA Viruses for Cancer Therapy

Alongside the development and progress in cancer immunotherapy, research in oncolytic viruses (OVs) continues advancing novel treatment strategies to the clinic. With almost 50 clinical trials carried out over the last decade, the opportunities for intervention using OVs are expanding beyond the old-fashioned concept of "lytic killers", with promising breakthrough therapeutic strategies focused on leveraging the immunostimulatory potential of different viral platforms. This review presents an overview of non-human-adapted RNA viruses engineered for cancer therapy. Moreover, we describe the diverse strategies employed to manipulate the genomes of these viruses to optimize their therapeutic capabilities. By focusing on different aspects of this particular group of viruses, we describe the insights into the promising advancements in the field of virotherapy and its potential to revolutionize cancer treatment.

Viral vectors engineered for gene therapy

Gene therapy has seen major progress in recent years. Viral vectors have made a significant contribution through efficient engineering for improved delivery and safety. A large variety of indications such as cancer, cardiovascular, metabolic, hematological, neurological, muscular, ophthalmological, infectious diseases, and immunodeficiency have been targeted. Viral vectors based on adenoviruses, adeno-associated viruses, herpes simplex viruses, retroviruses including lentiviruses, alphaviruses, flaviviruses, measles viruses, rhabdoviruses, Newcastle disease virus, poxviruses, picornaviruses, reoviruses, and polyomaviruses have been used. Proof-of-concept has been demonstrated for different indications in animal models. Therapeutic efficacy has also been achieved in clinical trials. Several viral vector-based drugs have been approved for the treatment of cancer, and hematological, metabolic, and neurological diseases. Moreover, viral vector-based vaccines have been approved against COVID-19 and Ebola virus disease.

Alphaviruses in cancer immunotherapy

Alphaviruses have frequently been engineered for cancer therapy, cancer immunotherapy, and cancer vaccine development. As members of self-replicating RNA viruses, alphaviruses provide high levels of transgene expression through efficient self-amplifying of their RNA genome in host cells. Alphavirus vectors can be used as recombinant viral particles or oncolytic viruses. Alternatively, either naked or nanoparticle-encapsulated RNA and DNA replicons can be utilized. In the context of cancer prevention and treatment, antitumor, cytotoxic and suicide genes have been expressed from alphavirus vectors to provide tumor regression and tumor eradication. Moreover, immunostimulatory genes such as cytokines and chemokines have been used for cancer immunotherapy approaches. Expression of tumor antigens has been applied for cancer vaccine development. Alphavirus vectors has demonstrated tumor regression and even cure in various preclinical animal models. Immunization has elicited strong immune responses and showed protection against challenges with tumor cells in animal models. Several clinical trials have confirmed good safety and tolerability of alphaviruses in cancer patients although therapeutic efficacy will still require optimization.

Thymine-Modified Nanocarrier for Doxorubicin Delivery in Glioblastoma Cells

Brain tumor glioblastoma is one of the worst types of cancer. The blood-brain barrier prevents drugs from reaching brain cells and shields glioblastoma from treatment. The creation of nanocarriers to improve drug delivery and internalization effectiveness may be the solution to this issue. In this paper, we report on a new nanocarrier that was developed to deliver the anticancer drug doxorubicin to glioblastoma cells. The nanocarrier was obtained by nanoemulsion polymerization of diallyl disulfide with 1-allylthymine. Diallyl disulfide is a redox-sensitive molecule involved in redox cell activities, and thymine is a uracil derivative and one of the well-known bioactive compounds that can enhance the pharmacological activity of doxorubicin. Doxorubicin was successfully introduced into the nanocarrier with a load capacity of about 4.6%. Biological studies showed that the doxorubicin nanocarrier composition is far more cytotoxic to glioblastoma cells (T98G) than it is to cancer cells (M-HeLa) and healthy cells (Chang liver). The nanocarrier improves the penetration of doxorubicin into T98G cells and accelerates the cells' demise, as is evident from flow cytometry and fluorescence microscopy data. The obtained nanocarrier, in our opinion, is a promising candidate for further research in glioblastoma therapy.

Convection-enhanced delivery of immunomodulatory therapy for high-grade glioma

The prognosis for glioblastoma has remained poor despite multimodal standard of care treatment, including temozolomide, radiation, and surgical resection. Further, the addition of immunotherapies, while promising in a number of other solid tumors, has overwhelmingly failed in the treatment of gliomas, in part due to the immunosuppressive microenvironment and poor drug penetrance to the brain. Local delivery of immunomodulatory therapies circumvents some of these challenges and has led to long-term remission in select patients. Many of these approaches utilize convection-enhanced delivery (CED) for immunological drug delivery, allowing high doses to be delivered directly to the brain parenchyma, avoiding systemic toxicity. Here, we review the literature encompassing immunotherapies delivered via CED-from preclinical model systems to clinical trials-and explore how their unique combination elicits an antitumor response by the immune system, decreases toxicity, and improves survival among select high-grade glioma patients.

Options of Therapeutics and Novel Delivery Systems of Drugs for the Treatment of Melanoma

Melanoma is one of the most severe cancerous diseases. The cells employ multiple signaling pathways, such as ERK, HGF/c-MET, WNT, and COX-2 to cause the cell proliferation, survival, and metastasis. Treatment of melanoma, including surgery, chemotherapy, immunotherapy, radiation, and targeted therapy, is based on 4 major or 11 substages of the disease. Fourteen drugs, including dacarbazine, interferon α-2b, interleukin-12, ipilimumab, peginterferon α-2b, vemurafenib, trametinib, talimogene laherparepvec, cobimetinib, pembrolizumab, dabrafenib, binimetinib, encorafenib, and nivolumab, have been approved by the FDA for the treatment of melanoma. All of them are in conventional dosage forms of injection solutions, suspensions, oral tablets, or capsules. Major drawbacks of the treatment are side effects of the drugs and patients' incompliance to them. These are consequences of high doses and long-term treatments for the diseases. Currently more than 350 NCI-registered clinical trials are being carried out to treat advanced and/or metastatic melanoma using novel treatment methods, such as immune cell therapy, cancer vaccines, and new therapeutic targets. In addition, novel delivery systems using biomaterials of the approved drugs have been developed attempting to increase the drug delivery, targeting, stability, bioavailability, thus potentially reducing the toxicity and increasing the treatment effectiveness. Nanoparticles and liposomes have been emerging as advanced delivery systems which can improve drug stability and systemic circulation time. In this review, the most recent findings in the options for treatment and development of novel drug delivery systems for the treatment of melanoma are comprehensively discussed.

High Incidence of Intracerebral Hemorrhaging Associated with the Application of Low-Intensity Focused Ultrasound Following Acute Cerebrovascular Injury by Intracortical Injection

Low-intensity transcranial focused ultrasound (FUS) has gained momentum as a non-/minimally-invasive modality that facilitates the delivery of various pharmaceutical agents to the brain. With the additional ability to modulate regional brain tissue excitability, FUS is anticipated to confer potential neurotherapeutic applications whereby a deeper insight of its safety is warranted. We investigated the effects of FUS applied to the rat brain (Sprague-Dawley) shortly after an intracortical injection of fluorescent interstitial solutes, a widely used convection-enhanced delivery technique that directly (i.e., bypassing the blood-brain-barrier (BBB)) introduces drugs or interstitial tracers to the brain parenchyma. Texas Red ovalbumin (OA) and fluorescein isothiocyanate-dextran (FITC-d) were used as the interstitial tracers. Rats that did not receive sonication showed an expected interstitial distribution of OA and FITC-d around the injection site, with a wider volume distribution of OA (21.8 ± 4.0 µL) compared to that of FITC-d (7.8 ± 2.7 µL). Remarkably, nearly half of the rats exposed to the FUS developed intracerebral hemorrhaging (ICH), with a significantly higher volume of bleeding compared to a minor red blood cell extravasation from the animals that were not exposed to sonication. This finding suggests that the local cerebrovascular injury inflicted by the micro-injection was further exacerbated by the application of sonication, particularly during the acute stage of injury. Smaller tracer volume distributions and weaker fluorescent intensities, compared to the unsonicated animals, were observed for the sonicated rats that did not manifest hemorrhaging, which may indicate an enhanced degree of clearance of the injected tracers. Our results call for careful safety precautions when ultrasound sonication is desired among groups under elevated risks associated with a weakened or damaged vascular integrity.

IL12 immune therapy clinical trial review: Novel strategies for avoiding CRS-associated cytokines

Interleukin 12 (IL-12) is a naturally occurring cytokine that plays a key role in inducing antitumor immune responses, including induction of antitumor immune memory. Currently, no IL-12-based therapeutic products have been approved for clinical application because of its toxicities. On the basis of this review of clinical trials using primarily wild-type IL-12 and different delivery methods, we conclude that the safe utilization of IL-12 is highly dependent on the tumor-specific localization of IL-12 post administration. In this regard, we have developed a cell membrane-anchored and tumor-targeted IL-12-T (attIL12-T) cell product for avoiding toxicity from both IL-12 and T cells-induced cytokine release syndrome in peripheral tissues. A phase I trial using this product which seeks to avoid systemic toxicity and boost antitumor efficacy is on the horizon. Of note, this product also boosts the impact of CAR-T or TCR-T cell efficacy against solid tumors, providing an alternative approach to utilize CAR-T to overcome tumor resistance.

Alphaviruses in Immunotherapy and Anticancer Therapy

Alphaviruses have been engineered as expression vectors for vaccine development and gene therapy. Due to the feature of RNA self-replication, alphaviruses can provide exceptional direct cytoplasmic expression of transgenes based on the delivery of recombinant particles, naked or nanoparticle-encapsulated RNA or plasmid-based DNA replicons. Alphavirus vectors have been utilized for the expression of various antigens targeting different types of cancers, and cytotoxic and antitumor genes. The most common alphavirus vectors are based on the Semliki Forest virus, Sindbis virus and Venezuelan equine encephalitis virus, but the oncolytic M1 alphavirus has also been used. Delivery of immunostimulatory cytokine genes has been the basis for immunotherapy demonstrating efficacy in different animal tumor models for brain, breast, cervical, colon, lung, ovarian, pancreatic, prostate and skin cancers. Typically, therapeutic effects including tumor regression, tumor eradication and complete cure as well as protection against tumor challenges have been observed. Alphavirus vectors have also been subjected to clinical evaluations. For example, therapeutic responses in all cervical cancer patients treated with an alphavirus vector expressing the human papilloma virus E6 and E7 envelope proteins have been achieved.

Nanotherapeutic treatment of the invasive glioblastoma tumor microenvironment

Glioblastoma (GBM) is the most common malignant adult brain cancer with no curative treatment strategy. A significant hurdle in GBM treatment is effective therapeutic delivery to the brain-invading tumor cells that remain following surgery within functioning brain regions. Developing therapies that can either directly target these brain-invading tumor cells or act on other cell types and molecular processes supporting tumor cell invasion and recurrence are essential steps in advancing new treatments in the clinic. This review highlights some of the drug delivery strategies and nanotherapeutic technologies that are designed to target brain-invading GBM cells or non-neoplastic, invasion-supporting cells residing within the GBM tumor microenvironment.

Applications of self-replicating RNA

Self-replicating RNA viral vectors have been engineered for both prophylactic and therapeutic applications. Mainly the areas of infectious diseases and cancer have been targeted. Both positive and negative strand RNA viruses have been utilized including alphaviruses, flaviviruses, measles viruses and rhabdoviruses. The high-level of RNA amplification has provided efficient expression of viral surface proteins and tumor antigens. Immunization studies in animal models have elicit robust neutralizing antibody responses. In the context of infectious diseases, immunization with self-replicating RNA viral vectors has provided protection against challenges with lethal doses of pathogens in animal models. Similarly, immunization with vectors expressing tumor antigens has resulted in tumor regression and eradication and protection against tumor challenges in animal models. The transient nature and non-integration of viral RNA into the host genome are ideal features for vaccine development. Moreover, self-replicating RNA viral vectors show great flexibility as they can be applied as recombinant viral particles, RNA replicons or DNA replicon plasmids. Several clinical trials have been conducted especially in the area of cancer immunotherapy.

Alphaviruses in Cancer Therapy

Alphaviruses have been engineered as expression vectors for different strategies of cancer therapy including immunotherapy and cancer vaccine development. Administration of recombinant virus particles, RNA replicons and plasmid DNA-based replicons provide great flexibility for alphavirus applications. Immunization and delivery studies have demonstrated therapeutic efficacy in the form of reduced tumor growth, tumor regression and eradication of established tumors in different animal models for cancers such as brain, breast, colon, cervical, lung, ovarian, pancreas, prostate cancers, and melanoma. Furthermore, vaccinated animals have showed protection against challenges with tumor cells. A limited number of clinical trials in the area of brain, breast, cervical, colon prostate cancers and melanoma vaccines has been conducted. Particularly, immunization of cervical cancer patients elicited immune responses and therapeutic activity in all patients included in a phase I clinical trial. Moreover, stable disease and partial responses were observed in breast cancer patients and prolonged survival was achieved in colon cancer patients.

Modernistic and Emerging Developments of Nanotechnology in Glioblastoma-Targeted Theranostic Applications

Brain tumors such as glioblastoma are typically associated with an unstoppable cell proliferation with aggressive infiltration behavior and a shortened life span. Though treatment options such as chemotherapy and radiotherapy are available in combating glioblastoma, satisfactory therapeutics are still not available due to the high impermeability of the blood–brain barrier. To address these concerns, recently, multifarious theranostics based on nanotechnology have been developed, which can deal with diagnosis and therapy together. The multifunctional nanomaterials find a strategic path against glioblastoma by adjoining novel thermal and magnetic therapy approaches. Their convenient combination of specific features such as real-time tracking, in-depth tissue penetration, drug-loading capacity, and contrasting performance is of great demand in the clinical investigation of glioblastoma. The potential benefits of nanomaterials including specificity, surface tunability, biodegradability, non-toxicity, ligand functionalization, and near-infrared (NIR) and photoacoustic (PA) imaging are sufficient in developing effective theranostics. This review discusses the recent developments in nanotechnology toward the diagnosis, drug delivery, and therapy regarding glioblastoma.

Quantitative evaluation of PpSP15-LmSTI1 fusion gene expression following transfection with an alphavirus-derived self-amplifying mRNA and conventional DNA vaccine platforms

New vaccine platforms are crucial to address complex parasitic infections such as cutaneous leishmaniasis. Self-amplifying mRNA (SAM) based vaccines represent the next generation nucleic acid-based platform. In the present study, we compared the expression levels of PpSP15-LmSTI1 fusion gene in BHK-21 cells following transfection with Semliki Forest virus (SFV)-derived SAM, SFV-derived plasmid DNA (pSFV-PD) and conventional plasmid DNA (pcDNA3.1+). PpSP15-LmSTI1 fusion gene expression levels were evaluated at different time points, using quantitative Real-time PCR. All data were validated and normalized by two internal control genes. According to the results, mean values of relative expression were significantly higher for SFV-PD SAM/fusion than pcDNA/fusion and pSFV-PD/fusion at all concentrations and time points. Our results showed that higher levels of PpSp15-LmSTI1 antigen expression could be achieved using a SAM vector than pcDNA and pSFV-PD, making it a valuable and efficient alternative to conventional plasmid DNA-based vaccines against leishmaniasis.

Convection-enhanced drug delivery for glioblastoma: a review

INTRODUCTION

Convection-enhanced delivery (CED) is a method of targeted, local drug delivery to the central nervous system (CNS) that bypasses the blood-brain barrier (BBB) and permits the delivery of high-dose therapeutics to large volumes of interest while limiting associated systemic toxicities. Since its inception, CED has undergone considerable preclinical and clinical study as a safe method for treating glioblastoma (GBM). However, the heterogeneity of both, the surgical procedure and the mechanisms of action of the agents studied-combined with the additional costs of performing a trial evaluating CED-has limited the field's ability to adequately assess the durability of any potential anti-tumor responses. As a result, the long-term efficacy of the agents studied to date remains difficult to assess.

MATERIALS AND METHODS

We searched PubMed using the phrase "convection-enhanced delivery and glioblastoma". The references of significant systematic reviews were also reviewed for additional sources. Articles focusing on physiological and physical mechanisms of CED were included as well as technological CED advances.

RESULTS

We review the history and principles of CED, procedural advancements and characteristics, and outcomes from key clinical trials, as well as discuss the potential future of this promising technique for the treatment of GBM.

CONCLUSION

While the long-term efficacy of the agents studied to date remains difficult to assess, CED remains a promising technique for the treatment of GBM.

The Identification and Development of a Novel Oncolytic Virus: Alphavirus M1

Oncolytic virotherapy represents an ideal therapeutic platform for cancer in which natural or engineered viruses selectively replicate in and destroy tumor cells, whereas sparing normal cells. Oncolytic virotherapy is considered as a key contributor in modern immunotherapy. However, several challenges remain with regard to exploiting the potential of oncolytic viruses, such as the lack of biomarkers for precise treatment, the difficulty of systemic administration because of pre-existing neutralizing antibodies to popular oncolytic viral vectors in human serum and the lack of mature lyophilization technology for convenient transport and preservation of viral preparations. The M1 strain, which was isolated on Hainan Island of China in the 1960s, is a member of the alphavirus genus Togaviridae family. It was identified as a novel oncolytic virus in 2014. During the development of M1 virus, many challenges have been overcome: several biomarkers have been identified for precise treatment; systematic administration of M1 is suitable and feasible because of the extremely low percentage of pre-existing neutralizing antibodies in the general population, and a lyophilized powder that maintains high biological stability has been developed. This review provides an encyclopedia of studies supporting M1 as an oncolytic virus, including the biological characteristics, tumor selectivity and its mechanism, tumor killing mechanism, combination therapy, and nonclinical pharmacokinetics of M1 virus. The future development direction of oncolytic virus M1 is also discussed at the end of the review.

Nanotechnology and Nanocarrier-Based Drug Delivery as the Potential Therapeutic Strategy for Glioblastoma Multiforme: An Update

Simple Summary

Glioblastoma multiforme (GBM) are among the most lethal tumors. The highly invasive nature and presence of GBM stem cells, as well as the blood brain barrier (BBB) which limits chemotherapeutic drugs from entering the tumor mass, account for the high chance of treatment failure. Recent developments have found that nanoparticles can be conjugated to liposomes, dendrimers, metal irons, or polymeric micelles, which enhance the drug-loaded compounds to efficiently penetrate the BBB, thus offering new possibilities for overcoming GBM stem cell-mediated resistance to chemotherapy and radiation therapy. In addition, there have been new emerging strategies that use nanocarriers for successful GBM treatment in animal models. This review highlights the recent development of nanotechnology and nanocarrier-based drug delivery for treatment of GBMs, which may be a promising therapeutic strategy for this tumor entity.

Abstract

Glioblastoma multiforme (GBM) is the most common and malignant brain tumor with poor prognosis. The heterogeneous and aggressive nature of GBMs increases the difficulty of current standard treatment. The presence of GBM stem cells and the blood brain barrier (BBB) further contribute to the most important compromise of chemotherapy and radiation therapy. Current suggestions to optimize GBM patients’ outcomes favor controlled targeted delivery of chemotherapeutic agents to GBM cells through the BBB using nanoparticles and monoclonal antibodies. Nanotechnology and nanocarrier-based drug delivery have recently gained attention due to the characteristics of biosafety, sustained drug release, increased solubility, and enhanced drug bioactivity and BBB penetrability. In this review, we focused on recently developed nanoparticles and emerging strategies using nanocarriers for the treatment of GBMs. Current studies using nanoparticles or nanocarrier-based drug delivery system for treatment of GBMs in clinical trials, as well as the advantages and limitations, were also reviewed.

Self-Replicating RNAs Drive Protective Anti-tumor T Cell Responses to Neoantigen Vaccine Targets in a Combinatorial Approach

Historically poor clinical results of tumor vaccines have been attributed to weakly immunogenic antigen targets, limited specificity, and vaccine platforms that fail to induce high-quality polyfunctional T cells, central to mediating cellular immunity. We show here that the combination of antigen selection, construct design, and a robust vaccine platform based on the Synthetically Modified Alpha Replicon RNA Technology (SMARRT), a self-replicating RNA, leads to control of tumor growth in mice. Therapeutic immunization with SMARRT replicon-based vaccines expressing tumor-specific neoantigens or tumor-associated antigen were able to generate polyfunctional CD4⁺ and CD8⁺ T cell responses in mice. Additionally, checkpoint inhibitors, or co-administration of cytokine also expressed from the SMARRT platform, synergized to enhance responses further. Lastly, SMARRT-based immunization of non-human primates was able to elicit high-quality T cell responses, demonstrating translatability and clinical feasibility of synthetic replicon technology for therapeutic oncology vaccines.

Semliki Forest virus-based immunotherapy for cancer

Introduction: Immunotherapy has been introduced as a modern alternative for the treatment of various cancers, including the stimulation of the immune system by introduction of immunostimulatory molecules. Application of viral and non-viral vectors have provided a substantial contribution to improved delivery and expression of these immunostimulators.Areas covered: Alphavirus vectors, based on Semliki Forest virus, have allowed immunization with self-replicating RNA, recombinant virus particles, and layered DNA/RNA vectors. The attractive features of alphaviruses comprise their broad host range and extreme RNA replication in infected cells resulting in very high recombinant protein expression levels providing enhanced immune responses and an excellent basis for immunotherapy.Expert opinion: Immunization studies in animal tumor models have elicited strong humoral and cellular immune response, have provided prophylactic protection against tumor challenges, and have generated therapeutic efficacy in tumor-bearing animals. Clinical trials have indicated safe use of alphavirus vectors, making them attractive for cancer immunotherapy.

Poly(lactic-co-glycolic acid) nanoparticle-mediated interleukin-12 delivery for the treatment of diabetic retinopathy

Background

Diabetic retinopathy (DR) is a complication of diabetes that affects the eyes and vision. It is a leading cause of visual impairment and blindness in working-age people. Vascular endothelial growth factor-A (VEGF-A) is a primary initiator and potential mediator of DR. Matrix metalloproteinase-9 (MMP-9) plays a progressive role in the onset and severity of DR. Interleukin-12 (IL-12) is a cytokine of the chemokine family that could reduce the levels of MMP-9 and VEGF-A and suppress tumor angiogenesis. We hypothesize that IL-12 may also have superior therapeutic efficacy against DR. However, protein drugs are prone to degradation by various proteases after drug injection. Therefore, they have short half-lives and low blood concentrations. The objective of this study was to develop IL-12-loaded nanoparticles for long-term and sustained DR treatment.

Methods

IL-12-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (IL-12-PNP) were developed by double emulsion. The characteristics, anti-DR activity, and mechanisms of IL-12-PNP were examined in vitro and in vivo.

Results

The nanoparticles had suitable particle size (~132.8 nm), drug encapsulation efficiency (~34.7%), and sustained drug release profile. Compared with IL-12 and blank nanoparticles, IL-12-PNP showed better inhibitory efficacy against VEGF-A and MMP-9 expression in rat endothelial cells and DR mouse retina. Intraocular IL-12-PNP administration significantly reduced retinal damage in DR mice as they presented with increased thickness and decreased neovascularization after treatment.

Conclusion

These data indicate that IL-12-PNP is an effective drug delivery platform for DR therapy. It restores the thickness and reduces neovascularization of the retinas of DR mice.

Convection-Enhanced Delivery in Malignant Gliomas: A Review of Toxicity and Efficacy

Malignant gliomas are undifferentiated or anaplastic gliomas. They remain incurable with a multitude of modalities, including surgery, radiation, chemotherapy, and alternating electric field therapy. Convection-enhanced delivery (CED) is a local treatment that can bypass the blood-brain barrier and increase the tumor uptake of therapeutic agents, while decreasing exposure to healthy tissues. Considering the multiple choices of drugs with different antitumor mechanisms, the supra-additive effect of concomitant radiation and chemotherapy, CED appears as a promising modality for the treatment of brain tumors. In this review, the CED-related toxicities are summarized and classified into immediate, early, and late side effects based on the time of onset, and local and systemic toxicities based on the location of toxicity. The efficacies of CED of various therapeutic agents including targeted antitumor agents, chemotherapeutic agents, radioisotopes, and immunomodulators are covered. The phase III trial PRECISE compares CED of IL13-PE38QQR, an interleukin-13 conjugated to Pseudomonas aeruginosa exotoxin A, to Gliadel® Wafer, a polymer loaded with carmustine. However, in this case, CED had no significant median survival improvement (11.3 months vs. 10 months) in patients with recurrent glioblastomas. In phase II studies, CED of recombinant poliovirus (PVSRIPO) had an overall survival of 21% vs. 14% for the control group at 24 months, and 21% vs. 4% at 36 months. CED of Tf-diphtheria toxin had a response rate of 35% in recurrent malignant gliomas patients. On the other hand, the TGF-β2 inhibitor Trabedersen, HSV-1-tk ganciclovir, and radioisotope 131I-chTNT-1/B mAb had a limited response rate. With this treatment, patients who received CED of the chemotherapeutic agent paclitaxel and immunomodulator, oligodeoxynucleotides containing CpG motifs (CpG-ODN), experienced intolerable toxicity. Toward the end of this article, an ideal CED treatment procedure is proposed and the methods for quality assurance of the CED procedure are discussed.

The Journey of in vivo Virus Engineered Dendritic Cells From Bench to Bedside: A Bumpy Road

Dendritic cells (DCs) are recognized as highly potent antigen-presenting cells that are able to stimulate cytotoxic T lymphocyte (CTL) responses with antitumor activity. Consequently, DCs have been explored as cellular vaccines in cancer immunotherapy. To that end, DCs are modified with tumor antigens to enable presentation of antigen-derived peptides to CTLs. In this review we discuss the use of viral vectors for in situ modification of DCs, focusing on their clinical applications as anticancer vaccines. Among the viral vectors discussed are those derived from viruses belonging to the families of the Poxviridae, Adenoviridae, Retroviridae, Togaviridae, Paramyxoviridae, and Rhabdoviridae. We will further shed light on how the combination of viral vector-based vaccination with T-cell supporting strategies will bring this strategy to the next level.

Clinical Evaluations of Toxicity and Efficacy of Nanoparticle-Mediated Gene Therapy

Considerable efforts have been devoted to develop safe and efficient gene therapies for life-threatening or inherited diseases. The choice of gene delivery vehicle plays key roles in enhancing the therapeutic effect of nucleic acid cargo. To date, gene therapy approaches involving both viral vectors and nonviral vectors have been evaluated in clinical trials. With improvements in material science and nanotechnologies, positively charged nanoparticles have emerged as potential gene delivery vehicles. In this review, we highlight clinical trials that examined cationic nanocarrier-mediated gene therapy as well as discuss both the toxicity and efficacy of nanocarrier-based therapeutics.

Oncolytic Alphaviruses in Cancer Immunotherapy

Oncolytic viruses show specific targeting and killing of tumor cells and therefore provide attractive assets for cancer immunotherapy. In parallel to oncolytic viral vectors based on adenoviruses and herpes simplex viruses, oncolytic RNA viruses and particularly alphaviruses have been evaluated as delivery vehicles. Immunization studies in experimental rodent models for various cancers including glioblastoma, hematologic, hepatocellular, colon, cervix, and lung cancer as well as melanoma have been conducted with naturally occurring oncolytic alphavirus strains such as M1 and Sindbis AR339. Moreover, animals were vaccinated with engineered oncolytic replication-deficient and -competent Semliki Forest virus, Sindbis virus and Venezuelan equine encephalitis virus vectors expressing various antigens. Vaccinations elicited strong antibody responses and resulted in tumor growth inhibition, tumor regression and even complete tumor eradication. Vaccination also led to prolonged survival in several animal models. Furthermore, preclinical evaluation demonstrated both prophylactic and therapeutic efficacy of oncolytic alphavirus administration. Clinical trials in humans have mainly been limited to safety studies so far.

Targeted Nanotechnology in Glioblastoma Multiforme

Gliomas, and in particular glioblastoma multiforme, are aggressive brain tumors characterized by a poor prognosis and high rates of recurrence. Current treatment strategies are based on open surgery, chemotherapy (temozolomide) and radiotherapy. However, none of these treatments, alone or in combination, are considered effective in managing this devastating disease, resulting in a median survival time of less than 15 months. The efficiency of chemotherapy is mainly compromised by the blood-brain barrier (BBB) that selectively inhibits drugs from infiltrating into the tumor mass. Cancer stem cells (CSCs), with their unique biology and their resistance to both radio- and chemotherapy, compound tumor aggressiveness and increase the chances of treatment failure. Therefore, more effective targeted therapeutic regimens are urgently required. In this article, some well-recognized biological features and biomarkers of this specific subgroup of tumor cells are profiled and new strategies and technologies in nanomedicine that explicitly target CSCs, after circumventing the BBB, are detailed. Major achievements in the development of nanotherapies, such as organic poly(propylene glycol) and poly(ethylene glycol) or inorganic (iron and gold) nanoparticles that can be conjugated to metal ions, liposomes, dendrimers and polymeric micelles, form the main scope of this summary. Moreover, novel biological strategies focused on manipulating gene expression (small interfering RNA and clustered regularly interspaced short palindromic repeats [CRISPR]/CRISPR associated protein 9 [Cas 9] technologies) for cancer therapy are also analyzed. The aim of this review is to analyze the gap between CSC biology and the development of targeted therapies. A better understanding of CSC properties could result in the development of precise nanotherapies to fulfill unmet clinical needs.

Survivin a radiogenetic promoter for glioblastoma viral gene therapy independently from CArG motifs

Background

Radiogenetic therapy is a novel approach in the treatment of cancer, which employs genetic modification to alter the sensitivity of tumor cells to the effect of applied radiation.

Aim

To select a potent radiation inducible promoter in the context of brain tumors and to investigate if CArG radio responsive motifs or other elements in the promoter nucleotide sequences can correlate to its response to radiation.

Methods

To select initial candidates for promoter inducible elements, the levels of mRNA expression of six different promoters were assessed using Quantitative RTPCR in D54 MG cells before and after radiation exposure. Recombinant Ad/reporter genes driven by five different promoters; CMV, VEGF, FLT-1, DR5 and survivin were constructed. Glioma cell lines were infected with different multiplicity of infection of the (promoter) Ad or CMV Ad. Cells were then exposed to a range of radiation (0–12 Gy) at single fraction. Fluorescent microscopy, Luc assay and X-gal staining was used to detect the level of expression of related genes. Different glioma cell lines and normal astrocytes were infected with Ad survivin and exposed to radiation. The promoters were analyzed for presence of CArG radio-responsive motifs and CCAAT box consensus using NCBI blast bioinformatics software.

Results

Radiotherapy increases the expression of gene expression by 1.25–2.5 fold in different promoters other than survivin after 2 h of radiation. RNA analysis was done and has shown an increase in copy number of tenfold for survivin. Most importantly cells treated with RT and Ad Luc driven by survivin promoter showed a fivefold increase in expression after 2 Gy of radiation in comparison to non-irradiated cells. Presence or absence of CArG motifs did not correlate with promoter response to radiation. Survivin with the best response to radiation had the lowest number of CCAAT box.

Conclusion

Survivin is a selective potent radiation inducible promoter for glioblastoma viral gene therapy and this response to radiation could be independent of CArG motifs.

Nanotechnology Applications for Diffuse Intrinsic Pontine Glioma

Diffuse intrinsic pontine gliomas (DIPGs) are invariably fatal tumors found in the pons of elementary school aged children. These tumors are grade II-IV gliomas, with a median survival of less than 1 year from diagnosis when treated with standard of care (SOC) therapy. Nanotechnology may offer therapeutic options for the treatment of DIPGs. Multiple nanoparticle formulations are currently being investigated for the treatment of DIPGs. Nanoparticles based upon stable elements, polymer nanoparticles, and organic nanoparticles are under development for the treatment of brain tumors, including DIPGs. Targeting of nanoparticles is now possible as delivery techniques that address the difficulty in crossing the blood brain barrier (BBB) are developed. Theranostic nanoparticles, a combination of therapeutics and diagnostic nanoparticles, improve imaging of the cancerous tissue while delivering therapy to the local region. However, additional time and attention should be directed to developing a nanoparticle delivery system for treatment of the uniformly fatal pediatric disease of DIPG.

Liposome technologies and drug delivery to the CNS

Brain and nervous system disorders represent a large unmet medical need. Central nervous system drug development is hampered by the restricted transport of drugs across the blood-brain barrier. Different strategies to deliver drugs to the brain have been developed. We discuss the current status of development of liposomal drug delivery to the brain. There is a growing interest in targeted delivery of liposomes to the brain and much progress has been made towards successful development of novel treatments for patients with devastating brain diseases.

Replicon RNA Viral Vectors as Vaccines

Single-stranded RNA viruses of both positive and negative polarity have been used as vectors for vaccine development. In this context, alphaviruses, flaviviruses, measles virus and rhabdoviruses have been engineered for expression of surface protein genes and antigens. Administration of replicon RNA vectors has resulted in strong immune responses and generation of neutralizing antibodies in various animal models. Immunization of mice, chicken, pigs and primates with virus-like particles, naked RNA or layered DNA/RNA plasmids has provided protection against challenges with lethal doses of infectious agents and administered tumor cells. Both prophylactic and therapeutic efficacy has been achieved in cancer immunotherapy. Moreover, recombinant particles and replicon RNAs have been encapsulated by liposomes to improve delivery and targeting. Replicon RNA vectors have also been subjected to clinical trials. Overall, immunization with self-replicating RNA viruses provides high transient expression levels of antigens resulting in generation of neutralizing antibody responses and protection against lethal challenges under safe conditions.

Getting into the brain: liposome-based strategies for effective drug delivery across the blood-brain barrier

This review summarizes articles that have been reported in literature on liposome-based strategies for effective drug delivery across the blood–brain barrier. Due to their unique physicochemical characteristics, liposomes have been widely investigated for their application in drug delivery and in vivo bioimaging for the treatment and/or diagnosis of neurological diseases, such as Alzheimer’s, Parkinson’s, stroke, and glioma. Several strategies have been used to deliver drug and/or imaging agents to the brain. Covalent ligation of such macromolecules as peptides, antibodies, and RNA aptamers is an effective method for receptor-targeting liposomes, which allows their blood–brain barrier penetration and/or the delivery of their therapeutic molecule specifically to the disease site. Additionally, methods have been employed for the development of liposomes that can respond to external stimuli. It can be concluded that the development of liposomes for brain delivery is still in its infancy, although these systems have the potential to revolutionize the ways in which medicine is administered.

Role of nanotechnology and gene delivery systems in TRAIL-based therapies

Since its identification as a member of the tumour necrosis factor (TNF) family, TRAIL (TNF-related apoptosis-inducing ligand) has emerged as a new avenue in apoptosis-inducing cancer therapies. Its ability to circumvent the chemoresistance of conventional therapeutics and to interact with cancer stem cells (CSCs) self-renewal pathways, amplified its potential as a cancer apoptotic agent. Many recombinant preparations of this death ligand and monoclonal antibodies targeting its death receptors have been tested in monotherapy and combinational clinical trials. Gene therapy is a new approach for cancer treatment which implies viral or non-viral functional transgene induction of apoptosis in cancer cells or repair of the underlying genetic abnormality on a molecular level. The role of this approach in overcoming the traditional barriers of radiation and chemotherapeutics systemic toxicity, risk of recurrence, and metastasis made it a promising platform for cancer treatment. The recent first Food Drug Administration (FDA) approved oncolytic herpes virus for melanoma treatment brings forth the potency of the cancer gene therapy approach in the future. Many gene delivery systems have been studied for intratumoural TRAIL gene delivery alone or in combination with chemotherapeutic agents to produce synergistic cancer cytotoxicity. However, there still remain many obstacles to be conquered for this different gene delivery systems. Nanomedicine on the other hand offers a new frontier for clinical trials and biomedical research. The FDA approved nanodrugs motivates horizon exploration for other nanoscale designed particles’ implications in gene delivery. In this review we aim to highlight the molecular role of TRAIL in apoptosis and interaction with cancer stem cells (CSCs) self-renewal pathways. Finally, we also aim to discuss the different roles of gene delivery systems, mesenchymal cells, and nanotechnology designs in TRAIL gene delivery.

Gene Therapy Applications of Viral Vectors

Viral vectors have frequently been applied in gene therapy with the final goal of treating various diseases in the areas of neurology, neurodegeneration, metabolic disease, and cancer. Vectors have been engineered based on AAV, adenoviruses, alphaviruses, herpes simplex viruses, lentiviruses, and retroviruses. Some vectors are suitable for short-term episomal transgene expression, whereas others are integrated into the host cell genome to provide long-term expression. Additionally, hybrid vectors with favorable features from different viruses have been developed. Therapeutic genes of choice have typically been toxic genes such as thymidine kinase, pro-apoptotic genes like Bax, and immunostimulatory genes (for instance, interleukin-12). A large number of animal studies have demonstrated proof of concept of viral gene therapy. Many types of viral vectors have been employed in more than 700 clinical trials that have been carried out or are currently in progress.

Convection-enhanced delivery in glioblastoma: a review of preclinical and clinical studies

Glioblastoma is the most common malignant brain tumor, and it carries an extremely poor prognosis. Attempts to develop targeted therapies have been hindered because the blood-brain barrier prevents many drugs from reaching tumors cells. Furthermore, systemic toxicity of drugs often limits their therapeutic potential. A number of alternative methods of delivery have been developed, one of which is convection-enhanced delivery (CED), the focus of this review. The authors describe CED as a therapeutic measure and review preclinical studies and the most prominent clinical trials of CED in the treatment of glioblastoma. The utilization of this technique for the delivery of a variety of agents is covered, and its shortcomings and challenges are discussed in detail.

Gene therapy approaches against cancer using in vivo and ex vivo gene transfer of interleukin-12

IL-12 is an immunostimulatory cytokine with strong antitumor properties. Systemic administration of IL-12 in cancer patients led to severe toxic effects, prompting the development of gene therapy vectors able to express this cytokine locally in tumors. Both nonviral and viral vectors have demonstrated a high antitumor efficacy in preclinical tumor models. Some of these vectors, including DNA electroporation, adenovirus and ex vivo transduced dendritic cells, were tested in patients, showing low toxicity and moderate antitumor efficacy. IL-12 activity can be potentiated by molecules with immunostimulatory, antiangiogenic or cytotoxic activity. These combination therapies are of clinical interest because they could lower the threshold for IL-12 efficacy, increasing the therapeutic potential of gene therapy and preventing the toxicity mediated by this cytokine.

Principles of pharmacotherapy

This chapter will review the challenges in pharmacotherapy in primary brain tumors that include the presence of the blood-brain barrier, a blood-tumor barrier, active drug efflux pumps, and high plasma protein binding of agents. The approaches to improve the delivery of drugs to the brain will be discussed. Often the management of brain tumors involves the use of corticosteroids and enzyme-inducing antiseizure medications that can have significant drug interactions that may impact the efficacy or toxicity of drugs used to treat these patients. Various techniques used to assess drug distribution to the brain will be reviewed.

Novel delivery methods bypassing the blood-brain and blood-tumor barriers

Glioblastoma (GBM) is the most common primary brain tumor and carries a grave prognosis. Despite years of research investigating potentially new therapies for GBM, the median survival rate of individuals with this disease has remained fairly stagnant. Delivery of drugs to the tumor site is hampered by various barriers posed by the GBM pathological process and by the complex physiology of the blood-brain and blood-cerebrospinal fluid barriers. These anatomical and physiological barriers serve as a natural protection for the brain and preserve brain homeostasis, but they also have significantly limited the reach of intraparenchymal treatments in patients with GBM. In this article, the authors review the functional capabilities of the physical and physiological barriers that impede chemotherapy for GBM, with a specific focus on the pathological alterations of the blood-brain barrier (BBB) in this disease. They also provide an overview of current and future methods for circumventing these barriers in therapeutic interventions. Although ongoing research has yielded some potential options for future GBM therapies, delivery of chemotherapy medications across the BBB remains elusive and has limited the efficacy of these medications.

Computational and Pharmacological Target of Neurovascular Unit for Drug Design and Delivery

The blood-brain barrier (BBB) is a dynamic and highly selective permeable interface between central nervous system (CNS) and periphery that regulates the brain homeostasis. Increasing evidences of neurological disorders and restricted drug delivery process in brain make BBB as special target for further study. At present, neurovascular unit (NVU) is a great interest and highlighted topic of pharmaceutical companies for CNS drug design and delivery approaches. Some recent advancement of pharmacology and computational biology makes it convenient to develop drugs within limited time and affordable cost. In this review, we briefly introduce current understanding of the NVU, including molecular and cellular composition, physiology, and regulatory function. We also discuss the recent technology and interaction of pharmacogenomics and bioinformatics for drug design and step towards personalized medicine. Additionally, we develop gene network due to understand NVU associated transporter proteins interactions that might be effective for understanding aetiology of neurological disorders and new target base protective therapies development and delivery.

Alphavirus vectors as tools in neuroscience and gene therapy

Alphavirus-based vectors have been engineered for in vitro and in vivo expression of heterelogous genes. The rapid and easy generation of replication-deficient recombinant particles and the broad range of host cell infection have made alphaviruses attractive vehicles for applications in neuroscience and gene therapy. Efficient delivery to primary neurons and hippocampal slices has allowed localization studies of gene expression and electrophysiological recordings of ion channels. Alphavirus vectors have also been applied for in vivo delivery to rodent brain. Due to the strong local transient expression provided by alphavirus vectors a number of immunization and gene therapy approaches have demonstrated both therapeutic and prophylactic efficacy in various animal models.

Alphaviruses in gene therapy

Alphavirus vectors present an attractive approach for gene therapy applications due to the rapid and simple recombinant virus particle production and their broad range of mammalian host cell transduction. Mainly three types of alphavirus vectors, namely naked RNA, recombinant particles and DNA/RNA layered vectors, have been subjected to preclinical studies with the goal of achieving prophylactic or therapeutic efficacy, particularly in oncology. In this context, immunization with alphavirus vectors has provided protection against challenges with tumor cells. Moreover, alphavirus intratumoral and systemic delivery has demonstrated substantial tumor regression and significant prolonged survival rates in various animal tumor models. Recent discoveries of the strong association of RNA interference and disease have accelerated gene therapy based approaches, where alphavirus-based gene delivery can play an important role.

Current strategies for targeted delivery of bio-active drug molecules in the treatment of brain tumor

Brain tumor is one of the most challenging diseases to treat. The major obstacle in the specific drug delivery to brain is blood-brain barrier (BBB). Mostly available anti-cancer drugs are large hydrophobic molecules which have limited permeability via BBB. Therefore, it is clear that the protective barriers confining the passage of the foreign particles into the brain are the main impediment for the brain drug delivery. Hence, the major challenge in drug development and delivery for the neurological diseases is to design non-invasive nanocarrier systems that can assist controlled and targeted drug delivery to the specific regions of the brain. In this review article, our major focus to treat brain tumor by study numerous strategies includes intracerebral implants, BBB disruption, intraventricular infusion, convection-enhanced delivery, intra-arterial drug delivery, intrathecal drug delivery, injection, catheters, pumps, microdialysis, RNA interference, antisense therapy, gene therapy, monoclonal/cationic antibodies conjugate, endogenous transporters, lipophilic analogues, prodrugs, efflux transporters, direct conjugation of antitumor drugs, direct targeting of liposomes, nanoparticles, solid-lipid nanoparticles, polymeric micelles, dendrimers and albumin-based drug carriers.

Focused ultrasound-induced blood-brain barrier opening to enhance interleukin-12 delivery for brain tumor immunotherapy: a preclinical feasibility study

BACKGROUND

Interleukin-12 (IL-12) has long been considered to be effective in triggering an anticancer immune response, however, the dosage has been limited by potential systemic immunotoxicity. Since focused ultrasound (FUS) has been confirmed to temporally and locally open the blood-brain barrier (BBB), the purpose of this study was to elucidate the possibility of combining FUS-induced BBB opening with IL-12 delivery to enhance the anticancer immunological response for glioma treatment.

METHODS

FUS energy combined with microbubble administration was delivered transcranially to open BBB, and C-6 glioma rats were used in this study. The efficacy in inducing BBB opening and the corresponding immunological response were primarily evaluated in normal animals. The anticancer immune-triggering chemokine, IL-12, was intraperitoneally administered during the treatment phase to evaluate the effect of immunological response on tumor progression. Glioma animals were sub-grouped to evaluate the effect of the immune response in suppressing glioma when IL-12 was combined with FUS-induced BBB opening. We performed flow cytometry to verify consequent immune cell population changes of peripheral/ tissue lymphocytes as well as macrophages from the animals. Brain sections of sacrificed animals were also used for histological and immunohistochemical analysis. IL-12 level among experimental groups were measured via ELISA analysis. We also analyzed survival and followed tumor progression in vivo via T2-weighted magnetic resonance imaging.

RESULTS

FUS-induced BBB opening had no obvious effect on the T lymphocytes population in normal animals, either in the brain or systemically. Yet, it triggered mild changes in the tumor-infiltrating lymphocyte (TIL) population, particularly in numbers of CD3+CD8+ cytotoxic T lymphocytes (CTLs) in the tumor region. IL-12 administration triggered a profound increase in all TIL populations, including CD3+CD4+ T helper cells (Th), CTL, and CD4+CD25+ regulatory T cells (Treg), but combined FUS-BBB opening with IL-12 administration produced the most significant IL-12 increase, CTL increase and CTL/Treg ratio increase, thus contributing to the most significant suppression of tumor progression and increased animal survival.

CONCLUSION

This study provides evidence that FUS-BBB opening can enhance immune-modulating agent delivery to the brain, which improve the anticancer immune response in brain tumor treatment.

Convection-enhanced delivery to the central nervous system

Convection-enhanced delivery (CED) is a bulk flow–driven process. Its properties permit direct, homogeneous, targeted perfusion of CNS regions with putative therapeutics while bypassing the blood-brain barrier. Development of surrogate imaging tracers that are co-infused during drug delivery now permit accurate, noninvasive real-time tracking of convective infusate flow in nervous system tissues. The potential advantages of CED in the CNS over other currently available drug delivery techniques, including systemic delivery, intrathecal and/or intraventricular distribution, and polymer implantation, have led to its application in research studies and clinical trials. The authors review the biophysical principles of convective flow and the technology, properties, and clinical applications of convective delivery in the CNS.

RNA-based drugs and vaccines

RNA-based approaches have provided novel alternatives for modern drug discovery. The application of RNA as therapeutic agents has, until recently, been hampered by issues related to poor delivery and stability, but chemical modifications and new delivery approaches have increased progress. Moreover, the discovery of the importance of RNA in gene regulation and gene silencing has revealed new drug targets, especially related to treatment of cancer and other diseases. Recent engineering of small molecules designed from RNA sequences to target miRNAs opens up new possibilities in drug development. Furthermore, RNA-based vaccines have been engineered applying RNA virus vectors and non-viral delivery for vaccine development.

Nanomedicine in cerebral palsy

Cerebral palsy is a chronic childhood disorder that can have diverse etiologies. Injury to the developing brain that occurs either in utero or soon after birth can result in the motor, sensory, and cognitive deficits seen in cerebral palsy. Although the etiologies for cerebral palsy are variable, neuroinflammation plays a key role in the pathophysiology of the brain injury irrespective of the etiology. Currently, there is no effective cure for cerebral palsy. Nanomedicine offers a new frontier in the development of therapies for prevention and treatment of brain injury resulting in cerebral palsy. Nanomaterials such as dendrimers provide opportunities for the targeted delivery of multiple drugs that can mitigate several pathways involved in injury and can be delivered specifically to the cells that are responsible for neuroinflammation and injury. These materials also offer the opportunity to deliver agents that would promote repair and regeneration in the brain, resulting not only in attenuation of injury, but also enabling normal growth. In this review, the current advances in nanotechnology for treatment of brain injury are discussed with specific relevance to cerebral palsy. Future directions that would facilitate clinical translation in neonates and children are also addressed.

Oncolytic virotherapy for malignant glioma: translating laboratory insights into clinical practice

Glioblastoma multiforme, one of the most common and aggressive brain tumors in adults, is highly resistant to currently available therapies and often recurs. Due to its poor prognosis and difficult management, there is an urgent need for the development and translation of new anti-glioma therapeutic approaches into the clinic. In this context, oncolytic virotherapy arises as an exciting treatment option for glioma patients. These natural or genetically engineered viruses are able to effectively infect cancer cells, inducing a specific anti-tumor cytotoxic effect. In addition, some viruses have been redesigned to modulate glioma microenvironment, to express cytokines to boost a systemic anti-glioma immune response and to incorporate angiostatic genes to decrease glioma vasculature. Although recent clinical trials have confirmed the safety of oncolytic virotherapies in the brain, their moderate clinical efficacy has not yet matched the encouraging preclinical laboratory results. In this review, we will discuss the leading anti-glioma virotherapy approaches that are presently under preclinical and clinical evaluation. We will also review different delivery methods, in vivo virus behavior, fate, replication, intratumoral spread, activation of anti-tumor immune response, and targeting of glioma stem cells. We will focus on the advantages and limitations of each therapeutic approach and how to overcome these hurdles to effectively translate exciting laboratory results into promising clinical trials.

Ultrasound-assisted convection-enhanced delivery to the brain in vivo with a novel transducer cannula assembly: laboratory investigation

OBJECT

In convection-enhanced delivery (CED), drugs are infused locally into tissue through a cannula inserted into the brain parenchyma to enhance drug penetration over diffusion strategies. The purpose of this study was to demonstrate the feasibility of ultrasound-assisted CED (UCED) in the rodent brain in vivo using a novel, low-profile transducer cannula assembly (TCA) and portable, pocket-sized ultrasound system.

METHODS

Forty Sprague-Dawley rats (350-450 g) were divided into 2 equal groups (Groups 1 and 2). Each group was divided again into 4 subgroups (n = 5 in each). The caudate of each rodent brain was infused with 0.25 wt% Evans blue dye (EBD) in phosphate-buffered saline at 2 different infusion rates of 0.25 μl/minute (Group 1), and 0.5 μl/minute (Group 2). The infusion rates were increased slowly over 10 minutes from 0.05 to 0.25 μl/minute (Group 1) and from 0.1 to 0.5 μl/minute (Group 2). The final flow rate was maintained for 20 minutes. Rodents in the 4 control subgroups were infused using the TCA without ultrasound and without and with microbubbles added to the infusate (CED and CED + MB, respectively). Rodents in the 4 UCED subgroups were infused without and with microbubbles added to the infusate (UCED and UCED + MB) using the TCA with continuous-wave 1.34-MHz low-intensity ultrasound at a total acoustic power of 0.11 ± 0.005 W and peak spatial intensity at the cannula tip of 49.7 mW/cm(2). An additional 4 Sprague-Dawley rats (350-450 g) received UCED at 4 different and higher ultrasound intensities at the cannula tip ranging from 62.0 to 155.0 mW/cm(2) for 30 minutes. The 3D infusion distribution was reconstructed using MATLAB analysis. Tissue damage and morphological changes to the brain were assessed using H & E.

RESULTS

The application of ultrasound during infusion (UCED and UCED + MB) improved the volumetric distribution of EBD in the brain by a factor of 2.24 to 3.25 when there were no microbubbles in the infusate and by a factor of 1.16 to 1.70 when microbubbles were added to the infusate (p < 0.001). On gross and histological examination, no damage to the brain tissue was found for any acoustic exposure applied to the brain.

CONCLUSIONS

The TCA and ultrasound device show promise to improve the distribution of infused compounds during CED. The results suggest further studies are required to optimize infusion and acoustic parameters for small compounds and for larger molecular weight compounds that are representative of promising antitumor agents. In addition, safe levels of ultrasound exposure in chronic experiments must be determined for practical clinical evaluation of UCED. Extension of these experiments to larger animal models is warranted to demonstrate efficacy of this technique.

Novel delivery strategies for glioblastoma

Brain tumors--particularly glioblastoma multiforme--pose an important public health problem in the United States. Despite surgical and medical advances, the prognosis for patients with malignant gliomas remains grim: current therapy is insufficient with nearly universal recurrence. A major reason for this failure is the difficulty of delivering therapeutic agents to the brain: better delivery approaches are needed to improve treatment. In this article, we summarize recent progress in drug delivery to the brain, with an emphasis on convection-enhanced delivery of nanocarriers. We examine the potential of new delivery methods to permit novel drug- and gene-based therapies that target brain cancer stem cells and discuss the use of nanomaterials for imaging of tumors and drug delivery.