Phase I/II study of immunotherapy using autologous tumor lysate-pulsed dendritic cells in patients with metastatic renal cell carcinoma

Dual-mRNA Delivery Using Tumor Cell Lysate-Based Multifunctional Nanoparticles as an Efficient Colon Cancer Immunogene Therapy

Background

Messenger RNA (mRNA)-based immunogene therapy holds significant promise as an emerging tumor therapy approach. However, the delivery efficiency of existing mRNA methods and their effectiveness in stimulating anti-tumor immune responses require further enhancement. Tumor cell lysates containing tumor-specific antigens and biomarkers can trigger a stronger immune response to tumors. In addition, strategies involving multiple gene therapies offer potential optimization paths for tumor gene treatments.

Methods

Based on the previously developed ideal mRNA delivery system called DOTAP-mPEG-PCL (DMP), which was formed through the self-assembly of 1.2-dioleoyl-3-trimethylammonium-propane (DOTAP) and methoxypoly (ethylene glycol)-b-poly (ε-caprolactone) (mPEG-PCL), we introduced a fused cell-penetrating peptide (fCPP) into the framework and encapsulated tumor cell lysates to form a novel nanovector, termed CLSV system (CLS: CT26 tumor cell lysate, V: nanovector). This system served a dual purpose of facilitating the delivery of two mRNAs and enhancing tumor immunogene therapy through tumor cell lysates.

Results

The synthesized CLSV system had an average size of 241.17 nm and a potential of 39.53 mV. The CLSV system could not only encapsulate tumor cell lysates, but also deliver two mRNAs to tumor cells simultaneously, with a transfection efficiency of up to 60%. The CLSV system effectively activated the immune system such as dendritic cells to mature and activate, leading to an anti-tumor immune response. By loading Bim-encoded mRNA and IL-23A-encoded mRNA, CLSV/Bim and CLSV/IL-23A complexes were formed, respectively, to further induce apoptosis and anti-tumor immunity. The prepared CLSV/dual-mRNA complex showed significant anti-cancer effects in multiple CT26 mouse models.

Conclusion

Our results suggest that the prepared CLSV system is an ideal delivery system for dual-mRNA immunogene therapy.

The role of macrophages-mediated communications among cell compositions of tumor microenvironment in cancer progression

Recent studies have revealed that tumor-associated macrophages are the most abundant stromal cells in the tumor microenvironment and play an important role in tumor initiation and progression. Furthermore, the proportion of macrophages in the tumor microenvironment is associated with the prognosis of patients with cancer. Tumor-associated macrophages can polarize into anti-tumorigenic phenotype (M1) and pro-tumorigenic phenotype (M2) by the stimulation of T-helper 1 and T-helper 2 cells respectively, and then exert opposite effects on tumor progression. Besides, there also is wide communication between tumor-associated macrophages and other immune compositions, such as cytotoxic T cells, regulatory T cells, cancer-associated fibroblasts, neutrophils and so on. Furthermore, the crosstalk between tumor-associated macrophages and other immune cells greatly influences tumor development and treatment outcomes. Notably, many functional molecules and signaling pathways have been found to participate in the interactions between tumor-associated macrophages and other immune cells and can be targeted to regulate tumor progression. Therefore, regulating these interactions and CAR-M therapy are considered to be novel immunotherapeutic pathways for the treatment of malignant tumors. In this review, we summarized the interactions between tumor-associated macrophages and other immune compositions in the tumor microenvironment and the underlying molecular mechanisms and analyzed the possibility to block or eradicate cancer by regulating tumor-associated macrophage-related tumor immune microenvironment.

Engineered porous/hollow Burkholderia pseudomallei loading tumor lysate as a vaccine

Due to its size, shape, and inherent expression of pathogen-associated molecular patterns and invasion-assistant adhesion proteins, Burkholderia pseudomallei can easily attach to, and then be internalized by, dendritic cells (DCs), leading to more efficient antigen cross-presentation if modified as carrier. Herein, we engineered Burkholderia pseudomallei as a porous/hollow carrier (SB) for loading tumor lysates (L) and adjuvant CpG (C) to be used as a tumor vaccine (SB-LC). We found that the adhesion proteins of Burkholderia pseudomallei promote internalization of the SB-LC vaccine by DCs, and result in enhanced DC maturation and antigen cross-presentation. SB-LC induces robust cellular and humoral antitumor responses that synergistically inhibit tumor growth with minimal adverse side effects in several tumor models. Moreover, SB-LC vaccination reverses the immunosuppressive tumor microenvironment, apparently as a result of CD8⁺-induced tumor ferroptosis. Thus, SB-LC is a potential model tumor vaccine for translating into a clinically viable treatment option.

The role of dendritic cells in tumor microenvironments and their uses as therapeutic targets

Dendritic cells (DC), which consist of several different subsets, specialize in antigen presentation and are critical for mediating the innate and adaptive immune responses. DC subsets can be classified into conventional, plasmacytoid, and monocyte-derived DC in the tumor microenvironment, and each subset plays a different role. Because of the role of intratumoral DCs in initiating antitumor immune responses with tumor-derived antigen presentation to T cells, DCs have been targeted in the treatment of cancer. By regulating the functionality of DCs, several DC-based immunotherapies have been developed, including administration of tumor-derived antigens and DC vaccines. In addition, DCs participate in the mechanisms of classical cancer therapies, such as radiation therapy and chemotherapy. Thus, regulating DCs is also important in improving current cancer therapies. Here, we will discuss the role of each DC subset in antitumor immune responses, and the current status of DC-related cancer therapies.

Two Decades of Global Progress in Authorized Advanced Therapy Medicinal Products: An Emerging Revolution in Therapeutic Strategies

The introduction of advanced therapy medicinal products (ATMPs) to the global pharma market has been revolutionizing the pharmaceutical industry and has opened new routes for treating various types of cancers and incurable diseases. In the past two decades, a noticeable part of clinical practices has been devoting progressively to these products. The first step to develop such an ATMP product is to be familiar with other approved products to obtain a general view about this industry trend. The present paper depicts an overall perspective of approved ATMPs in different countries, while reflecting the degree of their success in a clinical point of view and highlighting their main safety issues and also related market size as a whole. In this regard, published articles regarding safety, efficacy, and market size of approved ATMPs were reviewed using the search engines PubMed, Scopus, and Google Scholar. For some products which the related papers were not available, data on the relevant company website were referenced. In this descriptive study, we have introduced and classified approved cell, gene, and tissue engineering-based products by different regulatory agencies, along with their characteristics, manufacturer, indication, approval date, related regulatory agency, dosage, product description, price and published data about their safety and efficacy. In addition, to gain insights about the commercial situation of each product, we have gathered accessible sale reports and market size information that pertain to some of these products.

Recent Advances in Good Manufacturing Practice-Grade Generation of Dendritic Cells

Dendritic cells (DCs) are pivotal regulators of immune responses, specialized in antigen presentation and bridging the gap between the innate and adaptive immune system. Due to these key features, DCs have become a pillar of the continuously growing field of cellular therapies. Here we review recent advances in good manufacturing practice strategies and their individual specificities in relation to DC production for clinical applications. These take into account both small-scale experimental approaches as well as automated systems for patient care.

Antitumour dendritic cell vaccination in a priming and boosting approach

Mobilizing antitumour immunity through vaccination potentially constitutes a powerful anticancer strategy but has not yet provided robust clinical benefits in large patient populations. Although major hurdles still exist, we believe that currently available strategies for vaccines that target dendritic cells or use them to present antitumour antigens could be integrated into existing clinical practice using prime-boost approaches. In the priming phase, these approaches capitalize on either standard treatment modalities to trigger in situ vaccination and release tumour antigens or vaccination with dendritic cells loaded with tumour lysates or patient-specific neoantigens. In a second boost phase, personalized synthetic vaccines specifically boost T cells that were triggered during the priming phase. This immunotherapy approach has been enabled by the substantial recent improvements in dendritic cell vaccines. In this Perspective, we discuss these improvements, highlight how the prime-boost approach can be translated into clinical practice and provide solutions for various anticipated hurdles.

Nano and Microparticle Emerging Strategies for Treatment of Autoimmune Diseases: Multiple Sclerosis and Type 1 Diabetes

Autoimmune diseases affect 10% of the world's population, and 1 in 200 people worldwide suffer from either multiple sclerosis (MS) or type 1 diabetes (T1D). While the targeted organ systems are different, MS and T1D share similarities in terms of autoreactive immune cells playing a critical role in pathogenesis. Both diseases can be managed only symptomatically without curative remission, and treatment options are limited and non-specific. Most current therapies cause some degree of systemic immune suppression, leaving the patients susceptible to opportunistic infections and other complications. Thus, there is considerable interest in the development of immunotherapies not associated with generalized immune suppression for these diseases. This review presents current and preclinical strategies for MS and T1D treatment, emphasizing those aimed to modulate the immune response, including the most recent strategies for tolerance induction. A central focus is on the emerging approaches using nano- and microparticle platforms, their evolution as immunotherapeutic carriers, including those incorporating specific antigens to induce tolerance and reduce unwanted generalized immune suppression.

A novel T-cell epitope in the transmembrane region of the hepatitis B virus envelope protein responds upon dendritic cell expansion

Restoring antiviral immunity is a promising immunotherapeutic approach to the treatment of chronic hepatitis B virus (HBV) infection. Dendritic cells play a crucial role in triggering antiviral immunity. In this study, we identified immunodominant epitopes prevalent in CD8⁺ T cell responses. We characterized the hierarchy of HBV epitopes targeted by CD8⁺ T cells following autologous monocyte-derived dendritic cell (moDC) expansion in HBV-infected subjects with distinct disease stages: treatment-naïve (TN group, n = 168), treatment with complete virological response (TR group, n = 72), and resolved HBV infection (RS group, n = 28). T cell responses against 32 HBV epitopes were measured upon moDC expansion. Several subdominant epitopes that triggered HBV-specific CD8⁺ T cell responses were identified. These epitopes’ responses varied in individuals with different disease stages. Moreover, the most immunodominant and immunoprevalent epitope included the envelope residues 256-270 (Env_256-270), corresponding to amino acid residues 93-107 in the small HBV surface protein (SHBs) across three patient groups. The frequency of Env_256-270-specific interferon-γ-producing T cells was the highest in the RS group and the lowest in the TN group. In addition, individuals with HLA-A*02:03/02:06/02:07 were capable of responding to Env_256-270. Env_256-270-specific CD8⁺ T cells tolerated amino acid variations within the epitope detected in HBV genotypes B and C. This suggests that Env_256-270 in SHBs is crucial in HBV-specific T cell immunity following autologous moDC expansion. It might be a potential target epitope for dendritic-cell-based immunotherapy for CHB patients with complete viral suppression by long-term NAs treatment.

PEGylated tumor cell membrane vesicles as a new vaccine platform for cancer immunotherapy

Despite the promise and advantages of autologous cancer cell vaccination, it remains challenging to induce potent anti-tumor immune responses with traditional immunization strategies with whole tumor cell lysate. In this study, we sought to develop a simple and effective approach for therapeutic vaccination with autologous whole tumor cell lysate. Endogenous cell membranes harvested from cancer cells were formed into PEGylated nano-vesicles (PEG-NPs). PEG-NPs exhibited good serum stability in vitro and draining efficiency to local lymph nodes upon subcutaneous administration in vivo. Vaccination with PEG-NPs synthesized from murine melanoma cells elicited 3.7-fold greater antigen-specific cytotoxic CD8+ T lymphocyte responses, compared with standard vaccination with freeze-thawed lysate in tumor-bearing mice. Importantly, in combination with anti-programmed death-1 (αPD-1) IgG immunotherapy, PEG-NP vaccination induced 4.2-fold higher frequency of antigen-specific T cell responses (P < 0.0001) and mediated complete tumor regression in 63% of tumor-bearing animals (P < 0.01), compared with FT lysate + αPD-1 treatment that exhibited only 13% response rate. In addition, PEG-NPs + αPD-1 IgG combination immunotherapy protected all survivors against a subsequent tumor cell re-challenge. These results demonstrate a general strategy for eliciting anti-tumor immunity using endogenous cancer cell membranes formulated into stable vaccine nanoparticles.

Identification of patient-specific and tumor-shared T cell receptor sequences in renal cell carcinoma patients

A major requirement for cancer immunotherapy is the development of biomarkers for prognosis and for monitoring therapy response. In an attempt to evaluate the immune response of renal cell carcinoma (RCC) patients, tumor lesions and / or blood samples from 12 RCC patients underwent deep T cell receptor (TCR) sequencing. Despite the low number of samples, different TCR distribution patterns could be detected. Most of the RCC patients presented "patient-specific" TCR sequences, and those clonotypes were present at higher frequency in tumor lesions suggesting a specific extravasation from the blood. Comparison among the tumor samples revealed also "patient-shared" TCR patterns. Indeed, a central core of 16 different TCRs were shared by 3 patients, whereas other 6 patients shared between 4 and 6 TCR sequences, with two sub-groups sharing 12 to 17 different clonotypes. The relative frequencies of shared clonotypes were very different varying from < 1% to a maximum of 37% of the total TCR repertoire. These data confirm the presence of tumor-specific TCR within the cancer tissue and suggest the existence of shared epitopes among different patients that might be used as targets for tumor immunotherapy.

An antigen-specific semi-therapeutic treatment with local delivery of tolerogenic factors through a dual-sized microparticle system blocks experimental autoimmune encephalomyelitis

Antigen-specific treatments are highly desirable for autoimmune diseases in contrast to treatments which induce systemic immunosuppression. A novel antigen-specific therapy has been developed which, when administered semi-therapeutically, is highly efficacious in the treatment of the mouse model for multiple sclerosis, experimental autoimmune encephalomyelitis (EAE). The treatment uses dual-sized, polymeric microparticles (dMPs) loaded with specific antigen and tolerizing factors for intra- and extra-cellular delivery, designed to recruit and modulate dendritic cells toward a tolerogenic phenotype without systemic release. This approach demonstrated robust efficacy and provided complete protection against disease. Therapeutic efficacy required encapsulation of the factors in controlled-release microparticles and was antigen-specific. Disease blocking was associated with a reduction of infiltrating CD4⁺ T cells, inflammatory cytokine-producing pathogenic CD4⁺ T cells, and activated macrophages and microglia in the central nervous system. Furthermore, CD4⁺ T cells isolated from dMP-treated mice were anergic in response to disease-specific, antigen-loaded splenocytes. Additionally, the frequency of CD86^hiMHCII^hi dendritic cells in draining lymph nodes of EAE mice treated with Ag-specific dMPs was reduced. Our findings highlight the efficacy of microparticle-based drug delivery platform to mediate antigen-specific tolerance, and suggest that such a multi-factor combinatorial approach can act to block autoimmunity.

Immunological Analysis and Generation of Dendritic Cells From Lavage Fluid Obtained by Cell-Free and Concentrated Ascites Reinfusion Therapy

Cell-free and concentrated ascites reinfusion therapy (CART) is an effective treatment for patients with refractory ascites. Cellular components such as cancer cells and blood cells are removed and discarded. The aim of this study was to investigate the alteration of immune cells in lavage fluid and the generation of dendritic cells (DCs) from lavage fluid obtained by CART. Flow cytometry analysis showed a trend toward immunosuppression and impairment in innate immunity in lavage fluid. Immature DCs with downregulation of CD14 and increased antigen-uptake were generated by culturing monocytes obtained from lavage fluid with GM-CSF and IL4. Following the culture with proinflammatory mediators, mature DCs with upregulation of CD83 and potent ability of T cell activation were induced. There were no significant phenotypical or functional differences between these DCs and DCs derived from peripheral blood, indicating lavage fluid might be employed for an alternative cellular source for the generation of DCs.

Past, present and forecast of transfusion medicine: What has changed and what is expected to change?

Blood transfusion is the second most used medical procedures in health care systems worldwide. Over the last few decades, significant changes have been evolved in transfusion medicine practices. These changes were mainly needed to increase safety, efficacy, and availability of blood products as well as reduce recipients' unnecessary exposure to allogeneic blood. Blood products collection, processing, and storage as well as transfusion practices throughout all patient populations were the main stream of these changes. Health care systems across the world have adopted some or most of these changes to reduce transfusion risks, to improve overall patients' outcome, and to reduce health care costs. In this article, we are going to present and discuss some of these recent modifications and their impact on patients' safety.

The Efficacy of CIK-Based Immunotherapies for Advanced Solid Tumors

OBJECTIVE

To investigate the efficacy of cytokine-induced killer cell-based immunotherapies in patients with advanced malignant solid tumors and the difference in clinical efficiency among 3 kinds of cytokine-induced killer cell-based immunotherapies.

METHODS

One hundred forty-six cases with advanced solid tumor, 230 cycles of cytokine-induced killer cell-based immunotherapies, were involved in this study. T-lymphocyte subsets, carcinoembryonic antigen, and adverse reactions were recorded.

RESULTS

CD3⁺ T lymphocyte, Th, NKT, and Th/Tc were increased after cytokine-induced killer cell-based treatment, from 55.67 ± 3.64 to 84.12 ± 5.15, 26.56 ± 4.47 to 42.76 ± 3.68, 1.82 ± 0.58 to 7.08 ± 0.92, 0.79 ± 3.64 to 1.35 ± 0.20, respectively ( P < .001). Carcinoembryonic antigen was decreased from 398.39 ± 219.16 to 127.26 ± 153.41 ( P < .001). Difference values were greater than 0 ( P < .001). Difference value of carcinoembryonic antigen was obviously less than 0 ( P < .001). There was no obvious difference in all variations between cytokine-induced killer cell and DC+CIK groups ( P > .05). The highest amount of CD3⁺ T lymphocyte and Th was recorded after at least 4 cycles of immunotherapy. And CD8⁺ T/CD4⁺ T also began to decrease after 4 cycles of immunotherapy. Difference value of T lymphocyte and Tc of patients with surgery is higher than that of patients without surgery.

CONCLUSION

Cytokine-induced killer cell-based immunotherapy is capable of increasing T-lymphocyte subsets, recovering cellular immunity without severe side effects, and is suitable for different kinds of solid cancer. Clinical efficiency of cytokine-induced killer cell-based immunotherapy is influenced by many factors such as surgery, stage.

Current Status and Perspective of Immunotherapy in Gastrointestinal Cancers

Cancer immunotherapy is at dawn of the Renaissance after the Medieval Dark Ages. Recent advances of understanding tumor immunology and molecular drug development are leading us to the epoch of cancer immunotherapy. Some types of immunotherapy have shown to provide survival benefit for patients with solid tumors such as malignant melanoma, renal cell carcinoma, or non-small cell lung cancer. Several studies have suggested that immune checkpoint inhibition might be effective in some patients with gastrointestinal cancers. However, the era of cancer immunotherapy in gastrointestinal cancers is still in an inchoate stage. Here we briefly review the current status and perspective of immunotherapeutic approaches in patients with gastrointestinal cancers.

Recent advances in immuno-oncology and its application to urological cancers

Recent advances in immuno-oncology have the potential to transform the practice of medical oncology. Antibodies directed against negative regulators of T-cell function (checkpoint inhibitors), engineered cell therapies and innate immune stimulators, such as oncolytic viruses, are effective in a wide range of cancers. Immune'based therapies have had a clinically meaningful impact on the treatment of advanced melanoma, and the lessons regarding use of single agents and combinations in melanoma may be applicable to the treatment of urological cancers. Checkpoint inhibitors, cytokine therapy and therapeutic vaccines are already showing promise in urothelial bladder cancer, renal cell carcinoma and prostate cancer. Critical areas of future immuno-oncology research include the prospective identification of patients who will respond to current immune-based cancer therapies and the identification of new therapeutic agents that promote immune priming in tumours, and increase the rate of durable clinical responses.

A phase I/IIa study of adjuvant immunotherapy with tumour antigen-pulsed dendritic cells in patients with hepatocellular carcinoma

Background:

To date, no adjuvant treatment has been shown to have a clear benefit in patients with hepatocellular carcinoma (HCC). In this prospective phase I/IIa study, we evaluated the safety and efficacy of adjuvant dendritic cell (DC) therapy in HCC patients who received primary treatment for HCC.

Methods:

Twelve HCC patients who had no viable tumour after primary treatments were included. Dendritic cell vaccines pulsed with cytoplasmic transduction peptide-attached alpha-fetoprotein, glypican-3 and melanoma-associated antigen 1 recombinant fusion proteins were injected subcutaneously near to inguinal lymph nodes. Adverse effects, time to progression (TTP), and associated immune responses were evaluated after DC vaccination.

Results:

Nine of 12 patients had no tumour recurrence up to 24 weeks after DC vaccination. Among a total of 144 adverse events, 129 events (89.6%) were regarded as adverse drug reactions, all of which were grade 1 or 2. The majority of patients showed enhanced anti-tumour immune responses after DC vaccination. Recurrence-free patients exhibited relatively stronger anti-tumour immune responses than patients who developed recurrence after DC vaccination, as evidenced by lymphocyte proliferation and IFN-γ ELISPOT assays. The median time of TTP was 36.6 months in the DC-vaccination group and 11.8 months in the control group (hazard ratio, 0.41; 95% confidence interval, 0.18–0.95; P=0.0031 by log-rank test).

Conclusions:

Adjuvant DC vaccine for HCC was safe and well tolerated in phase I/IIa study, and preliminary efficacy data are encouraging to warrant further clinical study in patients with HCC after primary treatments.

Immunotherapy in Metastatic Renal Cell Carcinoma: A Comprehensive Review

Localized renal cell carcinoma (RCC) is often curable by surgery alone. However, metastatic RCC is generally incurable. In the 1990s, immunotherapy in the form of cytokines was the mainstay of treatment for metastatic RCC. However, responses were seen in only a minority of highly selected patients with substantial treatment-related toxicities. The advent of targeted agents such as vascular endothelial growth factor tyrosine kinase inhibitors VEGF-TKIs and mammalian target of rapamycin (mTOR) inhibitors led to a change in this paradigm due to improved response rates and progression-free survival, a better safety profile, and the convenience of oral administration. However, most patients ultimately progress with about 12% being alive at 5 years. In contrast, durable responses lasting 10 years or more are noted in a minority of those treated with cytokines. More recently, an improved overall survival with newer forms of immunotherapy in other malignancies (such as melanoma and prostate cancer) has led to a resurgence of interest in immune therapies in metastatic RCC. In this review we discuss the rationale for immunotherapy and recent developments in immunotherapeutic strategies for treating metastatic RCC.

Microencapsulation of tumor lysates and live cell engineering with MIP-3α as an effective vaccine

The combination of several potential strategies so as to develop new tumor vaccines is an attractive field of translational medicine. Pulsing tumor lysates with dendritic cells (DCs), in-vivo attraction of DCs by macrophage inflammatory protein 3α (MIP-3α), and reversion of the tumor suppressive microenvironment have been tested as strategies to develop tumor vaccines. In this study, we generated an alginate microsphere (named PaLtTcAdMIP3α) that encapsulated tumor lysates, live tumor cells engineering with a recombinant MIP-3α adenovirus and BCG. We used PaLtTcAdMIP3α as a model vaccine to test its antitumor activities. Our results showed that PaLtTcAdMIP3α expressed and excreted MIP-3α, which effectively attracted DCs ex vivo and in vivo. Injection of PaLtTcAdMIP3α into tumor-bearing mice effectively induced both therapeutic and prophylactic antitumor immunities in CT26, Meth A, B16-F10 and H22 models, but without any ensuing increase in adverse effects. Both tumor-specific cellular and humoral immune responses, especially the CD8(+) T cell-dependent cytotoxic T immunity, were found in the mice injected with PaLtTcAdMIP3α. The anti-tumor activity was abrogated completely by depletion of CD8(+) and partially by CD4(+) T lymphocytes. In addition, the number of IFN-γ-producing CD8(+) T cells in spleen and tumor tissues was significantly increased; but the number of CD4(+)CD25(+)FOXP3(+) regulatory T cells (Treg) in tumor tissues was decreased. These data strongly suggest that a combination of multi-current-using strategies such as the novel approach of using our PaLtTcAdMIP3α microspheres could be an effective tumor model vaccine.

Anti-CD27 Antibody Potentiates Antitumor Effect of Dendritic Cell-Based Vaccine in Prostate Cancer-Bearing Mice

In the current study, we investigated whether anti-CD27 monoclonal antibody can enhance the antitumor efficacy of a dendritic cell-based vaccine in prostate cancer-bearing mice. The overall therapeutic effect of a dendritic cell-based vaccine for prostate cancer remains moderate. A prostate cancer model was established by subcutaneous injection of RM-1 tumor cells into male C57BL/6 mice on day 0. After 4 days, tumor-bearing mice were treated with RM-1 tumor lysate-pulsed dendritic cells (i.e., dendritic cell-based vaccine), anti-CD27 monoclonal antibody, or a combination of RM-1 tumor lysate-pulsed dendritic cells with anti-CD27 monoclonal antibody. Mice were killed at 21 days after tumor cell implantation. Tumor size was measured for assessment of antitumor effect. Spleens were collected for analysis of antitumor immune responses. The antitumor immune responses were evaluated by measuring the proliferation and activity of T cells, which have the ability to kill tumor cells. The combination therapy with RM-1 tumor lysate-pulsed dendritic cells and anti-CD27 antibody significantly enhanced T-cell proliferation and activity, and significantly reduced tumor growth, compared with monotherapy with RM-1 tumor lysate-pulsed dendritic cells or anti-CD27 antibody. Our results suggest that combined treatment can strengthen antitumor efficacy by improving T-cell proliferation and activity.

Clinical use of dendritic cells for cancer therapy

Since the mid-1990s, dendritic cells have been used in clinical trials as cellular mediators for therapeutic vaccination of patients with cancer. Dendritic cell-based immunotherapy is safe and can induce antitumour immunity, even in patients with advanced disease. However, clinical responses have been disappointing, with classic objective tumour response rates rarely exceeding 15%. Paradoxically, findings from emerging research indicate that dendritic cell-based vaccination might improve survival, advocating implementation of alternative endpoints to assess the true clinical potency of dendritic cell-based vaccination. We review the clinical effectiveness of dendritic cell-based vaccine therapy in melanoma, prostate cancer, malignant glioma, and renal cell carcinoma, and summarise the most important lessons from almost two decades of clinical studies of dendritic cell-based immunotherapy in these malignant disorders. We also address how the specialty is evolving, and which new therapeutic concepts are being translated into clinical trials to leverage the clinical effectiveness of dendritic cell-based cancer immunotherapy. Specifically, we discuss two main trends: the implementation of the next-generation dendritic cell vaccines that have improved immunogenicity, and the emerging paradigm of combination of dendritic cell vaccination with other cancer therapies.

Therapeutic DC vaccination with IL-2 as a consolidation therapy for ovarian cancer patients: a phase I/II trial

While ovarian cancer (OvCa) responds well to surgery and conventional chemotherapy, a high recurrence rate of advanced OvCa is observed. In this phase I/II study, 10 OvCa patients with minimal residual disease were treated with autologous dendritic cells (DCs) and IL-2 to evaluate the safety and feasibility of this therapeutic strategy and to characterize the antigen-specific immune alterations induced through this treatment. Approximately 4 months after initial debulking and chemotherapy, patients received two subcutaneous doses of autologous monocyte-derived DCs pulsed with autologous tumor lysate and keyhole limpet hemocyanin (KLH) at 4-week intervals. After each DC inoculation, low-dose (200 mIU) IL-2 was introduced for 14 consecutive days as an immune adjuvant. The vaccination was well tolerated. In three out of 10 patients, the inclusion status after the initial therapy showed the maintenance of complete remission (CR) after DC vaccination for 83, 80.9 and 38.2 months without disease relapse. One patient with stable disease (SD) experienced the complete disappearance of tumor after DC vaccination, and this status was maintained for 50.8 months until tumor recurrence. In two patients with partial response (PR) was not responding to DC vaccination and their disease recurred. In the three patients with disease free long-term survival, significant immune alterations were observed, including increased natural killer (NK) activity, IFN-γ-secreting T cells, immune-stimulatory cytokine secretion and reduced immune-suppressive factor secretion after DC vaccination. Thus, in patients with NED status and increased overall survival, DC vaccination induced tumor-related immunity, potentially associated with long-term clinical responses against OvCa.

Intratumoral gene therapy versus intravenous gene therapy for distant metastasis control with 2-diethylaminoethyl-dextran methyl methacrylate copolymer non-viral vector-p53

Lung cancer still remains to be challenged by novel treatment modalities. Novel locally targeted routes of administration are a methodology to enhance treatment and reduce side effects. Intratumoral gene therapy is a method for local treatment and could be used either in early-stage lung cancer before surgery or at advanced stages as palliative care. Novel non-viral vectors are also in demand for efficient gene transfection to target local cancer tissue and at the same time protect the normal tissue. In the current study, C57BL/6 mice were divided into three groups: (a) control, (b) intravenous and (c) intatumoral gene therapy. The novel 2-Diethylaminoethyl-Dextran Methyl Methacrylate Copolymer Non-Viral Vector (Ryujyu Science Corporation) was conjugated with plasmid pSicop53 from the company Addgene for the first time. The aim of the study was to evaluate the safety and efficacy of targeted gene therapy in a Lewis lung cancer model. Indeed, although the pharmacokinetics of the different administration modalities differs, the intratumoral administration presented increased survival and decreased distant metastasis. Intratumoral gene therapy could be considered as an efficient local therapy for lung cancer.

Dendritic cell-based vaccination for renal cell carcinoma: challenges in clinical trials

After decades of research, dendritic cell (DC)-based vaccines for renal cell carcinoma have progressed from preclinical rodent models and safety assessments to Phase I/II clinical trials. DC vaccines represent a promising therapy that has produced measurable immunological responses and prolonged survival rates. However, there is still much room to improve in terms of therapeutic efficacy. The key issues that affect the efficiency and reliability of DC therapy include the selection of patients who will respond best to treatment, the proper preparation and administration of DC vaccines, and a combination of DC vaccination with other immune-enhancing therapies (e.g., removal of Tregs, CTLA-4 blockade and lymphodepletion). Additional antiangiogenic agents will hopefully lead to greater survival benefits for patients in early disease stages. This review focuses on the different approaches of DC-based vaccination against renal cell carcinoma and potential strategies to enhance the efficacy of DC vaccination.

Role of vaccine therapy for renal cell carcinoma in the era of targeted therapy

Renal cell carcinoma is the most common malignant tumor originating from the kidney. Compared with other solid tumors, it does not respond to traditional management modalities, such as chemotherapy and radiotherapy. However, it is well known that renal cell carcinoma represents one of the most immune-responsive cancers and several immunotherapeutic strategies have been investigated in the management of renal cell carcinoma with variable degrees of success. The development of immunotherapy with α-interferon or high-dose interleukin-2 is the best established treatment, and is associated with durable disease control. Although the lack of defined antigens in renal cell carcinoma has hindered more specific vaccine development, research regarding vaccination therapy has been of special interest for the treatment of renal cell carcinoma for more than 30 years. At present, there are three types of cell-based vaccines in renal cell carcinoma treatment: autologous tumor-cell vaccines, genetically modified tumor vaccines and dendritic cell-based vaccines. A further type is peptide-based vaccination with tumor-associated antigens as possible targets, such as carbonic anhydrase IX, survivin and telomerase that are overexpressed in renal cell carcinoma. In the present article, we review data from completed clinical trials of vaccine therapy, and discuss future trials to assess the current knowledge and future role of vaccine therapy for renal cell carcinoma in the era of recently developed targeted therapy.

Allogeneic partially HLA-matched dendritic cells pulsed with autologous tumor cell lysate as a vaccine in metastatic renal cell cancer: a clinical phase I/II study

Multi-kinase inhibitors have been established for the treatment of advanced renal cell cancer, but long-term results are still disappointing and immunotherapeutic approaches remain an interesting experimental option particularly in patients with a low tumor burden. DC are crucial for antigen-specific MHC-restricted T cell immunity. Furthermore, allogeneic HLA-molecules pose a strong immunogenic signal and may help to induce tumor-specific T cell responses. In this phase I/II trial, 7 patients with histologically confirmed progressive metastatic RCC were immunized repetitively with 1 × 10 (7) allogeneic partially HLA-matched DC pulsed with autologous tumor lysate following a schedule of 8 vaccinations over 20 weeks. Patients also received 3 Mio IE IL-2 s.c. once daily starting in week 4. Primary endpoints of the study were feasibility and safety. Secondary endpoints were immunological and clinical responses. Vaccination was feasible and safe with no severe toxicity being observed. No objective response could be documented. However, while all patients had documented progress at study entry, 29% of the patients showed SD throughout the study with a mean TTP of 24.6 weeks (range 5 to 96 weeks). In 3/7 patients, TH1-polarized immune responses against RCC-associated antigens were observed. In one patient showing a minimal clinical response and a TTP of 96 weeks, clonally proliferated T cells against yet undefined antigens were induced by the vaccine. Vaccination with tumor antigen loaded DC remains an interesting experimental approach, but should rather be applied in the situation of minimal residual disease after systemic therapy. Additional depletion of regulatory cells might be a promising strategy.

Dendritic Cell (DC) Vaccine in Mouse Lung Cancer Minimal Residual Model; Comparison of Monocyte-derived DC vs. Hematopoietic Stem Cell Derived-DC

The anti-tumor effect of monocyte-derived DC (MoDC) vaccine was studied in lung cancer model with feasible but weak Ag-specific immune response and incomplete blocking of tumor growth. To overcome this limitation, the hematopoietic stem cell-derived DC (SDC) was cultured and the anti-tumor effect of MoDC & SDC was compared in mouse lung cancer minimal residual model (MRD). Therapeutic DCs were cultured from either CD34⁺ hematopoietic stem cells with GM-CSF, SCF and IL-4 for 14 days (SDC) or monocytes with GM-CSF and IL-4 for 7 days (MoDC). DCs were injected twice by one week interval into the peritoneum of mice that are inoculated with Lewis Lung Carcinoma cells (LLC) one day before the DC injection. Anti-tumor responses and the immune modulation were observed 3 weeks after the final DC injection. CD11c expression, IL-12 and TGF-β secretion were higher in SDC but CCR7 expression, IFN-γ and IL-10 secretion were higher in MoDC. The proportion of CD11c⁺CD8a⁺ cells was similar in both DC cultures. Although both DC reduced the tumor burden, histological anti-tumor effect and the frequencies of IFN-γ secreting CD8⁺ T cells were higher in SDC treated group than in MoDC. Conclusively, although both MoDC and SDC can induce the anti-tumor immunity, SDC may be better module as anti-tumor vaccine than MoDC in mouse lung cancer.

Phase I/II study of immunotherapy using tumor antigen-pulsed dendritic cells in patients with hepatocellular carcinoma

Dendritic cells (DCs) are increasingly used as adjuvants for vaccination strategies; however, there has been very little development in DC vaccines for patients with hepatocellular carcinoma (HCC). In this study, we assessed the safety, feasibility and efficacy of a multiple tumor-associated antigen (TAA)-pulsed DC vaccine in 5 patients with advanced HCC. DCs were generated by culturing blood monocytes in the presence of granulocyte macrophage-colony stimulating factor and interleukin-4 for 5 days. The DC vaccine was prepared by pulsing DCs with cytoplasmic transduction peptide-attached α-fetoprotein, glypican-3 and MAGE-1 recombinant fusion proteins and cultivating them in the presence of maturation cocktail. DCs were injected subcutaneously near the inguinal lymph nodes, followed by topical application of toll-like receptor-7 agonist around the injection site. We showed that our DC vaccine was safe and well-tolerated over 6 vaccinations in 5 patients. All 5 patients showed T cell responses against TAAs. Clinical benefit was observed in one of the 5 patients. In conclusion, the feasibility, safety and immune activity of DCs pulsed with TAAs were confirmed in HCC patients. However, clinical response was detected only in one patient. Future trials may consider applying this therapy in a less advanced stage to obtain better clinical responses.

Dendritic cells in the pathogenesis and treatment of human diseases: a Janus Bifrons?

Dendritic cells (DCs) represent the bridging cell compartment between a variety of nonself antigens (i.e., microbial, cancer and vaccine antigens) and adaptive immunity, orchestrating the quality and potency of downstream immune responses. Because of the central role of DCs in the generation and regulation of immunity, the modulation of DC function in order to shape immune responses is gaining momentum. In this respect, recent advances in understanding DC biology, as well as the required molecular signals for induction of T-cell immunity, have spurred many experimental strategies to use DCs for therapeutic immunological approaches for infections and cancer. However, when DCs lose control over such 'protective' responses - by alterations in their number, phenotype and/or function - undesired effects leading to allergy and autoimmune clinical manifestations may occur. Novel therapeutic approaches have been designed and currently evaluated in order to address DCs and silence these immunopathological processes. In this article we present recent concepts of DC biology and some medical implications in view of therapeutic opportunities.

Generation of anti-tumour immune response using dendritic cells pulsed with carbonic anhydrase IX-Acinetobacter baumannii outer membrane protein A fusion proteins against renal cell carcinoma

Carbonic anhydrase IX (CA9), a specific molecular marker for renal cell carcinoma (RCC), serves as a potential target for RCC-specific immunotherapy using dendritic cells (DCs). However, pulsing of DCs with CA9 alone is not sufficient for generation of a therapeutic anti-tumour immune response against RCC. In this study, in order to generate a potent anti-tumour immune response against RCC, we produced recombinant CA9-Acinetobacter baumannii outer membrane protein A (AbOmpA) fusion proteins, designated CA9-AbOmpA, and investigated the ability of DCs pulsed with CA9-AbOmpA fusion proteins in a murine renal cell carcinoma (RENCA) model. A recombinant CA9-AbOmpA fusion protein was composed of a unique proteoglycan-related region of CA9 (1-120 amino acids) fused at the C-terminus with transmembrane domain of AbOmpA (1-200 amino acids). This fusion protein was capable of inducing DC maturation and interleukin (IL)-12 production in DCs. Interaction of DCs pulsed with CA9-AbOmpA fusion proteins with naive T cells stimulated secretion of IL-2, interferon (IFN)-γ and tumour necrosis factor (TNF)-α in T cells. Lymphocytes harvested from mice immunized with DCs pulsed with CA9-AbOmpA fusion proteins secreted IFN-γ and showed a specific cytotoxic activity against CA9-expressing RENCA (RENCA-CA9) cells. Administration of CA9-AbOmpA-pulsed DC vaccine suppressed growth of RENCA-CA9 cells in mice with an established tumour burden. These results suggest that DCs pulsed with CA9-AbOmpA fusion proteins generate a specific anti-tumour immune response against RCC, which can be utilized in immunotherapy of RCC.

Immunotherapy for renal cell carcinoma

Although several cytokines have shown antitumor activity in renal cell carcinoma (RCC), the most consistent results have been reported with interleukin-2 (IL-2) and interferon (IFN). Recent insights into how the immune response to a tumor is regulated hold the promise of allowing patients to obtain a durable response to immunotherapy, perhaps without the significant toxicity associated with conventional approaches. This review describes how improvements in patient selection, combination therapy, and investigational agents might expand and better define the role of immunotherapy in metastatic RCC.

Vaccination therapy in renal cell carcinoma: current position and future options in metastatic and localized disease

As renal cell carcinoma represents one of the most immune-responsive cancers, immunotherapy exhibits a suitable treatment basis. Beside nonspecific stimulation via cytokines, passive specific and active immunotherapy are also appropriate options to recognize and destroy tumor cells. For more than 30 years, research regarding vaccination therapy has been of special interest for the treatment of renal cell carcinoma. However, apart from occasional promising results in Phase I and II trials, vaccination therapy is still considered experimental in this tumor entity, especially owing to missing results from Phase III trials demonstrating clinical efficacy. In the present article, we review data from completed clinical trials of vaccination therapy and also discuss scheduled future trials, in order to assess the current position and possible future fields of application of vaccination therapy in renal cell carcinoma in the era of recently developed targeted therapies.

Combinatorial therapy for liver metastatic colon cancer: dendritic cell vaccine and low-dose agonistic anti-4-1BB antibody co-stimulatory signal

BACKGROUND

The combination of dendritic cell (DC) vaccine and 4-1BB ligation may be a suitable choice of immunotherapy for incurable cancer. However, at anti-tumor effector doses over 100 μg, 4-1BB Ab ligation is toxic to CD4(+) T cells, thus limiting its therapeutic use.

MATERIALS AND METHODS

A liver metastatic colon cancer model was established by hepatic injection of CT26 cells into Balb/c mice. Intraperitoneal administration of 1 × 10(6)/200 μL/mouse therapeutic-DCs (tumor lysate pulsed-DCs, P-DCs) began on d 7 after tumor cell inoculation. A P-DC injection was performed twice within a 1-wk interval. Agonistic anti 4-1BB Ab was intraperitoneally injected on d 7, 9, and 11 after tumor cell inoculation. Animals were sacrificed on d 21, and tumor growth was determined by weighing the liver with the tumor.

RESULTS

In the 20 μg 4-1BB ligation group, significant induction of CD3(+)CD8(+) T cells was observed without toxicity to CD3(+)CD4(+) T cells. DC vaccine treatment induced tumor antigen-specific Th1 cytokine (IL-2 and IFN-γ) secretion from the splenic lymphocytes. Ligation of 4-1BB reduced the DC vaccine-related IL-10 secretion and regulatory T cell population. Compared with anti-tumor effect of DC vaccine or 20 μg 4-1BB Ab alone, the combination therapy significantly increased the tumor rejection power to the level observed with higher doses of 4-1BB Ab alone. The combination therapy did not induce high-dose 4-1BB-related toxicity with CD4(+) T cell reduction, but did significantly induce tumor antigen-specific IFN-γ secreting effector CD8(+) cytotoxic T cells.

CONCLUSIONS

The data from our study reveal the value of using a DC vaccine combined with as little as 20 μg 4-1BB Ab as an improved immunotherapeutic for cancer.

Dendritic cell based tumor vaccination in prostate and renal cell cancer: a systematic review and meta-analysis

BACKGROUND

More than 200 clinical trials have been performed using dendritic cells (DC) as cellular adjuvants in cancer. Yet the key question whether there is a link between immune and clinical response remains unanswered. Prostate and renal cell cancer (RCC) have been extensively studied for DC-based immunotherapeutic interventions and were therefore chosen to address the above question by means of a systematic review and meta-analysis.

METHODOLOGY/PRINCIPAL FINDINGS

Data was obtained after a systematic literature search from clinical trials that enrolled at least 6 patients. Individual patient data meta-analysis was performed by means of conditional logistic regression grouped by study. Twenty nine trials involving a total of 906 patients were identified in prostate cancer (17) and RCC (12). Objective response rates were 7.7% in prostate cancer and 12.7% in RCC. The combined percentages of objective responses and stable diseases (SD) amounted to a clinical benefit rate (CBR) of 54% in prostate cancer and 48% in RCC. Meta-analysis of individual patient data (n = 403) revealed the cellular immune response to have a significant influence on CBR, both in prostate cancer (OR 10.6, 95% CI 2.5-44.1) and in RCC (OR 8.4, 95% CI 1.3-53.0). Furthermore, DC dose was found to have a significant influence on CBR in both entities. Finally, for the larger cohort of prostate cancer patients, an influence of DC maturity and DC subtype (density enriched versus monocyte derived DC) as well as access to draining lymph nodes on clinical outcome could be demonstrated.

CONCLUSIONS/SIGNIFICANCE

As a 'proof of principle' a statistically significant effect of DC-mediated cellular immune response and of DC dose on CBR could be demonstrated. Further findings concerning vaccine composition, quality control, and the effect of DC maturation status are relevant for the immunological development of DC-based vaccines.

Immunotherapy for renal cell carcinoma

Immunotherapy plays a significant role in the management of renal cell carcinoma (RCC) patients with metastatic disease because RCC is highly resistant to both chemotherapy and radiation therapy. Many reports illustrate various approaches to the treatment of RCC, such as cytokine-, antigen- or dendritic cell- (DC-) based immunotherapy, and the safety and effectiveness of immunotherapy have been highlighted by multiple clinical trials. Although antitumor immune responses and clinically significant outcomes have been achieved in these trials, the response rate is still low, and very few patients show long-term clinical improvement. Recently, the importance of immune regulation by antigen-presenting cells (APC) and regulatory T cells (Treg cells) has also been discussed. The authors outline the principles of cell-mediated tumor immunotherapy and discuss clinical trials of immunotherapy for RCC.

Concomitant tumor and autoantigen vaccination supports renal cell carcinoma rejection

Efficient tumor vaccination frequently requires adjuvant. Concomitant induction of an autoimmune response is discussed as a means to strengthen a weak tumor Ag-specific response. We asked whether the efficacy of dendritic cell (DC) vaccination with the renal cell carcinoma Ags MAGE-A9 (MAGE9) and G250 could be strengthened by covaccination with the renal cell carcinoma autoantigen GOLGA4. BALB/c mice were vaccinated with DC loaded with MHC class I-binding peptides of MAGE9 or G250 or tumor lysate, which sufficed for rejection of low-dose RENCA-MAGE9 and RENCA-G250 tumor grafts, but only retarded tumor growth at 200 times the tumor dose at which 100% of animals will develop a tumor. Instead, 75-100% of mice prevaccinated concomitantly with Salmonella typhimurium transformed with GOLGA4 cDNA in a eukaryotic expression vector rejected 200 times the tumor dose at which 100% of animals will develop tumor. In a therapeutic setting, the survival rate increased from 20-40% by covaccination with S. typhimurium-GOLGA4. Autoantigen covaccination significantly strengthened tumor Ag-specific CD4(+) and CD8(+) T cell expansion, particularly in peptide-loaded DC-vaccinated mice. Covaccination was accompanied by an increase in inflammatory cytokines, boosted IL-12 and IFN-gamma expression, and promoted a high tumor Ag-specific CTL response. Concomitant autoantigen vaccination also supported CCR6, CXCR3, and CXCR4 upregulation and T cell recruitment into the tumor. It did not affect regulatory T cells, but slightly increased myeloid-derived suppressor cells. Thus, tumor cell eradication was efficiently strengthened by concomitant induction of an immune response against a tumor Ag and an autoantigen expressed by the tumor cell. Activation of autoantigen-specific Th cells strongly supports tumor-specific Th cells and thereby CTL activation.

Immune responses in patients with metastatic renal cell carcinoma treated with dendritic cells pulsed with tumor lysate

Patients with metastatic renal cell carcinoma (mRCC) have a limited life expectancy but still a subset of these patients develop immune and clinical responses after immunotherapy including dendritic cell (DC) vaccination. In a recently published phase I/II trials, fourteen HLA-A2 negative patients with progressive mRCC were vaccinated with autologous DC pulsed with allogeneic tumour lysate. Low-dose IL-2 administered subcutaneously was given concomitantly. In this study, we analysed lysate specific proliferation of PBMCs from these patients together with the TH1/TH2 balance of the responding T cells. Also, serum concentrations of IL-10, IL-12, IL-15, IL-17 and IL-18 from these patients and additional thirteen HLA-A2 positive mRCC patients treated with autologous DC pulsed with survivin and telomerase peptides were analysed during vaccination to identify systemic immune responses and potential response biomarkers. In HLA-A2 negative mRCC patients a spontaneous predominance of TH1 secreting tumour lysate specific T cells was observed prior to vaccination in patients attaining stable disease (SD) during treatment whereas patients with continued progressive disease (PD) had a mixed TH1/TH2 response. The TH1/TH2 balance was unchanged during vaccination also when tumour lysate specific T cell responses increased. An increase in IL-12, IL-17 and IL-18 serum concentrations was observed during vaccination but no difference between patients with SD and PD was observed. IL-10 or IL-15 was not measurable in serum.

Clinical and immunologic effects of intranodal autologous tumor lysate-dendritic cell vaccine with Aldesleukin (Interleukin 2) and IFN-{alpha}2a therapy in metastatic renal cell carcinoma patients

PURPOSE

To evaluate the clinical and immunologic outcomes of DC (dendritic cell) vaccine with interleukin (IL)-2 and IFN-alpha 2a in metastatic renal cell carcinoma patients.

EXPERIMENTAL DESIGN

Eighteen consented and eligible patients were treated. Peripheral blood monocytes were cultured ex vivo into mature DCs and loaded with autologous tumor lysate. Treatment consisted of five cycles of intranodal vaccination of DCs (1 x 10(7) cells/1 mL Lactated Ringer's solution), 5-day continuous i.v. infusion of IL-2 (18MiU/m2), and three s.c. injections of IFN-alpha 2a (6MiU) every other day. Response Evaluation Criteria in Solid Tumors criteria were used for disease assessment. Correlative immunologic end points included peripheral blood lymphocyte cell phenotype and function as well as peripheral blood anti-renal cell carcinoma antibody and cytokine levels.

RESULTS

All patients received between two and five treatment cycles. Toxicities consisted of known and expected cytokine side effects. Overall objective clinical response rate was 50% with three complete responses. Median time to progression for all patients was 8 months, and median survival has not been reached (median follow up of 37+ months). Treatment-related changes in correlative immunologic end points were noted and the level of circulating CD4(+) T regulatory cells had a strong association with outcome. Pre-IP-10 serum levels approached significance for predicting outcome.

CONCLUSIONS

The clinical and immunologic responses observed in this trial suggest an interaction between DC vaccination and cytokine therapy. Our data support the hypothesis that modulation of inflammatory, regulatory, and angiogenic pathways are necessary to optimize therapeutic benefit in renal cell carcinoma patients. Further exploration of this approach is warranted.

Synergy between dendritic cells and GM-CSF-secreting tumor cells for the treatment of a murine renal cell carcinoma

Dendritic cell (DC) immunotherapy for cancer certainly holds promises but definitely needs improvements, especially for enhancing tumor-specific responses able to eradicate preexisting tumors. To this end, we investigated here, for the treatment of a preimplanted murine renal cell carcinoma Renca, a new vaccination approach combining injection of DC and granulocyte macrophage colony-stimulating factor (GM-CSF) gene-transduced tumor cells. When treatment by either DC or Renca-mGM-CSF cells alone had no therapeutic effect at all, combined vaccines induced therapeutic response in 50% of the tumor-bearing mice, in a GM-CSF dose-dependent manner. Importantly, all these cured mice were protected against a rechallenge with parental Renca cells, indicating the generation of memory immune response. The combined vaccines induced elevated cytotoxic responses in all the cured mice and half of the uncured ones and a stronger systemic CD4+ T-cell-mediated interferon-gamma production in the cured vaccinated mice as compared with uncured ones. In conclusion, vaccines associating DC and GM-CSF-secreting tumor cells induce high therapeutic effect in mice with preexisting renal cell carcinoma that are correlated to the induction of specific CD8 and CD4+ T-cell responses. This original vaccination approach should be further evaluated in a clinical trial for the treatment of metastatic human renal cell carcinoma.