Modification of tumor cells by a low dose of Newcastle disease virus. III. Potentiation of tumor-specific cytolytic T cell activity via induction of interferon-alpha/beta

Newcastle Disease Virus Virotherapy: Unveiling Oncolytic Efficacy and Immunomodulation

In virotherapy, cancer cells are eradicated via viral infection, replication, and dissemination (oncolysis).

BACKGROUND

This study aims to evaluate the oncolytic potential of Newcastle disease virus (NDV) against colon cancer and explore the immune response associated with its therapeutic effects.

METHODS

NDV was tested for its oncolytic potential in colon cancer cell lines using MTT assays and apoptosis assessments. Tumor-induced mice were treated with NDV, tumor cell lysate (TCL), or a combination of both. After the euthanasia of murine subjects, an assessment of oncolytic efficacy was performed through flow cytometry analysis of murine blood and tumor tissue, targeting CD83, CD86, CD8, and CD4. An ELISA was also performed to examine interferon-gamma levels, interleukin-4 levels, interleukin-12 levels, and interleukin-10 levels in serum and spleen homogenate.

RESULTS

Cell viability was low in HCT116 and HT-29, indicating a cytotoxic effect in the MTT assay. NDV+TCL recorded the highest rate of cell death (56.72%). NDV+TCL had accelerated cell death after 48 h, reaching 58.4%. The flow cytometry analysis of the blood and tumor of mice with induced tumor treated with combined treatment revealed elevated levels of CD83, CD86, CD8, and CD4 (76.3, 66.9, 83.7, and 14.4%, respectively). The ELISA levels of IFN-γ, IL-4, and IL-12 in serum and the spleen homogenate were elevated (107.6 ± 9.25 pg/mL). In contrast, the expression of IL-10 was significantly reduced (1 ± 0.79).

Counteracting Immunosuppression in the Tumor Microenvironment by Oncolytic Newcastle Disease Virus and Cellular Immunotherapy

An apparent paradox exists between the evidence for spontaneous systemic T cell- mediated anti-tumor immune responses in cancer patients, observed particularly in their bone marrow, and local tumor growth in the periphery. This phenomenon, known as "concomitant immunity" suggests that the local tumor and its tumor microenvironment (TME) prevent systemic antitumor immunity to become effective. Oncolytic Newcastle disease virus (NDV), an agent with inherent anti-neoplastic and immune stimulatory properties, is capable of breaking therapy resistance and immunosuppression. This review updates latest information about immunosuppression by the TME and discusses mechanisms of how oncolytic viruses, in particular NDV, and cellular immunotherapy can counteract the immunosuppressive effect of the TME. With regard to cellular immunotherapy, the review presents pre-clinical studies of post-operative active-specific immunotherapy and of adoptive T cell-mediated therapy in immunocompetent mice. Memory T cell (MTC) transfer in tumor challenged T cell-deficient nu/nu mice demonstrates longevity and functionality of these cells. Graft-versus-leukemia (GvL) studies in mice demonstrate complete remission of late-stage disease including metastases and cachexia. T cell based immunotherapy studies with human cells in human tumor xenotransplanted NOD/SCID mice demonstrate superiority of bone marrow-derived as compared to blood-derived MTCs. Results from clinical studies presented include vaccination studies using two different types of NDV-modified cancer vaccine and a pilot adoptive T-cell mediated therapy study using re-activated bone marrow-derived cancer-reactive MTCs. As an example for what can be expected from clinical immunotherapy against tumors with an immunosuppressive TME, results from vaccination studies are presented from the aggressive brain tumor glioblastoma multiforme. The last decades of basic research in virology, oncology and immunology can be considered as a success story. Based on discoveries of these research areas, translational research and clinical studies have changed the way of treatment of cancer by introducing and including immunotherapy.

Molecular Mechanisms of Anti-Neoplastic and Immune Stimulatory Properties of Oncolytic Newcastle Disease Virus

Oncolytic viruses represent interesting anti-cancer agents with high tumor selectivity and immune stimulatory potential. The present review provides an update of the molecular mechanisms of the anti-neoplastic and immune stimulatory properties of the avian paramyxovirus, Newcastle Disease Virus (NDV). The anti-neoplastic activities of NDV include (i) the endocytic targeting of the GTPase Rac1 in Ras-transformed human tumorigenic cells; (ii) the switch from cellular protein to viral protein synthesis and the induction of autophagy mediated by viral nucleoprotein NP; (iii) the virus replication mediated by viral RNA polymerase (large protein (L), associated with phosphoprotein (P)); (iv) the facilitation of NDV spread in tumors via the membrane budding of the virus progeny with the help of matrix protein (M) and fusion protein (F); and (v) the oncolysis via apoptosis, necroptosis, pyroptosis, or ferroptosis associated with immunogenic cell death. A special property of this oncolytic virus consists of its potential for breaking therapy resistance in human cancer cells. Eight examples of this important property are presented and explained. In healthy human cells, NDV infection activates the RIG-MAVs immune signaling pathway and establishes an anti-viral state based on a strong and uninhibited interferon α,ß response. The review also describes the molecular determinants and mechanisms of the NDV-mediated immune stimulatory effects, in which the viral hemagglutinin-neuraminidase (HN) protein plays a prominent role. The six viral proteins provide oncolytic NDV with a special profile in the treatment of cancer.

Combinatorial Approaches for Cancer Treatment Using Oncolytic Viruses: Projecting the Perspectives through Clinical Trials Outcomes

Recent cancer immunotherapy breakthroughs have fundamentally changed oncology and revived the fading hope for a cancer cure. The immune checkpoint inhibitors (ICI) became an indispensable tool for the treatment of many malignant tumors. Alongside ICI, the application of oncolytic viruses in clinical trials is demonstrating encouraging outcomes. Dozens of combinations of oncolytic viruses with conventional radiotherapy and chemotherapy are widely used or studied, but it seems quite complicated to highlight the most effective combinations. Our review summarizes the results of clinical trials evaluating oncolytic viruses with or without genetic alterations in combination with immune checkpoint blockade, cytokines, antigens and other oncolytic viruses as well. This review is focused on the efficacy and safety of virotherapy and the most promising combinations based on the published clinical data, rather than presenting all oncolytic virus variations, which are discussed in comprehensive literature reviews. We briefly revise the research landscape of oncolytic viruses and discuss future perspectives in virus immunotherapy, in order to provide an insight for novel strategies of cancer treatment.

Less Can Be More: The Hormesis Theory of Stress Adaptation in the Global Biosphere and Its Implications

A dose-response relationship to stressors, according to the hormesis theory, is characterized by low-dose stimulation and high-dose inhibition. It is non-linear with a low-dose optimum. Stress responses by cells lead to adapted vitality and fitness. Physical stress can be exerted through heat, radiation, or physical exercise. Chemical stressors include reactive species from oxygen (ROS), nitrogen (RNS), and carbon (RCS), carcinogens, elements, such as lithium (Li) and silicon (Si), and metals, such as silver (Ag), cadmium (Cd), and lead (Pb). Anthropogenic chemicals are agrochemicals (phytotoxins, herbicides), industrial chemicals, and pharmaceuticals. Biochemical stress can be exerted through toxins, medical drugs (e.g., cytostatics, psychopharmaceuticals, non-steroidal inhibitors of inflammation), and through fasting (dietary restriction). Key-lock interactions between enzymes and substrates, antigens and antibodies, antigen-presenting cells, and cognate T cells are the basics of biology, biochemistry, and immunology. Their rules do not obey linear dose-response relationships. The review provides examples of biologic stressors: oncolytic viruses (e.g., immuno-virotherapy of cancer) and hormones (e.g., melatonin, stress hormones). Molecular mechanisms of cellular stress adaptation involve the protein quality control system (PQS) and homeostasis of proteasome, endoplasmic reticulum, and mitochondria. Important components are transcription factors (e.g., Nrf2), micro-RNAs, heat shock proteins, ionic calcium, and enzymes (e.g., glutathion redox enzymes, DNA methyltransferases, and DNA repair enzymes). Cellular growth control, intercellular communication, and resistance to stress from microbial infections involve growth factors, cytokines, chemokines, interferons, and their respective receptors. The effects of hormesis during evolution are multifarious: cell protection and survival, evolutionary flexibility, and epigenetic memory. According to the hormesis theory, this is true for the entire biosphere, e.g., archaia, bacteria, fungi, plants, and the animal kingdoms.

Cancer Vaccines and Oncolytic Viruses Exert Profoundly Lower Side Effects in Cancer Patients than Other Systemic Therapies: A Comparative Analysis

This review compares cytotoxic drugs, targeted therapies, and immunotherapies with regard to mechanisms and side effects. Targeted therapies relate to small molecule inhibitors. Immunotherapies include checkpoint inhibitory antibodies, chimeric antigen receptor (CAR) T-cells, cancer vaccines, and oncolytic viruses. All these therapeutic approaches fight systemic disease, be it micro-metastatic or metastatic. The analysis includes only studies with a proven therapeutic effect. A clear-cut difference is observed with regard to major adverse events (WHO grades 3-4). Such severe side effects are not observed with cancer vaccines/oncolytic viruses while they are seen with all the other systemic therapies. Reasons for this difference are discussed.

New Insights into Mechanisms of Long-term Protective Anti-tumor Immunity Induced by Cancer Vaccines Modified by Virus Infection

The topic is how to achieve long-term protective anti-tumor immunity by anti-cancer vaccination and what are its mechanisms. Cancer vaccines should instruct the immune system regarding relevant cancer targets and contain signals for innate immunity activation. Of central importance is T-cell mediated immunity and thus a detailed understanding of cognate interactions between tumor antigen (TA)-specific T cells and TA-presenting dendritic cells. Microbes and their associated molecular patterns initiate early inflammatory defense reactions that can contribute to the activation of antigen-presenting cells (APCs) and to costimulation of T cells. The concommitant stimulation of naive TA-specific CD4+ and CD8+ T cells with TAs and costimulatory signals occurs in T-APC clusters that generate effectors, such as cytotoxic T lymphocytes and T cell mediated immunological memory. Information about how such memory can be maintained over long times is updated. The role that the bone marrow with its specialized niches plays for the survival of memory T cells is emphasized. Examples are presented that demonstrate long-term protective anti-tumor immunity can be achieved by post-operative vaccination with autologous cancer vaccines that are modified by virus infection.

A Novel C Type CpG Oligodeoxynucleotide Exhibits Immunostimulatory Activity In Vitro and Enhances Antitumor Effect In Vivo

Background

C type CpG oligodeoxynucleotides (CpG-C ODNs), possessing the features of both A type and B type CpG ODNs, exert a variety of immunostimulatory activities and have been demonstrated as an effective antitumor immunotherapy. Based on the structural characteristics, we designed 20 potential ODNs with the aim of synthesizing an optimal, novel CpG-C ODN specific to human and murine Toll-like receptor 9 (TLR9). We also sought to investigate the in vitro immunostimulatory and in vivo antitumor effects of the novel CpG-C ODN.

Methods

Twenty potential CpG-C ODNs were screened for their ability to secrete interferon (IFN)-α, and interleukin (IL)-6 and tumor necrosis factor (TNF)-α production for the three most promising sequences were assayed in human peripheral blood mononuclear cells (PBMCs) by enzyme-linked immunosorbent assay (ELISA) or cytometric bead array assay. The functions of human and mouse B cells, and cytokine production in mice induced by the most promising sequence, HP06T07, were determined by flow cytometry and ELISA. Growth and morphology of tumor tissues in in vivo murine models inoculated with CT26 cells were analyzed by a growth inhibition assay and immunohistochemistry, respectively.

Results

Among the 20 designed ODNs, HP06T07 significantly induced IFN-α, IL-6, and TNF-α secretion, and promoted B-cell activation and proliferation in a dose-dependent manner in human PBMCs and mouse splenocytes in vitro. Intratumoral injection of HP06T07 notably suppressed tumor growth and prolonged survival in the CT26 subcutaneous mouse model in a dose-dependent manner. HP06T07 administered nine times at 2-day intervals (I2) eradicated tumor growth at both primary and distant sites of CT26 tumors. HP06T07 restrained tumor growth by increasing the infiltration of T cells, NK cells, and plasmacytoid dendritic cells (pDCs).

Conclusions

HP06T07, a novel CpG-C ODN, shows potent immunostimulatory activity in vitro and suppresses tumor growth in the CT26 subcutaneous mouse model.

Breaking Therapy Resistance: An Update on Oncolytic Newcastle Disease Virus for Improvements of Cancer Therapy

Resistance to therapy is a major obstacle to cancer treatment. It may exist from the beginning, or it may develop during therapy. The review focusses on oncolytic Newcastle disease virus (NDV) as a biological agent with potential to break therapy resistance. This avian virus combines, upon inoculation into non-permissive hosts such as human, 12 described anti-neoplastic effects with 11 described immune stimulatory properties. Fifty years of clinical application of NDV give witness to the high safety profile of this biological agent. In 2015, an important milestone was achieved, namely the successful production of NDV according to Good Manufacturing Practice (GMP). Based on this, IOZK in Cologne, Germany, obtained a GMP certificate for the production of a dendritic cell vaccine loaded with tumor antigens from a lysate of patient-derived tumor cells together with immunological danger signals from NDV for intracutaneous application. This update includes single case reports and retrospective analyses from patients treated at IOZK. The review also presents future perspectives, including the concept of in situ vaccination and the combination of NDV or other oncolytic viruses with checkpoint inhibitors.

Non-replicating Newcastle Disease Virus as an adjuvant for DNA vaccine enhances antitumor efficacy through the induction of TRAIL and granzyme B expression

The potential of non-replicating Newcastle Disease Virus (NDV) as an adjuvant for DNA vaccination remains to be elucidated. To assess the therapeutic effects of DNA vaccine (HPV-16 E7 gene) adjuvanted with NDV, female C57/BL6 mice were inoculated with murine TC-1 cells of human papillomavirus (HPV)-related carcinoma, expressing human papillomavirus 16 (HPV-16) E6/E7 antigens, and immunized with DNA vaccine alone or pretreated with NDV. One week after third immunization, Cytotoxic T lymphocytes (CTLs), splenocyte proliferation, cytokine balance (IFN-γ, IL-4 and IL-12 secretions) and intratumoral expression of cytotoxicity related proteins in tumor lysates were investigated. The results showed that treatment with non-replicating NDV prior to DNA vaccine induced tumor-specific cytolytic and splenocyte proliferation responses. The levels of cytokines IL-12, IL-4 and IFN-γ after treating with combined E7-DNA -non-replicating NDV (NDV-DNA Vaccine) were significantly higher than those of control groups. The intratumoral granzyme B and Tumor Necrosis Factor Related Apoptosis Inducing Ligand (TRAIL)-mediated apoptosis was also significantly increased. Tumor therapeutic experiments showed that the NDV pretreatment could reduce the tumor progression of established E7-expressing TC-tumors. Taken together these data suggest that the significant antitumor responses evidenced during treatment with non-replicating NDV prior to DNA vaccine are due, in part, to strong E7-induced cellular immunity and enhanced expression of cytotoxicity related proteins in the tumor microenvironment. These observations indicated the potential of non-replicating NDV as an adjuvant for enhancing therapeutic DNA vaccines -induced immunity and antitumor responses.

Immunobiology of Newcastle Disease Virus and Its Use for Prophylactic Vaccination in Poultry and as Adjuvant for Therapeutic Vaccination in Cancer Patients

Newcastle disease (ND) is one of the most important diseases of poultry worldwide. In the last decades, molecular research has gained a lot of new information about its causative agent, newcastledisease virus (NDV). In poultry industry, certain strains of NDV have been used for preventive vaccination for more than 60 years. NDV has also been applied to cancer patients with beneficial effects for about 50 years, but this is less well known. The molecular basis for these differential effects of NDV in birds and man have been elucidated in the last decades and are explained in this review. The anti-neoplastic and immune-stimulatory properties in non-permissive hosts such as mouse and man have to do with the strong type I interferon responses induced in these foreign species. Additionally, NDV has the potential to break various types of tumor resistances and also to affect liver fibrosis. A main section is devoted to the benefits of clinical application of NDV and NDV-based vaccines to cancer patients. Reverse genetics technology allowed developing NDV into a vector suitable for gene therapy. Examples will be provided in which genetically engineered NDV is being used successfully as vector against new emerging viruses.

Fifty Years of Clinical Application of Newcastle Disease Virus: Time to Celebrate!

This review provides an overview of 50 years of basic and clinical research on an oncolytic avian virus, Newcastle Disease Virus (NDV), which has particular anti-neoplastic and immune stimulatory properties. Of special interest is the fact that this biological agent induces immunogenic cell death and systemic anti-tumor immunity. Furthermore, localized oncolytic virotherapy with NDV was shown to overcome systemic tumor resistance to immune checkpoint blockade immunotherapy. Clinical experience attests to low side effects and a high safety profile. This is due among others to the strong virus-induced type I interferon response. Other viral characteristics are lack of interaction with host cell DNA, lack of genetic recombination and independence of virus replication from cell proliferation. In this millennium, new recombinant strains of viruses are being produced with improved therapeutic properties. Clinical applications include single case observations, case series studies and Phase I to III studies.

Recombinant Newcastle disease virus (NDV/Anh-IL-2) expressing human IL-2 as a potential candidate for suppresses growth of hepatoma therapy

Newcastle disease virus (NDV) have shown oncolytic therapeutic efficacy in preclinical study and are currently approved for clinical trials. NDV Anhinga strain which is a mesogenic strain should be classified as lytic strain and has a therapeutic efficacy in hepatocellular cancer. In this study, we evaluated the capacity of NDV Anhinga strain to elicit immune reaction in vivo and the possibility for using as a vaccine vector for expressing tumor therapeutic factors. Interleukin-2 (IL-2) could boost the immune response against the tumor cells. Therefore, we use NDV Anhinga strain as backbone to construct a recombinant virus (NDV/Anh-IL-2) expressing IL-2. The virus growth curve showed that the production of recombinant NDV/Anh-IL-2 was slightly delayed compared to the wild type. The NDV/Anh-IL-2 strain could express soluble IL-2 and effectively inhibit the growth of hepatocellular carcinoma in vivo. 60 days post-treatment, mice which were completely cured by previous treatment were well protected when rechallenged with the same tumor cell. From the H&E-stained sections, intense infiltration of lymphocyte was observed in the NDV Anhinga strain treated group, especially in NDV/Anh-IL-2 group. The NDV Anhinga strain could not only kill the tumor directly, but could also elicit immune reaction and a potent immunological memory when killing tumor in vivo. In conclusion, the Anhinga strain could be an effective vector for tumor therapy; the recombinant NDV/Anh-IL-2 strain expressing soluble IL-2 is a promising candidate for hepatoma therapy.

Oncolytic Newcastle disease virus as a prospective anti-cancer therapy. A biologic agent with potential to break therapy resistance

INTRODUCTION

Oncolytic viruses (OVs) selectively replicate in tumor cells and cause cancer cell death. Most OVs in clinical studies are genetically engineered. In contrast, the avian Newcastle disease virus (NDV) is a naturally oncolytic RNA virus. While anti-viral immunity is considered a major problem in achieving maximal tumor cell killing by OVs, this review discusses the importance of NDV immunogenic cell death (ICD) and how anti-viral immune responses can be integrated to induce maximal post-oncolytic T-cell-mediated anti-tumor immunity. Since replication of NDV is independent of host cell DNA replication (which is the target of many cytostatic drugs and radiotherapy) and because of other findings, oncolytic NDV is a candidate agent to break therapy resistance of tumor cells.

AREAS COVERED

Properties of this avian paramyxovirus are summarized with special emphasis to its anti-neoplastic and immune-stimulatory properties. The review then discusses prospective anti-cancer therapies, including treatments with NDV alone, and combinations with an autologous NDV-modified tumor cell vaccine or with a viral oncolysate pulsed dendritic cell vaccine. Various combinatorial approaches between these and with other modalities are also reviewed.

EXPERT OPINION

Post-oncolytic anti-tumor immunity based on ICD is in the expert's opinion of greater importance for long-term therapeutic effects than maximal tumor cell killing. Of the various combinatorial approaches discussed, the most promising and feasible for clinical practice appears to be the combination of systemic NDV pre-treatment with anti-tumor vaccination.

Autologous tumor cell vaccines for post-operative active-specific immunotherapy of colorectal carcinoma: long-term patient survival and mechanism of function

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Surgery remains the primary curative treatment but nearly 50% of patients relapse as consequence of micrometastatic or minimal residual disease (MRD) at the time of surgery. Spontaneous T-cell-mediated immune responses to CRC tumor-associated antigens (TAAs) in tumor-draining lymph nodes and in the bone marrow (BM) lead to infiltration of the tumors by lymphocytes. Certain types of such tumor-infiltrating lymphocytes (TILs) have a positive and others a negative impact on the patients' prognosis. This review focuses on advances in CRC active-specific immunotherapy (ASI), in particular on results from randomized controlled clinical studies employing therapeutic autologous tumor cell vaccines. The observed improvement of long-term survival is explained by activation and mobilization of a pre-existing repertoire of tumor-reactive memory T cells which, according to recent discoveries, reside in distinct niches of patients' bone marrow in neighborhood with hematopoietic (HSC) and mesenchymal (MSC) stem cells. Interestingly, memory T cells also contain a subset of stem memory T cells (SMTs) in addition to effector (EMTs) and central memory T cells (CMTs). The mechanism of function of a therapeutic vaccine in a chronic disease is distinct from that of prophylactic vaccines which have to generate de novo protective immune responses. The advantage of autologous vaccines for mobilization of a broad and highly individual repertoire of memory T cells will be discussed.

Recombinant IFN-α2a-NGR exhibits higher inhibitory function on tumor neovessels formation compared with IFN-α2a in vivo and in vitro

We previously reported that NGR-fused IFN-α2a (IFN-α2a-NGR) exhibited similar biological activities with native IFN-α2a and was well-tolerated in mice, rats and monkeys. In the current study, we evaluated the mechanisms of this fusion protein on angiogenesis and tumor formation. Our data indicated that IFN-α2a-NGR has the ability to target tumor blood vessels while preserving the original function of native IFN-α2a. IFN-α2a-NGR was found to be concentrated in the tumor tissues, particularly around the vessel areas. In contrast to IFN-α2a, IFN-α2a-NGR significantly decreased microvessel density and increased the apoptosis of vascular endothelial cells. IFN-α2a-NGR also decreased the expression of VEGF and bFGF in tumor cells. Significant inhibition of invasion, migration, tube formation and induction of apoptosis of endothelial cells were observed in IFN-α2a-NGR-treated group. In conclusion, results from in vitro and in vivo experiments indicate that IFN-α2a-NGR is a promising anti-angiogenic agent with greater therapeutic efficacy than IFN-α2a.

Oncolytic Newcastle Disease Virus as Cutting Edge between Tumor and Host

Oncolytic viruses (OVs) replicate selectively in tumor cells and exert anti-tumor cytotoxic activity. Among them, Newcastle Disease Virus (NDV), a bird RNA virus of the paramyxovirus family, appears outstanding. Its anti-tumor effect is based on: (i) oncolytic activity and (ii) immunostimulation. Together these activities facilitate the induction of post-oncolytic adaptive immunity. We will present milestones during the last 60 years of clinical evaluation of this virus. Two main strategies of clinical application were followed using the virus (i) as a virotherapeutic agent, which is applied systemically or (ii) as an immunostimulatory agent combined with tumor cells for vaccination of cancer patients. More recently, a third strategy evolved. It combines the strategies (i) and (ii) and includes also dendritic cells (DCs). The first step involves systemic application of NDV to condition the patient. The second step involves intradermal application of a special DC vaccine pulsed with viral oncolysate. This strategy, called NDV/DC, combines anti-cancer activity (oncolytic virotherapy) and immune-stimulatory properties (oncolytic immunotherapy) with the high potential of DCs (DC therapy) to prime naive T cells. The aim of such treatment is to first prepare the cancer-bearing host for immunocompetence and then to instruct the patient's immune system with information about tumor-associated antigens (TAAs) of its own tumor together with danger signals derived from virus infection. This multimodal concept should optimize the generation of strong polyclonal T cell reactivity targeted against the patient's TAAs and lead to the establishment of a long-lasting memory T cell repertoire.

Effects of interferon-α-transduced tumor cell vaccines and blockade of programmed cell death-1 on the growth of established tumors

Interferon-alpha (IFN-α) has strong antitumor effects, and IFN-α gene therapy has been used clinically against some cancers. In this study, we evaluated the efficacy of the combination of IFN-α-transduced tumor cell vaccines and programmed cell death 1 (PD-1) blockade, and investigated the mechanisms of the antitumor effects of the combined therapy. A poorly immunogenic murine colorectal cancer cell line, MC38, was transduced to overexpress IFN-α. In a therapeutic model, parental tumor-bearing mice were inoculated with MC38-IFNα cells and an anti-PD-1 antagonistic antibody. Analyses of immunohistochemistry and tumor-specific lysis were performed. The outgrowth of the established tumors was significantly reduced in mice treated with the combination of IFN-α and anti-PD-1. Immunohistochemical analyses of the therapeutic model showed marked infiltration of CD4(+) cells and CD8(+) cells in the established MC38 tumors of mice treated with both IFN-α and anti-PD-1. Significant tumor-specific cytolysis was detected when splenocytes of mice that were treated with both IFN-α and anti-PD-1 were used as effector cells. These results suggest that blockade of the PD-1 PD-ligand enhanced the Th1-type antitumor immune responses induced by IFN-α. The combination of IFN-α gene-transduced tumor cell vaccines and PD-1 blockade may be a possible candidate for a cancer vaccine for clinical trials.

Safety and clinical usage of newcastle disease virus in cancer therapy

Newcastle disease virus (NDV) is an avian virus that causes deadly infection to over 250 species of birds, including domestic and wild-type, thus resulting in substantial losses to the poultry industry worldwide. Many reports have demonstrated the oncolytic effect of NDV towards human tumor cells. The interesting aspect of NDV is its ability to selectively replicate in cancer cells. Some of the studies have undergone human clinical trials, and favorable results were obtained. Therefore, NDV strains can be the potential therapeutic agent in cancer therapy. However, investigation on the therapeutic perspectives of NDV, especially human immunological effects, is still ongoing. This paper provides an overview of the current studies on the cytotoxic and anticancer effect of NDV via direct oncolysis effects or immune stimulation. Safety of NDV strains applied for cancer immunotherapy is also discussed in this paper.

Respiratory syncytial virus interferon antagonist NS1 protein suppresses and skews the human T lymphocyte response

We recently demonstrated that the respiratory syncytial virus (RSV) NS1 protein, an antagonist of host type I interferon (IFN-I) production and signaling, has a suppressive effect on the maturation of human dendritic cells (DC) that was only partly dependent on released IFN-I. Here we investigated whether NS1 affects the ability of DC to activate CD8+ and CD4+ T cells. Human DC were infected with RSV deletion mutants lacking the NS1 and/or NS2 genes and assayed for the ability to activate autologous T cells in vitro, which were analyzed by multi-color flow cytometry. Deletion of the NS1, but not NS2, protein resulted in three major effects: (i) an increased activation and proliferation of CD8+ T cells that express CD103, a tissue homing integrin that directs CD8+ T cells to mucosal epithelial cells of the respiratory tract and triggers cytolytic activity; (ii) an increased activation and proliferation of Th17 cells, which have recently been shown to have anti-viral effects and also indirectly attract neutrophils; and (iii) decreased activation of IL-4-producing CD4+ T cells--which are associated with enhanced RSV disease--and reduced proliferation of total CD4+ T cells. Except for total CD4+ T cell proliferation, none of the T cell effects appeared to be due to increased IFN-I signaling. In the infected DC, deletion of the NS1 and NS2 genes strongly up-regulated the expression of cytokines and other molecules involved in DC maturation. This was partly IFN-I-independent, and thus might account for the T cell effects. Taken together, these data demonstrate that the NS1 protein suppresses proliferation and activation of two of the protective cell populations (CD103+ CD8+ T cells and Th17 cells), and promotes proliferation and activation of Th2 cells that can enhance RSV disease.

Antitumor vaccination by Newcastle Disease Virus Hemagglutinin-Neuraminidase plasmid DNA application: changes in tumor microenvironment and activation of innate anti-tumor immunity

A plasmid encoding the Hemagglutinin-Neuraminidase (HN) protein of Newcastle Disease Virus (pHN) was tested for its capacity to stimulate innate anti-tumor activity in tumor-bearing mice. We observed that application of the pHN plasmid at the ear pinna site (i.e.) of mice induces higher levels of systemic interferon-α and reduced tumor growth in the prophylactic mammary carcinoma DA3 tumor model in comparison to application of a control plasmid not encoding the HN protein. Analysis of the tumor microenvironment revealed a significant increase in NK cell infiltration and decrease in infiltration of CD11b(+)Gr-1(high) myeloid cells bearing the myeloid-derived suppressor cell (MDSC) phenotype after vaccination with the pHN DNA compared to a control DNA. Finally, innate immunity and partially type I IFN responses were proved important for the reduction of s.c. RMA-S tumor growth after pHN vaccination, as shown with the use of RAG2(-/-) and RAG2(-/-)IFNAR1(-/-) mice. These data demonstrate that triggering innate immunity by pHN application at the ear pinna of mice modulates the immune cell compartment in the tumor microenvironment and reduces tumor growth. This highlights thus the potential adjuvant activity of the HN gene in tumor therapy.

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.

Genetic associations in type I interferon related pathways with autoimmunity

Type I interferons play an outstanding role in innate and adaptive immunity by enhancing functions of dendritic cells, inducing differentiation of monocytes, promoting immunoglobulin class switching in B cells and stimulating effector functions of T cells. The increased production of IFNα/β by plasmacytoid dendritic cells could be responsible for not only efficient antiviral defence, but it also may be a pathological factor in the development of various autoimmune disorders. The first evidence of a genetic link between type I interferons and autoimmune diseases was the observation that elevated IFNα activity is frequently detected in the sera of patients with systemic lupus erythematosus, and that this trait shows high heritability and familial aggregation in their first-degree healthy relatives. To date, a number of genes involved in interferon signalling have been associated with various autoimmune diseases. Patients with systemic lupus erythematosus, Sjögren's syndrome, dermatomyositis, psoriasis, and a fraction of patients with rheumatoid arthritis display a specific expression pattern of interferon-dependent genes in their leukocytes, termed the interferon signature. Here, in an attempt to understand the role of type I interferons in the pathogenesis of autoimmunity, we review the recent advances in the genetics of autoimmune diseases focusing on the association of genes involved in type I interferon pathways.

Newcastle disease virus: a promising vector for viral therapy, immune therapy, and gene therapy of cancer

This review deals with the avian paramyxovirus Newcastle disease virus (NDV) and describes properties that explain its oncolytic activity, its tumor-selective replication behavior, and its immune-stimulatory capacity with human cells. The strong interferon response of normal cells upon contact with NDV appears to be the basis for the good tolerability of the virus in cancer patients and for its immune stimulatory properties, whereas the weak interferon response of tumor cells explains the tumor selectivity of replication and oncolysis. Various concepts for the use of this virus for cancer treatment are pointed out and results from clinical studies are summarized. Reverse genetics technology has made it possible recently to clone the genome and to introduce new foreign genes thus generating new recombinant viruses. These can, in the future, be used to transfer new therapeutic genes into tumors and also to immunize against new emerging pathogens. The modular nature of gene transcription, the undetectable rate of recombination, and the lack of a DNA phase in the replication cycle make NDV a suitable candidate for the rational design of a safe and stable vaccine and gene therapy vector.

Dendritic cells stimulated with cytidine-phosphate-guanosine oligodeoxynucleotides and interferon-alpha-expressing tumor cells effectively reduce outgrowth of established tumors in vivo

Dendritic cells (DC) are potent antigen-presenting cells that elicit immune responses to foreign antigens. We have previously demonstrated the synergistic effects of cytidine-phosphate-guanosine (CpG) oligodeoxynucleotides (ODN) and interferon (IFN)-alpha on DC maturation in vitro. In the present study, the antitumor effects of DC preincubated with IFN-alpha gene-overexpressing murine colorectal cancer MC38 cells (MC38-IFN-alpha) and CpG ODN were evaluated in a poorly immunogenic murine cancer system. When we injected DC preincubated with MC38-IFNalpha and CpG ODN subcutaneously to mice bearing MC38 wild-type tumors, the outgrowth of the established parental tumors was suppressed significantly compared with that following administration of DC with MC38-IFN-alpha (P = 0.008). All mice injected with DC preincubated with MC38-IFN-alpha and CpG ODN rejected a subsequent parental tumor challenge. Immunohistochemical and flow cytometric analyses showed that CD4(+), CD8(+), and NK1.1(+) cells markedly infiltrated the established tumors of mice treated with DC preincubated with MC38-IFN-alpha and CpG ODN. From the results in immune cell-depleted mice, CD4(+) and asialo-GM-1(+) cells seemed to contribute to the antitumor effects induced by the combination DC therapy. Furthermore, non-specific cytolysis was detected when splenocytes of mice inoculated with DC preincubated with MC38-IFNalpha and CpG ODN were used as effector cells. Using an interleukin (IL)-12-neutralizing antibody it was suggested that IL-12 stimulates natural killer cells and contributes in part to the antitumor effects induced by DC incubated with CpG ODN and IFN-alpha. As DC-based immunotherapy with CpG ODN and IFN-alpha-expressing tumor cells induces a potent antitumor immune response, it should be considered for clinical application.

Dendritic cell therapy with interferon-alpha synergistically suppresses outgrowth of established tumors in a murine colorectal cancer model

Both dendritic cell (DC)-based immunotherapy and interferon (IFN)-alpha therapy have been proved to have potent long-lasting antitumor effects. In anticipation of synergistic antitumor effects, we performed combination therapy with DCs and IFN-alpha gene-transduced murine colorectal cancer MC38 cells (MC38-IFN-alpha). DCs incubated with MC38-IFN-alpha, but not neomycin-resistance gene-transduced MC38 cells (MC38-Neo), effectively enhanced proliferation of allogeneic splenocytes in vitro. In 12 of 17 mice, DCs in combination with MC38-IFN-alpha prevented the development of a parental tumor, while DCs and MC38-Neo did in only three of 17 mice (P=0.008). In a therapeutic model of an established parental tumor, inoculation of DCs and MC38-IFN-alpha suppressed the growth of the established parental tumors significantly compared with the administration of DCs with MC38-Neo or naive splenocytes with MC38-IFN-alpha (P=0.016 and 0.024, respectively). Analyses of immunohistochemistry and tumor-infiltrating mononuclear cells showed that CD8(+), CD11c(+), and NK1.1(+) cells markedly infiltrated the established tumors of mice treated with DCs and MC38-IFN-alpha. From the results of observation of parental tumor outgrowth in immune cell-depleted mice, CD8(+) cells, and asialo-GM-1(+) cells were thought to contribute to the antitumor effects induced by the combination therapy. Furthermore, MC38-specific cytolysis was detected when splenocytes of mice inoculated with DCs and MC38-IFN-alpha cells were stimulated with MC38-IFN-alpha cells in vitro. Since DC-based immunotherapy in combination with IFN-alpha-expressing tumor cells induces potent antitumor cellular immune responses, it should be considered for clinical application.

Cutting Edge: Enhancement of Antibody Responses Through Direct Stimulation of B and T Cells by Type I IFN

Type I IFN (IFN-alphabeta) is induced rapidly by infection and plays a key role in innate antiviral defense. IFN-alphabeta also exerts stimulatory effects on the adaptive immune system and has been shown to enhance Ab and T cell responses. We have investigated the importance of B and T cells as direct targets of IFN-alphabeta during IFN-alpha-mediated augmentation of the Ab response against a soluble protein Ag. Strikingly, the ability of IFN-alpha to stimulate the Ab response and induce isotype switching was markedly reduced in mice in which B cells were selectively deficient for the IFN-alphabetaR. Moreover, IFN-alpha-mediated enhancement of the Ab response was also greatly impaired in mice in which T cells were selectively IFN-alphabetaR-deficient. These results indicate that IFN-alphabetaR signaling in both B and T cells plays an important role in the stimulation of Ab responses by IFN-alphabeta.

Intradermal injection of Newcastle disease virus-modified autologous melanoma cell lysate and interleukin-2 for adjuvant treatment of melanoma patients with resectable stage III disease

BACKGROUND

The value of active specific immunotherapy (ASI) for the treatment of solid tumours still has to be assessed. The objective was to test an autologous tumour cell vaccine for adjuvant treatment of stage III melanoma patients.

PATIENTS AND METHODS

After open vaccination of 12 patients, another 17 patients were recruited for a randomized double-blind trial comparing treatment with the vaccine (n = 9) and with a placebo (n = 8). Intracutaneous vaccinations were given postoperatively in weeks 2, 4, 6, 12, 24 and thereafter every 6 months if sufficient vaccine material was available. Patients were followed for 60-84 months.

RESULTS

Median disease-free survival time was 5 months for open-treated, 4 months for verum-treated and 6 months for placebo-treated patients. Corresponding median overall survival times were 30.5, 18 and 18.5 months, respectively. There were no remarkable differences between the verum and the placebo group.

CONCLUSIONS

Adjuvant treatment of melanoma patients with an autologous ASI vaccine did not show clinical efficacy in this cohort of melanoma patients.

T-cell triggering by CD3- and CD28-binding molecules linked to a human virus-modified tumor cell vaccine

The aim was to develop T cell costimulatory molecules that are broadly applicable to augment anti-tumor immune responses upon application of a virus-modified tumor vaccine to cancer patients. We generated recombinant bispecific single-chain antibodies with one specificity directed against the CD3 or the CD28 antigen on human T cells and the other against the viral target molecule hemagglutinin-neuraminidase (HN) of Newcastle Disease Virus (NDV). By re-directing unstimulated primary human T cells against HN-expressing NDV-infected tumor cells, the bispecific molecule bsHN-CD3 cross-linked effector and target cells and rapidly induced cytotoxicity at nanomolar concentrations. The bsHN-CD28 molecule exerted T cell co-stimulatory function. Maximal T cell activation was achieved with tumor cells infected by NDV and modified with both new stimulatory molecules. This was revealed by T cell proliferation, upregulation of CD69 and CD25 and by release of cytokines, interferons and chemokines. The new molecules combine high-effectivity with specificity and safety.

Antitumor vaccination in patients with head and neck squamous cell carcinomas with autologous virus-modified tumor cells

Prognosis of patients with advanced head and neck squamous cell carcinomas (HNSCC) is still poor. Therefore, we analyzed whether antitumor vaccination with a virus-modified autologous tumor cell vaccine is feasible and safe in HNSCC patients. Furthermore, we determined the influence on disease-free survival and overall survival and the vaccination-induced antitumor reactivity. In a nonrandomized pilot study, 20 patients were vaccinated postoperatively. Vaccine was prepared from the tumor cell cultures of patients by infection of the cells with Newcastle Disease Virus, followed by gamma-irradiation, and vaccine was applied up to five times. Antitumor immune reactivity was determined in the skin by delayed type hypersensitivity skin reaction and in the blood by enzyme-linked immunospot assay. Establishment of tumor cell cultures was successful in about 80% of the cases. After vaccination, we observed no severe side effects. Percentages of survival of vaccinated patients with stage III and stage IV tumors (n = 18) were 61% at 5 years. Immune monitoring revealed significant increases of antitumor delayed type hypersensitivity reactivity especially in disease-free patients, and in a significant proportion of vaccinated patients the presence of tumor-reactive T-cells in the peripheral blood even 5 to 7 years after the last vaccination. Postoperative vaccination with virus-modified autologous tumor cells seems to be feasible and safe and may improve the prognosis of HNSCC patients with advanced tumors. This could be supported by antitumor immune responses that we observed especially in long-term surviving patients.

Antitumor vaccination of patients with glioblastoma multiforme: a pilot study to assess feasibility, safety, and clinical benefit

PURPOSE

Prognosis of patients with glioblastoma is poor. Therefore, in glioblastoma patients, we analyzed whether antitumor vaccination with a virus-modified autologous tumor cell vaccine is feasible and safe. Also, we determined the influence on progression-free survival and overall survival and on vaccination-induced antitumor reactivity.

PATIENTS AND METHODS

In a nonrandomized study, 23 patients were vaccinated and compared with nonvaccinated controls (n = 87). Vaccine was prepared from patient's tumor cell cultures by infection of the cells with Newcastle Disease Virus, followed by gamma-irradiation, and applied up to eight times. Antitumor immune reactivity was determined in skin, blood, and relapsed tumor by delayed-type hypersensitivity skin reaction, ELISPOT assay, and immunohistochemistry, respectively.

RESULTS

Establishment of tumor cell cultures was successful in approximately 90% of patients. After vaccination, we observed no severe side effects. The median progression-free survival of vaccinated patients was 40 weeks (v 26 weeks in controls; log-rank test, P = .024), and the median overall survival of vaccinated patients was 100 weeks (v 49 weeks in controls; log-rank test, P < .001). Forty-five percent of the controls survived 1 year, 11% survived 2 years, and there were no long-term survivors (> or = 3 years). Ninety-one percent of vaccinated patients survived 1 year, 39% survived 2 years, and 4% were long-term survivors. In the vaccinated group, immune monitoring revealed significant increases of delayed-type hypersensitivity reactivity, numbers of tumor-reactive memory T cells, and numbers of CD8(+) tumor-infiltrating T-lymphocytes in secondary tumors.

CONCLUSION

Postoperative vaccination with virus-modified autologous tumor cells seems to be feasible and safe and to improve the prognosis of patients with glioblastomas. This could be substantiated by the observed antitumor immune response.

Cross-priming of CD8+ T cells stimulated by virus-induced type I interferon

CD8+ T cell responses can be generated against antigens that are not expressed directly within antigen-presenting cells (APCs), through a process known as cross-priming. To initiate cross-priming, APCs must both capture extracellular antigen and receive specific activation signals. We have investigated the nature of APC activation signals associated with virus infection that stimulate cross-priming. We show that infection with lymphocytic choriomeningitis virus induces cross-priming by a mechanism dependent on type I interferon (IFN-alpha/beta). Activation of cross-priming by IFN-alpha/beta was independent of CD4+ T cell help or interaction of CD40 and CD40 ligand, and involved direct stimulation of dendritic cells. These data identify expression of IFN-alpha/beta as a mechanism for the induction of cross-priming during virus infections.

Interferon-alpha and interleukin-12 gene therapy of cancer: interferon-alpha induces tumor-specific immune responses while interleukin-12 stimulates non-specific killing

Cytokine gene therapy is applied in clinical studies of tumors, and IFN-alpha and IL-12 are widely used for cancer immunotherapy. Using a poorly immunogenic murine colorectal cancer cell line, MC38, we compared antitumor effects of IFN-alpha and IL-12. Transduced MC38 cell lines expressing IFN-alpha or IL-12 (MC38-IFNalpha or MC38-IL12, respectively) were established using retroviral vectors. Transduction of IFN-alpha or IL-12 gene to MC38 cells significantly reduced tumorigenicity in immunocompetent mice. When tumor-free mice initially injected with MC38-IFNalpha or MC38-IL12 cells were reinjected contralaterally with wild-type MC38 cells (MC38-WT) after 35 days, 7 of 12 or 2 of 12 mice rejected MC38-WT cells, respectively. In therapy-model mice with established tumor derived from MC38-WT cells, inoculation of gene-transduced cells significantly suppressed growth of the tumor in MC38-IFNalpha-inoculated groups, but not in the IL-12-inoculated group. Immunohistologic and flow cytometric analyses showed marked infiltration of CD8(+) cells in wild-type tumors of mice inoculated with IFN-alpha-expressing cells. Leukocyte-depletion experiments implicated CD8(+) T cells in tumor rejection induced by IFN-alpha-transduction; both CD8(+) T cells and natural killer cells were implicated in the more modest antitumor effect from IL-12 expression. To investigate induction of tumor-specific immune responses, we stimulated splenocytes from tumor-free mice twice in vitro with genetically modified MC38 cells. In vitro stimulations with MC38-IFNalpha cells induced definite MC38-specific lysis, but not stimulations with MC38-IL-12 cells. Injecting combination of MC38-IFNalpha and MC38-IL-12 cells caused an additive antitumor effect in the therapy model. These data suggested that IFN-alpha induces cytotoxic T lymphocytes and elicits long-lasting tumor-specific immunity, whereas IL-12 seems to stimulate non-specific killing. With additional refinements, combined IFN-alpha and IL-12 gene therapy might warrant clinical trials.

CD4+ T helper cell-independent antitumor response mediated by murine IFN-beta gene delivery in immunocompetent mice

Previously, we provided evidence that adenovirus-mediated interferon-beta (IFN-beta) gene therapy inhibits tumor formation and causes dramatic regression of established tumors in immunodeficient mice. We suggested that local IFN-beta gene therapy with adenoviral vectors could be an effective treatment for cancer. In this report, the actions of murine IFN-beta (MuIFN-beta) gene delivery on both subcutaneous and metastatic tumors were evaluated in syngeneic immunocompetent mice. We found that the antitumor response mediated by MuIFN-beta gene delivery relied on CD8(+) T cells but was completely independent of CD4(+) T cells. In fact, depletion of CD4(+) T cells appeared to enhance the effect on tumor inhibition and animal survival induced by adenovirus-MuIFN-beta gene delivery. Therefore, adenovirus-MuIFN-beta gene therapy can bypass CD4(+) T helper (Th) cells and activate an effective CD8(+) T cell-dependent antitumor immunity in immunocompetent mice. Furthermore, we found that depletion of macrophages but not natural killer (NK) cells suppressed the antitumor response induced by MuIFN-beta gene therapy. These data, together with our previous results, suggest that in the clinical setting, local adenovirus-mediated IFN-beta gene therapy may lead to an efficient and long-lasting eradication of tumors by a direct antitumor effect and via activation of the innate and the adoptive immune systems.

Preliminary results of active specific immunization with modified tumor cell vaccine in glioblastoma multiforme

OBJECT

Treatment for glioblastoma multiforme has failed to show any progress for decades. While specific immunization with tumor cells modified with Newcastle-Disease-Virus (NDV) has been reported successful in some extracerebral tumors, its effect on glioblastoma is unknown. We report on 11 patients, in whom this approach was analyzed.

METHODS

A vaccine was produced from autologous tumor cell cultures of 11 patients with glioblastoma. After completed surgery and radiotherapy an intracutaneous vaccination was performed 4 times with a 2 week interval and finally after 3 months. Local reactions, general side effects and survival were monitored closely.

RESULTS

The local reaction of the skin after injection of vaccine increased from 1.67 to 4.05 cm2 in 8 weeks. The skin reaction after parallel injection of inactivated, untreated tumor cells increased from 0.11 to 1.09 cm2. The median survival was 46 weeks (mean 60 weeks). No side effects were noted.

CONCLUSION

Active specific immunization with NDV-modified glioblastoma cells produced a noticeable peripheral immune response. In this preliminary series survival of patients was not significantly longer after active specific immunization than after combined treatment of surgery, radiotherapy and chemotherapy. As there were no side effects, however, active specific immunization may be considered an alternative in the management of glioblastoma.

IFN-alpha-expressing tumor cells enhance generation and promote survival of tumor-specific CTLs

IFN-alpha gene therapy has been successfully applied in several tumor models. Our studies involving the murine colorectal adenocarcinoma cell line MC38 confirm that IFN-alpha transduction of a poorly immunogenic tumor cell reduces tumorigenicity and leads to long-lasting tumor immunity. To investigate the effect of IFN-alpha transduction on the development of antitumor immune responses, we restimulated splenocytes from MC38-immune mice in vitro. Detection of MC38-specific cytotoxicity was markedly enhanced when murine IFN-alpha2-transduced MC38 (MC38-IFNalpha) or CD80-transduced MC38 (MC38-CD80) was used for restimulation compared with wild type (MC38-WT) or neomycin resistance gene-transduced MC38 (MC38-Neo) cells. MC38-specific CD8+ CTL line and clone were established from splenocytes of mouse immunized with MC38-IFNalpha. Stimulation with MC38-IFNalpha as well as MC38-CD80 enhanced the proliferation of MC38-specific CTLs in vitro much more effectively than stimulation with WT or MC38-Neo (p < 0.05). Coincubation of MC38-specific CTLs with MC38-IFNalpha or MC38-CD80 resulted in significantly less DNA fragmentation (8.0% and 12.8%, respectively) compared with coincubation of the CTLs with MC38-WT (43.5%; p < 0.001) or MC38-Neo cells (38.1%; p < 0.003). These results suggest that prevention of apoptotic cell death in tumor-specific CTLs may be one mechanism by which IFN-alpha-expressing tumor cells can promote the generation of antitumor immunity. The effect of IFN-alpha on CTLs appears to be similar to that of CD80, which also prevents apoptotic cell death after stimulation of T lymphocytes.

Cancer vaccines with emphasis on a viral oncolysate melanoma vaccine

Biotherapy of malignant diseases has become the fourth treatment modality besides surgery, chemo- and radiotherapy. Whole cell melanoma vaccines with or without BCG and other adjuvants, purified ganglioside and shed antigens, recombinant viruses carrying tumor antigens, dendritic cells pulsed with antigenic peptides etc. are in clinical trials. Efficacious viral oncolysate vaccines induce the host to mount tumor-specific cytotoxic T-cell response and prevention of relapses is supported by clinical trials. The use of "polyvalent" whole cell vaccines vs. purified or genetically engineered single antigen vaccines is justified as i. only very few single tumor antigens are present in all tumors of a given histological type; and ii. antigen modulation occurs in tumors rendering them resistant to immune attack generated by vaccine against a single antigen. Thus polyvalent vaccines immunize against several antigens vs. against a selected antigen.

Human tumor cell modification by virus infection: an efficient and safe way to produce cancer vaccine with pleiotropic immune stimulatory properties when using Newcastle disease virus

Direct infection of tumor cells with viruses transferring protective or therapeutic genes, a frequently used procedure for production of tumor vaccines in human gene therapy, is an approach which is often limited by the number of tumor cells that can reliably be infected as well as by issues of selectivity and safety. We report an efficient, selective and safe way of infecting human tumor cells with a natural virus with interesting pleiotropic immune stimulatory properties, the avian paramyxovirus Newcastle disease virus (NDV). Two of the six viral genes (HN and F) modify the tumor cell surface by introduction of new adhesion molecules for lymphocyte interactions and other viral genes stimulate host cell genes and local production of cytokines and chemokines which can recruit a broad antitumor response in vivo. A large variety of human tumor cells is shown to be efficiently infected by NDV with viral replication being independent of tumor cell proliferation. Such properties make NDV a suitable agent for modification of noncultured freshly isolated and gamma-irradiated patient-derived tumor cells. For the apathogenic non-lytic strain NDV-Ulster which is used in our clinical vaccine trials, we demonstrate selective replication in tumor cells as compared with corresponding normal cells. Furthermore, we present evidence that new virions produced by infected tumor cells are non-infectious using three different quantitative test methods. Our results demonstrate feasibility and broad applicability of this strategy of human tumor vaccine modification. Post-operative vaccination with the autologous virus-modified vaccine ATV-NDV thus provides a reasonable potential for pleiotropic modifications of the immune response of cancer patients against their own tumor.

Interferon alpha and Tat involvement in the immunosuppression of uninfected T cells and C-C chemokine decline in AIDS

HIV type 1 (HIV-1) not only directly kills infected CD4(+) T cells but also induces immunosuppression of uninfected T cells. Two immunosuppressive proteins, interferon alpha (IFNalpha) and extracellular Tat, mediate this process because specific antibodies against these proteins prevent generation of suppressor cells in HIV-1-infected peripheral blood mononuclear cell cultures. Furthermore, the production of C-C chemokines in response to immune cell activation, initially enhanced by IFNalpha and Tat, ultimately is inhibited by these proteins in parallel with their induction of immunosuppression. The clinical corollary is the immunosuppression of uninfected T cells and the decline in C-C chemokine release found at advanced stages of HIV-1 infection paralleling rising levels of IFNalpha and extracellular Tat. We, therefore, suggest that IFNalpha and Tat may be critical targets for anti-AIDS strategies.

Anti-cytokine autoantibodies: epiphenomenon or critical modulators of cytokine action

Low amounts of high-affinity autoantibodies to various cytokines have been detected in sera from healthy donors. Their levels, although highly variable, are increased in the circulation of patients subjected to cytokine therapy or suffering from a variety of immunoinflammatory diseases. It has been suggested that these autoantibodies play a regulatory role in the intensity and duration of an immune response. The antibodies may prevent the binding of a cytokine to its specific cell surface receptor thereby neutralizing its biological activity in vivo. They may also act as carrier proteins preventing the rapid elimination of a cytokine from the circulation and thus increase its bioactivity. Additionally or alternatively, autoantibodies may modulate cytokine-induced intracellular signal transduction pathways or trigger complement-mediated cytotoxicity towards cells carrying membrane-bound cytokines. The autoantibodies may exert their regulatory role in compliance with the other factors that control cytokine activity, including soluble cytokine receptors, cell surface decoy receptors, and receptor antagonists. Although not favored by many investigators, a less sophisticated role for naturally occurring anti-cytokine autoantibodies should be considered as well. Recent evidence has shown that autoantibodies are generated at a high frequency as part of a response to foreign antigens. These antibodies are produced by B cells arising from the process of somatic mutation. Thus anti-cytokine autoantibodies may be the result of a "leaky" B cell response triggered by immunoinflammatory processes. High-titered autoantibodies induced by cytokine therapy are of clinical concern since their occurrence is often associated with the loss of response to treatment. Moreover, they may also neutralize endogenously produced cytokines with possible pathological consequences. In this paper we have reviewed the available information on the biological and clinical significance of both naturally occurring and therapeutically induced anti-cytokine autoantibodies in animals and man with the emphasis on antibodies directed to interferons.

The neglected role of type I interferon in the T-cell response: implications for its clinical use

Originally described as an antiviral substance, type I interferon (IFN) was subsequently shown to exert multiple biological effects and is now the most frequently used cytokine in the treatment of some viral and neoplastic diseases. Although early studies described various effects on the immune system, the role of type I IFN as an immunoregulatory molecule has long been neglected. Here, Filippo Belardelli and Ion Gresser summarize recent experimental results on the interactions of type I IFN with T cells, which may prove important in its use in patients.

Preferential cytotoxic effect of Newcastle disease virus on lymphoma cells

Susceptibility of lymphoma cells (Daudi, HD-Mar) to Newcastle disease virus toxicity was found to be higher than that of lymphoblastoid cells (Milstein) and of resting peripheral blood lymphocyte (PBL). Phytohemagglutinin- and/or pokeweed-mitogen-activated PBL however, exhibited, elevated sensitivity, similar to that of lymphoma cells. The level of cytotoxicity was monitored by cell viability, inhibition of DNA synthesis and release of 51Cr. When Daudi cells were mixed with PBL they were significantly more sensitive to the killing effect of the virus (70% mortality compared to 30% 30 h after infection, P < 0.05). The degree of sensitivity to viral cytotoxicity was unrelated to the efficacy of adsorption, which was similar for all cell lines as shown by immunofluorescent staining and flow cytometry. Also an influenza strain A/PR/8/34 (H1N1) adsorbed but did not affect the viability of any of the cells tested. Our results demonstrate that New-castle disease virus caused preferential damage to lymphoma cells as compared to non-cancerous normal cells.

The essential role of endogenous IFN alpha/beta in the anti-metastatic action of sensitized T lymphocytes in mice injected with Friend erythroleukemia cells

Adoptive transfer of splenic T lymphocytes from DBA/2 mice immunized against Friend erythroleukemia cells (FLC) inhibited the development of visceral metastases and increased the survival time of DBA/2 mice challenged i.v. with parental FLC 24 hr to 2 months later. Immune spleen cells were ineffective in mice pre-treated with potent neutralizing antibody to mouse IFN alpha/beta (but not to IFN gamma), demonstrating the essential participation of endogenous IFN alpha/beta in the inhibitory action of immune T lymphocytes against FLC metastases. These findings suggest that the reported inability of immune T lymphocytes to exert an anti-FLC effect in immunodeficient DBA/2 mutant beige (bg/bg) mice (unless these mice had also been treated with IFN alpha/beta), may have been due to lower levels of endogenous IFN alpha/beta in DBA/2 bg/bg mice than in normal DBA/2+/bg mice. Experimental results in support of this hypothesis are presented.

Synergistic role of type I interferons in the induction of protective cytotoxic T lymphocytes

Differentiation of cytolytic T cells can be supported by type I and type II interferons (IFN). To characterize the role of type I interferons further we tested the role of recombinant IFN-alpha and IFN-beta on the induction of a weak immune response, against a low immunogenic tumor, which has been shown to be increased by IFN. Both type I interferons IFN-alpha and IFN-beta were able to support the differentiation of cytolytic T lymphocytes (CTL). In case of IFN-alpha no correlation with the antiviral activity could be seen by comparison of IFN-alpha1 and IFN-alpha4. The maximal in vitro effects were achieved with very low concentrations in the range of 1-100 IU/ml. IFN-alpha showed the strongest effects, if added in the early phase of the mixed leukocyte culture, whereas IFN-beta was most effective when given at the last day the culture. In combination, both IFNs gave additional/synergistic effects, whereby addition of IFN-alpha at day 0 and IFN-beta at day 4 led to maximal specific CTL responses. In vivo augmentation of the anti-tumor immune response by both types of IFNs supported the in vitro findings and also the synergistic effect of both types of IFNs could be demonstrated. Therefore we propose that IFN-alpha is relevant in the induction of CTL responses, i.e., the conversion of precursor T cell into mature cells and growth promotion whereby IFN-beta might trigger the lytic machinery of the cells and promote differentiation. This synergistic efficacy is also operative in tumor rejection.

Biotherapy of cancer. Perspectives of immunotherapy and gene therapy

Prospects for a new biologically based strategy of cancer treatment are being discussed. While physically and chemically based therapies, such as radio- and chemotherapy, are not directed against cancer tissue only and have a suppressive effect on the immune system, immunotherapy and gene therapy, which are discussed here, try to be more selective and to stimulate rather than suppress antitumor immune mechanisms. On the basis of personal experience with these new technologies, good future prospects are predicted for the application of cancer vaccines and immune T lymphocytes for active specific immunization (ASI) and adoptive immunotherapy (ADI) respectively. While ASI strategies aim at micrometastases being affected by activated host immune T cells, and might find a place for postoperative adjuvant treatment in high-risk cancer patients, cellular therapies such as ADI do not require an intact host immune system and could therefore also find application in advanced stages of disease. In spite of the exciting new perspectives of immuno- and gene therapy for the cancer patient, this therapy is not yet a defined discipline and requires years of further research.

Effective anti-metastatic melanoma vaccination with tumor cells transfected with MHC genes and/or infected with Newcastle disease virus (NDV)

The therapeutic efficacy of active immunization with B16-F10.9 melanoma cells transfected with syngeneic major histocompatibility complex (MHC) class-I genes, modified by infection with Newcastle Disease virus (NDV) or modified by both treatments, was compared. B16-F10.9 tumor-bearing mice were treated at various stages of tumor growth and metastasis with irradiated, modified tumor-cell vaccines. Irradiated tumor cells and H-2Db transfectants did not stimulate anti-tumor immunity while H-2Kb transfectants and NDV-modified F10.9 cells showing low and high expression of MHC class-I genes efficiently prevented metastasis of small established tumors. NDV-modified parental-cell vaccines functioned optimally and improved overall survival by about 60%, also at early stages of metastasis establishment. A synergistic effect of H-2Kb expression and virus modification on rejection of micrometastases was observed in mice bearing advanced tumors. Postoperative vaccination of mice carrying multiple metastases with NDV-modified vaccines caused significant, but incomplete, reduction of metastatic tumor load. The therapeutic effect of NDV-modified tumor vaccines was dependent on multiple immune mechanisms. Depletion of CD8, CD4 or NK cells by in vivo treatment with monoclonal antibodies reversed the immunotherapeutic effects of the vaccine. Thus, tumor xenogenization and gene modification may act synergistically to vaccinate against advanced tumors, while single modalities can effectively vaccinate against metastasis at early stages of tumor growth.