Human and mouse IFN-beta gene therapy exhibits different anti-tumor mechanisms in mouse models

Sequential Therapy with Ropeginterferon Alfa-2b and Anti-Programmed Cell Death 1 Antibody for Inhibiting the Recurrence of Hepatitis B-Related Hepatocellular Carcinoma: From Animal Modeling to Phase I Clinical Results

Hepatocellular carcinoma (HCC) usually recurs after curative surgical resection. Currently, no approved adjuvant therapy has been shown to reduce HCC recurrence rates. In this study, the in vivo effect of sequential combination treatment with recombinant mouse interferon-alpha (rmIFN-α) and an anti-mouse-PD1 antibody on hepatitis B virus (HBV) clearance in mice was evaluated. A Phase I clinical trial was then conducted to assess the safety, tolerability, and inhibitory activity of sequential therapy with ropeginterferon alfa-2b and nivolumab in patients with HCC recurrence who underwent curative surgery for HBV-related HCC. The animal modeling study showed that HBV suppression was significantly greater with the rmIFN-α and anti-PD1 sequential combination treatment in comparison with sole treatment with rmIFN-α or anti-PD1. In the Phase I study, eleven patients completed the sequential therapy with ropeginterferon alfa-2b every two weeks for six doses at 450 µg, followed by three doses of nivolumab every two weeks up to 0.75 mg/kg. A notable decrease in or clearance of HBV surface antigen was observed in two patients. The dose-limiting toxicity of grade 3 alanine transaminase and aspartate aminotransferase increases was observed in one patient. The maximum tolerated dose was then determined. To date, no HCC recurrence has been observed. The treatment modality was well tolerated. These data support the further clinical development of sequential combination therapy as a post-surgery prophylactic measure against the recurrence of HBV-related HCC.

Antitumor activity of pegylated human interferon β as monotherapy or in combination with immune checkpoint inhibitors via tumor growth inhibition and dendritic cell activation

Type I interferons (IFN), especially human IFN alpha (IFNα), have been utilized for antitumor therapy for decades. Human interferon beta (IFNβ) is rarely used for cancer treatment, despite advantages over IFNα in biological activities such as tumor growth inhibition and dendritic cell (DC) activation. The utilization of pegylated human IFNβ (PEG-IFNβ), as monotherapy or in combination with immune checkpoint inhibitors (ICIs) was evaluated in this study through in vivo efficacy studies in syngeneic mouse melanoma, non-small cell lung cancer (NSCLC), and colon adenocarcinoma (COAD) models resistant to immune checkpoint inhibitors (ICIs). In vitro comparative study of PEG-IFNβ and pegylated IFNα-2b was performed in terms of tumor growth inhibition against human melanoma, NSCLC and COAD cell lines and activation of human monocyte-derived DCs (MoDCs). Our data demonstrate that the in vivo antitumor effects of PEG-IFNβ are partially attributable to tumor growth-inhibitory effects and DC-activating activities, superior to pegylated IFNα-2b. Our findings suggest that utilizing PEG-IFNβ as an antitumor therapy can enhance the therapeutic effect of ICIs in ICI-resistant tumors by directly inhibiting tumor growth and induction of DC maturation.

Amyloids and brain cancer: molecular linkages and crossovers

Amyloids are high-order proteinaceous formations deposited in both intra- and extracellular spaces. These aggregates have tendencies to deregulate cellular physiology in multiple ways; for example, altered metabolism, mitochondrial dysfunctions, immune modulation, etc. When amyloids are formed in brain tissues, the endpoint often is death of neurons. However, interesting but least understood is a close connection of amyloids with another set of conditions in which brain cells proliferate at an extraordinary rate and form tumor inside brain. Glioblastoma is one such condition. Increasing number of evidence indicate a possible link between amyloid formation and depositions in brain tumors. Several proteins associated with cell cycle regulation and apoptotic pathways themselves have shown to possess high tendencies to form amyloids. Tumor suppressor protein p53 is one prominent example that mutate, oligomerize and form amyloids leading to loss- or gain-of-functions and cause increased cell proliferation and malignancies. In this review article, we present available examples, genetic links and common pathways that indicate that possibly the two distantly placed pathways: amyloid formation and developing cancers in the brain have similarities and are mechanistically intertwined together.

Cytokine sustained delivery for cancer therapy; special focus on stem cell- and biomaterial- based delivery methods

As immune regulators, cytokines serve critical role as signaling molecules in response to danger, tissue damage, or injury. Importantly, due to their vital role in immunological surveillance, cytokine therapy has become a promising therapeutics for cancer therapy. Cytokines have, however, been used only in certain clinical settings. Two key characteristics of cytokines contribute to this clinical translational challenge: first, they are highly pleiotropic, and second, in healthy physiology, they are typically secreted and act very locally in tissues. Systemic administration of the cytokines can consequently result in serious side effects. Thus, scientists have sought various strategies to circumvent theses hurdles. Recent in vivo reports signify that cytokine delivery platforms can increase their safety and therapeutic efficacy in tumor xenografts. Meanwhile, cytokine delivery using multipotent stem cells, in particular mesenchymal stem/stromal cells (MSCs), and also a diversity of particles and biomaterials has demonstrated greater capability in this regards. Herein, we take a glimpse into the recent advances in cytokine sustained delivery using stem cells and also biomaterials to ease safe and effective treatments of a myriad of human tumors.

A Favorable Benefit-Risk Balance Maybe Expected with the Replication-defective Adenovirus-mediated Interferon Gene Therapy for Cancer Treatment

Two months ago, the US FDA has approved a non-replicating adenovirus encoding interferon alfa-2b (IFN-a2b) for high-risk, Bacillus Calmette-Guérin (BCG)-unresponsive non-muscle invasive bladder cancer. This LETTER TO THE EDITOR provides the insights regarding the use of a replication-defective adenovirus-mediated IFN therapy for cancer treatment and explains why a positive clinical benefit-risk profile can be expected from using this approach. This approach can lead to more gene therapy approvals for cancer treatment.

An anti-cancer surveillance by the interplay between interferon-beta and retinoblastoma protein RB1

Interferon-beta (IFN-β), an extracellular cytokine that initiates signaling pathways for gene regulation, has been demonstrated to function as a tumor suppressor protein through lentiviral gene transduction. In this article, I review the relevant previous works and propose a cell cycle-based, tumor suppressor protein-mediated mechanism of anti-cancer surveillance. IFN-β induces a tumor cell cycle alteration that leads to S phase accumulation, senescence entry, and a loss of tumorigenicity in solid tumor cells. IFN-β does not show a significant cell cycle effect in their normal counterparts. Retinoblastoma protein RB1, another tumor suppressor protein, tightly controls the cell cycle and differentiation of normal cells, preventing them from being significantly impacted by the IFN-β effect. The interplay between IFN-β and RB1 acts as a mechanism of cell cycle-based, tumor suppressor protein-mediated anti-cancer surveillance that can selectively suppress solid tumor or proliferating transformed cells from the loss of control leading to cancer. This mechanism has important implications for the treatment of solid tumors.

Induction of Immune-Stimulating Factors and Oncolysis Upon p14ARF Gene Transfer in Melanoma Cell Lines

Together with an anti-tumor immune response, oncolysis using a recombinant viral vector promises to eliminate cancer cells by both gene transfer and host-mediated functions. In this study we explore oncolysis induced by nonreplicating adenoviral vectors used for p14^ARF and interferon-β (hIFNβ) gene transfer in human melanoma cell lines, revealing an unexpected role for p14^ARF in promoting cellular responses predictive of immune stimulation. Oncolysis was confirmed when UACC-62 (p53 wild-type) cells succumbed upon p14^ARF gene transfer in vitro, whereas SK-Mel-29 (p53-mutant) benefitted from its combination with hIFNβ. In the case of UACC-62, in situ gene therapy in nude mice yielded reduced tumor progression in response to the p14^ARF and hIFNβ combination. Potential for immune stimulation was revealed where p14^ARF gene transfer in vitro was sufficient to induce emission of immunogenic cell death factors in UACC-62 and upregulate pro-immune genes, including IRF1, IRF7, IRF9, ISG15, TAP-1, and B2M. In SK-Mel-29, p14^ARF gene transfer induced a subset of these factors. hIFNβ was, as expected, sufficient to induce these immune-stimulating genes in both cell lines. This work is a significant advancement for our melanoma gene therapy strategy because we revealed not only the induction of oncolysis, but also the potential contribution of p14^ARF to immune stimulation.

Optogenetic-controlled immunotherapeutic designer cells for post-surgical cancer immunotherapy

Surgical resection is the main treatment option for most solid tumors, yet cancer recurrence after surgical resection remains a significant challenge in cancer therapy. Recent advances in cancer immunotherapy are enabling radical cures for many tumor patients, but these technologies remain challenging to apply because of side effects related to uncontrollable immune system activation. Here, we develop far-red light-controlled immunomodulatory engineered cells (FLICs) that we load into a hydrogel scaffold, enabling the precise optogenetic control of cytokines release (IFN-β, TNF-α, and IL-12) upon illumination. Experiments with a B16F10 melanoma resection mouse model show that FLICs-loaded hydrogel implants placed at the surgical wound site achieve sustainable release of immunomodulatory cytokines, leading to prevention of tumor recurrence and increased animal survival. Moreover, the FLICs-loaded hydrogel implants elicit long-term immunological memory that prevents against tumor recurrence. Our findings illustrate that this optogenetic perioperative immunotherapy with FLICs-loaded hydrogel implants offers a safe treatment option for solid tumors based on activating host innate and adaptive immune systems to inhibit tumor recurrence after surgery. Beyond extending the optogenetics toolbox for immunotherapy, we envision that our optogenetic-controlled living cell factory platform could be deployed for other biomedical contexts requiring precision induction of bio-therapeutic dosage.

Systematic Review of Pediatric Brain Tumors in Neurofibromatosis Type 1: Status of Gene Therapy

As oncology practice is rapidly shifting away from toxic chemotherapy, gene therapy provides a highly specific therapeutic approach for brain tumors. In this systematic review, we investigate gene therapy’s status in pediatric brain tumors and future recommendations. The search was conducted systematically using PubMed, Cochrane, Google Scholar, and ClinicalTrials.gov databases. The field search used in the process was selected based on the keywords and Medical Subject Headings (MeSH), depending on the database used. We included cases of neurofibromatosis type 1 (NF1) brain tumors in all age groups with the additional inclusion of English language, free full text, articles published within the last 20 years, randomized controlled trials (RCTs), observational studies, systematic reviews, and meta-analyses. We excluded case reports, case studies, and editorials. The search identified a total of 1,213 articles from the databases. We included 19 studies with 16 narrative reviews, one systematic review, and two randomized clinical trials with 43 patients. After reviewing all data in the articles, we found that gene therapy can improve standard treatment efficacy when used as adjuvant therapy. It can be used to overcome barriers such as chemotherapy resistance by downregulating resistance genes. It is associated with mild toxicity when compared with other available treatment options, but given the overall poor prognosis in pediatric brain tumors, further studies are warranted.

Emerging immune-based technologies for high-grade gliomas

INTRODUCTION

The selection of a tailored and successful strategy for high-grade gliomas (HGGs) treatment is still a concern. The abundance of aberrant mutations within the heterogenic genetic landscape of glioblastoma strongly influences cell expansion, proliferation, and therapeutic resistance. Identification of immune evasion pathways opens the way to novel immune-based strategies. This review intends to explore the emerging immunotherapies for HGGs. The immunosuppressive mechanisms related to the tumor microenvironment and future perspectives to overcome glioma immunity barriers are also debated.

AREAS COVERED

An extensive literature review was performed on the PubMed/Medline and ClinicalTrials.gov databases. Only highly relevant articles in English and published in the last 20 years were selected. Data about immunotherapies coming from preclinical and clinical trials were summarized.

EXPERT OPINION

The overall level of evidence about the efficacy and safety of immunotherapies for HGGs is noteworthy. Monoclonal antibodies have been approved as second-line treatment, while peptide vaccines, viral gene strategies, and adoptive technologies proved to boost a vivid antitumor immunization. Malignant brain tumor-treating fields are ever-changing in the upcoming years. Constant refinements and development of new routes of drug administration will permit to design of novel immune-based treatment algorithms thus improving the overall survival.

Novel Pegylated Interferon for the Treatment of Chronic Viral Hepatitis

Ropeginterferon alfa-2b is a novel mono-pegylated and extra-long-acting interferon, being developed for the treatment of myeloproliferative neoplasm (MPN) and chronic viral hepatitis. It has a favorable pharmacokinetic profile and less frequent dosing schedule, i.e., once every two to four weeks, compared to conventional pegylated interferon products, which have multiple isomers and are administered weekly. It was approved for the long-term treatment of polycythemia vera, an MPN, and has been included in the NCCN clinical practice guidelines for this indication. Ropeginterferon alfa-2b has demonstrated efficacy and showed a favorable safety profile for the treatment of chronic viral hepatitis in several clinical studies. In this article, we review its pharmacokinetics and available clinical data and suggest that ropeginterferon alfa-2b administered once every two weeks can serve as a new treatment option for patients with chronic viral hepatitis, including chronic hepatitis B, C, and D.

Chemical and Biomolecular Strategies for STING Pathway Activation in Cancer Immunotherapy

The stimulator of interferon genes (STING) cellular signaling pathway is a promising target for cancer immunotherapy. Activation of the intracellular STING protein triggers the production of a multifaceted array of immunostimulatory molecules, which, in the proper context, can drive dendritic cell maturation, antitumor macrophage polarization, T cell priming and activation, natural killer cell activation, vascular reprogramming, and/or cancer cell death, resulting in immune-mediated tumor elimination and generation of antitumor immune memory. Accordingly, there is a significant amount of ongoing preclinical and clinical research toward further understanding the role of the STING pathway in cancer immune surveillance as well as the development of modulators of the pathway as a strategy to stimulate antitumor immunity. Yet, the efficacy of STING pathway agonists is limited by many drug delivery and pharmacological challenges. Depending on the class of STING agonist and the desired administration route, these may include poor drug stability, immunocellular toxicity, immune-related adverse events, limited tumor or lymph node targeting and/or retention, low cellular uptake and intracellular delivery, and a complex dependence on the magnitude and kinetics of STING signaling. This review provides a concise summary of the STING pathway, highlighting recent biological developments, immunological consequences, and implications for drug delivery. This review also offers a critical analysis of an expanding arsenal of chemical strategies that are being employed to enhance the efficacy, safety, and/or clinical utility of STING pathway agonists and lastly draws attention to several opportunities for therapeutic advancements.

Molecular characterization of type I IFN-induced cytotoxicity in bladder cancer cells reveals biomarkers of resistance

Although anti-tumor activities of type I interferons (IFNs) have been recognized for decades, the molecular mechanisms contributing to clinical response remain poorly understood. The complex functions of these pleiotropic cytokines include stimulation of innate and adaptive immune responses against tumors as well as direct inhibition of tumor cells. In high-grade, Bacillus Calmette-Guérin (BCG)-unresponsive non-muscle-invasive bladder cancer, nadofaragene firadenovec, a non-replicating adenovirus administered locally to express the IFNα2b transgene, embodies a novel approach to deploy the therapeutic activity of type I IFNs while minimizing systemic toxicities. Deciphering which functions of type I IFN are required for clinical activity will bolster efforts to maximize the efficacy of nadofaragene firadenovec and other type I IFN-based therapies, and inform strategies to address resistance. As such, we characterized the phenotypic and molecular response of human bladder cancer cell lines to IFNα delivered in multiple contexts, including adenoviral delivery. We found that constitutive activation of the type I IFN signaling pathway is a biomarker for resistance to both transcriptional response and direct cytotoxic effects of IFNα. We present several genes that discriminate between sensitive and resistant tumor cells, suggesting they should be explored for utility as biomarkers in future clinical trials of type I IFN-based anti-tumor therapies.

Against the Resilience of High-Grade Gliomas: Gene Therapies (Part II)

Introduction: High-grade gliomas (HGGs) still have a high rate of recurrence and lethality. Gene therapies were projected to overcome the therapeutic resilience of HGGs, due to the intrinsic genetic heterogenicity and immune evasion pathways. The present literature review strives to provide an updated overview of the novel gene therapies for HGGs treatment, highlighting evidence from clinical trials, molecular mechanisms, and future perspectives. Methods: An extensive literature review was conducted through PubMed/Medline and ClinicalTrials.gov databases, using the keywords “high-grade glioma,” “glioblastoma,” and “malignant brain tumor”, combined with “gene therapy,” “oncolytic viruses,” “suicide gene therapies,” “tumor suppressor genes,” “immunomodulatory genes,” and “gene target therapies”. Only articles in English and published in the last 15 years were chosen, further screened based on best relevance. Data were analyzed and described according to the PRISMA guidelines. Results: Viruses were the most vehicles employed for their feasibility and transduction efficiency. Apart from liposomes, other viral vehicles remain largely still experimental. Oncolytic viruses and suicide gene therapies proved great results in phase I, II preclinical, and clinical trials. Tumor suppressor, immunomodulatory, and target genes were widely tested, showing encouraging results especially for recurrent HGGs. Conclusions: Oncolytic virotherapy and suicide genes strategies are valuable second-line treatment options for relapsing HGGs. Immunomodulatory approaches, tumor suppressor, and target genes therapies may implement and upgrade standard chemoradiotherapy. Future research aims to improve safety profile and prolonging therapeutic effectiveness. Further clinical trials are needed to assess the efficacy of gene-based therapies.

Nonreplicating Adenoviral Vectors: Improving Tropism and Delivery of Cancer Gene Therapy

Recent preclinical and clinical studies have used viral vectors in gene therapy research, especially nonreplicating adenovirus encoding strategic therapeutic genes for cancer treatment. Adenoviruses were the first DNA viruses to go into therapeutic development, mainly due to well-known biological features: stability in vivo, ease of manufacture, and efficient gene delivery to dividing and nondividing cells. However, there are some limitations for gene therapy using adenoviral vectors, such as nonspecific transduction of normal cells and liver sequestration and neutralization by antibodies, especially when administered systemically. On the other hand, adenoviral vectors are amenable to strategies for the modification of their biological structures, including genetic manipulation of viral proteins, pseudotyping, and conjugation with polymers or biological membranes. Such modifications provide greater specificity to the target cell and better safety in systemic administration; thus, a reduction of antiviral host responses would favor the use of adenoviral vectors in cancer immunotherapy. In this review, we describe the structural and molecular features of nonreplicating adenoviral vectors, the current limitations to their use, and strategies to modify adenoviral tropism, highlighting the approaches that may allow for the systemic administration of gene therapy.

Current Approaches for Glioma Gene Therapy and Virotherapy

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in the adult population and it carries a dismal prognosis. Inefficient drug delivery across the blood brain barrier (BBB), an immunosuppressive tumor microenvironment (TME) and development of drug resistance are key barriers to successful glioma treatment. Since gliomas occur through sequential acquisition of genetic alterations, gene therapy, which enables to modification of the genetic make-up of target cells, appears to be a promising approach to overcome the obstacles encountered by current therapeutic strategies. Gene therapy is a rapidly evolving field with the ultimate goal of achieving specific delivery of therapeutic molecules using either viral or non-viral delivery vehicles. Gene therapy can also be used to enhance immune responses to tumor antigens, reprogram the TME aiming at blocking glioma-mediated immunosuppression and normalize angiogenesis. Nano-particles-mediated gene therapy is currently being developed to overcome the BBB for glioma treatment. Another approach to enhance the anti-glioma efficacy is the implementation of viro-immunotherapy using oncolytic viruses, which are immunogenic. Oncolytic viruses kill tumor cells due to cancer cell-specific viral replication, and can also initiate an anti-tumor immunity. However, concerns still remain related to off target effects, and therapeutic and transduction efficiency. In this review, we describe the rationale and strategies as well as advantages and disadvantages of current gene therapy approaches against gliomas in clinical and preclinical studies. This includes different delivery systems comprising of viral, and non-viral delivery platforms along with suicide/prodrug, oncolytic, cytokine, and tumor suppressor-mediated gene therapy approaches. In addition, advances in glioma treatment through BBB-disruptive gene therapy and anti-EGFRvIII/VEGFR gene therapy are also discussed. Finally, we discuss the results of gene therapy-mediated human clinical trials for gliomas. In summary, we highlight the progress, prospects and remaining challenges of gene therapies aiming at broadening our understanding and highlighting the therapeutic arsenal for GBM.

Combined p14ARF and Interferon-β Gene Transfer to the Human Melanoma Cell Line SK-MEL-147 Promotes Oncolysis and Immune Activation

Immune evasion is an important cancer hallmark and the understanding of its mechanisms has generated successful therapeutic approaches. Induction of immunogenic cell death (ICD) is expected to attract immune cell populations that promote innate and adaptive immune responses. Here, we present a critical advance for our adenovirus-mediated gene therapy approach, where the combined p14ARF and human interferon-β (IFNβ) gene transfer to human melanoma cells led to oncolysis, ICD and subsequent activation of immune cells. Our results indicate that IFNβ alone or in combination with p14ARF was able to induce massive cell death in the human melanoma cell line SK-MEL-147, though caspase 3/7 activation was not essential. In situ gene therapy of s.c. SK-MEL-147 tumors in Nod-Scid mice revealed inhibition of tumor growth and increased survival in response to IFNβ alone or in combination with p14ARF. Emission of critical markers of ICD (exposition of calreticulin, secretion of ATP and IFNβ) was stronger when cells were treated with combined p14ARF and IFNβ gene transfer. Co-culture of previously transduced SK-MEL-147 cells with monocyte-derived dendritic cells (Mo-DCs) derived from healthy donors resulted in increased levels of activation markers HLA-DR, CD80, and CD86. Activated Mo-DCs were able to prime autologous and allogeneic T cells, resulting in increased secretion of IFNγ, TNF-α, and IL-10. Preliminary data showed that T cells primed by Mo-DCs activated with p14ARF+IFNβ-transduced SK-MEL-147 cells were able to induce the loss of viability of fresh non-transduced SK-MEL-147 cells, suggesting the induction of a specific cytotoxic population that recognized and killed SK-MEL-147 cells. Collectively, our results indicate that p14ARF and IFNβ delivered by our adenoviral system induced oncolysis in human melanoma cells accompanied by adaptive immune response activation and regulation.

Response of human melanoma cell lines to interferon-beta gene transfer mediated by a modified adenoviral vector

Since melanomas often retain wild type p53, we developed an adenoviral vector, AdRGD-PG, which provides robust transduction and transgene expression in response to p53. Previously, this vector was used for interferon-β gene transfer in mouse models of melanoma, resulting in control of tumor progression, but limited cell killing. Here, the AdRGD-PG-hIFNβ vector encoding the human interferon-β cDNA (hIFNβ) was used to transduce human melanoma cell lines SK-MEL-05 and SK-MEL-147 (both wild type p53). In vitro, cell death was induced in more than 80% of the cells and correlated with elevated annexinV staining and caspase 3/7 activity. Treatment with hIFNβ promoted cell killing in neighboring, non-transduced cells, thus revealing a bystander effect. In situ gene therapy resulted in complete inhibition of tumor progression for SK-MEL-147 when using nude mice with no evidence of hepatotoxicity. However, the response in Nod-Scid mice was less robust. For SK-MEL-05, tumor inhibition was similar in nude and Nod-Scid mice and was less efficient than seen for SK-MEL-147, indicating both cell type and host specific responses. The AdRGD-PG-hIFNβ vector provides extensive killing of human melanoma cells in vitro and a potent anti-tumor effect in vivo. This study provides a critical advance in the development of our melanoma gene therapy approach.

Perspectives for cancer immunotherapy mediated by p19Arf plus interferon-beta gene transfer

While cancer immunotherapy has gained much deserved attention in recent years, many areas regarding the optimization of such modalities remain unexplored, including the development of novel approaches and the strategic combination of therapies that target multiple aspects of the cancer-immunity cycle. Our own work involves the use of gene transfer technology to promote cell death and immune stimulation. Such immunogenic cell death, mediated by the combined transfer of the alternate reading frame (p14ARF in humans and p19Arf in mice) and the interferon-β cDNA in our case, was shown to promote an antitumor immune response in mouse models of melanoma and lung carcinoma. With these encouraging results, we are now setting out on the road toward translational and preclinical development of our novel immunotherapeutic approach. Here, we outline the perspectives and challenges that we face, including the use of human tumor and immune cells to verify the response seen in mouse models and the incorporation of clinically relevant models, such as patient-derived xenografts and spontaneous tumors in animals. In addition, we seek to combine our immunotherapeutic approach with other treatments, such as chemotherapy or checkpoint blockade, with the goal of reducing dosage and increasing efficacy. The success of any translational research requires the cooperation of a multidisciplinary team of professionals involved in laboratory and clinical research, a relationship that is fostered at the Cancer Institute of Sao Paulo.

Transcriptomic profiles of human foreskin fibroblast cells in response to orf virus

Orf virus has been utilized as a safe and efficient viral vector against not only diverse infectious diseases, but also against tumors. However, the nature of the genes triggered by the vector in human cells is poorly characterized. Using RNA sequencing technology, we compared specific changes in the transcriptomic profiles in human foreskin fibroblast cells following infection by the orf virus. The results indicated that orf virus upregulates or downregulates expression of a variety of genes, including genes involved in antiviral immune response, apoptosis, cell cycle and a series of signaling pathways, such as the IFN and p53-signaling pathways. The orf virus stimulates or inhibits immune gene expression such as chemokines, chemokine receptors, cytokines, cytokine receptors, and molecules involved in antigen uptake and processing after infection. Expression of pro-apoptotic genes increased at 8 hours post-infection. The p53 signaling pathway was activated to induce apoptosis at the same time. However, the cell cycle program was promoted after infection, which may be due to the immunomodulatory genes of the orf virus. This presents the first description of transcription profile changes in human foreskin fibroblast cells after orf virus infection and provides an in-depth analysis of the interaction between the host and orf virus. These data offer new insights into the understanding of the mechanisms of infection by orf virus and identify potential targets for future studies.

Novel pegylated interferon-β as strong suppressor of the malignant ascites in a peritoneal metastasis model of human cancer

Malignant ascites manifests as an end‐stage event during the progression of a number of cancers and lacks a generally accepted standard therapy. Interferon‐β (IFN‐β) has been used to treat several cancer indications; however, little is known about the efficacy of IFN‐β on malignant ascites. In the present study, we report on the development of a novel, engineered form of human and murine IFN‐β, each conjugated with a polyethylene glycol molecule (PEG‐hIFN‐β and PEG‐mIFN‐β, respectively). We provide evidence that these IFN‐β molecules retain anti‐viral potency comparable to unmodified IFN‐β in vitro and manifested improved pharmacokinetics in vivo. Interestingly, PEG‐mIFN‐β significantly inhibited the accumulation of ascites fluid and vascular permeability of the peritoneal membrane in models of ovarian cancer and gastric cancer cell xenograft mice. We further show that PEG‐hIFN‐β directly suppresses VEGF₁₆₅‐induced hyperpermeability in a monolayer of human vascular endothelial cells and that PEG‐mIFN‐β enhanced gene expression for a number of cell adhesion related molecules in mouse vascular endothelial cells. Taken together, these findings unveil a hitherto unrecognized potential of IFN‐β in maintaining vascular integrity, and provide proof‐of‐mechanism for a novel and long‐acting pegylated hIFN‐β for the therapeutic treatment of malignant ascites.

Peginterferon Beta-1a Shows Antitumor Activity as a Single Agent and Enhances Efficacy of Standard of Care Cancer Therapeutics in Human Melanoma, Breast, Renal, and Colon Xenograft Models

Because of its tumor-suppressive effect, interferon-based therapy has been used for the treatment of melanoma. However, limited data are available regarding the antitumor effects of pegylated interferons, either alone or in combination with approved anticancer drugs. We report that treatment of human WM-266-4 melanoma cells with peginterferon beta-1a induced apoptotic markers. Additionally, peginterferon beta-1a significantly inhibited the growth of human SK-MEL-1, A-375, and WM-266-4 melanoma xenografts established in immunocompromised mice. Peginterferon beta-1a regressed large, established WM-266-4 xenografts in nude mice. Treatment of SK-MEL-1 tumor-bearing mice with a combination of peginterferon beta-1a and the MEK inhibitor PD325901 ((R)-N-(2,3-dihydroxypropoxy)-3,4-difluoro-2-(2-fluoro-4-iodophenylamino)benzamide) significantly improved tumor growth inhibition compared with either agent alone. Examination of the antitumor activity of peginterferon beta-1a in combination with approved anticancer drugs in breast and renal carcinomas revealed improved antitumor activity in these preclinical xenograft models, as did the combination of peginterferon beta-1a and bevacizumab in a colon carcinoma xenograft model.

Systemic AAV9-IFNβ gene delivery treats highly invasive glioblastoma

BACKGROUND

Complete surgical removal of all glioblastoma (GBM) cells is impossible due to extensive infiltration into brain parenchyma that ultimately leads to tumor recurrence. The current standard of care affords modest improvements in survival. New therapeutic interventions are needed to prevent recurrence. Local AAV-hIFNβ gene delivery to the brain was previously shown to eradicate noninvasive orthotopic U87 tumors in mice. However, widespread CNS gene delivery may be necessary to treat invasive GBMs. Here we investigated the therapeutic effectiveness of systemically infused AAV9-hIFNβ against an invasive orthotopic GBM8 model.

METHODS

Mice bearing human GBM8 brain tumors expressing firefly luciferase (Fluc) were treated systemically with different doses of scAAV9-hIFNβ vector. Therapeutic efficacy was assessed by sequential bioluminescence imaging of tumor Fluc activity and animal survival. Brains were analyzed post mortem for the presence and appearance of tumors. Two transcriptionally restricted AAV vectors were used to assess the therapeutic contribution of peripheral hIFNβ.

RESULTS

Systemic infusion of scAAV9-hIFNβ vector induced complete regression of established GBM8 tumors in a dose-dependent manner. The efficacy of this approach was also dependent on the stage of tumor growth at the time of treatment. We also showed that peripherally produced hIFNβ contributed considerably to the therapeutic effect of scAAV9-hIFNβ. A comparative study of systemic and unilateral intracranial delivery of scAAV9-hIFNβ in a bilateral GBM8 tumor model showed the systemic route to be the most effective approach for treating widely dispersed tumors.

CONCLUSIONS

Systemic delivery of AAV9-IFNβ is an attractive approach for invasive and multifocal GBM treatment.

Experimental therapies: gene therapies and oncolytic viruses

Glioblastoma is the most common and aggressive primary brain tumor in adults. Over the past three decades, the overall survival time has only improved by a few months, therefore novel alternative treatment modalities are needed to improve clinical management strategies. Such strategies should ultimately extend patient survival. At present, the extensive insight into the molecular biology of gliomas, as well as into genetic engineering techniques, has led to better decision processes when it comes to modifying the genome to accommodate suicide genes, cytokine genes, and tumor suppressor genes that may kill cancer cells, and boost the host defensive immune system against neoantigenic cytoplasmic and nuclear targets. Both nonreplicative viral vectors and replicating oncolytic viruses have been developed for brain cancer treatment. Stem cells, microRNAs, nanoparticles, and viruses have also been designed. These have been armed with transgenes or peptides, and have been used both in laboratory-based experiments as well as in clinical trials, with the aim of improving selective killing of malignant glioma cells while sparing normal brain tissue. This chapter reviews the current status of gene therapies for malignant gliomas and highlights the most promising viral and cell-based strategies under development.

Microarray technology to investigate genes associated with papillary thyroid carcinoma

DNA microarray data on thyroid tissue from patients with papillary thyroid carcinoma (PTC) and from healthy controls were compared in order to investigate the regulatory genes and uncover the underlying regulatory network in PTC. The DNA microarray data set, GSE3678, was downloaded from Gene Expression Omnibus database. This included seven thyroid tissue samples from patients with PTC and seven samples from healthy controls. Raw data were processed and differentially expressed genes (DEGs) were identified using corresponding R packages. Gene regulation analysis was conducted using TRANSFAC® and TRED. A total of 171 DEGs were obtained. A regulatory network was then established, using 104 of the DEGs. Subsequently, pathway enrichment analyses of the genes were conducted using Database for Annotation, Visualization and Integrated Discovery (DAVID) online tool. Three differentially expressed transcription factors were identified: Trefoil factor 3, cut‑like homeobox 2 and forkhead box protein A2. The most significant pathways involving the 104 DEGs were pathways involved in cancer. Biological process analysis using DAVID, suggested that these genes were associated with the positive regulation of gene expression, gene transcription and metabolic processes. The present study identified a range of genes associated with the development of PTC. The results of the present study were beneficial for understanding the regulatory mechanisms involved in PTC, and for developing clinical diagnostic and therapeutic approaches for this disease.

Overview of current immunotherapeutic strategies for glioma

In the last decade, numerous studies of immunotherapy for malignant glioma (glioblastoma multiforme) have brought new knowledge and new hope for improving the prognosis of this incurable disease. Some clinical trials have reached Phase III, following positive outcomes in Phase I and II, with respect to safety and immunological end points. Results are encouraging especially when considering the promise of sustained efficacy by inducing antitumor immunological memory. Progress in understanding the mechanisms of tumor-induced immune suppression led to the development of drugs targeting immunosuppressive checkpoints, which are used in active clinical trials for glioblastoma multiforme. Insights related to the heterogeneity of the disease bring new challenges for the management of glioma and underscore a likely cause of therapeutic failure. An emerging therapeutic strategy is represented by a combinatorial, personalized approach, including the standard of care: surgery, radiation, chemotherapy with added active immunotherapy and multiagent targeting of immunosuppressive checkpoints.

Adipose tissue-derived mesenchymal stem cells cultured at high density express IFN-β and suppress the growth of MCF-7 human breast cancer cells

Although it has been reported that mesenchymal stem cells (MSCs) suppress tumor growth in vitro and in vivo, little is known about the underlying molecular mechanisms. We found that type I interferon is expressed in adipose tissue-derived stem cells (ASCs) cultured at high density, and ASCs and their conditioned medium (ASC-CM) suppress the growth of MCF-7 cells in vitro. Growth inhibition was amplified by glucose deprivation that resulted from high density culture of ASCs after 3days. The cytotoxic effect of the ASC-CM obtained from high density culture of ASCs was neutralized by anti-IFN-β antibody. STAT1 was phosphorylated in MCF-7 cells treated with ASC-CM, and JAK1/JAK2 inhibitor treatment decreased STAT1 phosphorylation. The cytotoxic effect of ASC-CM was reduced especially by JAK1 inhibitors in MCF-7 cells. Our findings suggest that ASCs cultured at high density express type I interferons, which suppresses tumor growth via STAT1 activation resulting from IFN-β secretion in MCF-7 breast cancer cells.

Gene therapy for malignant glioma

Glioblastoma multiforme (GBM) is the most frequent and devastating primary brain tumor in adults. Despite current treatment modalities, such as surgical resection followed by chemotherapy and radiotherapy, only modest improvements in median survival have been achieved. Frequent recurrence and invasiveness of GBM are likely due to the resistance of glioma stem cells to conventional treatments; therefore, novel alternative treatment strategies are desperately needed. Recent advancements in molecular biology and gene technology have provided attractive novel treatment possibilities for patients with GBM. Gene therapy is defined as a technology that aims to modify the genetic complement of cells to obtain therapeutic benefit. To date, gene therapy for the treatment of GBM has demonstrated anti-tumor efficacy in pre-clinical studies and promising safety profiles in clinical studies. However, while this approach is obviously promising, concerns still exist regarding issues associated with transduction efficiency, viral delivery, the pathologic response of the brain, and treatment efficacy. Tumor development and progression involve alterations in a wide spectrum of genes, therefore a variety of gene therapy approaches for GBM have been proposed. Improved viral vectors are being evaluated, and the potential use of gene therapy alone or in synergy with other treatments against GBM are being studied. In this review, we will discuss the most commonly studied gene therapy approaches for the treatment of GBM in preclinical and clinical studies including: prodrug/suicide gene therapy; oncolytic gene therapy; cytokine mediated gene therapy; and tumor suppressor gene therapy. In addition, we review the principles and mechanisms of current gene therapy strategies as well as advantages and disadvantages of each.

Strategies in gene therapy for glioblastoma

Glioblastoma (GBM) is the most aggressive form of brain cancer, with a dismal prognosis and extremely low percentage of survivors. Novel therapies are in dire need to improve the clinical management of these tumors and extend patient survival. Genetic therapies for GBM have been postulated and attempted for the past twenty years, with variable degrees of success in pre-clinical models and clinical trials. Here we review the most common approaches to treat GBM by gene therapy, including strategies to deliver tumor-suppressor genes, suicide genes, immunomodulatory cytokines to improve immune response, and conditionally-replicating oncolytic viruses. The review focuses on the strategies used for gene delivery, including the most common and widely used vehicles (i.e., replicating and non-replicating viruses) as well as novel therapeutic approaches such as stem cell-mediated therapy and nanotechnologies used for gene delivery. We present an overview of these strategies, their targets, different advantages, and challenges for success. Finally, we discuss the potential of gene therapy-based strategies to effectively attack such a complex genetic target as GBM, alone or in combination with conventional therapy.

Multimodal immunogenic cancer cell death as a consequence of anticancer cytotoxic treatments

Apoptotic cell death generally characterized by a morphologically homogenous entity has been considered to be essentially non-immunogenic. However, apoptotic cancer cell death, also known as type 1 programmed cell death (PCD), was recently found to be immunogenic after treatment with several chemotherapeutic agents and oncolytic viruses through the emission of various danger-associated molecular patterns (DAMPs). Extensive studies have revealed that two different types of immunogenic cell death (ICD) inducers, recently classified by their distinct actions in endoplasmic reticulum (ER) stress, can reinitiate immune responses suppressed by the tumor microenvironment. Indeed, recent clinical studies have shown that several immunotherapeutic modalities including therapeutic cancer vaccines and oncolytic viruses, but not conventional chemotherapies, culminate in beneficial outcomes, probably because of their different mechanisms of ICD induction. Furthermore, interests in PCD of cancer cells have shifted from its classical form to novel forms involving autophagic cell death (ACD), programmed necrotic cell death (necroptosis), and pyroptosis, some of which entail immunogenicity after anticancer treatments. In this review, we provide a brief outline of the well-characterized DAMPs such as calreticulin (CRT) exposure, high-mobility group protein B1 (HMGB1), and adenosine triphosphate (ATP) release, which are induced by the morphologically distinct types of cell death. In the latter part, our review focuses on how emerging oncolytic viruses induce different forms of cell death and the combinations of oncolytic virotherapies with further immunomodulation by cyclophosphamide and other immunotherapeutic modalities foster dendritic cell (DC)-mediated induction of antitumor immunity. Accordingly, it is increasingly important to fully understand how and which ICD inducers cause multimodal ICD, which should aid the design of reasonably multifaceted anticancer modalities to maximize ICD-triggered antitumor immunity and eliminate residual or metastasized tumors while sparing autoimmune diseases.

Resistance to oncolytic myxoma virus therapy in nf1(-/-)/trp53(-/-) syngeneic mouse glioma models is independent of anti-viral type-I interferon

Despite promising preclinical studies, oncolytic viral therapy for malignant gliomas has resulted in variable, but underwhelming results in clinical evaluations. Of concern are the low levels of tumour infection and viral replication within the tumour. This discrepancy between the laboratory and the clinic could result from the disparity of xenograft versus syngeneic models in determining in vivo viral infection, replication and treatment efficacy. Here we describe a panel of primary mouse glioma lines derived from Nf1^+/−Trp53^+/− mice in the C57Bl/6J background for use in the preclinical testing of the oncolytic virus Myxoma (MYXV). These lines show a range of susceptibility to MYXV replication in vitro, but all succumb to viral-mediated cell death. Two of these lines orthotopically grafted produced aggressive gliomas. Intracranial injection of MYXV failed to result in sustained viral replication or treatment efficacy, with minimal tumour infection that was completely resolved by 7 days post-infection. We hypothesized that the stromal production of Type-I interferons (IFNα/β) could explain the resistance seen in these models; however, we found that neither the cell lines in vitro nor the tumours in vivo produce any IFNα/β in response to MYXV infection. To confirm IFNα/β did not play a role in this resistance, we ablated the ability of tumours to respond to IFNα/β via IRF9 knockdown, and generated identical results. Our studies demonstrate that these syngeneic cell lines are relevant preclinical models for testing experimental glioma treatments, and show that IFNα/β is not responsible for the MYXV treatment resistance seen in syngeneic glioma models.

Antitumor effect of recombinant human interferon-β adenovirus on esophageal squamous cell cancer in vitro

Interferon (IFN)-β has efficient antitumor effect both in vitro and in vivo, but its clinical implication is limited by short half-life and systemic toxicities. Gene therapy could be the choice to avoid the defects. Adenovirus vector containing human IFN-β gene was transfected into esophageal squamous cell carcinoma KYSE150 cells. Expression of human (h)IFN-β was detected by reverse transcription polymerase chain reaction and immunocytochemistry in KYSE150 cells. Cell growth and clonogenic assays, and flow cytometry were used to observe the antiproliferation effect and apoptosis on tumor cells, respectively. Reverse transcription polymerase chain reaction and immunocytochemistry showed obvious hIFN-β expression in KYSE150 cells after transfection and the tumor cell proliferation was obviously inhibited through cell proliferation and clonogenic assays. Flow cytometry analysis showed 27.3% cell apoptosis in adenovirus vector containing human IFN-β gene transfection group compared with 1.12% in empty vector control group. These findings indicate that hIFN-β gene mediated by recombinant adenovirus may have antitumor activity against human esophageal carcinoma cell by inducing apoptosis in vitro.

Treating brain tumor-initiating cells using a combination of myxoma virus and rapamycin

BACKGROUND

Intratumoral heterogeneity in glioblastoma multiforme (GBM) poses a significant barrier to therapy in certain subpopulation such as the tumor-initiating cell population, being shown to be refractory to conventional therapies. Oncolytic virotherapy has the potential to target multiple compartments within the tumor and thus circumvent some of the barriers facing conventional therapies. In this study, we investigate the oncolytic potential of myxoma virus (MYXV) alone and in combination with rapamycin in vitro and in vivo using human brain tumor-initiating cells (BTICs).

METHODS

We cultured fresh GBM specimens as neurospheres and assayed their growth characteristics in vivo. We then tested the susceptibility of BTICs to MYXV infection with or without rapamycin in vitro and assessed viral biodistribution/survival in vivo in orthotopic xenografts.

RESULTS

The cultured neurospheres were found to retain stem cell markers in vivo, and they closely resembled human infiltrative GBM. In this study we determined that (i) all patient-derived BTICs tested, including those resistant to temozolomide, were susceptible to MYXV replication and killing in vitro; (ii) MYXV replicated within BTICs in vivo, and intratumoral administration of MYXV significantly prolonged survival of BTIC-bearing mice; (iii) combination therapy with MYXV and rapamycin improved antitumor activity, even in mice bearing "advanced" BTIC tumors; (iv) MYXV treatment decreased expression of stem cell markers in vitro and in vivo.

CONCLUSIONS

Our study suggests that MYXV in combination with rapamycin infects and kills both the BTICs and the differentiated compartments of GBM and may be an effective treatment even in TMZ-resistant patients.

Chapter eight--Oncolytic adenoviruses for cancer immunotherapy: data from mice, hamsters, and humans

Adenovirus is one of the most commonly used vectors for gene therapy and two products have already been approved for treatment of cancer in China (Gendicine(R) and Oncorine(R)). An intriguing aspect of oncolytic adenoviruses is that by their very nature they potently stimulate multiple arms of the immune system. Thus, combined tumor killing via oncolysis and inherent immunostimulatory properties in fact make these viruses in situ tumor vaccines. When further engineered to express cytokines, chemokines, tumor-associated antigens, or other immunomodulatory elements, they have been shown in various preclinical models to induce antigen-specific effector and memory responses, resulting both in full therapeutic cures and even induction of life-long tumor immunity. Here, we review the state of the art of oncolytic adenovirus, in the context of their capability to stimulate innate and adaptive arms of the immune system and finally how we can modify these viruses to direct the immune response toward cancer.

Interferon-β-armed oncolytic adenovirus induces both apoptosis and necroptosis in cancer cells

Interferon-β (IFN-β) has been widely used in cancer therapy, but the clinical trial results are generally disappointing. Our previous studies have shown that an oncolytic adenovirus carrying IFN-β (ZD55-IFN-β) exhibits significant anti-tumor activities. However, the underlying mechanisms are not clear. Here we showed that ZD55-IFN-β infection-induced S-phase cell cycle arrest in a p53-dependent manner by activating the ataxia telangiectasia mutated-dependent DNA damage pathway. In addition, ZD55-IFN-β infection could initiate both caspase-dependent apoptosis and necroptosis in cancer cells. More importantly, ZD55-IFN-β showed a synergistic effect on cancer cells when combined with doxorubicin. These results suggest that the combination of ZD55-IFN-β with doxorubicin may represent a promising clinical strategy in cancer therapy.

Interferon-β sensitivity of tumor cells correlates with poor response to VA7 virotherapy in mouse glioma models

In our recent study, replicative alphaviral vector VA7 was found to be effective against orthotopic human U87-glioma xenografts in an athymic mouse model eradicating the tumors with single intravenous (i.v.) injection. Here, we tested the efficacy of VA7 in immunocompetent orthotopic GL261 and CT-2A glioma models of C57BL/6 mouse in vivo. The cell lines were susceptible to VA7 infection in vitro, but GL261 infection was highly restricted in confluent cell cultures, and mouse interferon-β (IFNβ) pretreatment prevented the replication of VA7 in both cell lines. When mice bearing orthotopic GL261 or CT-2A tumors were administered neurotropic VA7, either i.v. or intracranially (i.c.), the vector was unable to infect the tumor and no survival benefit was achieved. Pretreatments with immunosuppressive cyclophosphamide (CPA) and rapamycin markedly lowered serum-neutralizing antibodies (NAbs) but had no effect on tumor infection or survival. Intracranial GL261 tumors were refractory also in athymic C57BL/6 mice, which have serious defects in their adaptive immunity. Implanted VA7-infected GL261 cells formed tumors with only slightly delayed kinetics and without improving survival thus excluding the participation of physical barriers and indicating robust host IFN action. Mouse and human IFNβ do not seem be species cross-reactive, which might limit the translational relevance of xenograft models in oncolytic virotherapy.

Experimental approaches for the treatment of malignant gliomas

Malignant gliomas, which include glioblastomas and anaplastic astrocytomas, are the most common primary tumors of the brain. Over the past 30 years, the standard treatment for these tumors has evolved to include maximal safe surgical resection, radiation therapy and temozolomide chemotherapy. While the median survival of patients with glioblastomas has improved from 6 months to 14.6 months, these tumors continue to be lethal for the vast majority of patients. There has, however, been recent substantial progress in our mechanistic understanding of tumor development and growth. The translation of these genetic, epigenetic and biochemical findings into therapies that have been tested in clinical trials is the subject of this review.

Neural precursor cells as a novel target for interferon-beta

The immunomodulating agent interferon-beta (IFNbeta) is administered therapeutically in several autoimmune diseases and endogenously released by immune cells during diverse infections. As in recent years a variety of pro- and anti-inflammatory substances were shown to influence significantly neural precursor cells that are implicated in a variety of regenerative mechanisms but also in tumor growth, we studied a possible effect of IFNbeta on neural precursor cells derived from murine embryonic day 14 neurospheres. First, we demonstrated that interferon type-I receptors are expressed on neural precursor cells and that these cells respond to IFNbeta treatment by up-regulating IFNbeta inducible genes including Myxovirus 1 and viperin. Furthermore, we could show for the first time that IFNbeta treatment significantly inhibited the proliferation of neural precursor cells possibly through induction of p21, a cyclin-dependent kinase inhibitor. IFNbeta did not exert cytotoxic or neuroprotective effects and we could not see effects on the differentiation of neural precursor cells into total amounts of neurons, astrocytes or oligodendrocytes. However, we found that IFNbeta markedly diminished neurite outgrowth and neuronal maturation of neural precursor-derived neurons.

A phase I trial of Ad.hIFN-beta gene therapy for glioma

Interferon-beta (IFN-beta) is a pleiotropic cytokine with antitumoral activity. In an effort to improve the therapeutic index of IFN-beta by providing local, sustained delivery of IFN-beta to gliomas, the safety and biological activity of a human IFN-beta (hIFN-beta)-expressing adenovirus vector (Ad.hIFN-beta) was evaluated in patients with malignant glioma by stereotactic injection, followed 4-8 days later by surgical removal of tumor with additional injections of Ad.hIFN-beta into the tumor bed. Eleven patients received Ad.hIFN-beta in cohorts of 2 x 10(10), 6 x 10(10), or 2 x 10(11) vector particles (vp). The most common adverse events were considered by the investigator as being unrelated to treatment. One patient, who was enrolled in the cohort with the highest dose levels, experienced dose-limiting, treatment-related Grade 4 confusion following the post-operative injection. Ad.hIFN-beta DNA was detected within the tumor, blood, and nasal swabs in a dose-dependent fashion and hIFN-beta protein was detectable within the tumor. At the highest doses tested, a reproducible increase in tumor cell apoptosis in post-treatment versus pre-treatment biopsies with associated tumor necrosis was observed. Direct Ad.hIFN-beta injection into the tumor and the surrounding normal brain areas after surgical removal was feasible and associated with apoptosis induction.

Continuous delivery of IFN-beta promotes sustained maturation of intratumoral vasculature

IFNs have pleiotropic antitumor mechanisms of action. The purpose of this study was to further investigate the effects of IFN-beta on the vasculature of human xenografts in immunodeficient mice. We found that continuous, systemic IFN-beta delivery, established with liver-targeted adeno-associated virus vectors, led to sustained morphologic and functional changes of the tumor vasculature that were consistent with vessel maturation. These changes included increased smooth muscle cell coverage of tumor vessels, improved intratumoral blood flow, and decreased vessel permeability, tumor interstitial pressure, and intratumoral hypoxia. Although these changes in the tumor vasculature resulted in more efficient tumor perfusion, further tumor growth was restricted, as the mature vasculature seemed to be unable to expand to support further tumor growth. In addition, maturation of the intratumoral vasculature resulted in increased intratumoral penetration of systemically administered chemotherapy. Finally, molecular analysis revealed increased expression by treated tumors of angiopoietin-1, a cytokine known to promote vessel stabilization. Induction of angiopoietin-1 expression in response to IFN-beta was broadly observed in different tumor lines but not in those with defects in IFN signaling. In addition, IFN-beta-mediated vascular changes were prevented when angiopoietin signaling was blocked with a decoy receptor. Thus, we have identified an alternative approach for achieving sustained vascular remodeling-continuous delivery of IFN-beta. In addition to restricting tumor growth by inhibiting further angiogenesis, maturation of the tumor vasculature also improved the efficiency of delivery of adjuvant therapy. These results have significant implications for the planning of combination anticancer therapy.

Enhancement of Human Melanoma Antigen Expression by IFN-β

Although many immunotherapeutic investigations have focused on improving the effector limb of the antitumor response, few studies have addressed preventing the loss of tumor-associated Ag (TAA) expression, associated with immune escape by tumors. We found that TAA loss from human melanomas usually results from reversible gene down-regulation, rather than gene deletion or mutation. Previously, we showed that inhibitors of MAPK-signaling pathways up-regulate TAA expression in melanoma cell lines. We have now identified IFN-beta as an additional stimulus to TAA expression, including Melan-A/MART-1, gp100, and MAGE-A1. IFN-beta (but neither IFN-alpha nor IFN-gamma) augmented both protein and mRNA expression of melanocytic TAA in 15 melanoma lines (irrespective of initial Ag-expression levels). Treatment of low Ag melanoma lines with IFN-beta increased expression of melanocyte-lineage Ags, inducing susceptibility to lysis by specific CTLs. Treatment with IFN-beta also enhances expression of class I HLA molecules, thereby inducing both nominal TAA and the presenting HLA molecule. Data from fluorescent cellular reporter systems demonstrated that IFN-beta triggers promoter activation, resulting in augmentation of Ag expression. In addition to enhancing TAA expression in melanomas, IFN-beta also stimulated expression of the melanocytic Ag gp100 in cells of other neural crest-derived tumor lines (gliomas) and certain unrelated tumors. Because IFN-beta is already approved for human clinical use in other contexts, it may prove useful as a cotreatment for augmenting tumor Ag expression during immunotherapy.

Antitumor efficacy of AAV-mediated systemic delivery of interferon-beta

Type I interferons (alpha/beta) have significant antitumor activity although their short half-life and systemic side effects have limited their clinical utility. An alternative dosing schedule of continuous, low-level delivery, as is achieved by gene therapy, rather than intermittent, high concentration pulsed-dosing, might avoid the toxicity of interferon while maintaining its antitumor efficacy. We have tested a gene therapy approach in murine tumor models to treat malignancies that have shown responsiveness to interferon in clinical trials. The tumor cell lines used were moderately sensitive to the direct effects of human interferon-beta (hIFN-beta) in vitro. For in vivo testing, systemic delivery of hIFN-beta was generated following liver-targeted delivery of adeno-associated virus (AAV) vector carrying the hIFN-beta transgene. This prevented engraftment of subcutaneous human gliomas, and orthotopic, localized (intrarenal) and disseminated (primarily pulmonary) human renal cell carcinomas; and caused regression of established tumors at these sites. In a syngeneic, immunocompetent model of melanoma, AAV IFN-beta treatment limited subcutaneous tumor growth and prevented disseminated disease. A significant decrease in mean intratumoral vessel density was demonstrated in hIFN-beta-treated tumors, suggesting that in addition to a direct tumoricidal effect, the antitumor efficacy of AAV IFN-beta in this study was due to its ability to inhibit angiogenesis.

Adenovirus delivery provides extended interferon-alpha exposure and augments treatment of metastatic carcinoma

Type I interferons (e.g. IFNalpha2b) have been successfully used to treat a variety of hematological malignancies, but have not been efficacious for treatment of most solid tumors. We tested the hypothesis that delivery of type I interferon utilizing recombinant adenovirus (rAd) vectors may improve treatment efficacy of metastatic carcinomas by providing increased interferon exposure resulting from continuous transgene expression. Treatment of mice with a rAd-vector expressing hybrid-IFN (rAd-IFNalpha2alpha1) inhibited 4T1 mammary carcinoma tumor growth and induced tumor regression in a dose-dependent manner. Moreover, rAd-IFNalpha2alpha1 treatment reduced hepatic and pulmonary metastatic burden. A comparison of local and systemic routes of administration demonstrated that intratumoral delivery of rAd-IFNalpha2alpha1 was sufficient for inhibition of tumor growth. Moreover, it reduced toxicity associated with high-dose systemic IFNalpha2alpha1 exposure. Interestingly, antitumor activity following intratumoral treatment was due, in part, to the immunostimulatory capacity of the rAd vector component. Furthermore, systemic administration of rAd-IFNalpha2alpha1 potentiated the immunotherapeutic effect induced by local intralesional delivery of empty-rAd vector. These results suggest continuous interferon-alpha exposure may provide improved antitumor responses for metastatic carcinomas. Additionally, immunostimulatory responses induced by rAd-IFNalpha2alpha1 may mitigate the immune-evasive tumor microenvironment.

Adenovirus-mediated interferon alpha gene transfer induces regional direct cytotoxicity and possible systemic immunity against pancreatic cancer

We previously demonstrated a characteristically high sensitivity of pancreatic cancer cells to interferon alpha (IFN-alpha) gene transfer, which induced a more prominent growth suppression and cell death in pancreatic cancer cells than in other types of cancers and normal cells. The IFN-alpha protein can exhibit both direct cytotoxicity and indirect immunological antitumour activity. Here, we dissected and examined the two mechanisms, taking advantage of the fact that IFN-alpha did not show any cross-species activity in its in vivo effect. When a human IFN-alpha adenovirus was injected into subcutaneous xenografts of human pancreatic cancer cells in nude mice, tumour growth was significantly suppressed due to cell death in an adenoviral dose-dependent manner. The IFN-alpha protein concentration was markedly increased in the injected subcutaneous tumour, but leakage of the potent cytokine into the systemic blood circulation was minimal. When a mouse IFN-alpha adenovirus was injected into the same subcutaneous tumour system, all mice showed significant tumour inhibition, an effect that was dependent on the indirect antitumour activities of IFN-alpha, notably a stimulation of natural killer cells. Moreover, in this case, tumour regression was observed not only for the injected subcutaneous tumours but also for the untreated tumours at distant sites. This study suggested that a local IFN-alpha gene therapy is a promising therapeutic strategy for pancreatic cancer, due to its dual mechanisms of antitumour activities and lack of significant toxicity.

Mesenchymal stem cells: potential precursors for tumor stroma and targeted-delivery vehicles for anticancer agents

BACKGROUND

High concentrations of interferon beta (IFN-beta) inhibit malignant cell growth in vitro. However, the therapeutic utility of IFN-beta in vivo is limited by its excessive toxicity when administered systemically at high doses. Mesenchymal stem cells (MSC) can be used to target delivery of agents to tumor cells. We tested whether MSC can deliver IFN-beta to tumors, reducing toxicity.

METHODS

Human MSC were transduced with an adenoviral expression vector carrying the human IFN-beta gene (MSC-IFN-beta cells). Flow cytometry was used to measure tumor cell proliferation among in vitro co-cultures of MSC-IFN-beta cells and human MDA 231 breast carcinoma cells or A375SM melanoma cells. We used a severe combined immunodeficiency mouse xenograft model (4-10 mice per group) to examine the effects of injected MSC-IFN-beta cells and human recombinant IFN-beta on the growth of MDA 231- and A375SM-derived pulmonary metastases in vivo and on survival. All statistical tests were two-sided.

RESULTS

Co-culture of MSC-IFN-beta cells with A375SM cells or MDA 231 cells inhibited tumor cell growth as compared with growth of the tumor cells cultured alone (differences in mean percentage of control cell growth: -94.0% [95% confidence interval [CI] = -81.2% to -106.8%; P<.001] and -104.8% [95% CI = -82.1% to -127.5%; P<.001], respectively). Intravenous injection of MSC-IFN-beta cells into mice with established MDA 231 or A375SM pulmonary metastases led to incorporation of MSC in the tumor architecture and, compared with untreated control mice, to prolonged mouse survival (median survival for MDA 231-injected mice: 60 and 37 days for MSC-injected and control mice, respectively [difference = 23.0 days (95% CI = 14.5 to 34.0 days; P<.001]; median survival for A375SM-injected mice: 73.5 and 30.0 days for MSC-injected and control mice, respectively [difference = 43.5 days (95% CI = 37.0 to 57.5 days; P<.001]). By contrast, intravenous injection of recombinant IFN-beta did not prolong survival in the same models (median survival for MDA 231-injected mice: 41.0 and 37.0 days for IFN-beta-injected and control mice, respectively [difference = 4 days, 95% CI = -5 to 10 days; P = .308]; median survival for A375SM-injected mice: 32.0 and 30.0 days for IFN-beta-injected and control mice, respectively [difference = 2 days, 95% CI = 0 to 4.5 days; P = .059]).

CONCLUSIONS

Injected MSC-IFN-beta cells suppressed the growth of pulmonary metastases, presumably through the local production of IFN-beta in the tumor microenvironment. MSC may be an effective platform for the targeted delivery of therapeutic proteins to cancer sites.