Current status of melanoma vaccines

BACKGROUND: Malignant melanoma is increasing worldwide faster than any other cancer and the American lifetime risk is estimated to reach 1 in 75 by the year 2000. Active specific immunotherapy with vaccines is evolving as a promising new modality in the treatment of malignant melanoma. OBJECTIVE: To present a concise and understandable summary of the key molecular and clinical concepts of melanoma vaccines currently under investigation, the history that led to their development, and their anticipated clinical response. METHODS: The recent advances in the field of melanoma immunobiology and the newest experiment vaccines are reviewed. RESULTS: There is no effective melanoma vaccine that successfully treats or prevents melanoma. However, their use has been associated with regression or delayed disease progression in some cases. The minority of patients who do have a major clinical response to vaccine therapy experience an improvement in survival. Even in those patients in whom melanoma vaccines cannot improve survival, the paucity of severe side effects has provided a quality of life superior to standard multiagent chemotherapy. CONCLUSION: Melanoma vaccines are relatively safe immunotherapeutic modalities for the management of malignant melanoma. The clinical effectiveness of melanoma vaccines is unclear and adequately controlled studies need yet to be performed. Current melanoma vaccines manipulate antigen presentation networks and combine the best cellular and antibody antitumor immune response effective in mediating tumor protective immunity; these combination vaccines hold the most promise. The ideal melanoma vaccine will ultimately prevent melanoma.     

Effect of aging on detrusor function in males

Some of the most dramatic advances in the treatment of cancer have used the immune system in combination with conventional or transplantation chemotherapy. Adoptive immunotherapy has been used for relapses after allogeneic bone marrow transplantation, and it has been particularly effective for chronic myeloid leukemia. Adoptive immunotherapy also has been used for Epstein-Barr virus-related lymphomas developing after allogeneic marrow transplantations. Cellular therapy, including the infusion of tumor-reactive immune cells, has been used to mediate response of established solid tumors. This has been used for therapeutic benefit for renal cell carcinoma, melanoma, lung cancer, and breast cancer. Current research is focusing on reducing the toxicity of these approaches as well as further defining the appropriate target tissue.     

Transloading of tumor cells with foreign major histocompatibility complex class I peptide ligand: a novel general strategy for the generation of potent cancer vaccines

The major hurdle to be cleared in active immunotherapy of cancer is the poor immunogenicity of cancer cells. In previous attempts to overcome this problem, whole tumor cells have been used as vaccines, either admixed with adjuvant(s) or genetically engineered to express nonself proteins or immunomodulatory factors before application. We have developed a novel approach to generate an immunogeneic, highly effective vaccine: major histocompatibility complex (MHC) class I-positive cancer cells are administered together with MHC class I-matched peptide ligands of foreign, nonself origin, generated by a procedure we term transloading. Murine tumor lines of the H2-Kd or the H2-Db haplotype, melanoma M-3 and B16-F10, respectively, as well as colon carcinoma CT-26 (H2-Kd), were transloaded with MHC-matched influenza virus-derived peptides and applied as irradiated vaccines. Mice bearing a deposit of live M-3 melanoma cells were efficiently cured by this treatment. In the CT-26 colon carcinoma and the B16-F10 melanoma, high efficacies were obtained against tumor challenge, suggesting the universal applicability of this new type of vaccine. With foreign peptide ligands adapted to the requirements of a desired MHC class I haplotype, this concept may be used for the treatment of human cancers.     

Experimental vaccine strategies for cancer immunotherapy

Recently, cancer immunotherapy has emerged as a therapeutic option for the management of cancer patients. This is based on the fact that our immune system, once activated, is capable of developing specific immunity against neoplastic but not normal cells. Increasing evidence suggests that cell-mediated immunity, particularly T-cell-mediated immunity, is important for the control of tumor cells. Several experimental vaccine strategies have been developed to enhance cell-mediated immunity against tumors. Some of these tumor vaccines have generated promising results in murine tumor systems. In addition, several phase I/II clinical trials using these vaccine strategies have shown extremely encouraging results in patients. In this review, we will discuss many of these promising cancer vaccine strategies. We will pay particular attention to the strategies employing dendritic cells, the central player for tumor vaccine development.     

Ex-vivo gene therapy using cytokine-transduced tumor vaccines: molecular and clinical pharmacology

Whether the current generation of cytokine gene-transduced tumor vaccines will show clinical efficacy is under study. Fortunately, the large safety profile so far observed with gene-transduced tumor vaccines can allow outpatient testing in large populations of patients in the adjuvant therapy situation. This will allow large studies statistically powered to see potentially important adjuvant therapy effects in the range that are observed for tamoxifen in breast cancer. For example, the outpatient, adjuvant therapy safety context has been established in the use of GM-CSF gene-transduced autologous prostate cancer vaccines following radical prostatectomy. Similar adjuvant therapy clinical trial efforts are anticipated with allogeneic breast, colon, pancreatic, and ovarian cancer in addition to prostate, renal cell carcinoma, and melanoma. The reverse translation of early clinical data back to basic laboratory research also suggests the field of cytokine gene-transduced tumor vaccine research will remain vibrant. Efforts are currently being directed on optimizing DC activation with polycistronic constructs of cytokine genes, and overexpressing the most relevant tumor-associated peptides. As in the case of antineoplastic drug development, not all lead compounds will become approved drugs in medical oncology. Rigorous yet innovative clinical trial designs will be key to the accelerated identification of cytokine gene-transduced vaccines that improve survival in cancer patients.     

Toward a human papillomavirus vaccine

Much progress has been made over the past 10 years with regard to development of a vaccine active against HPV. Successful protection has been achieved in animal models using species-specific papillomaviruses; however, HPV diversity may delay the development of successful HPV vaccines, especially those designed as therapeutic vaccines for the treatment of HPV-induced carcinoma and high-grade dysplasia of the cervix. Difficulties arise with regard to assessment of efficacy of potential vaccines. The impetus for long-term studies on vaccine efficacy will initially stem from in vitro evidence of responsiveness to the vaccine. The time when a vaccine will have an impact on the prevalence of high-grade dysplasia and invasive cancer is still some way off.     

New trends in the development of cancer vaccines

Recent advances in understanding of the molecular mechanisms of antigen processing and presentation, and the identification of tumor-associated antigens in melanoma and other cancers, have stimulated the development of a new generation cancer vaccines. This review summarizes the most recent approaches for the design of safe and more effective vaccines for cancer. Peptide-based vaccines are safe and can be synthesized with high purity and reproducibility. Recombinant viruses encoding tumor-associated antigens allow efficient delivery and precise control over the form and the quantity of the delivered antigens. DNA-based vaccines induce long-lasting immune responses and are considered very safe. Antigen-loaded dendritic cells, and the use of newly developed adjuvants are also very promising new approaches. In this review, we also discuss the possible clinical applications and future directions for vaccine development.     

Cancer vaccines. Part 2

Cancer vaccines are being widely studied for the purpose of immune modulation and subsequent antitumor effects. This article cites only a few examples of the many studies underway. Many vaccines have shown efficacy in eliciting systemic responses with minimal toxicities. The use of vaccines as a modality of cancer therapy in combination with chemotherapy, surgery, and radiation therapy is also being investigated. Although the routine use of approved vaccines is still a goal for the future, instituting this fourth modality of cancer therapy is not too distant. Phase III trials with both melanoma and colon cancer vaccines have been completed. Synthetic carbohydrate antigen vaccines have shown efficacy in several tumor types during Phase II trials and are also generating enthusiasm. The potential impact of vaccine therapy on the profession of pharmacy may involve patient counseling regarding management of side effects and possibly also dispensing of vaccine therapy products to patients directly for home administration. As ambulatory sites open in conjunction with pharmacy services and pharmacists obtain prescribing authority, pharmacists' active involvement in vaccine counseling and administration seems likely.     

A personal (biased) perspective on cancer "vaccines"

The use of active specific immunotherapy (ASI) for cancer (cancer "vaccines") is still in its scientific infancy despite several decades of clinical and basic research. What has been established is the principle that stimulation of the immune response by "crude" (i.e., whole cell-derived) vaccines has led, in a proportion of patients, to rejection of tumor masses, in some instances for 10 years or more. Scientific investigations into the nature of recognition of tumor antigenic determinants (epitopes) by cytolytic T cells have begun to elucidate the mechanisms underlying rejection, making more precise vaccines possible. Yet there should be caution about assuming that a single epitope or even a few epitopes combined will be as effective as the "crude" materials, which might better be thought of as "polyvalent." ASI in at least one instance may have cured melanoma in a patient with metastatic disease, but that patient developed another immunologically and genetically distinct melanoma. This may provide an example of both immunological surveillance against the emergence of new melanomas and immunological selection of an immunologically resistant tumor. Combinations of vaccines with cytokines, cytolytic T cell infusions, or chemotherapy may improve the response rates and durations of survival achievable with vaccines alone. The best rationale for synthetically derived vaccines may be for prophylaxis-that is, as a true vaccine-where the use of tumor-derived materials in normal individuals is difficult to justify ethically.     

Breast cancer immunotherapy: current status and future prospects

The development of an immunotherapeutic approach to cancer is the concern for many immunologists, but despite the impressive progress over the past decade, such as the identification of tumour antigens and antigenic peptides as potential targets, there are still many obstacles in eliciting an effective immune response to eradicate cancer. Mucins have attracted interest as potential targets for immunotherapy in the development of vaccines for cancers expressing Mucin1 (MUC1; e.g. breast, pancreas, ovary etc.). All of the identified targets for cancer, including MUC1, are normal proteins; however MUC1 expressed on tumours can be considered as tumour specific due to their overexpression, altered glycosylation and its ubiquitous distribution on the cell surface rather than at the secretory pole in adenocarcinomas. These observations have led to the development of several different approaches to immunize against breast cancer using synthetic carbohydrates or peptides conjugated to carriers and given together with a variety of adjuvants to elicit the appropriate immune response. Mannan, a polymannose carbohydrate isolated from the cell wall of yeast, is an appropriate and effective protein carrier for eliciting a cellular (T1-type) or humoral (T2-type) immune response depending on the mode of conjugation (oxidized or reduced). In addition, mannan holds promise and opens many avenues as a carrier for vaccine development for other antigens. Several clinical trials are in progress to evaluate the immunogenicity of MUC1 and its suitability as to use for immunotherapy/vaccine for breast cancer.     

Bone marrow-generated dendritic cells pulsed with tumor extracts or tumor RNA induce antitumor immunity against central nervous system tumors

Recent studies have shown that the brain is not a barrier to successful active immunotherapy that uses gene-modified autologous tumor cell vaccines. In this study, we compared the efficacy of two types of vaccines for the treatment of tumors within the central nervous system (CNS): dendritic cell (DC)-based vaccines pulsed with either tumor extract or tumor RNA, and cytokine gene-modified tumor vaccines. Using the B16/F10 murine melanoma (B16) as a model for CNS tumor, we show that vaccination with bone marrow-generated DCs, pulsed with either B16 cell extract or B16 total RNA, can induce specific cytotoxic T lymphocytes against B16 tumor cells. Both types of DC vaccines were able to protect animals from tumors located in the CNS. DC-based vaccines also led to prolonged survival in mice with tumors placed before the initiation of vaccine therapy. The DC-based vaccines were at least as effective, if not more so, as vaccines containing B16 tumor cells in which the granulocytic macrophage colony-stimulating factor gene had been modified. These data support the use of DC-based vaccines for the treatment of patients with CNS tumors.     

Spontaneous intracranial hypotension: spinal MR findings

Several melanosome glycoproteins have been shown to be antigenic in humans. Correlation of antigen-specific immune responses in patients with the autoimmune disease vitiligo, therapy-induced hypopigmentation, and cutaneous melanoma has not been well studied. We examined antibody responses to a melanocyte autoantigen, tyrosinase-related protein-2 (TRP-2), as it is highly expressed in cutaneous melanoma and melanocytes. TRP-2 recombinant protein was synthesized for western blot and affinity anti-TRP-2 enzyme-linked immunosorbent assay. We demonstrated that patients with malignant melanoma, vitiligo, and active-specific immunotherapy-induced depigmentation had significant anti-TRP-2 IgG titers. The highest level of anti-TRP-2 IgG response was found in vitiligo patients. Induction and enhancement of anti-TRP-2 IgG responses were observed in melanoma patients treated with a polyvalent melanoma cell vaccine containing TRP-2. Active-specific immunotherapy could induce and/or augment the TRP-2 IgG antibody titers. Melanoma patients who developed hypopigmentation and had improved survival after polyvalent melanoma cell vaccine had significantly augmented anti-TRP-2 antibody responses compared with patients with poor prognosis. This study demonstrates that TRP-2 autoantigen is immunogenic in humans. TRP-2 antibody responses provide a linkage between autoimmune responses by vitiligo patients and melanoma patients responding to immunotherapy who have induced hypopigmentation.     

Cellular vaccines

This project is devoted to the development of novel cellular vaccines designed to treat cancer patients. These cellular vaccines present and enhance immunogens, which will elicit a potent immune response. The goal is to achieve safe and effective immune reaction against the patient's own tumour. (1) Autologous cellular vaccines are prepared by processing circulating blood mononuclear cells outside of the patient's body (ex vivo) to differentiate them into antigen-presenting cells (APCs). Monocyte-derived APCs (MD-APCs) are then grown in the presence of exogenous target antigens (tumour cell debris, or apoptotic bodies) to become fully mature APCs. (2) Functionality for antigen presentation to T cells of ex vivo MD-APCs is evaluated in vivo. (3) Cellular vaccines are tested in selected rodent animal models. Efficiency and immune response are monitored in pertinent experimental systems for cancer. Pharmacological data are generated for clinical investigation. Tolerance and biologic effects are documented in primates. (4) The first clinical trials on cancer patients are taking place in 1998 on melanoma and prostate cancer to validate the concept. Specialized cell processors with dedicated software and standardized controls are being developed and used for the preparation of cellular vaccines. (5) The evaluation of new non-viral vectors and the validation of new non-viral transfection methods of mononuclear cells with marker genes is in progress and will lead to the ex vivo transfection of genes coding for immunostimulating cytokines or for tumour antigens in MD-APCs. Efficiency will be validated in vitro and in animal models. The ex vivo and animal model studies validate the clinical relevance of this new cellular immunotechnology. Clinical validation of individual autologous cellular vaccines in specific indications for which no treatment is presently available will allow the development of cellular and gene immunotherapy for other types of cancers.     

Molecular biology of human melanoma development and progression

In the United States, Australia, Northern Europe, and Canada, malignant melanoma is increasing at a faster rate than any other cancer, with the exception of lung cancer in women. Major advances have been made in the molecular biology and immunology of melanoma. These advances in basic science have led to more rational approaches to specifically targeting melanoma cells, with promising results in the clinic. An increased understanding of how melanoma spreads has led to more selective, less invasive surgical procedures that do not compromise patient health. Combinations of chemotherapy and immunotherapy are now available for patients with advanced melanoma that affect both the length and quality of the patients' lives. This review of the molecular biology of melanoma development and progression discusses the disease's etiology, molecular genetics, cell-surface antigens, experimental models, biological markers, and new forms of treatment. As we continue to learn more about malignant melanoma, we will be able to devise more specific and effective treatments that will give patients with this potentially deadly disease longer and more productive lives.     

New approaches to the development of virus vaccines for veterinary use

The marked progress in recombinant deoxyribonucleic acid (DNA) technology during the past decade has led to the development of a variety of safe new vaccine vectors which are capable of efficiently expressing foreign immunogens. These have been based on a variety of virus types--poxviruses, herpesviruses and adenoviruses--and have led to the production of many new potential recombinant vaccines. Of these recombinant vaccines, the rabies vaccine, in which the rabies G protein is expressed in a vaccinia vector, has been widely used in the field to prevent the spread of rabies both in Europe and in the United States of America. A recombinant Newcastle disease virus vaccine, using fowlpox virus as the vector to express immunogenic proteins from the Newcastle disease virus, has been licensed as the first commercial recombinant vectored vaccine. Many other recombinant virus vaccines are still at the stage of laboratory or field testing. The most recent breakthrough in vaccinology has been the success with the use of naked DNA as a means of vaccination. This approach has shown great promise in mouse model systems and has now become the most active field in new vaccine development. Molecular redesigning of conventional ribonucleic acid (RNA) viruses to obtain more stable attenuated vaccines was previously possible only for positive-strand RNA viruses, such as poliovirus. However, recent advances in molecular biological techniques have enabled the rescuing of negative-strand viruses from DNA copies of their genomes. This has made it possible to engineer specific changes in the genomes of Rhabdoviridae and Paramyxoviridae, both of which include several viruses of veterinary importance. The authors describe the current progress in the development of vector vaccines, DNA vaccines and vaccines based on engineered positive- and negative-strand RNA virus genomes, with special emphasis on their application to diseases of veterinary importance.     

A preclinical model to assess the antigenicity of an HLA-A2 melanoma cell vaccine

BACKGROUND: The authors have demonstrated that immunization with melanoma whole-cell vaccine (MCV) augments T-cell responses to melanoma and that cytotoxic T-cells (CTL) recognize allogeneic melanoma-bearing shared HLA-A antigens. A preclinical model was developed to assess CTL activation in vitro using melanoma lines as stimulators. HLA-A2 expression is predominant in melanoma patients and plays a role in HLA class I restricted CTL killing of melanomas. The authors hypothesized that a MCV consisting of allogeneic HLA-A2 melanomas may be as good as autologous melanoma MCV for HLA-A2 patients. METHODS: CTL were generated from peripheral blood lymphocytes of patients with HLA-A2 melanoma by stimulation with autologous melanoma, allogeneic melanoma (HLA-A2 or non-HLA-A2), or allogeneic MCV (mixed HLA-A2 and non-HLA-A2 melanomas). RESULTS: HLA-A2 MCV and autologous melanoma were similar and significantly better stimulators than the others. Specificity also was supported by CTL killing and mixed lymphocyte tumor reaction assays. CONCLUSIONS: These studies provide important information for the studying immunization of patients with HLA-A2 melanoma with an allogeneic HLA-A2 MCV in a Phase I clinical trial.     

Cancer gene therapy using tumor cells infected with recombinant vaccinia virus expressing GM-CSF

The efficacy of a recombinant vaccinia virus (rvv-mGM-CSF) expressing murine granulocyte-macrophage colony stimulating factor (GM-CSF) for use in cancer gene therapy was evaluated. C57BL/6 mice with established B16-F10 melanoma were treated by s.c. injection of irradiated B16 cells infected with two different recombinant vaccinia virus (rvv) constructs. Mice treated with rvv-mGM-CSF vaccine survived longer (p < 0.05), were free of palpable tumors (> 4 mm) longer (p < 0.02), and had smaller mean tumor volumes (p < 0.005) compared to those treated with irradiated B16 cells infected with a control rvv (rvv-lacZ) expressing Escherichia coli beta-galactosidase or irradiated uninfected B16 cells. The vaccine appeared to be B16 tumor cell specific, because there was no therapeutic effect when heterologous but syngeneic (H-2b) colon adenocarcinoma cells, MC-38 infected with rvv-mGM-CSF were used as vaccine. In this model, rvv expressing interleukin-2 (IL-2) was ineffective. In addition, experimental lung metastasis of B16 tumor cells was significantly inhibited by rvv-mGM-CSF vaccine compared to several control vaccines when the vaccine was applied either by i.p. route (p < 0.006) or by s.c. injection (p < 0.0008). B16 cells expressing mGM-CSF after infection with rvv-mGM-CSF or transduction with a retroviral vector, were equally effective (p > 0.14) as vaccines against lung metastasis. Inhibition of metastasis was also B16 tumor cell specific. These data suggest that this approach of cancer gene therapy has a potential for use in cancer patients.     

Vaccines and other adjuvant therapies for melanoma

Patients with thick primary melanomas or regional lymph node involvement are at high risk of relapse. Investigations of adjuvant therapy over the past 30 years show only one significantly positive trial employing high dose interferon-alpha-2b. This is a potentially toxic regimen, therefore, other better-tolerated forms of adjuvant immunotherapy are being studied. Recent advances in basic science have led to a better understanding of the T-cell response to human cancer. This article discusses the background and current clinical trials of active specific immunotherapies for melanoma, including peptide and ganglioside vaccines.     

Association of copper to metallothionein in hepatic lysosomes of Long-Evans cinnamon (LEC) rats during the development of hepatitis [se e comments

After decades of research, the adjuvant therapy of patients with melanoma has recently shown significant survival and relapse-free interval benefit for the intravenous and subcutaneous administration of maximally tolerable dosages of recombinant IFN alpha 2b in a trial conducted by the ECOG (E1684). Despite the toxicity of this therapy, retrospective analyses of its impact upon quality-of-life using Q-TWiST methods and cost-efficacy analyses all argue for the benefit and utility of this intervention, especially for node-positive patients with resectable melanoma at highest risk of relapse. A confirmatory trial has been completed and will mature in the spring of 1998. The impact of lower dosages of IFN, apparent transiently during and for a period of time following treatment has not been sustained with longer follow-up in a number of trials. Current approaches in Europe and North America focus upon refinement of dose and duration of treatment with IFN and their potential interactions with, and comparison with, active specific immunotherapy with vaccines. A recently emerging area of research is the patient with stage IIA melanoma and the potential role of an abbreviated high-dose regimen of IFN alpha in this patient subset.     

Cytotoxicity of synthetic barium hydroxyapatite

Development of an effective immunotherapeutic approach for treatment of CNS tumors must take into account the unique anatomic and immunologic features of the brain. We explored the antitumor immune response in the brain elicited by nonreplicating melanoma cells genetically engineered to produce either granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-2 (IL-2) in a paracrine fashion. Using a new model of intracranial melanoma in C57BL/6 mice, the cytokine-producing cells were given either as a subcutaneous vaccine to induce systemic antitumor immunity or as a direct injection into the brain as local immunotherapy. We found that GM-CSF-transduced cells, as a subcutaneous vaccine but not as an intracranial injection, afforded some protection from intracranial challenge with the wild-type tumor. In contrast, direct intracranial injection of tumor cells secreting IL-2 was protective whereas flank vaccination with IL-2 transductants was not. Combination therapy with both the subcutaneous GM-CSF-transductants as a vaccine and local administration of IL-2-transductants in the brain achieved a synergistic response. These findings provide a basis for the application of paracrine cytokine delivery to brain cancer therapy both as a systemic vaccine and via local administration. The demonstration of synergy between paracrine cytokine therapies holds promise as a novel therapy for brain tumors.