Viral oncolysate in the management of malignant melanoma. I. Preparation of the oncolysate and measurement of immunologic responses

Engineering Non-Human RNA Viruses for Cancer Therapy

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

Emerging Nano-/Biotechnology Drives Oncolytic Virus-Activated and Combined Cancer Immunotherapy

Oncolytic viruses (OVs) as one promising antitumor methods have made important contributions to tumor immunotherapy, which arouse increasing attention. They provide the dual mechanisms including direct killing effect toward tumor cells and immune activation for elevating antitumor responses, which have been proved in many preclinical studies. Especially, natural or genetically modified viruses as clinical immune preparations have emerged as a new promising approach objective to oncology treatment. The approval of talimogene laherparepvec (T-VEC) by the U.S. Food and Drug Administration (FDA) for the therapy of advanced melanoma could be considered as a milestone achievement in the clinical translation of OV. In this review, we first discussed the antitumor mechanisms of OVs with an emphasis on targeting, replication, and propagation. We further outlined the state of the art of current OVs in tumor and underlined the activated biological effects especially including immunity. More significantly, the enhanced immune responses based on OVs were systematically discussed from different perspectives such as combination with immunotherapy, genetic engineering of OVs, integration with nanobiotechnology or nanoparticles, and antiviral response counteraction, where their principles were shed light on. The development of OVs in the clinics was also highlighted to analyze the actuality and concerns of different OV applications in clinical trials. At last, the future perspectives and challenges of OVs as an already widely accepted treatment means were discussed. This review will provide a systematic review and deep insight into OV development and also offer new opportunities and guidance pathways to drive the further clinical translation.

Newcastle Disease Virus at the Forefront of Cancer Immunotherapy

Preclinical and clinical studies dating back to the 1950s have demonstrated that Newcastle disease virus (NDV) has oncolytic properties and can potently stimulate antitumor immune responses. NDV selectively infects, replicates within, and lyses cancer cells by exploiting defective antiviral defenses in cancer cells. Inflammation within the tumor microenvironment in response to NDV leads to the recruitment of innate and adaptive immune effector cells, presentation of tumor antigens, and induction of immune checkpoints. In animal models, intratumoral injection of NDV results in T cell infiltration of both local and distant non-injected tumors, demonstrating the potential of NDV to activate systemic adaptive antitumor immunity. The combination of intratumoral NDV with systemic immune checkpoint blockade leads to regression of both injected and distant tumors, an effect further potentiated by introduction of immunomodulatory transgenes into the viral genome. Clinical trials with naturally occurring NDV administered intravenously demonstrated durable responses across numerous cancer types. Based on these studies, further exploration of NDV is warranted, and clinical studies using recombinant NDV in combination with immune checkpoint blockade have been initiated.

Recent advances of oncolytic virus in cancer therapy

Oncolytic viruses have been taking the front stage in biological therapy for cancer recently. The first and most potent virus to be used in oncolytic virotherapy is human adenovirus. Recently, ongoing extensive research has suggested that other viruses like herpes simplex virus (HSV) and measles virus can also be considered as potential candidates in cancer therapy. An HSV-based oncolytic virus, T-VEC, has completed phase Ш clinical trial and has been approved by the U.S. Food and Drug Administration (FDA) for use in biological cancer therapy. Moreover, the vaccine strain of the measles virus has shown impressive results in pre-clinical and clinical trials. Considering their therapeutic efficacy, safety, and reduced side effects, the use of such engineered viruses in biological cancer therapy has the potential to establish a milestone in cancer research. In this review, we summarize the recent clinical advances in the use of oncolytic viruses in biological therapy for cancer. Additionally, this review evaluates the potential viral candidates for their benefits and shortcomings and sheds light on the future prospects.

Therapeutic vaccination immunomodulation: forming the basis of all cancer immunotherapy

Recent immunotherapy advances have convincingly demonstrated complete tumour removal with long-term survival. These impressive clinical responses have rekindled enthusiasm towards immunotherapy and tumour antigen vaccination providing 'cures' for melanoma and other cancers. However, many patients still do not benefit; sometimes harmed by severe autoimmune toxicity. Checkpoint inhibitors (anti-CTLA4; anti-PD-1) and interleukin-2 (IL-2) are 'pure immune drivers' of pre-existing immune responses and can induce either desirable effector-stimulatory or undesirable inhibitory-regulatory responses. Why some patients respond well, while others do not, is presently unknown, but might be related to the cellular populations being 'driven' at the time of dosing, dictating the resulting immune response. Vaccination is in-vivo immunotherapy requiring an active host response. Vaccination for cancer treatment has been skeptically viewed, arising partially from difficulty demonstrating clear, consistent clinical responses. However, this article puts forward accumulating evidence that 'vaccination' immunomodulation constitutes the fundamental, central, intrinsic property associated with antigen exposure not only from exogenous antigen (allogeneic or autologous) administration, but also from endogenous release of tumour antigen (autologous) from in-vivo tumour-cell damage and lysis. Many 'standard' cancer therapies (chemotherapy, radiotherapy etc.) create waves of tumour-cell damage, lysis and antigen release, thus constituting 'in-vivo vaccination' events. In essence, whenever tumour cells are killed, antigen release can provide in-vivo repeated vaccination events. Effective anti-tumour immune responses require antigen release/supply; immune recognition, and immune responsiveness. With better appreciation of endogenous vaccination and immunomodulation, more refined approaches can be engineered with prospect of higher success rates from cancer therapy, including complete responses and better survival rates.

Newcastle disease virus strain AF2240 as an oncolytic virus: A review

The discovery of tumour selective virus-mediated apoptosis marked the birth of an alternative cancer treatment in the form of oncolytic viruses. Even though, its oncolytic efficiency was demonstrated more than 50 years ago, safety concerns which resulted from mild to lethal side effects hampered the progress of oncolytic virus research. Since the classical oncolytic virus studies rely heavily on its natural oncolytic ability, virus manipulation was limited, thereby, restricted efforts to improve its safety. In order to circumvent such restriction, experiments involving non-human viruses such as the avian Newcastle disease virus (NDV) was conducted using cultured cells, animal models and human subjects. The corresponding reports on its significant tumour cytotoxicity along with impressive safety profile initiated immense research interest in the field of oncolytic NDV. The varying degree of oncolytic efficiency and virulency among NDV strains encouraged researchers from all around the world to experiment with their respective local NDV isolates in order to develop an oncolytic virus with desirable characteristics. Such desirable features include high tumour-killing ability, selectivity and low systemic cytotoxicity. The Malaysian field outbreak isolate, NDV strain AF2240, also currently, receives significant research attention. Apart from its high cytotoxicity against tumour cells, this strain also provided fundamental insight into NDV-mediated apoptosis mechanism which involves Bax protein recruitment as well as death receptor engagement. Studies on its ability to selectively induce apoptosis in tumour cells also resulted in a proposed p38 MAPK/NF-κB/IκBα pathway. The immunogenicity of AF2240 was also investigated through PBMC stimulation and macrophage infection. In addition, the enhanced oncolytic ability of this strain under hypoxic condition signifies its dynamic tumour tropism. This review is aimed to introduce and discuss the aforementioned details of the oncolytic AF2240 strain along with its current challenges which outlines the future research direction of this virus.

Replication-Competent Viruses as Cancer Immunotherapeutics: Emerging Clinical Data

Replication-competent (oncolytic) viruses (OV) as cancer immunotherapeutics have gained an increasing level of attention over the last few years while the clinical evidence of virus-mediated antitumor immune responses is still anecdotal. Multiple clinical studies are currently ongoing and more immunomonitoring results are expected within the next five years. All viruses can be recognized by the immune system and are therefore potential candidates for immune therapeutics. However, each virus activates innate immune system by using different combination of recognition receptors/pathways which leads to qualitatively different adaptive immune responses. This review summarizes immunological findings in cancer patients following treatment with replication-competent viruses.

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.

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.

Recombinant Newcastle disease virus Anhinga strain (NDV/Anh-EGFP) for hepatoma therapy

Hepatocellular carcinoma remains one of the most common malignant tumors in the world. Newcastle disease virus (NDV) has been proved to be an efficient oncolytic agent. NDV tumor killing efficacy is not only dependening on the NDV strain but the type of tumor targeted. It is significant to discover more effective and safe oncolytic strains. We investigated the effectiveness of genetically engineered NDV Anhinga strain in hepatoma treatment. The modified virus containing an insertion of enhanced green fluorescent protein (EGFP), named NDV/Anh-EGFP. The antitumor efficacy of the recombinant virus on hepatoma was examined both in vivo and in vitro. NDV Anhinga strain, which could be classified as a lytic strain, is an effective oncolytic agent on hepatoma. There was no significant difference in the TCID50 and growth capability between the recombinant NDV and the parental. NDV/Anh-EGFP can obviously inhibit hepatocarcinoma development in vitro and in vivo. We demonstrate Anhinga strain could become a potent candidate for clinical carcinoma therapy especially for hepatocarcinoma.

Oncolytic Newcastle disease virus for cancer therapy: old challenges and new directions

Newcastle disease virus (NDV) is an avian paramyxovirus, which has been demonstrated to possess significant oncolytic activity against mammalian cancers. This review summarizes the research leading to the elucidation of the mechanisms of NDV-mediated oncolysis, as well as the development of novel oncolytic agents through the use of genetic engineering. Clinical trials utilizing NDV strains and NDV-based autologous tumor cell vaccines will expand our knowledge of these novel anticancer strategies and will ultimately result in the successful use of the virus in the clinical setting.

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.

The emerging role of viruses in the treatment of solid tumours

There is increasing optimism for the use of non-pathogenic viruses in the treatment of many cancers. Initial interest in oncolytic virotherapy was based on the observation of an occasional clinical resolution of a lymphoma after a systemic viral infection. In many cancers, by comparison with normal tissues, the competency of the cellular anti-viral mechanism is impaired, thus creating an exploitable difference between the tumour and normal cells, as an unimpeded viral proliferation in cancer cells is eventually cytocidal. In addition to their oncolytic capability, these particular viruses may be engineered to facilitate gene delivery to tumour cells to produce therapeutic effects such as cytokine secretion and anti -tumour immune responses prior to the eventual cytolysis. There is now promising clinical experience with these viral strategies, particularly as part of multimodal studies, and already several clinical trials are in progress. The limitations of standard cancer chemotherapies, including their lack of specificity with consequent collateral toxicity and the development of cross-resistance, do not appear to apply to viral-based therapies. Furthermore, virotherapy frequently restores chemoradiosensitivity to resistant tumours and has also demonstrated efficacy against cancers that historically have a dismal prognosis. While there is cause for optimism, through continued improvements in the efficiency and safety of systemic delivery, through the emergence of alternative viral agents and through favourable clinical experiences, clinical trials as part of multimodal protocols will be necessary to define clinical utility. Significant progress has been made and this is now a major research area with an increasing annual bibliography.

Oncolytic viruses in cancer therapy

Oncolytic virotherapy is a promising form of gene therapy for cancer, employing nature’s own agents to find and destroy malignant cells. The purpose of this review is to provide an introduction to this very topical field of research and to point out some of the current observations, insights and ideas circulating in the literature. We have strived to acknowledge as many different oncolytic viruses as possible to give a broader picture of targeting cancer using viruses. Some of the newest additions to the panel of oncolytic viruses include the avian adenovirus, foamy virus, myxoma virus, yaba-like disease virus, echovirus type 1, bovine herpesvirus 4, Saimiri virus, feline panleukopenia virus, Sendai virus and the non-human coronaviruses. Although promising, virotherapy still faces many obstacles that need to be addressed, including the emergence of virus-resistant tumor cells.

Oncolytic viruses

Viruses capable of inducing lysis of malignant cells through their replication process are known as "oncolytic" viruses. Clinical trials in oncology have been performed with oncolytic viruses for nearly fifty years. Both systemic and intratumoral routes of administration have been explored. Toxicity has generally been limited to injection site pain, transient fever and tumor necrosis. Responses with early crude materials were usually short in duration; however, recent trials with gene attenuated viruses suggest more prolonged duration to responses observed.

Adjuvant treatment of locally advanced renal cancer with autologous virus-modified tumor vaccines

We report on 208 patients with locally advanced renal-cell carcinoma who received a surgical adjuvant vaccination with autologous, Newcastle disease virus (NDV)-modified, and lethally irradiated tumor cells in combination with low-dose recombinant interleukin-2 and interferon-alpha. The pathological stage was defined as pT2-3a, N1-2, MO (n = 107); pT3b-4 NO, MO (n = 68); and pT3b-4, N1-2, MO (n = 23). The follow-up of 203 evaluable patients showed a median disease-free survival of 21+ months (range, 2-64+ months). In all, 18 relapses (9%) occurred in spite of initial vaccination therapy. Those patients presented with local relapse (n = 3), lymph node metastases (n = 10), and/or distant organ metastases (n = 9). All patients relapsing during the first 6 months after the onset of treatment had primary lymph node involvement of the disease. An analysis of the patient subgroup with a follow-up of more than 22 months showed 10 relapses among 56 patients (18%) along with a median follow-up of 39 months (range, 23-64 months). Toxicity was very mild, manifesting as flu-like symptoms and fevers of up to 38 degrees C. At 8 and 24 weeks after the start of vaccination, anti-NDV serum antibodies were detectable in 70% and 100% of the patients tested, respectively. In comparison with historical data based on the natural course of patients with locally advanced renal-cell cancer, our results demonstrate an improvement of the disease-free survival after surgical adjuvant treatment with autologous, NDV-modified tumor vaccines in combination with low-dose cytokines.

A ten-year follow-up on stage II malignant melanoma patients treated postsurgically with Newcastle disease virus oncolysate

Newcastle disease virus oncolysate was examined as an adjunctive immunotherapeutic agent in the postsurgical management of 83 cases of Stage II malignant melanoma. At this time, all the patients have been under observation for at least 10 years, and over 60% are alive and free of recurrent disease. Older studies in the United States report postsurgical survival figures for Stage II cases of 5-15%. More contemporary studies indicate a 33% survival at 10 years. The unusual disease-free survival periods in the present study, including exceptional survivals in 21 patients with head and neck disease and six cases with cerebral metastases, suggest a unique role for the administration of Newcastle disease virus oncolysate in the management of Stage II malignant melanoma patients.

Newcastle disease virus selectively kills human tumor cells

Newcastle disease virus (NDV), strain 73-T, has previously been shown to be cytolytic to mouse tumor cells. In this study, we have evaluated the ability of NDV to replicate in and kill human tumor cells in culture and in athymic mice. Plaque assays were used to determine the cytolytic activity of NDV on six human tumor cell lines, fibrosarcoma (HT1080), osteosarcoma (KHOS), cervical carcinoma (KB8-5-11), bladder carcinoma (HCV29T), neuroblastoma (IMR32), and Wilm's tumor (G104), and on nine different normal human fibroblast lines. NDV formed plaques on all tumor cells tested as well as on chick embryo cells (CEC), the native host for NDV. Plaques did not form on any of the normal fibroblast lines. To detect NDV replication, virus yield assays were performed which measured virus particles in infected cell culture supernatants. Virus yield increased 10,000-fold within 24 hr in tumor and CEC supernatants. Titers remained near zero in normal fibroblast supernatants. In vivo tumoricidal activity was evaluated in athymic nude Balb-c mice by subcutaneous injection of 9 x 10(6) tumor cells followed by intralesional injection of either live or heat-killed NDV (1.0 x 10(6) plaque forming units [PFU]), or medium. After live NDV treatment, tumor regression occurred in 10 out of 11 mice bearing KB8-5-11 tumors, 8 out of 8 with HT-1080 tumors, and 6 out of 7 with IMR-32 tumors. After treatment with heat-killed NDV no regression occurred (P less than 0.01, Fisher's exact test). Nontumor-bearing mice injected with 1.0 x 10(8) PFU of NDV remained healthy. These results indicate that NDV efficiently and selectively replicates in and kills tumor cells, but not normal cells, and that intralesional NDV causes complete tumor regression in athymic mice with a high therapeutic index.

Immunotherapy for malignant melanoma: a review and update

Several different approaches to the application of specific active immunotherapy for the adjuvant therapy of melanoma have developed independently. Specific active immunotherapy refers to autologous or allogenic inoculation or transplantation of tumor cells or cell products into patients with cancer. Several different types of tumor vaccines have been studied and have been combined with different immunotherapeutic modalities. This report will include a review of several of those different techniques and will also review the observed 5-year survival rates for a melanoma tumor homogenate (concentrated) vaccine, developed by L.J. Humphrey and colleagues.

T cell responses to ovarian tumor vaccines: identification and significance for future immunotherapy

The cellular immune responses to ovarian cancer patients treated with viral oncolysates (VO) ovarian tumor vaccines to vaccines are described. CD3+ cells proliferated after stimulation with the tumor vaccines in a dose-dependent manner. The proliferation of CD3+ cells stimulated with the tumor vaccine was blocked by anti-HLA-DR monoclonal antibody and anti-CD4 mAb indicating that CD3+ CD4+ cells from the blood of the patients treated with VO recognize tumor derived determinants in conjunction with MHC class II antigens. The regulatory activity of the T cells collected after VO treatment was assayed by co-cultivation with PBMC collected before VO treatment. These cells demonstrated increased helper activity for immunoglobin production by cells collected before vaccination and secreted IL-2 in response to stimulation by vaccine. Finally, when biochemical fractionation of the components of VO was attempted, PBMC from VO treated patients responded by proliferation to several fractions suggesting that they recognize multiple epitopes in the ovarian tumor vaccine. Therefore, these data provide novel evidence for the involvement of the T cells in response to ovarian tumor vaccines.

Prevention of metastatic spread by postoperative immunotherapy with virally modified autologous tumor cells. II. Establishment of specific systemic anti-tumor immunity

The successful application of a non-oncogenic virus, Newcastle disease virus (NDV), which can be used to modify a highly metastatic tumor to become more immunogenic is reported. Such NDV modified tumor cells were found to be effective as tumor vaccine for anti-metastatic therapy in combination with surgical removal of the primary tumor. The protection in the animals seen after this treatment is paralleled by an establishment of specific systemic anti-tumor immunity. This protective immunity depended on recognition of a distinct tumor antigen. The therapy protocol also worked in animals bearing the plastic adhesive variant ESb-MP. It did not work, however, when using an immune escape variant not expressing a specific tumor antigen.

Immune response of chimpanzee to purified melanoma 250 kilodalton tumor-associated antigen

Melanoma high molecular weight tumor-associated antigen (TAA), having a molecular weight of 250 kilodaltons (Kd), was purified from a crude cell membrane extract through a combination of lectin affinity, immunoadsorption, and high performance liquid molecular filtration chromatography. Compared to the starting extract, purified TAA was 600-fold higher in TAA activity per microgram of protein. Purified TAA was used to immunize a chimpanzee and the resulting antiTAA immune response was evaluated. Postimmune chimpanzee serum reacted in solid phase radioimmunoassay against purified TAA with a titer in excess of 100,000. In contrast, preimmune serum had a titer of less than 100 in the same assay. By immunoprecipitation analysis, we were able to demonstrate reactivity of the chimpanzee immune serum with a 250 Kd TAA in spent culture medium from melanoma cells metabolically labeled with 35S-methionine and with iodinated purified 250 Kd TAA. Reactivity of the chimpanzee antiserum for the 250 Kd TAA was confirmed in blocking and reciprocal immunodepletion studies using murine monoclonal antibody 9.2.27. These studies suggest that the 250 Kd TAA defined by murine monoclonal antibodies may prove to be immunogenic in man and that manipulation of the immune response to this TAA might be used to the clinical benefit of the patient.

Prevention of metastatic spread by postoperative immunotherapy with virally modified autologous tumor cells. I. Parameters for optimal therapeutic effects

Effective anti-metastatic therapy was achieved in a mouse tumor model by combining surgery with post-operative immunotherapy using virus-modified autologous tumor cells. No therapeutic effect was observed when using for immunotherapy the nonmodified autologous tumor ESb, which is only weakly immunogenic and highly metastatic. The viral modification was achieved by infecting the tumor with an avirulent strain of Newcastle disease virus (NDV), which led to expression of viral antigens and to an increase in the tumor cells' immunogenicity. Parameters which were of decisive influence for success or failure of therapy were the time of operation of the primary tumor and the dose of virus which was admixed to a standard dose of irradiated tumor cells. There was a low dose optimum of NDV at about 100 hemagglutinating units per 25 X 10(6) tumor cells. The therapeutic effect observed was less pronounced if the virus was given separately from the tumor cells. Post-operative immunotherapy with NDV-modified tumor cells had the following therapeutic effects: (1) disappearance of micrometastases from visceral organs as ascertained by a sensitive bioassay; (2) life prolongation in virtually all animals when compared to controls (operated only); (3) cures in about 50% of the treated animals. The possible mechanism of this therapeutic effect and its potential for clinical application are discussed.

Malignant melanoma. Inflammatory mononuclear cell infiltrates in cerebral metastases during concurrent therapy with viral oncolysate

Five patients with advanced malignant melanoma, treated with viral oncolysate, had solitary central nervous system metastases that were removed surgically. Histologic examination revealed striking and significant mononuclear inflammatory cell infiltrates, consisting of a mean of 60% plasma cells and a lesser proportion of lymphocytes at the edges of the lesions, within their supporting fibrovascular trabeculae, and among the tumor cells. Comparable inflammatory changes were not found in solitary metastatic malignant melanomas removed surgically from the brains of 19 patients not treated with viral oncolysate. Similarly, multiple metastatic malignant melanomas obtained postmortem from the brains of 12 patients not treated with viral oncolysate showed minimal inflammatory responses. Ultrastructural examination of material from a single treated patient revealed morphologic abnormalities of the blood-brain barrier, changes that were perhaps conducive to infiltration of the neoplasm by inflammatory cells. The authors suggest that administration of viral oncolysate enhances the inflammatory cell response to metastatic malignant melanoma in the brain.

Adjuvant therapy of cutaneous malignant melanoma: a critical review

The emergence of revised definitions for the high-risk patient with cutaneous malignant melanoma prompts us to re-examine the current status of adjuvant therapy in this disease. We wish to address the question, "once a cutaneous melanoma is surgically removed and the patient is currently free of disease but at high risk for metastases, what can be done to prevent recurrence"?

Current status and future prospects for adjuvant therapy of melanoma

Advances in the treatment of melanoma have resulted mainly from improved surgical management of the primary tumour assisted by a greater appreciation of major prognostic factors in the natural history of the disease. Further improvement in the treatment of melanoma will depend largely on introduction of methods to prevent recurrence of the disease. The present review discusses criteria for selection of patients with a high risk of recurrent disease and the adjuvant treatment that has been used in past studies to prevent recurrences. With few exceptions various regimens of chemotherapy, non-specific immunotherapy with bacterial products or combinations of these treatments have not increased disease free or survival periods. Immunotherapy with various sources of melanoma antigens or with viral lysates of melanoma cells have produced encouraging results in uncontrolled studies and require further evaluation. Several advances appear to provide scope for new initiatives in immunotherapy. These include an appreciation of the role of suppressor cells in regulation of immune responses against tumour cells and possible methods to inhibit their activity. A second is the definition of various lymphokines involved in generation of immune responses (particularly interleukin 2) and development of in vitro methods for large scale production of these factors. Thirdly, methods are becoming available to define the heterogeneity of tumour cells in terms of cell surface antigens or their release of soluble factors which may help select treatments appropriate to each patient.

A phase II study on the postsurgical management of Stage II malignant melanoma with a Newcastle disease virus oncolysate

A Newcastle disease virus lysate of malignant melanoma cells was examined for its possible value in delaying the progression of malignant melanoma with palpable regional node disease (Stage II) to disseminated melanoma (Stage III). This Phase II study was carried out in a group of 32 patients following therapeutic lymphadenectomy. The patients were not prospectively randomized. In each patient, the viral oncolysate was administered subcutaneously at regular intervals over 3 years. The cumulated progressions to disseminated disease at 1, 2 and 3 years were 6%, 8% and 12% of the study group, respectively. These experienced losses were considerably lower than in the control group and in similar control groups described by other investigators. The results suggest that an oncolysate prepared with Newcastle disease virus is a helpful adjunct to surgery in the management of Stage II malignant melanoma.

Viral oncolysate in the management of malignant melanoma. II. Clinical studies

Melanoma cell oncolysate, prepared with Newcastle disease virus, was administered as an immunostimulant to 13 patients with metastatic melanoma. The oncolysate was well tolerated. Six treated patients evidenced a decrease in the size of skin nodules or diseased lymph nodes. Visceral lesions were not favorably influenced to any marked degree. One case of fulminating disease showed a change to slow progression and survived a year longer than was otherwise expected. Another patient, whose melanoma could not be controlled by surgery or chemotherapy, has been in complete remission for 2 years. It appears that viral oncolysate might be particularly helpful to patients with early disease.