Treatment of patients with progressive unresectable metastatic melanoma with a heterologous polyvalent melanoma whole cell vaccine

Cancer Vaccines in the Immunotherapy Era: Promise and Potential

Therapeutic vaccines are a promising alternative for active immunotherapy for different types of cancers. Therapeutic cancer vaccines aim to prevent immune system responses that are not targeted at the tumors only, but also boost the anti-tumor immunity and promote regression or eradication of the malignancy without, or with minimal, adverse events. Clinical trial data have pushed the development of cancer vaccines forward, and the US Food and Drug Administration authorized the first therapeutic cancer vaccine. In the present review, we discuss the various types of cancer vaccines and different approaches for the development of therapeutic cancer vaccines, along with the current state of knowledge and future prospects. We also discuss how tumor-induced immune suppression limits the effectiveness of therapeutic vaccinations, and strategies to overcome this barrier to design efficacious, long-lasting anti-tumor immune responses in the generation of vaccines.

Methods for improving the immunogenicity and efficacy of cancer vaccines

INTRODUCTION

Cancer vaccines represent one of the oldest immunotherapy strategies. A variety of tumor-associated antigens have been exploited to investigate their immunogenicity as well as multiple strategies for vaccine administration. These efforts have led to the development of several clinical trials in tumors with different histological origins to test the clinical efficacy of cancer vaccines. However, suboptimal clinical results have been reported mainly due to the lack of optimized strategies to induce strong and sustained systemic tumor antigen-specific immune responses.

AREAS COVERED

We provide an overview of different types of cancer vaccines that have been developed and used in the context of clinical studies. Moreover, we review different preclinical and clinical strategies pursued to enhance the immunogenicity, stability, and targeting at tumor site of cancer vaccines.

EXPERT OPINION

Additional and appropriate preclinical studies are warranted to optimize the immunogenicity and delivery of cancer vaccines. The appropriate choice of target antigens is challenging; however, the exploitation of neoantigens generated from somatic mutations of tumor cells represents a promising approach to target highly immunogenic tumor-specific antigens. Remarkably, the investigation of the combination of cancer vaccines with immunomodulating agents able to skew the tumor microenvironment from immunosuppressive to immunostimulating will dramatically improve their clinical efficacy.

Autoantibodies May Predict Immune-Related Toxicity: Results from a Phase I Study of Intralesional Bacillus Calmette-Guérin followed by Ipilimumab in Patients with Advanced Metastatic Melanoma

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of advanced melanoma. The first ICI to demonstrate clinical benefit, ipilimumab, targets cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4); however, the long-term overall survival is just 22%. More than 40 years ago intralesional (IL) bacillus Calmette-Guérin (BCG), a living attenuated strain of Mycobacterium bovis, was found to induce tumor regression by stimulating cell-mediated immunity following a localized and self-limiting infection. We evaluated these two immune stimulants in combination with melanoma with the aim of developing a more effective immunotherapy and to assess toxicity. In this phase I study, patients with histologically confirmed stage III/IV metastatic melanoma received IL BCG injection followed by up to four cycles of intravenous ipilimumab (anti-CTLA-4) (ClinicalTrials.gov number NCT01838200). The trial was discontinued following treatment of the first five patients as the two patients receiving the escalation dose of BCG developed high-grade immune-related adverse events (irAEs) typical of ipilimumab monotherapy. These irAEs were characterized in both patients by profound increases in the repertoire of autoantibodies directed against both self- and cancer antigens. Interestingly, the induced autoantibodies were detected at time points that preceded the development of symptomatic toxicity. There was no overlap in the antigen specificity between patients and no evidence of clinical responses. Efforts to increase response rates through the use of novel immunotherapeutic combinations may be associated with higher rates of irAEs, thus the imperative to identify biomarkers of toxicity remains strong. While the small patient numbers in this trial do not allow for any conclusive evidence of predictive biomarkers, the observed changes warrant further examination of autoantibody repertoires in larger patient cohorts at risk of developing irAEs during their course of treatment. In summary, dose escalation of IL BCG followed by ipilimumab therapy was not well tolerated in advanced melanoma patients and showed no evidence of clinical benefit. Measuring autoantibody responses may provide early means for identifying patients at risk from developing severe irAEs during cancer immunotherapy.

Antigen-specific versus antigen-nonspecific immunotherapeutic approaches for human melanoma: the need for integration for optimal efficacy?

Due to its immunogenecity and evidence of immune responses resulting in tumor regression, metastatic melanoma has been the target for numerous immunotherapeutic approaches. Unfortunately, based on the clinical outcomes, even the successful induction of tumor-specific responses does not correlate with efficacy. Immunotherapies can be divided into antigen-specific approaches, which seek to induce T cells specific to one or several known tumor associated antigens (TAA), or with antigen-nonspecific approaches, which generally activate T cells to become nonspecifically lytic effectors. Here the authors critically review the different immunotherapeutic approaches in melanoma.

Overview of Tumor Cell–Based Vaccines

Whole-cell tumor vaccines have been investigated for more than 20 years for their efficacy in both preclinical models and in clinical trials in humans. There are clear advantages of whole-cell/polyepitope vaccination over those types of immunotherapy that target specific epitopes. Multiple and unknown antigens may be targeted to both the innate and adaptive immune system, and this may be further augmented by genetic modification of the vaccine cells to provide cytokines and costimulation. In this review, we give an overview of the field including the preclinical and clinical advances using unmodified and modified tumor-cell vaccines.

Immunophototherapy using PDT combined with rapid intratumoral dendritic cell injection

The capacity of photodynamic therapy (PDT) to induce localized cell death and tissue damage suggests that when applied to tumors it could create a local depot of tumor-associated antigens, which would be available for uptake and presentation to the immune system, potentially leading to improved tumor control. Dendritic cells (DCs) are the most potent cells for antigen uptake, presentation, and stimulation of the immune system. However, it is unclear whether DCs would retain their viability and functional capacity for the requisite trafficking to draining lymph nodes when adoptively transferred in close temporal and anatomic proximity to the site of PDT-induced cytotoxicity. We conducted studies of combined PDT and adoptive DC therapy, "immunophototherapy," in a female, Fisher 344 rat orthotopic mammary tumor model. Using 5-aminolevulinic acid as a pro-drug, we demonstrated kinetically favorable biologic conversion to the photosensitive protoporphyrin IX, appropriate trafficking of syngeneic bone marrow-derived DCs injected into PDT-treated tumors within 15 min of completion of therapy, and improved survival over either modality alone. These data indicate that DCs rapidly administered into the site of PDT retain their viability and functional status, supporting the further evaluation of immunophototherapy strategies.

Effect of proteasome inhibitors on proliferation and apoptosis of human cutaneous melanoma-derived cell lines

BACKGROUND

Cutaneous malignant melanoma is an aggressive type of skin cancer which causes disproportionate mortality in young and middle-aged adults. Once disseminated, melanoma can be considered an incurable disease, highly resistant to standard antineoplastic treatment, such as chemotherapy or radiation therapy. The proteasome represents a novel target for cancer therapy that can potentially be used in melanoma.

OBJECTIVES

To assess the effect of four structurally different proteasome inhibitors on human cutaneous melanoma-derived cell lines.

METHODS

Sixteen human cutaneous melanoma-derived cell lines which are original were obtained from patients who were treated by two of the authors. Cells were cultured, exposed to proteasome inhibitors (bortezomib, ALLN, MG-132 and epoxomicin) and then assayed for cell cycle and cell death analyses.

RESULTS

Proteasome inhibitors inhibited the in vitro growth of melanoma cells, and this effect was due to a reduction in cell proliferation rate and an induction of both caspase-dependent and caspase-independent cell death. Moreover, release of apoptosis-inducing factor was observed in the presence of the broad-specificity caspase inhibitor BAF (Boc-D-fmk). In addition, the four different proteasome inhibitors induced caspase 2 processing.

CONCLUSIONS

This study provides information regarding the in vitro effects of proteasome inhibitors on melanoma cell lines, and the molecular mechanisms involved. It also gives support to the future use of such inhibitors in the treatment of patients with melanoma, either administered alone or in combination with other drugs.

Antiproliferative effect of STI571 on cultured human cutaneous melanoma-derived cell lines

Standard antineoplastic treatment for metastatic melanoma is ineffective in the large majority of patients. Therefore, alternative approaches need to be investigated. STI571 is a new antineoplastic compound, which selectively inhibits the tyrosine kinase activity of ABL, c-Kit and platelet-derived growth factor receptor (PDGFR). Melanoma may express all of these proteins. The aim of this study was to investigate whether STI571 inhibits the in-vitro growth of melanoma cells. Nineteen cell lines were obtained from four primary and 15 metastatic melanomas of cutaneous origin. The percentages of positive cells for the putative targets of STI571 were as follows: ABL, 41-100%; c-Kit, 8-97%; PDGFR-alpha, 41-98%; PDGFR-beta, 51-99%. 3-(4,5-Dimethylthiazol-yl)-2,5-diphenyltetrazolium (MTT) and viability assays showed that STI571 clearly inhibits the proliferation of eight of the 19 (42.1%) cell lines. No relationship could be established between the expression of c-Kit, ABL, PDGFR-alpha or PDGFR-beta and the response of cell lines to STI571. Our study shows, for the first time, an antiproliferative effect of STI571 on human melanoma cell lines of cutaneous origin, raising the possibility of the future clinical use of STI571. The identification of the target of STI571 in human cutaneous melanoma cells would allow the selection of patients who could benefit from this treatment.

Interleukin-10 and the immune response against cancer: a counterpoint

Although interleukin-10 (IL-10) is commonly regarded as an anti-inflammatory, immunosuppressive cytokine that favors tumor escape from immune surveillance, a wealth of evidence is accumulating that IL-10 also possesses some immunostimulating properties. In fact, IL-10 has the pleiotropic ability of influencing positively and negatively the function of innate and adaptive immunity in different experimental models, which makes it questionable to merely categorize this cytokine as a target of anti-immune escape therapeutic strategies or rather, as an immunological adjuvant in the fight against cancer. Here, we review available data about the immunostimulating anticancer properties of IL-10, and in particular, we focus on the hypothesis that in contrast to what occurs in secondary lymphoid organs, IL-10 overexpression within the tumor microenvironment may catalyze cancer immune rejection.

Delayed disease progression after allogeneic cell vaccination in hormone-resistant prostate cancer and correlation with immunologic variables

PURPOSE

There are a significant number of patients with asymptomatic hormone-resistant prostate cancer who have increasing prostate-specific antigen (PSA) levels but little or no evaluable disease. The immunogenicity and minimal toxicity associated with cell-based vaccine therapy makes this approach attractive for these patients.

EXPERIMENTAL DESIGN

We have evaluated a vaccine comprising monthly intradermal injection of three irradiated allogeneic prostate cell lines (8 x 10(6) cells each) over 1 year. The first two doses were supplemented with bacille Calmette-Guérin as vaccine adjuvant. Twenty-eight hormone-resistant prostate cancer patients were enrolled. Patients were assessed clinically and PSA levels were measured monthly. Radiologic scans (X-ray, computed tomography, and bone scan) were taken at baseline and at intervals throughout the treatment period. Comprehensive monthly immunologic monitoring was undertaken including proliferation studies, activation markers, cytokine protein expression, and gene copy number. This longitudinal data was analyzed through predictive modeling using artificial neural network feed-forward/back-propagation algorithms with multilayer perceptron architecture.

RESULTS

Eleven of the 26 patients showed statistically significant, prolonged decreases in their PSA velocity (PSAV). None experienced any significant toxicity. Median time to disease progression was 58 weeks, compared with recent studies of other agents and historical control values of around 28 weeks. PSAV-responding patients showed a titratable T(H)1 cytokine release profile in response to restimulation with a vaccine lysate, while nonresponders showed a mixed T(H)1 and T(H)2 response. Furthermore, immunologic profile correlated with PSAV response by artificial neural network analysis. We found predictive power not only in expression of cytokines after maximal stimulation with phorbol 12-myristate 13-acetate, but also the method of analysis (qPCR measurement of IFN-gamma > qPCR measurement tumor necrosis factor-alpha > protein expression of IFN-gamma > protein expression of interleukin 2).

CONCLUSIONS

Whole cell allogeneic vaccination in hormone-resistant prostate cancer is nontoxic and improves the natural history of the disease. Longitudinal changes in immunologic function in vaccinated patients may be better interpreted through predictive modeling using tools such as the artificial neural network rather than periodic "snapshot" readouts.

Melanoma of the head and neck

Staging of cutaneous melanoma has changed in recent years with an increased emphasis upon thickness and ulceration on prognosis of early stage disease. Cutaneous melanoma of the head and neck is treated with complete surgical resection in early stage disease. Resection margins are determined by the size, depth, and presence of satellite lesions. Evaluation for regional and distant metastatic disease is necessary in all cases of advanced stage disease. Sentinel lymph node biopsy and possible parotidectomy and neck dissection should be considered in head and neck cutaneous melanomas greater than 1 mm in thickness or with ulceration. Adjuvant therapy may be indicated in advanced primary, nodal, and metastatic disease. Mucosal melanoma of the head and neck remains a difficult disease to treat, with high locoregional recurrence rates and poor prognosis despite aggressive therapy.

Development of HVJ Envelope Vector and Its Application to Gene Therapy

To create a highly efficient vector system that is minimally invasive, we initially developed liposomes that contained fusion proteins from the hemagglutinating virus of Japan (HVJ; Sendai virus). These HVJ-liposomes delivered genes and drugs to cultured cells and tissues. To simplify the vector system and develop more efficient vectors, the next approach was to convert viruses to non-viral vectors. Based on this concept, we recently developed the HVJ envelope vector. HVJ with robust fusion activity was inactivated, and exogenous DNA was incorporated into the viral envelope by detergent treatment and centrifugation. The resulting HVJ envelope vector introduced plasmid DNA efficiently and rapidly into both cultured cells in vitro and organs in vivo. Furthermore, proteins, synthetic oligonucleotides, and drugs have also been effectively introduced into cells using the HVJ envelope vector. The HVJ envelope vector is a promising tool for both ex vivo and in vivo gene therapy experiments. Hearing impairment in rats was prevented and treated by hepatocyte growth factor gene transfer to cerebrospinal fluid using HVJ envelope vector. For cancer treatment, tumor-associated antigen genes were delivered efficiently to mouse dendritic cells to evoke an anti-cancer immune response. HVJ envelope vector fused dendritic cells and tumor cells and simultaneously delivered cytokine genes, such as IL-12, to the hybrid cells. This strategy successfully prevented and treated cancers in mice by stimulating the presentation of tumor antigens and the maturation of T cells. For human gene therapy, a pilot plant to commercially produce clinical grade HVJ envelope vector has been established.