Adenovector engineered interleukin-2 expressing autologous plasma cell vaccination after high-dose chemotherapy for multiple myeloma - a phase 1 study

Current challenges in the manufacture of clinical-grade autologous whole cell vaccines for hematological malignancies

Autologous whole cell vaccines use a patient's own tumor cells as a source of antigen to elicit an anti-tumor immune response in vivo. Recently, the authors conducted a systematic review of clinical trials employing these products in hematological cancers that showed a favorable safety profile and trend toward efficacy. However, it was noted that manufacturing challenges limit both the efficacy and clinical implementation of these vaccine products. In the current literature review, the authors sought to define the issues surrounding the manufacture of autologous whole cell products for hematological cancers. The authors describe key factors, including the acquisition, culture, cryopreservation and transduction of malignant cells, that require optimization for further advancement of the field. Furthermore, the authors provide a summary of pre-clinical work that informs how the identified challenges may be overcome. The authors also highlight areas in which future basic research would be of benefit to the field. The goal of this review is to provide a roadmap for investigators seeking to advance the field of autologous cell vaccines as it applies to hematological malignancies.

Immunotherapy in hematological malignancies: recent advances and open questions

Over recent years, tremendous advances in immunotherapy approaches have been observed, generating significant clinical progress. Cancer immunotherapy has been shown, in different types of blood cancers, to improve the overall survival of patients. Immunotherapy treatment of hematopoietic malignancies is a newly growing field that has been accelerating over the past years. Several US FDA approved drugs and cell-based therapies are being exploited in the late stage of clinical trials. This review attempt to highlight and discuss the numerous innovative immunotherapy approaches of hematopoietic malignancy ranging from nonmyeloablative transplantation, T-cell immunotherapy, natural killer cells and immune agonist to monoclonal antibodies and vaccination. In addition, a brief discussion on the future advances and accomplishments required to counterpart the current immunotherapeutic approaches for hematopoietic malignancies were also highlighted.

Safety and efficacy of autologous whole cell vaccines in hematologic malignancies: A systematic review and meta-analysis

Autologous cell vaccines use a patient's tumor cells to stimulate a broad antitumor response in vivo. This approach shows promise for treating hematologic cancers in early phase clinical trials, but overall safety and efficacy remain poorly described. We conducted a systematic review assessing the use of autologous cell vaccination in treating hematologic cancers. Primary outcomes of interest were safety and clinical response, with secondary outcomes including survival, relapse rate, correlative immune assays and health-quality related metrics. We performed a search of MEDLINE, Embase and the Cochrane Register of Controlled Trials including any interventional trial employing an autologous, whole cell product in any hematologic malignancy. Risk of bias was assessed using a modified Institute of Health Economics tool. Across 20 single arm studies, only 341 of 592 enrolled participants received one or more vaccinations. Primary reasons for not receiving vaccination included rapid disease progression/death and manufacturing challenges. Overall, few high-grade adverse events were observed. One death was reported and attributed to a GM-CSF producing allogeneic cell line co-administered with the autologous vaccine. Of 58 evaluable patients, the complete response rate was 21.0% [95% CI, 10.4%-37.8%)] and overall response rate was 35.8% (95% CI, 24.4%-49.0%). Of 97 evaluable patients for survival, the 5-years overall survival rate was 64.9% (95% CI, 52.6%-77.2%) and disease-free survival was 59.7% (95% CI, 47.7%-71.7%). We conclude that, in hematologic malignancies, based on limited available data, autologous cell vaccines are safe and display a trend towards efficacy but that challenges exist in vaccine manufacture and administration.

Genetically engineered mesenchymal stem cells: targeted delivery of immunomodulatory agents for tumor eradication

Cancer immunotherapy emerged as a novel therapeutic option that employs enhanced or amended native immune system to create a robust response against malignant cells. The systemic therapies with immune-stimulating cytokines have resulted in substantial dose-limiting toxicities. Targeted cytokine immunotherapy is being explored to overcome the heterogeneity of malignant cells and tumor cell defense with a remarkable reduction of systemic side effects. Cell-based strategies, such as dendritic cells (DCs), fibroblasts or mesenchymal stem cells (MSCs) seek to minimize the numerous toxic side effects of systemic administration of cytokines for extended periods of time. The usual toxicities comprised of a vascular leak, hypotension, and respiratory insufficiency. Natural and strong tropism of MSCs toward malignant cells made them an ideal systemic delivery vehicle to direct the proposed therapeutic genes to the vicinity of a tumor where their expression could evoke an immune reaction against the tumor. Compared with other methods, the delivery of cytokines via engineered MSCs is safer and renders a more practical, and promising strategy. Large numbers of genes code for cytokines have been utilized to reengineer MSCs as therapeutic cells. This review highlights the recent findings on the cytokine gene therapy for human malignancies by focusing on MSCs application in cancer immunotherapy.

Mesenchymal Stem Cells: The Past Present and Future

The biomedical applications of mesenchymal stem cells (MSCs) have gained expanding attention over the past three decades. MSCs are easily obtained from various tissue types (e.g. bone marrow, fat, cord blood, etc.), are capable of self-renewal, and could be induced to differentiate into several cell lineages for countless biomedical applications. In addition, when transplanted, MSCs are not detected by immune surveillance, thus do not lead to graft rejection. Moreover, they can home towards affected tissues and induce their therapeutic effect in a cell-base and/or a cell-free manner. These properties, and many others, have made MSCs appealing therapeutic cell candidates (for cell and/or gene therapy) in myriad clinical conditions. However, similar to any other therapeutic tool, MSCs still have their own limitations and grey areas that entail more research for better understanding and optimization. Herein, we present a brief overview of various pre-clinical/clinical applications of MSCs in regenerative medicine and discuss limitations and future challenges.

Lymphocytic infiltration in the cutaneous lymphoma microenvironment after injection of TG1042

Background

Primary cutaneous lymphomas (CLs), characterized by an accumulation of clonal T or B lymphocytes preferentially localized in the skin, have been successfully treated with interferons (IFNs) which counterbalance the Th2-immunosuppressive state associated with this pathology. In a phase I/II clinical trial, we correlated the local immune infiltrate and the anti-tumor effects of repeated intralesional administrations of an adenovirus vector expressing human interferon-gamma (IFN-g) termed TG1042, in patients with advanced primary cutaneous T-cell lymphomas (CTCL) or multilesional cutaneous B-cell lymphomas (CBCL).

Methods

For each patient, variation in time of specific lymphocyte populations, defined by immunohistochemical stainings, was assessed in biopsies of injected lesions. For each patient, the change in local immune response was associated with the patient’s objective response at the end of the study.

Results

Immunohistochemical analyses of biopsies indicate that infiltration of CD8⁺ T lymphocytes and of TIA-1⁺ cytotoxic T-cells in lesions injected with TG1042 correlates with clinical benefit.

Conclusions

These data suggest for the first time that a CD8⁺ cytotoxic infiltrate, induced by local expression of IFN-g correlates with a clinical response.

Trial registration

The phase I step (TG1042.01) does not have a registration number. The phase II step (TG1042.06) registration number was NCT00394693.

Novel immunotherapies

Multiple myeloma is still a fatal disease. Despite advances in high-dose chemotherapy and stem-cell transplantation and the development of novel therapeutics, relapse of the underlying disease remains the primary cause of treatment failure. Strategies for posttransplantation immunomodulation are desirable for eradication of remaining tumor cells. To this end, immunotherapy aimed at inducing myeloma-specific immunity in patients has been explored. Idiotype protein, secreted by myeloma cells, has been the primary target for immunotherapy as it is the best defined tumor-specific antigen. This chapter focuses on novel immunotherapies that are being developed to treat patients with myeloma. I will discuss potential myeloma antigens, antigen-specific T cells, and their function on myeloma tumor cells, and T-cell-based and antibody-based immunotherapies for myeloma. Furthermore, clinical studies of T-cell-based immunotherapy in the form of vaccination, allogeneic stem-cell transplantation and donor lymphocyte infusions, with or without donor vaccination using patient-derived idiotype, and future application of donor-derived or patient-derived, antigen-specific T-cell infusion in this disease are also discussed. Based on the specificity of the immune effector molecules and cells, immunotherapies with specific T cells or therapeutic antibodies may represent novel strategies for the treatment of multiple myeloma in the near future.

Improved Therapeutic Outcome Following Combination Immunogene Vaccination Therapy in Murine Myeloma

Increasing evidence suggests a role for immunologic vaccination and therapy in the management of minimal residual myeloma. We have previously demonstrated a synergistic effect of combining the Th1 stimulating cytokine IL-12 with the co-stimulatory molecule CD80 in murine myeloma vaccination therapy. We reasoned that the efficacy of such treatment might be further improved by incorporating additional gene products which enhance the function of antigen presenting cells. Studies were therefore conducted with murine myeloma BM1 cells expressing Flt3L (membrane bound or soluble forms) or GM-CSF and the IL-12 x CD80 combination. Single agent and combined therapeutic approaches were explored. All gene-modified BM1 cells, except BM1/IL-12 x CD80, developed tumors when subcutaneously injected into BALB/c mice. As prophylactic tumor vaccines, the combined use of gene-modified BM1/sFlt3L+GM-CSF+IL-12 x CD80 was most effective, providing 100% protection against subsequent parental BM1 tumor challenge. By comparison, only partial protection was observed with any single gene-engineered tumor vaccine. Notably, IL-12 x CD80 coexpressing BM1 cell vaccines were the most effective therapeutic vaccine in a minimal disease model. Such protective vaccination was achieved by stimulation of lymphocyte proliferation and enhancement of cytotoxic lymphocyte activity.

Clinical results of vaccine therapy for cancer: learning from history for improving the future

Active, specific immunotherapy for cancer holds the potential of providing an approach for treating cancers, which have not been controlled by conventional therapy, with very little or no associated toxicity. Despite advances in the understanding of the immunological basis of cancer vaccine therapy as well as technological progress, clinical effectiveness of this therapy has often been frustratingly unpredictable. Hundreds of preclinical and clinical studies have been performed addressing issues related to the generation of a therapeutic immune response against tumors and exploring a diverse array of antigens, immunological adjuvants, and delivery systems for vaccinating patients against cancer. In this chapter, we have summarized a number of clinical trials performed in various cancers with focus on the clinical outcome of vaccination therapy. We have also attempted to draw objective inferences from the published data that may influence the clinical effectiveness of vaccination approaches against cancer. Collectively the data indicate that vaccine therapy is safe, and no significant autoimmune reactions are observed even on long term follow-up. The design of clinical trials have not yet been optimized, but meaningful clinical effects have been seen in B-cell malignancies, lung, prostate, colorectal cancer, and melanoma. It is also obvious that patients with limited disease or in the adjuvant settings have benefited most from this targeted therapy approach. It is imperative that future studies focus on exploring the relationship between immune and clinical responses to establish whether immune monitoring could be a reliable surrogate marker for evaluating the clinical efficacy of cancer vaccines.

Viral Vaccines for Cancer Immunotherapy

The understanding that tumor cells can be recognized and eliminated by the immune system has led to intense interest in the development of cancer vaccines. Viruses are naturally occurring agents that cause human disease but have the potential to prevent disease when attenuated forms or subunits are used as vaccines before exposure. A large number of viruses have been engineered as attenuated vaccines for the expression of tumor antigens, immunomodulatory molecules, and as vehicles for direct destruction of tumor cells or expression of highly specific gene products. This article focuses on the major viruses that are under development as cancer vaccines, including the poxviruses, adenoviruses, adeno-associated viruses, herpesviruses, retroviruses, and lentiviruses. The biology supporting these viruses as vaccines is reviewed and clinical progress is reported.

Technical hurdles in a pilot clinical trial of combined B7-2 and GM-CSF immunogene therapy for glioblastomas and melanomas

OBJECTIVE

Malignant glioblastomas and melanomas continue to have a dismal prognosis despite advances in conventional therapy. This has led to investigations of novel treatment strategies including immunogene therapy. We report a pilot clinical trial of combined B7-2 and GM-CSF immunogene therapy for gliomas and melanomas and discuss technical hurdles encountered.

METHODS

Patients with recurrent malignant gliomas or medically refractory melanomas were vaccinated with irradiated autologous tumor cells transduced with B7-2 and GM-CSF genes using a retroviral vector. Patients were monitored for toxicity, inflammatory/immune reactions, and clinical status.

RESULTS

Vaccine preparation was attempted from 116 malignant glioma and 32 melanoma specimens. Adequate vaccines could only be prepared for five glioblastoma and three melanoma patients. Six patients (three recurrent glioblastomas and three melanomas) were actually vaccinated. Minor toxicities included flu-like symptoms (3/6), injection site erythema (4/6), and asymptomatic elevations in liver enzymes (3/6). Most patients showed evidence of an inflammatory response but specific anti-tumor immunity was not demonstrated. All six patients have died, although three patients with minimal residual disease at treatment had prolonged recurrence-free intervals after vaccination.

CONCLUSIONS

Combined B7-2 and GM-CSF immunogene therapy for glioblastomas and melanomas using autologous tumor cells has many technical pitfalls hindering large scale application and evaluation. As a result, this pilot study was too limited to draw meaningful conclusions regarding safety or anti-tumor immunity. While immunotherapy has been promising in pre-clinical studies, alternate strategies will be required to bring these benefits to patients.

Adenoviral-mediated transfer of human wild-type p53, GM-CSF and B7-1 genes results in growth suppression and autologous anti-tumor cytotoxicity of multiple myeloma cells in vitro

Multiple myeloma (MM) remains incurable despite the use of high-dose chemotherapy and stem cell transplantation. However, immunotherapy is expected to offer long-term disease control, or even possibly a cure. We have previously demonstrated the suppressive effect of a recombinant adenovirus carrying human wild-type p53, granulocyte-macrophage colony-stimulating factor, and B7-1 genes (Ad-p53/GM-CSF/B7-1) on the growth of laryngeal cancer cells. In the present study, we evaluated the effects of an Ad-p53/GM-CSF/B7-1-modified myeloma cell vaccine strategy aimed to induce apoptosis and to augment the immunogenicity of MM cells. Both MM cell lines and purified primary myeloma cells were infected with Ad-p53/GM-CSF/B7-1. High expression levels of these three genes were confirmed separately by Western blot, enzyme-linked immunosorbent assay (ELISA), and flow cytometry. When wild-type p53, GM-CSF and B7-1 genes were introduced, the growth of MM cells was inhibited via enhanced apoptosis and the immunogenicity of tumor cells was augmented. The combinatorial effect of these three genes on inducing cytotoxic T lymphocytes (CTLs) was more evident than that of p53 individually or any combinations of two (p53 plus GM-CSF or p53 plus B7-1). Furthermore, significant proliferation of autologous peripheral blood lymphocytes (PBLs) and specific cytotoxicity against autologous primary MM cells were induced in vitro. These results suggest that myeloma cell vaccination co-transferred with p53, GM-CSF and B7-1 genes may be a promising immunotherapeutic approach against MM.

Adenovirus as vehicle for anticancer genetic immunotherapy

Adenoviruses (Ads) are in the forefront of genetic immunization methods being developed against cancer. Their ability to elicit an effective immune response against tumor-associated antigens has been demonstrated in many model systems. Several clinical trials, which use Ad as vehicle for immunization, are already in progress. Preclinical studies have also demonstrated the efficacy of combining Ad-mediated immunization with adjuvants such as chemotherapeutic agents and cytokines. Issues related to sero-prevalence and safety of Ads, however, continue to pose a challenge and need to be addressed.

[Gene therapy: current situation and expectations]

En esta revisión se describe la situación actual de la terapia génica en enfermedades hematológicas, inmunológicas y en cáncer. En todas ellas el objetivo principal de los diversos abordajes de la terapia génica es el transducir los genes terapéuticos en la mayor parte de las células diana. A nivel de enfermedades crónicas o inmunológicas se requiere, asimismo, una expresión estable de los genes terapéuticos y a nivel de las células tumorales la eficiencia o porcentaje de células transducidas condiciona el éxito de los tratamientos. Por consiguiente, los vectores son uno de los elementos básicos para optimizar los abordajes y protocolos de terapia génica dado que sabemos que con el empleo de liposomas menos del 10% de las células van a ser transducidas, que con el empleo de retrovirus sólo se van a infectar células en replicación y que con los adenovirus va a haber una respuesta inflamatoria importante y una transducción transitoria del gen terapéutico. Asimismo se discuten los últimos abordajes en terapia génica del cáncer con virus de replicación selectiva, genes suicidas, etc.

Decreased tumorigenic potential of EphA2-overexpressing breast cancer cells following treatment with adenoviral vectors that express EphrinA1

The EphA2 receptor tyrosine kinase is frequently overexpressed in invasive breast cancer cells. Moreover, these malignant cells have unstable cell-cell contacts, which preclude EphA2 from interacting with its ligand, EphrinA1, which is anchored to the membrane of adjacent cells. This defect is important because ligand binding causes EphA2 to transmit signals that negatively regulate tumor cell growth and survival, whereas the absence of ligand binding favors these same behaviors. In our present study, human adenoviral type 5 (HAd) vectors were engineered to express secreted-forms of EphrinA1. These vectors were used to infect MDA-MB-231 human breast cancer cells, or MCF-10A human breast epithelial cells providing matched controls. Infection with HAd-EphrinA1-Fc (HAd vector expressing extracellular domain of human EphrinA1 attached to Fc portion of human IgG1 heavy chain) caused increased EphA2 activation and turnover and consequently decreased tumor cell viability in soft agar assays. Consistent with this observation, infection of MDA-MB-231 cells with HAd-EphrinA1-Fc prevented tumor formation in xenograft models. Furthermore, therapeutic modeling via intratumoral inoculation revealed that HAd-EphrinA1-Fc significantly inhibited subsequent tumor growth as compared to matched controls. These results suggest that targeting of EphA2 with adenoviral vectors may have therapeutic value.

Human cancer gene therapy with cytokine gene-modified cells

Cytokines can impede tumour growth and activate innate and adaptive immune responses, leading to elimination of cancer cells. For many years, it was believed that systemic administration of recombinant cytokines might become a standard treatment of different cancer types. However, due to a high toxicity of therapeutic doses and a low efficacy, even in combination with chemotherapy, this strategy is generally not accepted. On the other hand, cancer gene therapy approaches utilising cells modified with cytokine genes seem to represent a novel promising approach. For the last decade, numerous Phase I and II clinical trials evaluating different therapies based on cytokine gene-modified cells have been carried out. In the early studies, several strategies have been shown to improve clinical outcomes and induce strong antitumour immune responses. Recently, a few prospective, randomised, Phase III clinical trials have been initiated in order to finally determine the efficacy of particular cancer immunogene therapy strategies. This article reviews the present status and perspectives of clinical trials of cancer immunotherapies utilising cytokine gene-modified cells.

Adenovirus-mediated intralesional interferon-γ gene transfer induces tumor regressions in cutaneous lymphomas

Primary cutaneous lymphomas have been successfully treated with interferons (IFNs), counterbalancing the T-helper 2 (Th2)-skewing state. We undertook a phase 1, open-label, dose-escalating trial of repeated intratumoral administration of TG1042 in patients with advanced primary cutaneous T-cell lymphomas (CTCLs) and multilesional cutaneous B-cell lymphomas (CBCLs). TG1042 is a third-generation, nonreplicating human adenovirus vector containing a human IFN-γ cDNA insert. Nine patients (7 CTCL, 2 CBCL) were enrolled at the following TG1042 doses: 3 × 109, 3 × 1010, and 3 × 1011 total particles. Local clinical response was observed in 5 of 9 treated patients (3 patients with complete response [CR] and 2 patients with partial response [PR]). Out of these, 3 patients showed systemic CR with the clearance of other noninjected skin lesions. Clinical response lasted for a median of 3 months (range, 1-6 months). Adverse events were mostly of grades 1 and 2. Seven of 9 treated patients had a detectable TG1042-derived IFN-γ message in injected lesions after the first treatment cycle. A TG1042-IFN-γ message was also detectable after several treatment cycles. We demonstrate the induction of humoral immune response to lymphoma tumor-antigen se70-2 after treatment. Our study shows that intralesional injections of TG1042 are both safe and well tolerated. (Blood. 2004;104:1631-1638)

Cancer immunogene therapy: a review

Although immunotherapy has long held out promise as a specific, potent approach to cancer therapy, clinical applications have been unrewarding to date. However, advances in gene transfer technology and basic immunology have opened new avenues to stimulate antitumor immune responses including immunogene therapy. Many different approaches to immunogene therapy have been identified. These include transferring genes encoding proinflammatory proteins to tumor cells, suppressing immunosuppressive gene expression, and transferring proinflammatory genes and/or tumor antigen genes to professional antigen-presenting cells. In some cases, genes are transferred to tumor or antigen-presenting cells in situ. In others, gene transfer is performed ex vivo as part of preparing an anticancer vaccine. We discuss the underlying approach, relative success, and clinical application of various cancer immunogene therapy strategies, paying particular attention to immunogene therapy vaccines. Large numbers of preclinical studies have been reported, but only scattered clinical trial results have appeared in the literature. Although very successful preclinically, the ideal cancer immunogene therapy approach remains to be determined and will likely vary with tumor type. Clinical impact may be improved in the future as treatment protocols are refined.

Adenoviruses in oncology: a viable option?

The feasibility of using adenoviruses for gene therapy has been under close scrutiny recently, as it has become clear that significant toxicity can result from the strong immune response created by intravenous administration of large doses of first generation adenovirus vectors. This suggests that other vectors could be more useful for treatment of metabolic and hereditary disease, where widespread transduction is often necessary for effective gene replacement, and the viability of target cells is important. However, promising recent results in human cancer trials have confirmed that adenoviruses can be very useful in oncology. For cancer treatment, the unparalleled transduction efficacy of adenovirus in dividing and dormant cells is a major benefit. As the goal in cancer gene therapy is to kill infected tumour cells, long-term transgene expression is not necessary. In addition, the immune response generated against infected cells could be useful for eradicating uninfected tumour. Importantly, more than 670 cancer patients have been treated with adenovirus intratumorally, intra-arterially, intraperitoneally and intravenously with very manageable adverse effects and no unexpected severe or lethal toxicity. Currently, the most promising approaches are based on replication-competent agents that allow efficient tumour penetration because of their capacity for tissue-specific replication. In addition to transcriptional control, it is becoming clear that targeting is necessary for efficient tumour transduction and less infection of normal tissues. Exciting results are anticipated when the first selectively replicating targeted adenoviruses go to clinical trials. In conclusion, intense gene therapy and virological research have suggested that while other vectors could be more useful for treatment of hereditary disease, adenoviruses are highly promising and safe agents for oncology, as suggested in a number of early phase clinical trials.

Significant antitumor effects obtained by autologous tumor cell vaccine engineered to secrete interleukin (IL)-12 and IL-18 by means of the EBV/lipoplex

The EBV/lipoplex is a nonviral gene delivery system composed of a cationic lipid and Epstein-Barr virus (EBV)-based plasmid vector that carries the EBV oriP and EBV nuclear antigen 1 (EBNA1) gene. Because the EBNA1 supports retention, nuclear localization, and transcriptional upregulation of the oriP-bearing plasmid, cells transfected with the EBV/lipoplex express the transgene at a very high level. We hypothesized that tumor cells genetically manipulated with the EBV/lipoplex may be used as a tumor vaccine without drug selection, strongly contributing to immunotherapy of patients with malignancies. The cytokines interleukin (IL)-12 and IL-18 exert a variety of immune-regulatory functions including interferon (IFN)-gamma production and cytotoxic T lymphocyte (CTL) and natural killer (NK) activation. Here, we investigated the possible therapeutic effects of an autologous tumor cell vaccine in the B16 melanoma model. The vaccine was engineered to secrete IL-12 and IL-18 by means of the EBV/lipoplex. B16 cells were subcutaneously implanted into syngenic mice followed by repetitive immunization with irradiated B16 cells that had been transfected 3 days earlier by TFL2-3, a novel cationic lipid, with EBV-plasmid vectors encoding IL-12 and/or IL-18 genes (B16/mIL-12, B16/mIL-18, and B16/mIL-12+mIL-18). The mice vaccinated with B16/mIL-12 underwent strong tumor suppression accompanied by a high IFN-gamma production. Both CTL and NK activities were significantly elevated in these mice. When the tumor cell vaccine was prepared by means of conventional (non-EBV) plasmid vectors combined with the same cationic lipid, the therapeutic outcome was not as good, suggesting the superiority of the EBV-based plasmid in engineering these types of tumor vaccines. Vaccination with B16/mIL-18 was not effective in suppressing tumors, whereas B16/mIL-12+mIL-18 showed comparable antitumor therapeutic validity as B16/mIL-12 did. When IFN-gamma mutant (IFN-gamma(-/-) mice were treated, B16/mIL-12 vaccine did not show any therapeutic activity, suggesting the necessity of IFN-gamma in the anti-melanoma immune responses. In contrast, the antitumor effect was not affected by NK depletion in mice that received repetitive injections with anti-asialo GM1 antibody. Furthermore, vaccination with B16/mIL-12 significantly suppressed pulmonary metastases in mice that had been intravenously injected with parental B16. Our results suggest that the EBV/lipoplex is quite useful in generating an autologous tumor cell vaccine and that IL-12 is an important component of the vaccine.

Immunotherapy of metastatic melanoma by intratumoral injections of Vero cells producing human IL-2: phase II randomized study comparing two dose levels

BACKGROUND

Systemic IL-2 has shown some activity in metastatic melanoma, but its use is severely limited by toxicity. TG2001 is a product in which the human IL-2 cDNA was incorporated into the genome of Vero cells, a monkey fibroblast cell line. The goal of this intratumorally applied therapy was to create an antitumor immune response stimulated by xeno-antigens and local production of IL-2 in the close vicinity of tumor-specific antigens. TG2001 was reported to have a good safety profile in two previous dose-escalating phase I studies performed in 18 patients with various solid tumors, with encouraging clinical responses in three patients. The objectives of this study were to evaluate the tolerance and incidence of tumor regression in patients with metastatic melanoma, following repeated administration of Vero-IL-2 cells.

PATIENTS AND METHODS

This was on open-label, randomized phase II study comparing two doses of Vero-IL-2, 5x10(5) and 5x10(6) cells. Twenty-eight patients with metastatic melanoma were enrolled in the study, 14 in each treatment group. Patients received TG2001 by intratumoral injection on days 1, 3, and 5 every 4 weeks for four cycles, and every 8 weeks thereafter, until evidence of progressive disease (PD). Criteria for patient selection included histologically proven metastatic melanoma, with one tumor accessible for product administration, and at least another tumor site for response assessment. Evaluation included tumor measurements, humoral and T cell-mediated local and systemic immune response, humoral response to Vero cells, adverse events and standard laboratory parameters.

RESULTS

None of the patients achieved a confirmed objective response. Stable disease (SD) was seen in six (43%) and eight patients (57%) at the 5x10(5) and the 5x10(6) dose level, respectively. Two patients, one in each group, died during the study (i.e., within 1 month after the last injection) due to PD. Three patients exhibited antibody responses to Vero cells. T-cell immunity, serum cytokine levels and cytokine mRNA expression in tumor biopsies did not show meaningful alterations after therapy, except for a trend toward an increase in intratumoral TH2 cytokine (IL-4 and/or IL-10) levels. The study drug was well tolerated at both dose levels and side effects mainly consisted of injection site pain and erythema, and pyrexia.

CONCLUSION

The intratumoral administration of TG2001 was generally well tolerated in patients with metastatic melanoma, and transient disease stabilization was observed in 50% of patients.

Controversy in multiple myeloma transplants: tandem autotransplants and mini-allografts

Autologous stem cell transplantation appears to enhance outcome in multiple myeloma patients. To improve upon these results, various groups have utilized tandem autografts, as well as used reduced-conditioning allogeneic stem cell transplantation. These two approaches, discussed herein, have been promising. Inherent patient selection, however, appears to play a role and much of the data have not yet been subjected to peer-review scrutiny. At present, these strategies remain investigational and cannot be considered the standard-of-care for multiple myeloma patients.