Postoperative active specific immunization in curatively resected colorectal cancer patients with a virus-modified autologous tumor cell vaccine

Hypoxia effects on oncolytic virotherapy in Cancer: Friend or Foe?

Researchers have tried to find novel strategies for cancer treatment in the past decades. Among the utilized methods, administering oncolytic viruses (OVs) alone or combined with other anticancer therapeutic approaches has had promising outcomes, especially in solid tumors. Infecting the tumor cells by these viruses can lead to direct lysis or induction of immune responses. However, the immunosuppressive tumor microenvironment (TME) is considered a significant challenge for oncolytic virotherapy in treating cancer. Based on OV type, hypoxic conditions in the TME can accelerate or repress virus replication. Therefore, genetic manipulation of OVs or other molecular modifications to reduce hypoxia can induce antitumor responses. Moreover, using OVs with tumor lysis capability in the hypoxic TME may be an attractive strategy to overcome the limitations of the therapy. This review summarizes the latest information available in the field of cancer virotherapy and discusses the dual effect of hypoxia on different types of OVs to optimize available related therapeutic methods.

Advances in DNA- and RNA-Based Oncolytic Viral Therapeutics and Immunotherapies

The role of viruses has been studied extensively for use as curative cancer therapies. However, the natural immunogenicity of viruses and their interaction with the host’s immune system needs to be examined to determine the full effectiveness of the viral treatment. The prevalence of cancer is increasing globally, and treatments are needed to support the increasing body of patient care. Oncolytic viral therapies used existing pathogenic viruses, which are genetically modified to not cause disease in humans when administered using a vaccine viral vector. Immunotherapies are another avenue of recent interest that has gained much traction. This review will discuss oncolytic viral approaches using three DNA-based viruses, including herpes simplex virus (HSV), vaccinia virus, and adenovirus; as well as four RNA-based viruses, including reovirus, Newcastle disease virus (NDV), poliovirus, and measles virus (MV). It also examines the novel field of cancer-based immunotherapies.

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.

Application of Newcastle disease virus in the treatment of colorectal cancer

Colorectal cancer (CRC) is one of the main reasons of tumor-related deaths worldwide. At present, the main treatment is surgery, but the results are unsatisfactory, and the prognosis is poor. The majority of patients die due to liver or lung metastasis or recurrence. In recent years, great progress has been made in the field of tumor gene therapy, providing a new treatment for combating CRC. As oncolytic viruses selectively replicate almost exclusively in the cytoplasm of tumor cells and do not require integration into the host genome, they are safer, more effective and more attractive as oncolytic agents. Newcastle disease virus (NDV) is a natural RNA oncolytic virus. After NDV selectively infects tumor cells, the immune response induced by NDV’s envelope protein and intracellular factors can effectively kill the tumor without affecting normal cells. Reverse genetic techniques make NDV a vector for gene therapy. Arming the virus by inserting various exogenous genes or using NDV in combination with immunotherapy can also improve the anti-CRC capacity of NDV, and good results have been achieved in animal models and clinical treatment trials. This article reviews the molecular biological characteristics and oncolytic mechanism of NDV and discusses in vitro and in vivo experiments on NDV anti-CRC capacity and clinical treatment. In conclusion, NDV is an excellent candidate for cancer treatment, but more preclinical studies and clinical trials are needed to ensure its safety and efficacy.

Novel avenues in immunotherapies for colorectal cancer

Since it is known that the immune system affects tumor growth, it has been studied if immunotherapy can be developed to combat cancer. While some successes have been claimed, the increasing knowledge on tumor-immune interactions has, however, also shown the limitations of this approach. Tumors may show selective outgrowth of cells escaped from immune control. Escape variants arise spontaneously due to the genetically instable nature of tumor cells. This is one of the most obvious limitations of cancer immunotherapy. However, new therapies are becoming available, designed to respond to tumor-immune escape.

Attacking Postoperative Metastases using Perioperative Oncolytic Viruses and Viral Vaccines

Surgical resection of solid primary malignancies is a mainstay of therapy for cancer patients. Despite being the most effective treatment for these tumors, cancer surgery has been associated with impaired metastatic clearance due to immunosuppression. In preclinical surgery models and human cancer patients, we and others have demonstrated a profound suppression of both natural killer (NK) and T cell function in the postoperative period and this plays a major role in the enhanced development of metastases following surgery. Oncolytic viruses (OV) were originally designed to selectively infect and replicate in tumors, with the primary objective of directly lysing cancer cells. It is becoming increasingly clear, however, that OV infection results in a profound inflammatory reaction within the tumor, initiating innate and adaptive immune responses against it that is critical for its therapeutic benefit. This anti-tumor immunity appears to be mediated predominantly by NK and cytotoxic T cells. In preclinical models, we found that preoperative OV prevents postoperative NK cell dysfunction and attenuates tumor dissemination. Due to theoretical safety concerns of administering live virus prior to surgery in cancer patients, we characterized safe, attenuated versions of OV, and viral vaccines that could stimulate NK cells and reduce metastases when administered in the perioperative period. In cancer patients, we observed that in vivo infusion with oncolytic vaccinia virus and ex vivo stimulation with viral vaccines promote NK cell activation. These preclinical studies provide a novel and clinically relevant setting for OV therapy. Our challenge is to identify safe and promising OV therapies that will activate NK and T cells in the perioperative period preventing the establishment of micrometastatic disease in cancer patients.

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.

Efficiency of adjuvant active specific immunization with Newcastle disease virus modified tumor cells in colorectal cancer patients following resection of liver metastases: results of a prospective randomized trial

PURPOSE

Metastatic disease is a major cause of mortality in colorectal cancer patients. Even after complete resection of isolated liver metastases, recurrence develops in the majority of patients. Therefore, development of strategies to prevent recurrent liver metastases is of major clinical importance. The present prospectively randomised phase III trial investigates the efficiency of active specific immunotherapy (ASI) after liver resection for hepatic metastases of colorectal cancer.

METHODS

Patients with histologically confirmed liver metastases from colorectal cancer were randomised to the vaccination or control group. After complete resection of liver metastases, patients randomised to the vaccination group received six doses of Newcastle disease virus (NDV) infected autologous tumour cell vaccine (ATV-NDV). The primary end-point was overall survival, secondary end-points were disease-free survival and metastases-free survival.

RESULTS

Fifty-one patients were enrolled in the study with 50 patients available for analysis. The follow-up period was 116.1 +/- 23.8 month in the vaccination arm and 112.4 +/- 18.5 month in the control group. In the total patient group, no differences in the primary and secondary end-points were detected. Most interestingly, subgroup analysis revealed a significant advantage for vaccinated colon cancer patients with respect to overall survival [hazard ratio: 3.3; 95%, confidence interval (CI): 1.0-10.4; P = 0.042] and metastases-free survival (hazard ratio: 2.7; 95%, CI: 1.0-7.4; P = 0.047) in the intention-to-treat analysis.

CONCLUSION

Active specific immunotherapy in unselected colorectal cancer patients was not effective for prevention of recurrent metastatic disease. However, in colon cancer patients, ASI with ATV-NDV appears to be beneficial prolonging overall and metastases-free survival.

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.

Clinical trials of antitumor vaccination with an autologous tumor cell vaccine modified by virus infection: improvement of patient survival based on improved antitumor immune memory

For active specific immunotherapy of cancer patients, we designed the autologous virus-modified tumor cell vaccine ATV-NDV. The rationale of this vaccine is to link multiple tumor-associated antigens (TAAs) from individual patient-derived tumor cells with multiple danger signals (DS) derived from virus infection (dsRNA, HN, IFN-alpha). This allows activation of multiple innate immune responses (monocytes, dendritic cells, and NK cells) as well as adaptive immune responses (CD4 and CD8 memory T cells). Preexisting antitumor memory T cells from cancer patients could be activated by antitumor vaccination with ATV-NDV as seen by augmentation of antitumor memory delayed-type hypersensitivity (DTH) responses. In a variety of phase II vaccination studies, an optimal formulation of this vaccine could improve long-term survival beyond what is seen in conventional standard therapies. A new concept is presented which proposes that a certain threshold of antitumor immune memory plays an important role (1) in the control of residual tumor cells which remain after most therapies and (2) for long-term survival of treated cancer patients. This immune memory is T-cell based and most likely maintained by persisting TAAs from residual dormant tumor cells. Such immune memory was prominent in the bone marrow in animal tumor models as well as in cancer patients. Immunization with a tumor vaccine in which individual TAAs are combined with DS from virus infection appears to have a positive effect on antitumor immune memory and on patient survival.

Specific immunotherapy of cancer in elderly patients

The concept of immunotherapy of cancer is more than a century old, but only recently have molecularly defined therapeutic approaches been developed. In this review, we focus on the most promising approach, active therapeutic vaccination. The identification of tumour antigens can now be accelerated by methods allowing the amplification of gene products selectively or preferentially transcribed in the tumour. However, determining the potential immunogenicity of such gene products remains a demanding task, since major histocompatibility complex (MHC) restriction of T cells implies that for any newly defined antigen, immunogenicity will have to be defined for any individual MHC haplotype. Tumour-derived peptides eluted from MHC molecules of tumour tissue are also a promising source of antigen. Tumour antigens are mostly of weak immunogenicity, because the vast majority are tumour-associated differentiation antigens already 'seen' by the patient's immune system. Effective therapeutic vaccination will thus require adjuvant support, possibly by new approaches to immunomodulation such as bispecific antibodies or antibody-cytokine fusion proteins. Tumour-specific antigens, which could be a more potent target for immunotherapy, mostly arise by point mutations and have the disadvantage of being not only tumour-specific, but also individual-specific. Therapeutic vaccination will probably focus on defined antigens offered as protein, peptide or nucleic acid. Irrespective of the form in which the antigen is applied, emphasis will be given to the activation of dendritic cells as professional antigen presenters. Dendritic cells may be loaded in vitro with antigen, or, alternatively, initiation of an immune response may be approached in vivo by vaccination with RNA or DNA, given as such or packed into attenuated bacteria. The importance of activation of T helper cells has only recently been taken into account in cancer vaccination. Activation of cytotoxic T cells is facilitated by the provision of T helper cell-derived cytokines. T helper cell-dependent recruitment of elements of non-adaptive defence, such as leucocytes, natural killer cells and monocytes, is of particular importance when the tumour has lost MHC class I expression. Barriers to successful therapeutic vaccination include: (i) the escape mechanisms developed by tumour cells in response to immune attack; (ii) tolerance or anergy of the evoked immune response; (iii) the theoretical possibility of provoking an autoimmune reaction by vaccination against tumour-associated antigens; and (iv) the advanced age of many patients, implying reduced responsiveness of the senescent immune system.

Replication-selective virotherapy for cancer: Biological principles, risk management and future directions

In the search for novel cancer therapies that can be used in conjunction with existing treatments, one promising area of research is the use of viral vectors and whole viruses. This review describes the underlying biological principles and current status of the field, outlines approaches for improving clinical effectiveness and discusses the unique safety and regulatory issues surrounding viral therapies.

Future directions for the treatment of colorectal carcinoma

Most of these therapies, although still in the infant stages of their development, offer the potential for major advances in colorectal cancer therapy. Gene therapy is an entirely new medicinal paradigm for the treatment of cancer. Currently, the clinical application of these methods is limited by the need for a more through understanding of cancer immunology and the availability of better vector systems for efficient and selective tumor gene transfer. As increasing numbers of scientists and clinicians address these issues, better therapies will likely emerge.

Adjuvant treatment of colon and rectal cancer: impact of chemotherapy, radiotherapy, and immunotherapy on routine postsurgical patient management. Forschungsgruppe Onkologie Gastrointestinaler Tumoren (FOGT)

Colon cancer patients with UICC stage III or T4 N0 M0 stage II should receive postoperative adjuvant therapy, since relapse rates are high and surgical outcome has been improved by adjuvant treatment. The standard treatment is 5-fluourouracil plus levamisole; an alternative option is the combination of 5-fluourouracil and folinic acid. Stage II (T3 N0 M0) colon cancer patients should not receive adjuvant treatment outside of studies. Rectal cancer patients of stage II or III should receive postoperative radiochemotherapy with 45-54.4 Gy and 5-fluourouracil as standard treatment. Patients not eligible for radiotherapy may receive adjuvant chemotherapy only. Studies need to be conducted to improve adjuvant therapy in colorectal cancer. All qualified patients should be treated within these studies requiring sufficient patient numbers, as well as comparable surgical procedures, proper patient selection and stratification criteria, drug and dose intensities. Intraportal infusion may be as effective as systemic adjuvant treatment; the tumor type and stage for which benefit from this kind of treatment is consistently significant needs to be defined, since intraportal infusion of all resectable colorectal cancers is overtreatment. Both surgery and histopathological staging may be improved in some centers, and these require standardization and quality control.

The chemotherapy of colon cancer

Despite extensive clinical trials, mortality from colon cancer has remained essentially unchanged since the 1950s. However, the increasing numbers of complete and partial responses seen in clinical trials suggest that colon cancer can be successfully treated by chemotherapy, but only if the antitumour selectivity can be increased by a substantial amount. This will be possible by the introduction of new drugs with more precise mechanisms of action, such as those acting specifically on signalling or cell cycle control pathways shown to be aberrant in colon cancer. Alternatively, the selectivity of present day agents may be increased considerably by the selective activation of prodrugs in tumours (ADEPT) or by targeting them to tumours using polymers. Other new approaches using vaccines or some form of gene therapy will potentiate present chemotherapy, while the introduction of positron emission tomography (PET) scanning will allow the rapid detection of agents with activity that would have been missed by conventional measurements of response.

Immunologic host defense in melanoma: delineation of effector mechanisms involved and of strategies for the augmentation of their efficacy

There exists substantial evidence that the immune system plays an important role in the prevention and control of cancer. This evidence includes 1) the occasional clinical observation of spontaneous tumor regression, 2) the correlation of this phenomenon with the presence of tumor-infiltrating lymphocytes, and 3) the in vitro demonstration of the specificity of tumor-infiltrating lymphocytes for the autologous tumor. Because of the only weak immunogenicity of and the occurrence of active immunosuppression by the cancer, this response often does not suffice to combat the neoplasm successfully. One strategy for amplifying the anti-tumor immune response is vaccination of patients or experimental animals with cancer cells, the immunogenicity of which has been enhanced by the introduction of genes encoding immunostimulatory molecules. Several investigators have shown that transfection of certain types of cancer cells with the interleukin-2 gene reduces their tumorigenicity and that immunization with interleukin-2-transduced cancer cells protects animals from challenge with a tumorigenic dose of wild-type cancer cells. We have recently established a murine melanoma model (M-3) and have used it to elucidate the mechanism by which interleukin-2-transfected cancer cells can induce protective immunity. We will demonstrate the following: 1) that the mechanisms leading to the loss of tumorigenicity of interleukin-2-expressing cancer cells are somewhat different from those leading to the rejection of wild-type cancer cells in immunized animals, 2) that immunity resides within both CD4- and CD8-positive T cells, and 3) that host antigen-presenting cells are probably important in the induction of this protective anti-tumor immunity.

Local recurrence of colorectal cancer: the problem, mechanisms, management and adjuvant therapy

Local recurrence of colorectal cancer after 'curative' surgery is a major clinical problem. Typically, 50-70 per cent of patients presenting to a surgical clinic will undergo apparently curative surgery for disease and of these about 10-25 per cent will develop local recurrence, in either the tumour bed or bowel wall. The wide differences in local recurrence rate both between and within institutions is probably caused by variation in surgical technique. The main causes of local recurrence are inadequate excision of the primary tumour or the draining lymph nodes, and intraoperative tumour cell implantation. The most significant single factor prognostic of local recurrence is Dukes' tumour stage. Other important factors include tumour grade and fixity, level of the tumour in the rectum, blood and lymphatic vessel invasion, inadvertent perforation of the tumour during resection, and the surgeon's experience. The prognosis of patients with local recurrence is poor. Prevention of recurrence by adequate surgery and adjuvant therapy as well as its early detection offer the best prospect of improving results.

Somatic gene therapy for cancer: the utility of transferrinfection in generating 'tumor vaccines'

The last few years have seen the development of a branch of somatic gene therapy which aims at strengthening the immune surveillance of the body, leading to eradication of disseminated cancer tumor cells and occult micrometastases after surgical removal of the primary tumor. Such a tumor vaccination protocol calls for cultivation of the primary tumor tissue and the insertion of one of three types of genes into the isolated cultured tumor cells followed by irradiation of the transfected or transduced cells to render them incapable of further proliferation. The cells so treated constitute the 'tumor vaccine'. A review of the literature suggests that for mouse models, in the initial period after inoculation, rejection of the tumor cells is usually effected by non-T-cell immunity, whereas the long-term systemic immune response is based on cytotoxic T-cells. High expression of the gene inserted into the tumor cells may be critical for the success of the vaccination procedure. Examples are given which indicate that transferrinfection, a procedure to introduce genes by adenovirus-augmented receptor-mediated endocytosis, meets some important prerequisites for successful application of this type of gene therapy.

In vitro expansion and analysis of T lymphocyte microcultures obtained from the vaccination sites of cancer patients undergoing active specific immunization with autologous Newcastle-disease-virus-modified tumour cells

In order to understand further the effects of Newcastle-disease-virus(NDV)-modified tumour vaccines we investigated the feasibility of isolating lymphocytes from the site of injection of patients undergoing postoperative active specific immunization (ASI) with autologous NDV-modified tumour cells. Delayed-type-hypersensitivity(DTH)-like reactions from five cancer patients were surgically removed, minced and the tissue particles were digested with collagenase and DNase. Lymphoid cells recovered were expanded in a highly efficient limiting-dilution analysis system optimized for T cell growth [Moretta et al. (1983) J Exp Med 157: 743] and lymphocyte microcultures (clonal probability > 0.8) could be grown for up to 1 year. Analysis of the microcultures for phenotype and function showed that the majority were positive for CD4 (92%) and TCR alpha beta (96%). Concanavalin-A-induced production of interleukin-2 (IL-2), IL-6, interferon gamma and tumour necrosis factor alpha was detected in more than 70% of the microcultures. Lectin-dependent cytotoxicity was only very rarely observed. The general characteristics of the microcultures obtained support the notion of a DTH-like reaction taking place at the site of tumour cell challenge. The possibility of in vitro expansion and cultivation of T lymphocytes from ASI vaccination sites should help to elucidate further the role of these cells in active specific immunization against autologous tumour cells.

Vaccine therapy for HIV: a historical review of the treatment of infectious diseases by active specific immunization with microbe-derived antigens

A review of the history of 'vaccine therapy' for infectious diseases is presented. The concept originated when Auzias-Turenne introduced 'syphilitic vaccination' or 'syphilization' as a treatment for syphilis in Paris in the mid-1800s; his clinical studies probably influenced Pasteur's successful rabies postexposure vaccine trials. Robert Koch in Berlin in the 1890s observed that inoculation of tuberculin into patients with tuberculosis induced an inflammatory response in affected tissues, and advocated 'tuberculin therapy'. Sir Almroth Wright in London in the early 20th century devised methods to measure changes in serum 'opsonizing' activity in response to therapeutic inoculations with microbe-derived vaccines. Since the advent of antibiotics, active specific immunization with microbe-derived antigens (vaccine therapy) has been largely forgotten as a strategy for treatment of infectious diseases. Advances in antigen production and in molecular immunology now permit new tactics to probe, analyse and selectively alter in vivo human immune responses to infectious microbes. Our recent demonstration that vaccine therapy can boost natural immunity to HIV in infected patients should rekindle interest in this approach.

Establishment of cytotoxic CD4+ T cell clones from cancer patients treated by local immunotherapy

We have previously reported that the antitumor effect of OK-432, a Streptococcal preparation, is markedly augmented when injected intratumorally together with fibrinogen (Cancer, 69: 636-642, 1992). In order to elucidate the mechanism of the antitumor effects, we established T cell clones from regional lymph nodes of colorectal cancer patients who received this local immunotherapy. By culture of lymph node lymphocytes, in the presence of IL-2 and OK-432, 4 clones of T cells were established from 4 patients treated by local immunotherapy. These clones had a helper T cell phenotype (CD3+, CD4+, CD8-, CD56-, WT31+) and were successfully maintained for several months. The cells strongly expressed CD25 when stimulated with OK-432 and exhibited a high level of cytotoxic activity in part explained by the increased expression of ICAM-1 and LFA-1, and the release of TNF beta. These results suggest that the CD4+ T cells play a role in the antitumor mechanism of local immunotherapy.

Immunotherapy of colorectal cancer

Specific and nonspecific stimulation of the host immune system to reject cancer is an attractive concept that is just beginning to mature. Results with crude extracts and nonspecific immune stimulation have been variable. However, the recent observations of improved survival after administration of levamisole plus 5-fluorouracil in the adjuvant setting have made an impact on the treatment of colorectal cancer. Animal studies consistently show that immune therapies are most effective for disease that is not advanced. Thus, the small benefit seen with levamisole, a low toxicity immunomodulator, suggests that much more impressive results can be anticipated with more potent and specific agents. Postsurgical autologous tumor cell vaccine has been effective in some prospective randomized trials; in others, no benefit was found. The identification and purification of allogeneic tumor-associated antigens has lead to enhanced antigen-specific host cell-mediated immunity; this may result in more consistent antitumor effects. The current development of chemically defined immune adjuvants of low toxicity allows tumor-specific immune stimulation to be tested in high-risk apparently healthy patients after resection of colorectal cancer (Stages II and III). The influx of information regarding immune cell populations, cell-surface markers, and cytokines has fostered extensive exploration of lymphocyte stimulation, in vitro cell growth and expansion, and in vivo evaluation in patients with advanced cancer. Modest tumor response rates have been documented with adoptive transfer of lymphokine-activated killer cells and interleukin-2. Improved results are anticipated with the more potent tumor-infiltrating lymphocytes and specific in vitro sensitization of draining lymph node cells to autologous and allogeneic tumor antigens. Murine monoclonal antibodies specific for cell-surface markers, such as carcinoembryonic antigen, have been tested for their value in the diagnosis and therapy of colorectal cancer. A small response rate has been seen with single and multiple injections of C017-1A, a monoclonal antibody specific for colonic and pancreatic cancer. The development of antiidiotypic antibodies in these patients may have been important in those that responded to this type of therapy. However, laboratory evidence suggests that monoclonal antibody conjugated to a cytotoxic agent (i.e., radionuclide, drug, or toxin) should be much more effective. Radioimmunotherapy trials in the nude mouse model bearing human colon cancer xenografts showed good tumor incorporation of the radionuclide (yttrium 90 or iodine 131), inhibition of tumor growth, and long-term survival.(ABSTRACT TRUNCATED AT 400 WORDS)

Update on tumor vaccines

Vaccination against tumor has always been an attractive idea for the treatment of patients bearing tumor. By harnessing the host's own immune response the attack on tumor cells would act on a continuing basis, with emerging tumor cells stimulating their own destruction. However, the approach has been hampered by our poor understanding of the nature of tumor antigens and of the pathways by which immune cells might operate against tumor growth. Recent developments in molecular biology and immunology are remedying this deficiency and bringing vaccination to the forefront of new approaches to treatment of a range of tumors. Results obtained in B-cell tumors, where the idiotypic immunoglobulin at the cell surface provides a well-defined tumor antigen, are already indicating exciting possibilities as well as delineating problems. There is considerable clinical evidence that patients have some intrinsic ability to control tumor growth and that certain tumors remain dormant for long periods. Attempts to understand and perhaps stimulate the mechanisms involved are being made through the use of biological modifiers and by manipulating potential effector cells in vitro. Ideally this approach, which may include non-specific and specific elements, could be combined with specific vaccination in order to combat the apparent ability of many tumor cells to evade host defences.

Active specific immunotherapy with Newcastle-disease-virus-modified autologous tumor cells following resection of liver metastases in colorectal cancer. First evaluation of clinical response of a phase II-trial

A group of 23 colorectal cancer patients were treated by a new type of active specific immunotherapy (ASI) following complete surgical resection of liver metastases (RO resection). For ASI treatment we used a vaccine consisting of 1 x 10(7) autologous, irradiated (200 Gy) metastases-derived tumor cells incubated with 32 hemagglutination units (HU) of Newcastle disease virus (NDV). The adjuvant vaccine therapy was started 2 weeks after surgery and was repeated five times at 14-days intervals followed by one boost 3 months later. The delayed-type hypersensitivity (DTH) skin reactions to the vaccine were measured as well as the DTH reactions to a challenge test of 1 x 10(7) non-virus-modified autologous tumor cells from liver metastases or 1 x 10(7) autologous normal liver cells. In addition 32 HU NDV alone and a standard antigen test (Merieux test) were applied pre- and post-vaccination. The vaccination was well tolerated. In 13 of 23 patients an increasing reactivity against the vaccine was observed during the vaccination procedure. Nine patients (40%) experienced an increased DTH reactivity against autologous tumor cells following vaccination, while 17% or fewer showed an increased reactivity to Merieux test antigens, NDV, or normal liver cells. The increased antitumor response was not correlated to responsiveness to NDV alone, autologous liver cells, enzymes and culture medium used for vaccine preparation or standard antigens (Merieux test). After a follow-up of at least 18 months 61% of the vaccinated patients developed tumor recurrence in comparison to 87% of a matched control groups from the same institution that had been only surgically treated. The results of this phase II trial are encouraging and should stimulate further prospective randomized studies.

In situ activation of syngeneic tumour-specific cytotoxic T lymphocytes: intra-pinna immunization followed by restimulation in the peritoneal cavity

Tumour-specific cytotoxic T lymphocytes (CTL) are usually obtained after immunization in vivo and restimulation of immune cells in vitro. We here describe the generation of syngeneic tumour-specific CTL within no more than 9 days by priming and restimulation in vivo. This is achieved only if the correct sites are used both for primary immunization (ear pinna) and for restimulation (peritoneal cavity). The kinetics of immune T cell induction and of the secondary response in vivo will be reported. While a secondary CTL response could be generated in the peritoneal cavity, this was not possible in the spleen, no matter which routes of antigen restimulation were used. Upon transfer of immune spleen cells into the peritoneal cavity but not into the spleen, a secondary response could be generated upon in situ restimulation, indicating the importance of the correct microenvironment for this type of response. The peritoneal effector cells were true T cells and recognized a tumour-associated antigen in association with the Kd major histocompatibility (MHC class I) antigen. Finally the activated tumour-specific peritoneal exudate cells were able to transfer protective immunity without exogenous interleukin-2 into normal syngeneic mice.