Gene therapy of human melanoma. Immunization of patients with autologous tumor cells admixed with allogeneic melanoma cells secreting interleukin 6 and soluble interleukin 6 receptor

Insights Into Dendritic Cells in Cancer Immunotherapy: From Bench to Clinical Applications

Dendritic cells (DCs) are efficient antigen-presenting cells (APCs) and potent activators of naïve T cells. Therefore, they act as a connective ring between innate and adaptive immunity. DC subsets are heterogeneous in their ontogeny and functions. They have proven to potentially take up and process tumor-associated antigens (TAAs). In this regard, researchers have developed strategies such as genetically engineered or TAA-pulsed DC vaccines; these manipulated DCs have shown significant outcomes in clinical and preclinical models. Here, we review DC classification and address how DCs are skewed into an immunosuppressive phenotype in cancer patients. Additionally, we present the advancements in DCs as a platform for cancer immunotherapy, emphasizing the technologies used for in vivo targeting of endogenous DCs, ex vivo generated vaccines from peripheral blood monocytes, and induced pluripotent stem cell-derived DCs (iPSC-DCs) to boost antitumoral immunity.

Therapeutic gene modified cell based cancer vaccines

History of cancer immunotherapy lasts for more than 120 years. In 1891 William B. Coley injected bacteria into inoperable cancer (bone sarcoma) and observed tumor shrinkage. He is recognized as the "'"Father of Immunotherapy"'". Cancer immunotherapy is based on the ability of the immune system to recognize cancer cells and to affect their growth and expansion. Beside the fact that, tumor cells are genetically distinct from their normal counterparts, and should be recognized and eliminated by immune system, the tumor associated antigens (TAAs) are often poorly immunogenic due to immunoediting. This process allows tumor to evolve during continuous interactions with the host immune system, and eventually escape from immune surveillance. Furthermore, tumor microenvironment consists of immunosuppressive cells that release immunosuppressive factors including IL-6, IL-10, IDO, TGFβ or VEGF. Interactions between cancer and stroma cells create network of immunosuppressive pathways, while activation of immune defense is inhibited. A key to successful immunotherapy is to overcome the local immunosuppression within tumor microenvironment and activate mechanisms that lead to tumor eradication. There are two clinical approaches of immunotherapy: active and passive. Active immunotherapy involves stimulation of immune response to tumor associated antigens (TAAs), either non-specifically via immunomodulating agents or specifically employing cancer vaccines. This review presents the progress and breakthroughs in design, development and clinical application of selected cell-based tumor vaccines achieved due to the generation and development of gene transfer technologies.

Design of clinical trials for therapeutic cancer vaccines development

Advances in molecular and cellular biology as well as biotechnology led to definition of a group of drugs referred to as medicinal products of advanced technologies. It includes gene therapy products, somatic cell therapeutics and tissue engineering. Therapeutic cancer vaccines including whole cell tumor cells vaccines or gene modified whole cells belong to somatic therapeutics and/or gene therapy products category. The drug development is a multistep complex process. It comprises of two phases: preclinical and clinical. Guidelines on preclinical testing of cell based immunotherapy medicinal products have been defined by regulatory agencies and are available. However, clinical testing of therapeutic cancer vaccines is still under debate. It presents a serious problem since recently clinical efficacy of the number of cancer vaccines has been demonstrated that focused a lot of public attention. In general clinical testing in the current form is very expensive, time consuming and poorly designed what may lead to overlooking of products clinically beneficial for patients. Accordingly regulatory authorities and researches including Cancer Vaccine Clinical Trial Working Group proposed three regulatory solutions to facilitate clinical development of cancer vaccines: cost-recovery program, conditional marketing authorization, and a new development paradigm. Paradigm includes a model in which cancer vaccines are investigated in two types of clinical trials: proof-of-principle and efficacy. The proof-of-principle trial objectives are: safety; dose selection and schedule of vaccination; and demonstration of proof-of-principle. Efficacy trials are randomized clinical trials with objectives of demonstrating clinical benefit either directly or through a surrogate. The clinical end points are still under debate.

Clinical trials of active cancer immunotherapy

Active immunotherapy of cancer needs its own clinical trials' methodology. The standard methodology paradigm for clinical trials in oncology was developed for cytotoxic drugs, which differ dramatically from cancer vaccines in their mode of action and toxicity profile. To minimize the risk of overlooking benefits for patients, Mackiewicz and Nawrocki invite to open discussion on vaccine trials' methodology. Our point of view is based on several Phase I and II trials with hundreds of melanoma patients treated with allogenic cellular vaccine genetically modified with cytokine genes. We feel that a simplified two-stage clinical trial design without a separate Phase I is justified. In the first stage, preliminary efficacy together with proof-of-principle and feasibility issues could be addressed. For real efficacy assessment, careful consideration of end points is necessary. Immunologic responses and objective clinical responses are not the best measures of vaccine efficacy for many patients who benefit from treatment. Randomized single institution studies with time-to-event end points are probably well suited for such combined Phase I/II studies. In the second stage trial (Phase III), the final efficacy analysis with comparator arm is needed.

Interleukin-6 gene ablation in a transgenic mouse model of malignant skin melanoma

Interleukin (IL)-6 is a pleiotropic cytokine that has been shown to inhibit the growth of early stage and to promote the proliferation of advanced stage melanoma cells in vitro. In patients with metastasizing melanomas, highly increased IL-6 blood levels correlate with a poor response to chemotherapy and a worse overall prognosis, suggesting that IL-6 promotes melanoma progression in vivo. Here, we analyzed the role of IL-6 in melanoma development and progression in a transgenic mouse model. We bred IL-6-deficient mice with MT-ret transgenic animals predisposed for melanomas. While MT-ret transgenic animals develop severe melanosis of the skin and subcutis and subsequent melanomas at an incidence of 80% during their first year of life, MT-ret mice devoid of IL-6 developed preneoplastic melanosis and consecutive melanomas significantly less frequently (47%; P < 0.05). Moreover, the tumors were significantly smaller in the groups of MT-ret mice lacking one (P < 0.05) or both (P < 0.01) copies of the IL-6 gene. Immunoblot analysis revealed that ret transgene expression was not reduced in the skin of mice lacking IL-6, indicating that the observed decrease of melanoma incidence and of tumor sizes was not because of a down-regulation of transgene expression. Taken together, these results indicate that IL-6 enhances both the development of melanoma precursor lesions and the subsequent growth of the resulting tumors in the MT-ret model of melanoma development.

Immunization by particle-mediated transfer of the granulocyte-macrophage colony-stimulating factor gene into autologous tumor cells in melanoma or sarcoma patients: report of a phase I/IB study

The primary objective of this phase I study was to determine the safety of an autologous tumor vaccine given by intradermal injection of lethally irradiated granulocyte-macrophage colony-stimulating factor (GM-CSF) gene-transfected autologous melanoma and sarcoma cells. Secondary objectives included validation of the gene delivery technology (particle-mediated gene transfer), determining the host immune response to the tumor after vaccination, and monitoring patients for evidence of antitumor response. Sixteen patients were treated with either of two different doses of GM-CSF-treated tumor cells. One patient received treatment with both doses of tumor cells. No treatment-related local or systemic toxicity was noted in any patient. Patients administered 100% treated cells (i.e., with a preparation of tumor cells that had all been exposed to GM-CSF DNA transfection) had a more extensive lymphocytic infiltrate at the vaccine site than did patients given 10% treated cells (a preparation of tumor cells in which 10% had been exposed to GM-CSF transfection) or nontreated tumor. The generation of a systemic immune response to autologous tumor by a delayed-type hypersensitivity response to the intradermal placement of nontransfected tumor cells was noted in one patient. One patient had a transient partial response of metastatic tumor sites. The entire procedure, from tumor removal to vaccine placement, was accomplished in less than 6 hr in all patients. Four of 17 patient tumor preparations produced greater than 3.0 ng of GM-CSF per 10(6) cells per 24 hr in vitro. The one patient with greater than 30 ng of GM-CSF per 10(6) cells per 24 hr in vitro had positive DTH, a significant histologic inflammatory response, and clinically stable disease. This technique of gene transfer was safe and feasible, but resulted in clinically relevant levels of gene expression in only a minority of patients.

The designer cytokine hyper-IL-6 mediates growth inhibition and GM-CSF-dependent rejection of B16 melanoma cells

The low immunogenic B16 melanoma cell line was transfected with a mammalian expression vector containing the complementary DNA for a sIL-6R/IL-6 fusion protein, termed Hyper-IL-6 (H-IL-6), which was shown to have biological activities at 100-1000-fold lower concentrations than IL-6 in combination with sIL-6R. The secreted p84 glycoprotein was detected in the supernatant of transfected cells and was fully active on BAF3/gp130 cells, which respond to IL-6/sIL-6R but not to IL-6 alone. Administration of recombinant H-IL-6 to C57BL/6 mice resulted in a prolonged acute phase protein gene expression indicating long systemic persistence of the fusion protein. Transfected B16 cells (B16/H-IL6 cells) showed morphological alterations in combination with a dramatic growth inhibition in vitro. Subcutaneous injection in C57BL/6 mice resulted in an almost complete rejection of B16/H-IL6 cells. This effect was partially abolished in FVB/BL/6 mice transgenic for a GM-CSF receptor antagonist, indicating a GM-CSF-dependent rejection of H-IL-6 transfected B16 cells. These results demonstrate that the anti-tumor effect of cytokines like IL-6 which are secreted by transfected melanoma cells at least in part depends on GM-CSF activity.

Genetically modified tumour vaccines (GMTV) in melanoma clinical trials

Since melanoma is a model immunogenic malignancy incurable in the disseminated phase of its natural course different immunotherapeutic approaches are tested in clinical trials. A number of tumour vaccines genetically modified (GMTV), with various immunostimulatory factors, are tested in phase I/II clinical trials. These factors include cytokines, tumour antigens (TA), costimulatory molecules or HLA antigens. We have designed a novel, mixed auto/allogeneic cellular melanoma vaccine modified with the IL-6 and the sIL-6R genes. Preclinical studies in a mouse model demonstrated that the IL-6/sIL-6R based vaccine is able to elicit efficient anti-tumour responses, mediated by CD8+ and NK cells, which resulted in inhibition of the tumour growth, metastases formation and prolonged survival of the animals treated. Irradiation of vaccine cells does not only lead to their sterilisation but also causes increased secretion of exogenous IL-6 and sIL-6R. Since January 1996 we have vaccinated more than one hundred metastatic melanoma patients. Promising clinical results (22% CR+PR, 32% SD) and the evidence of immune responses in the vaccinated patients have prompted us to design a phase III clinical trial which is to be open in 2000.

Cancer vaccines

It has been more than 100 years since the first reported attempts to activate a patient's immune system to eradicate developing cancers. Although a few of the subsequent vaccine studies demonstrated clinically significant treatment effects, active immunotherapy has not yet become an established cancer treatment modality. Two recent advances have allowed the design of more specific cancer vaccine approaches: improved molecular biology techniques and a greater understanding of the mechanisms involved in the activation of T cells. These advances have resulted in improved systemic antitumor immune responses in animal models. Because most tumor antigens recognized by T cells are still not known, the tumor cell itself is the best source of immunizing antigens. For this reason, most vaccine approaches currently being tested in the clinics use whole cancer cells that have been genetically modified to express genes that are now known to be critical mediators of immune system activation. In the future, the molecular definition of tumor-specific antigens that are recognized by activated T cells will allow the development of targeted antigen-specific vaccines for the treatment of patients with cancer.

Gene therapy for melanoma in humans

As melanoma evolves, it interacts with the immune system. Based on this immunobiology, there are now a number of rationally designed attempts to develop genetically modified melanoma vaccines. This article outlines immunologic and other strategies in gene therapy for melanoma and provides an overview of current clinical trials.

Phase I/IB study of immunization with autologous tumor cells transfected with the GM-CSF gene by particle-mediated transfer in patients with melanoma or sarcoma

The objective of this Phase I study is to assess the acute and long-term toxicities of intradermal vaccination of cancer patients with lethally-irradiated tumor cells that have been transfected by particle-mediated gene transfer (PMGT) with gold particles coated with human granulocyte-macrophage colony stimulating factor (GM-CSF) DNA in a plasmid expression vector. The GM-CSF DNA-coated gold particles are delivered to tumor cells using helium pressure with a hand held gene delivery device. Preclinical studies have demonstrated that vaccination of mice with irradiated, GM-CSF-transfected melanoma cells provided protection from subsequent challenges with non-irradiated, non-transfected tumor cells. Ongoing human tumor immunotherapy studies use patients' melanoma or renal carcinoma cells transfected with a retroviral vector containing GM-CSF cDNA as a vaccine to elicit anti-tumor immune responses. PMGT transfection, unlike retroviral transfection, does not require tumor cells to proliferate in vitro to undergo gene transfer. Instead, tumor tissue can be dissociated into small tissue clumps or cell aggregates and then immediately transfected using the gene gun. PMGT physically inserts the DNA without the need for cell surface interaction with viral components or exposure of the patient to viral antigens. As described in this protocol, fresh human sarcoma and melanoma specimens can be transfected with the GM-CSF DNA-coated gold particles with subsequent production of biologically active GM-CSF protein. In this study tumor tissue will be obtained from patients with melanoma or sarcoma. Tumor tissue will be dissociated, irradiated, and transfected with GM-CSF DNA by PMGT. In this ascending dosage study, two dose levels of GM-CSF DNA will be studied in 2 groups of 6 patients each. Patients will receive two intradermal injections of the irradiated, transfected tumor in a single extremity. On days 3 and 14 post-vaccination, patients will undergo surgical excision of the vaccination sites to assess GM-CSF production and infiltration of immune effector cells. On Day 25, patients will undergo DTH testing with intradermal injection in their opposite extremity of 5 x 10(6) irradiated non-transfected autologous tumor cells cryopreserved at the time of vaccine preparation. This injection site will be assessed on day 28 post-vaccination and surgical excision of the DTH testing site will be performed on day 28 if a positive reaction is noted. The patients will be observed for local and systemic toxicity on days 2, 3, 5, 8, 14, 25, and 28 after the vaccination. Restaging of the patients' disease and long term toxicity evaluation will be performed at 3, 6, and 12 months and then yearly.

The function of the soluble interleukin 6 (IL-6) receptor in vivo: sensitization of human soluble IL-6 receptor transgenic mice towards IL-6 and prolongation of the plasma half-life of IL-6

Interleukin 6 (IL-6) is considered an important mediator of acute inflammatory responses. Moreover, IL-6 functions as a differentiation and growth factor of hematopoietic precursor cells, B cells, T cells, keratinocytes, neuronal cells, osteoclasts, and endothelial cells. IL-6 exhibits its action via a receptor complex consisting of a specific IL-6 receptor (IL-6R) and a signal transducing subunit (gp130). Soluble forms of both receptor components are generated by shedding and are found in patients with various diseases such as acquired immune deficiency syndrome, rheumatoid arthritis, and others. The function of the soluble (s)IL-6R in vivo is unknown. Since human (h)IL-6 acts on human and murine target cells, but murine IL-6 on murine cells only, we constructed transgenic mice expressing the hsIL-6R. We report here that in the presence of hsIL-6R, mice are hypersensitized towards hIL-6, mounting an acute phase protein gene induction at significantly lower IL-6 dosages compared to control animals. Furthermore, in hsIL-6R transgenic mice, the detected acute phase response persists for a longer period of time. The IL-6/IL-6R complex prolongs markedly the Il-6 plasma half-life. Our results reinforce the role of the hsIL-6R as an agonistic protein, help to understand the function of the hsIL-6R in vivo, and highlight the significance of the receptor in the induction of the acute phase response.