A pilot clinical trial of vaccination with dendritic cells pulsed with autologous tumor cells derived from malignant pleural effusion in patients with late-stage lung carcinoma

Dendritic Cell Vaccination in Non-Small Cell Lung Cancer: Remodeling the Tumor Immune Microenvironment

Non-small-cell lung cancer (NSCLC) remains one of the leading causes of death worldwide. While NSCLCs possess antigens that can potentially elicit T cell responses, defective tumor antigen presentation and T cell activation hinder host anti-tumor immune responses. The NSCLC tumor microenvironment (TME) is composed of cellular and soluble mediators that can promote or combat tumor growth. The composition of the TME plays a critical role in promoting tumorigenesis and dictating anti-tumor immune responses to immunotherapy. Dendritic cells (DCs) are critical immune cells that activate anti-tumor T cell responses and sustain effector responses. DC vaccination is a promising cellular immunotherapy that has the potential to facilitate anti-tumor immune responses and transform the composition of the NSCLC TME via tumor antigen presentation and cell-cell communication. Here, we will review the features of the NSCLC TME with an emphasis on the immune cell phenotypes that directly interact with DCs. Additionally, we will summarize the major preclinical and clinical approaches for DC vaccine generation and examine how effective DC vaccination can transform the NSCLC TME toward a state of sustained anti-tumor immune signaling.

Characteristics of tumor microenvironment and novel immunotherapeutic strategies for non-small cell lung cancer

Immune checkpoint inhibitor-based immunotherapy has revolutionized the treatment approach of non-small cell lung cancer (NSCLC). Monoclonal antibodies against programmed cell death-1 (PD-1) and PD-ligand 1 (PD-L1) are widely used in clinical practice, but other antibodies that can circumvent innate and acquired resistance are bound to undergo preclinical and clinical studies. However, tumor cells can develop and facilitate the tolerogenic nature of the tumor microenvironment (TME), resulting in tumor progression. Therefore, the immune escape mechanisms exploited by growing lung cancer involve a fine interplay between all actors in the TME. A better understanding of the molecular biology of lung cancer and the cellular/molecular mechanisms involved in the crosstalk between lung cancer cells and immune cells in the TME could identify novel therapeutic weapons in the old war against lung cancer. This article discusses the role of TME in the progression of lung cancer and pinpoints possible advances and challenges of immunotherapy for NSCLC.

Adoptive cell therapies in thoracic malignancies

Immunotherapy has gained great interest in thoracic malignancies in the last decade, first in non-small cell lung cancer (NSCLC), but also more recently in small-cell lung cancer (SCLC) and malignant pleural mesothelioma (MPM). However, while 15-20% of patients will greatly benefit from immune checkpoint blockers (ICBs), a vast majority will rapidly exhibit resistance. Reasons for this are multiple: non-immunogenic tumors, immunosuppressive tumor microenvironment or defects in immune cells trafficking to the tumor sites being some of the most frequent. Current progress in adoptive cell therapies could offer a way to overcome these hurdles and bring effective immune cells to the tumor site. In this review, we discuss advantages, limits and future perspectives of adoptive cell therapy (ACT) in thoracic malignancies from lymphokine-activated killer cells (LAK), cytokine-induced killer cells (CIK), natural killer cells (NK), dendritic cells (DC) vaccines and tumor-infiltrating lymphocytes (TILs) to TCR engineering and CARs. Trials are still in their early phases, and while there may still be many limitations to overcome, a combination of these different approaches with ICBs, chemotherapy and/or radiotherapy could vastly improve the way we treat thoracic cancers.

Safety and efficacy of dendritic cell-based immunotherapy (DCVAC/LuCa) combined with carboplatin/pemetrexed for patients with advanced non-squamous non-small-cell lung cancer without oncogenic drivers

Background

Our prospective, open-label, single-arm phase II study investigated the safety and efficacy of DCVAC/LuCa (dendritic cell vaccines for lung cancer) combined with standard carboplatin/pemetrexed in advanced non-squamous (nsq) non-small-cell lung cancer (NSCLC).

Patients and methods

Eligible patients had stage IV nsq NSCLC without oncogenic drivers and had not received prior systemic cancer therapy. Treatment consisted of carboplatin/pemetrexed for up to 6 cycles followed by 21 cycles of pemetrexed maintenance or until progression or intolerance. Non-progression patients after two cycles of chemotherapy started to receive DCVAC/LuCa subcutaneously (s.c.) on day 15 of cycle 3, and thereafter q3w (day 15 of chemotherapy cycles) for up to 15 doses. Dosing of DCVAC/LuCa s.c. varied among patients depending on the baseline number of leucocytes but remained constant for each single patient. Safety was assessed by adverse events (AEs), treatment-related adverse events (TRAEs), serious adverse events (SAEs), and adverse events of special interest (AESIs). Efficacy was measured by overall survival (OS), progression-free survival (PFS), time to progression (TTP), and objective response rate (ORR).

Results

Sixty-one patients were enrolled. In the safety population (n = 60), eight patients (13.33%) had grade 3 or greater TRAEs, and six patients (10.0%) showed SAEs which were not related to leukapheresis or DC vaccination. Six grade 1 AEs were considered to be related to leukapheresis. No AESIs or DCVAC/LuCa-induced AEs were observed. The 2-year survival rate in the modified intention-to-treat population (n = 44) was 52.57%. Median OS was not reached. Median PFS was 8.0 months, median TTP was 10.2 months, and the ORR was 31.82%.

Conclusion

In treatment-naïve stage IV nsq NSCLC patients without oncogenic drivers, the combination of carboplatin/pemetrexed and DCVAC/LuCa was well tolerated and showed promising efficacy. Therefore, a study to prove our immunotherapeutic concept in a randomized phase III trial is planned.

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We investigated the safety and efficacy of DCVAC/LuCa combined with standard carboplatin/pemetrexed in nsq NSCLC.

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The combination therapy showed a favorable tolerability profile in a selected Chinese population.

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The 2-year survival rate in the modified intention-to-treat population (n = 44) was 52.57%.

Ferroptosis-related gene AKR1C1 predicts the prognosis of non-small cell lung cancer

BACKGROUND

Ferroptosis is a newly discovered mode of cell death distinct from apoptosis and necrosis, and its activation contributes to anticancer therapy in a variety of cancers. However, the prognostic value of ferroptosis-related genes in non-small cell lung cancer (NSCLC) remains to be further investigated.

METHODS

NSCLC transcriptome mRNA-seq data set and corresponding clinical data set were downloaded from the Cancer Genome Atlas (TCGA). Then, bioinformatics approaches were subsequently employed to identify potential prognostic markers. Finally, the effects of candidate markers on NSCLC cell proliferation, migration, and ferroptosis were assessed by CCK8, colony formation, wound-healing assay, and functional assays related to ferroptosis.

RESULTS

A total of 37 common differentially expressed genes were screened based TCGA database. Six overall survival associated genes (ENPP2, ULK1, CP, LURAP1L, HIC1, AKR1C1) were selected to build survival model, of which hub gene AKR1C1 was with high expression and low ferroptosis level in NSCLC tumor. Further research showed that AKR1C1 was related with many pathways involved in the process of ferroptosis and associated with diverse cancer-infiltrating immune cells. Moreover, the results of in vitro experiments indicated that the expression of AKR1C1 was upregulated in NSCLC cell lines, and silencing AKR1C1 can inhibit the proliferation and migration of NSCLC cells and promote the occurrence of ferroptosis.

CONCLUSIONS

Our study revealed the potential role of ferroptosis-related gene AKR1C1 in NSCLC, which can be used for prognostic prediction in NSCLC.

Recent Advances and Future Perspective of DC-Based Therapy in NSCLC

Current treatment for patients with non-small-cell lung cancer (NSCLC) is suboptimal since therapy is only effective in a minority of patients and does not always induce a long-lasting response. This highlights the importance of exploring new treatment options. The clinical success of immunotherapy relies on the ability of the immune system to mount an adequate anti-tumor response. The activation of cytotoxic T cells, the effector immune cells responsible for tumor cell killing, is of paramount importance for the immunotherapy success. These cytotoxic T cells are primarily instructed by dendritic cells (DCs). DCs are the most potent antigen-presenting cells (APCs) and are capable of orchestrating a strong anti-cancer immune response. DC function is often suppressed in NSCLC. Therefore, resurrection of DC function is an interesting approach to enhance anti-cancer immune response. Recent data from DC-based treatment studies has given rise to the impression that DC-based treatment cannot induce clinical benefit in NSCLC by itself. However, these are all early-phase studies that were mainly designed to study safety and were not powered to study clinical benefit. The fact that these studies do show that DC-based therapies were well-tolerated and could induce the desired immune responses, indicates that DC-based therapy is still a promising option. Especially combination with other treatment modalities might enhance immunological response and clinical outcome. In this review, we will identify the possibilities from current DC-based treatment trials that could open up new venues to improve future treatment.

Dendritic Cell-Based Immunotherapy in Lung Cancer

Lung cancer remains the leading cause of cancer-related death worldwide. The advent of immune checkpoint inhibitors has led to a paradigm shift in the treatment of metastatic non-small cell and small cell lung cancer. However, despite prolonged overall survival, only a minority of the patients derive clinical benefit from these treatments suggesting that the full anti-tumoral potential of the immune system is not being harnessed yet. One way to overcome this problem is to combine immune checkpoint blockade with different strategies aimed at inducing or restoring cellular immunity in a tumor-specific, robust, and durable way. Owing to their unique capacity to initiate and regulate T cell responses, dendritic cells have been extensively explored as tools for immunotherapy in many tumors, including lung cancer. In this review, we provide an update on the nearly twenty years of experience with dendritic cell-based immunotherapy in lung cancer. We summarize the main results from the early phase trials and give an overview of the future perspectives within this field.

Small Particles, Big Effects: The Interplay Between Exosomes and Dendritic Cells in Antitumor Immunity and Immunotherapy

Dendritic cells play a fundamental role in the antitumor immunity cycle, and the loss of their antigen-presenting function is a recognized mechanism of tumor evasion. We have recently demonstrated the effect of exosomes extracted from serum of patients with acute myeloid leukemia as important inducers of dendritic cell immunotolerance, and several other works have recently demonstrated the effects of these nanoparticles on immunity to other tumor types as well. The aim of this review was to highlight the recent findings on the effects of tumor exosomes on dendritic cell functions, the mechanisms by which they can lead to tumor evasion, and their manipulation as a possible strategy in cancer treatment.

Lipid Accumulation in Peripheral Blood Dendritic Cells and Anticancer Immunity in Patients with Lung Cancer

We studied the subsets of peripheral blood dendritic cells (DCs) and lipid accumulation in DCs to investigate the involvement of DCs in the decreased anticancer immunity of advanced lung cancer patients. We analyzed the population of DC subsets in peripheral blood using flow cytometry. We then determined lipid accumulation in the DCs using BODIPY 650/665, a fluorophore with an affinity for lipids. Compared with healthy controls, the number of DCs in the peripheral blood of treatment-naive cancer patients was significantly reduced. In patients with stage III + IV disease, the numbers of myeloid DCs (mDCs) and plasmacytoid DCs were also significantly reduced. Lipid accumulation in DCs evaluated based on the fluorescence intensity of BODIPY 650/665 was significantly higher in stage III + IV lung cancer patients than in the controls. In the subset analysis, the fluorescence was highest for mDCs. The intracellularly accumulated lipids were identified as triglycerides. A decreased mixed leukocyte reaction was observed in the mDCs from lung cancer patients compared with those from controls. Taken together, the results show that lung cancer patients have a notably decreased number of peripheral blood DCs and their function as antigen-presenting cells is decreased due to their high intracellular lipid accumulation. Thereby, anticancer immunity is suppressed.

Neoepitopes as cancer immunotherapy targets: key challenges and opportunities

Over the last half century, it has become well established that cancers can elicit a host immune response that can target them with high specificity. Only within the last decade, with the advances in high-throughput gene sequencing and bioinformatics approaches, are we now on the forefront of harnessing the host's immune system to treat cancer. Recently, some strides have been taken toward understanding effective tumor-specific MHC I restricted epitopes or neoepitopes. However, many fundamental questions still remain to be addressed before this therapy can live up to its full clinical potential. In this review, we discuss the major hurdles that lie ahead and the work being done to address them.

Cellular immunotherapy of cancer: an overview and future directions

The clinical success of checkpoint inhibitors has led to a renaissance of interest in cancer immunotherapies. In particular, the possibility of ex vivo expanding autologous lymphocytes that specifically recognize tumor cells has attracted much research and clinical trial interest. In this review, we discuss the historical background of tumor immunotherapy using cell-based approaches, and provide some rationale for overcoming current barriers to success of autologous immunotherapy. An overview of adoptive transfer of lymphocytes, tumor infiltrating lymphocytes and dendritic cell therapies is provided. We conclude with discussing the possibility of gene-manipulating immune cells in order to augment therapeutic activity, including silencing of the immune-suppressive zinc finger orphan nuclear receptor, NR2F6, as an attractive means of overcoming tumor-associated immune suppression.

Generation of dendritic cell-based vaccine using high hydrostatic pressure for non-small cell lung cancer immunotherapy

High hydrostatic pressure (HHP) induces immunogenic death of tumor cells which confer protective anti-tumor immunity in vivo. Moreover, DC pulsed with HHP-treated tumor cells induced therapeutic effect in mouse cancer model. In this study, we tested the immunogenicity, stability and T cell stimulatory activity of human monocyte-derived dendritic cell (DC)-based HHP lung cancer vaccine generated in GMP compliant serum free medium using HHP 250 MPa. DC pulsed with HHP-killed lung cancer cells and poly(I:C) enhanced DC maturation, chemotactic migration and production of pro-inflammatory cytokines after 24h. Moreover, DC-based HHP lung cancer vaccine showed functional plasticity after transfer into serum-containing media and stimulation with LPS or CD40L after additional 24h. LPS and CD40L stimulation further differentially enhanced the expression of costimulatory molecules and production of IL-12p70. DC-based HHP lung cancer vaccine decreased the number of CD4+CD25+Foxp3+ T regulatory cells and stimulated IFN-γ-producing tumor antigen-specific CD4+ and CD8+ T cells from non-small cell lung cancer (NSCLC) patients. Tumor antigen specific CD8+ and CD4+ T cell responses were detected in NSCLC patient's against a selected tumor antigens expressed by lung cancer cell lines used for the vaccine generation. We also showed for the first time that protein antigen from HHP-killed lung cancer cells is processed and presented by DC to CD8+ T cells. Our results represent important preclinical data for ongoing NSCLC Phase I/II clinical trial using DC-based active cellular immunotherapy (DCVAC/LuCa) in combination with chemotherapy and immune enhancers.

Lung adenocarcinoma may be a more susceptive subtype to a dendritic cell-based cancer vaccine than other subtypes of non-small cell lung cancers: a multicenter retrospective analysis

OBJECTIVE

The J-SICT DC Vaccine Study Group provides dendritic cell (DC) vaccines for compassionate use under unified cell production and patient treatment regimens. We previously reported beneficial effects of DC vaccines on the overall survival of 62 patients with advanced non-small cell lung cancer (NSCLC) in a single-center analysis. Here, we extended analysis to 260 patients with NSCLC who were treated at six centers.

METHODS

Of the 337 patients who met the inclusion criteria, we analyzed 260 patients who received ≥5 peptide-pulsed DC vaccinations once every 2 weeks.

RESULTS

The mean survival time (MST) from diagnosis was 33.0 months (95 % confidence interval [CI]: 27.9-39.2), and that from time of first vaccination was 13.8 months (95 % CI 11.4-16.8). An erythema reaction at the injection site that was ≥30 mm in diameter was correlated most strongly with overall survival from the first vaccine (≥30 vs. < 30 mm: MST 20.4 vs. 8.8 months, P < 0.001). We reported a similar finding in our previous analysis of patients with advanced pancreatic cancer. Interestingly, although such findings were common between patients with adenocarcinoma and those with other subtypes, the former group experienced significantly prolonged overall survival and a higher response rate for erythema (56.3 vs. 37.3 %, respectively, P = 0.014).

CONCLUSIONS

This is the first multicenter study that suggests a possible clinical benefit of DC vaccines for patients with advanced NSCLC, especially those with adenocarcinoma. These findings suggest a specific potential responder population for DC vaccines and warrant further investigation in well-controlled prospective randomized trials.

A phase I clinical study of immunotherapy for advanced colorectal cancers using carcinoembryonic antigen-pulsed dendritic cells mixed with tetanus toxoid and subsequent IL-2 treatment

BACKGROUND

To better evaluate and improve the efficacy of dendritic cell (DC)-based cancer immunotherapy, we conducted a clinical study of patients with advanced colorectal cancer using carcinoembryonic antigen (CEA)-pulsed DCs mixed with tetanus toxoid and subsequent interleukin-2 treatment. The tetanus toxoid in the vaccine preparation serves as an adjuvant and provides a non-tumor specific immune response to enhance vaccine efficacy. The aims of this study were to (1) evaluate the toxicity of this treatment, (2) observe the clinical responses of vaccinated patients, and (3) investigate the immune responses of patients against CEA before and after treatment.

METHODS

Twelve patients were recruited and treated in this phase I clinical study. These patients all had metastatic colorectal cancer and failed standard chemotherapy. We first subcutaneously immunized patients with metastatic colorectal cancer with 1 × 10(6) CEA-pulsed DCs mixed with tetanus toxoid as an adjuvant. Patients received 3 successive injections with 1 × 10(6) CEA-pulsed DCs alone. Low-dose interleukin-2 was administered subcutaneously following the final DC vaccination to boost the growth of T cells. Patients were evaluated for adverse event and clinical status. Blood samples collected before, during, and after treatment were analyzed for T cell proliferation responses against CEA.

RESULTS

No severe treatment-related side effects or toxicity was observed in patients who received the regular 4 DC vaccine injections. Two patients had stable disease and 10 patients showed disease progression. A statistically significant increase in proliferation against CEA by T cells collected after vaccination was observed in 2 of 9 patients.

CONCLUSIONS

The results of this study indicate that it is feasible and safe to treat colorectal cancer patients using this protocol. An increase in the anti-CEA immune response and a clinical benefit was observed in a small fraction of patients. This treatment protocol should be further evaluated in additional colorectal cancer patients with modifications to enhance T cell responses.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier NCT00154713 ), September 8, 2005.

Dual Role of GM-CSF as a Pro-Inflammatory and a Regulatory Cytokine: Implications for Immune Therapy

Granulocyte macrophage colony stimulating factor (GM-CSF) is generally recognized as an inflammatory cytokine. Its inflammatory activity is primarily due its role as a growth and differentiation factor for granulocyte and macrophage populations. In this capacity, among other clinical applications, it has been used to bolster anti-tumor immune responses. GM-CSF-mediated inflammation has also been implicated in certain types of autoimmune diseases, including rheumatoid arthritis and multiple sclerosis. Thus, agents that can block GM-CSF or its receptor have been used as anti-inflammatory therapies. However, a review of literature reveals that in many situations GM-CSF can act as an anti-inflammatory/regulatory cytokine. We and others have shown that GM-CSF can modulate dendritic cell differentiation to render them "tolerogenic," which, in turn, can increase regulatory T-cell numbers and function. Therefore, the pro-inflammatory and regulatory effects of GM-CSF appear to depend on the dose and the presence of other relevant cytokines in the context of an immune response. A thorough understanding of the various immunomodulatory effects of GM-CSF will facilitate more appropriate use and thus further enhance its clinical utility.

[Immunotherapy for non-small cell lung cancer--novel approaches to improve patient outcome]

简介

通常，非小细胞肺癌（non-small cell lung cancer, NSCLC）诊断已为晚期，且预后较差。目前的NSCLC标准治疗总体治愈率低，有必要开发新的治疗方法。我们在本综述中提供了最新的免疫治疗干预临床数据，该手段可能能够提高免疫系统对细胞的应答。

方法

我们针对临床应用免疫疗法治疗NSCLC，检索了PubMed上的文章以及最近肿瘤学术会议上的摘要。

结果

Ⅱ期临床研究结果表明，靶向肿瘤细胞本身或其异常表达的肿瘤标志物的疫苗治疗（mucin1，黑色素瘤相关抗原3，或表皮生长因子），有望作为NSCLC免疫疗法。非抗原免疫治疗，如抗细胞毒T淋巴细胞抗原4单克隆抗体、talactoferrin alfa和toll-样受体9拮抗剂，作用于激活的免疫系统，与肿瘤抗原无关，可用于晚期NSCLC的治疗。目前一些免疫治疗正在进行Ⅲ期研究，以确定最佳治疗方案，并与NSCLC标准治疗对照，确定其临床疗效。

结论

越来越多的证据表明肺部肿瘤存在免疫应答。免疫治疗，包括疫苗治疗和非抗原免疫调节方法，可改善NSCLC的预后。而且，提高抗肿瘤免疫应答的治疗，与化疗有协同作用。生物标志物的明确以及免疫治疗作用机制的进一步阐明对于确定哪些患者更可能从免疫治疗中获益至关重要。

Interleukin 4 as a potential drug candidate for psoriasis

BACKGROUND

Interleukin 4 (IL-4) is the central cytokine driving the differentiation of naive CD4(+) T helper (TH) cells into anti-inflammatory IL-4-producing TH2 cells. In contrast, IL-12/IL-23 promotes the development of TH1/TH17 immune responses that induce organ-specific autoimmune diseases such as psoriasis or multiple sclerosis.

OBJECTIVE

We focus on the potential of IL-4 and TH2 induction to treat inflammatory autoimmune diseases.

METHODS

Here, we summarize the basics for the establishment of the in vitro and in vivo conditions for the generation of TH2 immune responses, followed by various experimental data showing the therapeutic use of IL-4 for the therapy of autoimmune diseases. This data and early experiences with recombinant human IL-4 (rhIL-4) in the therapy of patients with cancer set the basis for the clinical introduction of rhIL-4 in the treatment of patients with psoriasis in a Phase I/II trial.

CONCLUSION

IL-4 seems to act by inducing an anti-inflammatory phenotype and further clinical trials will explore the promising therapeutic potency of IL-4 in psoriasis during the upcoming era of biologics.

Impact of dendritic cell vaccines pulsed with Wilms' tumour-1 peptide antigen on the survival of patients with advanced non-small cell lung cancers

PURPOSE

Dendritic cell (DC)-based vaccines have been expected to serve as new therapeutic approaches for advanced non-small cell lung cancers (NSCLCs); however, their clinical outcomes have not been fully elucidated. We report a single-centre clinical study analysing factors affecting the survival of patients with advanced NSCLCs who received DC vaccines pulsed with or without Wilms' tumour protein-1 (WT1) peptide.

METHODS

Among 62 patients with previously treated inoperable or postoperatively relapsed NSCLCs who met the inclusion criteria, DCs from 47 (76%) patients who showed HLA-A2402/0201/0206 were pulsed with one or more corresponding WT1 peptide antigens. DC vaccines were intradermally injected biweekly.

RESULTS

Clinical responses based on response evaluation criteria in solid tumours (RECIST) were found in 31 (50%) patients at 3 months after the first DC vaccine (complete response: 1 (1.6%), partial response: 4 (6.5%), stable disease: 26 (41.9%)). Median survival time was 27 months (82% in 1 year and 54% in 2 years) from initial diagnosis, and that was 12 months (48% in 1 year and 22% in 2 years) from the first DC vaccination. Importantly, multivariate analyses revealed that only two factors, blood haemoglobin and the use of WT1 peptides, significantly affected the overall survival of patients from both initial diagnosis and first vaccination.

CONCLUSIONS

This study is the first to suggest that DC vaccines pulsed with WT1 may hold a significant impact to prolong the overall survival of patients with advanced NSCLCs.

The immunomodulatory activity of meningococcal lipoprotein Ag473 depends on the conformation made up of the lipid and protein moieties

We have previously demonstrated that the meningococcal antigen Ag473 in the presence of Freund’s adjuvant can elicit protective immune responses in mouse challenge model. In this study, we evaluated the structural requirement for the immunological activity and the possible signaling pathway of recombinant Ag473 antigen produced in E. coli. We found that lipidated Ag473 (L-Ag473) possesses an intrinsic adjuvant activity that could be attributed to its ability to activate dendritic cells and promote their maturation. In addition, we found that L-Ag473 can activate human monocytes and promote maturation of human monocyte-derived dendritic cells. These results provide an indirect support that L-Ag473 may also be immunogenic in human. Interestingly, the observed activity is dependent on the overall conformation of L-Ag473 because heating and proteinase K treatment can diminish and abolish the activity. Furthermore, our data suggest a species-differential TLR recognition of L-Ag473. Overall, these data suggest a new paradigm for the ligand-TLR interaction in addition to demonstrating the self-adjuvanting activity of the vaccine candidate L-Ag473.

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.

MUC1 immunotherapy

The overexpression and aberrant glycosylation of MUC1 is associated with a wide variety of cancers, making it an ideal target for immunotherapeutic strategies. This review highlights the main avenues of research in this field, focusing on adenocarcinomas, from the preclinical to clinical; the problems and possible solutions associated with each approach; and speculates on the direction of MUC1 immunotherapeutic research over the next 5-10 years.

Optimized systemic dosing with CpG DNA enhances dendritic cell-mediated rejection of a poorly immunogenic mammary tumor in BALB/c mice

To model a clinical trial of dendritic cell (DC) therapy of a poorly immunogenic mammary tumor, we treated BALB/c mice bearing an established TS/A mammary tumor with lysate-pulsed DCs and CpG DNA. We observed that the dose of CpG DNA required to activate DCs in vitro was insufficient to mediate tumor rejection in vivo. We therefore undertook in vivo studies to identify an optimized dose of CpG DNA for tumor therapy, defined as the lowest and least frequently administered dose of CpG DNA that mediated complete tumor rejection. We show that one priming dose of 15 nanomoles and one booster dose of 10 nanomoles of CpG DNA given 7 days apart, respectively, with lysate-loaded DCs were sufficient to mediate complete tumor rejection in vivo. This dose of CpG DNA was 42-fold higher than that required to activate DCs in vitro but was not associated with any toxicity in mice. Also, the cured mice rejected a subsequent challenge with fresh TS/A tumor, and both CD4(+) and CD8(+) T cells were required for tumor rejection. We conclude that effective DC-based therapy of a poorly immunogenic TS/A tumor is enhanced by optimized dosing of CpG DNA. Our data have important implications for DC-based clinical trials of breast cancer immunotherapy.

The prognostic value of intraepithelial and stromal innate immune system cells in non-small cell lung carcinoma

AIMS

The major value of prognostic markers in potentially curable non-small cell lung carcinoma (NSCLC) should be to guide therapy after surgical resection. The prognostic significance of tumour-infiltrating macrophages, their growth factor, macrophage colony-stimulating factor (M-CSF), and its receptor, colony-stimulating factor-1 receptor (CSF-1R), as well as natural killer cells and dendritic cells, is controversial. The aim of this study was to elucidate the prognostic significance of these markers in the epithelial and stromal compartments of NSCLC.

METHODS AND RESULTS

Tissue microarrays from 335 resected NSCLC, stage I-IIIA were constructed from duplicate cores of epithelial and stromal areas. Immunohistochemistry was used to evaluate epithelial and stromal areas for CD68, M-CSF, CSF-1R, CD56 and CD1a. On univariate analysis, increasing numbers of stromal CD1a+ (P = 0.011) and CD56+ cells (P = 0.014) correlated significantly with improved disease-specific survival (DSS). On multivariate analysis, stromal CD56+ cells were an independent prognostic factor for DSS (hazard ratio = 2.3, confidence interval = 1.1, 5.0, P = 0.031).

CONCLUSIONS

High density of stromal CD56+ cells is an independent factor associated with improved prognosis in resected NSCLC, suggesting that these cells mediate an antitumour immune response in the tumour stroma.

Semliki forest virus expressing interleukin-12 induces antiviral and antitumoral responses in woodchucks with chronic viral hepatitis and hepatocellular carcinoma

A vector based on Semliki Forest virus (SFV) expressing high levels of interleukin-12 (SFV-enhIL-12) has previously demonstrated potent antitumoral efficacy in small rodents with hepatocellular carcinoma (HCC) induced by transplantation of tumor cells. In the present study, the infectivity and antitumoral/antiviral effects of SFV vectors were evaluated in the clinically more relevant woodchuck model, in which primary HCC is induced by chronic infection with woodchuck hepatitis virus (WHV). Intratumoral injection of SFV vectors expressing luciferase or IL-12 resulted in high reporter gene activity within tumors and cytokine secretion into serum, respectively, demonstrating that SFV vectors infect woodchuck tumor cells. For evaluating antitumoral efficacy, woodchuck tumors were injected with increasing doses of SFV-enhIL-12, and tumor size was measured by ultrasonography following treatment. In five (83%) of six woodchucks, a dose-dependent, partial tumor remission was observed, with reductions in tumor volume of up to 80%, but tumor growth was restored thereafter. Intratumoral treatment further produced transient changes in WHV viremia and antigenemia, with >or=1.5-log(10) reductions in serum WHV DNA in half of the woodchucks. Antitumoral and antiviral effects were associated with T-cell responses to tumor and WHV antigens and with expression of CD4 and CD8 markers, gamma interferon, and tumor necrosis factor alpha in peripheral blood mononuclear cells, suggesting that immune responses against WHV and HCC had been induced. These experimental observations suggest that intratumoral administration of SFV-enhIL-12 may represent a strategy for treatment of chronic HBV infection and associated HCC in humans but indicate that this approach could benefit from further improvements.

Conditioning vaccination site with irradiated MIP-3alpha-transfected tumor cells enhances efficacy of dendritic cell-based cancer vaccine

Macrophage inflammation protein-3alpha (MIP-3alpha) is a chemokine expressed in inflamed tissue and capable of inducing migration of immature dendritic cells (DCs) or Langerhans cells. We postulated that conditioning vaccination sites with MIP-3alpha might enhance the efficacy of subsequently administered DC-based cancer vaccines. Our results demonstrate that subcutaneously injection of irradiated tumor cells expressing MIP-3alpha induces substantial cell infiltration to the injection site. Vaccination of irradiated tumor cells expressing MIP-3alpha followed by DCs pulsed with irradiated tumor cells can effectively suppress tumor growth in animals, which is significantly better than vaccination with irradiated MIP-3alpha-producing tumor cells or DCs pulsed with tumor cells alone. The protective effect was most evident when the MIP-3alpha-producing tumor cells and DC-based vaccines were injected at the same site. These results support the notion that this combination vaccination strategy might generate a more effective immune response to suppress the growth of tumor cells in animals.

Phenotype of dendritic cells generated in the presence of non-small cell lung cancer antigens - preliminary report

Therapeutic outcomes of definitively treated non-small-cell lung cancer (NSCLC) are unacceptably poor. It has been proposed that the manipulation of dendritic cells (DCs) as a "natural" vaccine adjuvant may prove to be a particularly effective way to stimulate antitumor immunity. Presently, there is no standardized methodology for preparing vaccines and many questions concerning the optimal source and type of antigens as well as maturation state and activity of DCs are still unsolved. The study population comprised of ten patients with histologically confirmed NSCLC (mean age: 67.63 +/- 6.15 years). Resected small tumor pieces were placed in tissue culture dishes containing different growth factors in order to obtain pure cancer cells. Seven days after the operation, the PBMC were collected and monocytes were purified by the adherence to culture dishes. Monocytes were cultured in RPMI 1640 medium supplemented with 10% of autologous plasma in the presence of rhIL-4 and rhGM-CSF to generate immature autologous (DCs). TNF-alpha with or without tumor cells' lysate were added to maturation of DCs. After 7 days of culture, DCs were harvested and the expression of CD1a, CD83, CD80, CD86 and HLA-DR antigens were analyzed by flow cytometry. We discovered higher (p=0.07) percentage of semimature DCs in tumor cell lysate culture in comparison with TNF-alpha culture (21.22 +/- 16.82% versus 11.27 +/- 11.64%). The expression of co-stimulatory and maturation markers (CD86, CD83 and HLA-DR) was higher on DCs from the culture with tumor cell lysate compared with TNF-alpha culture as a control. Specimen of NSCLC's culture prepared in this way could generate differences in DCs phenotype, which may have an influence on the therapeutic and protective antitumor immunity of the vaccine. Our research seems to be the next step in the development of DC-based vaccine. We are going to continue the investigation to start the preparation of a pattern of immunological vaccine against lung cancer.

Vaccine therapy in non-small-cell lung cancer

Lung cancer is the leading cause of death from cancer worldwide. First-line therapy is based on stage at diagnosis and can include chemotherapy, radiation, and surgery. Despite advances, the prognosis for advanced-stage lung cancer is very poor. Vaccines with the capability to activate the host immune system may have a role in second-line therapy. Advances in the understanding of cellular and molecular immunology are forming the basis for improving vaccine therapy. Most trials to date have demonstrated safety but inconsistent efficacy. Further research is needed to enhance this potential.

TGF-beta insensitive dendritic cells: an efficient vaccine for murine prostate cancer

Dendritic cells (DCs) are highly potent initiators of the immune response, but DC effector functions are often inhibited by immunosuppressants such as transforming growth factor beta (TGF-beta). The present study was conducted to develop a treatment strategy for prostate cancer using a TGF-beta-insensitive DC vaccine. Tumor lysate-pulsed DCs were rendered TGF-beta insensitive by dominant-negative TGF-beta type II receptor (TbetaRIIDN), leading to the blockade of TGF-beta signals to members of the Smad family, which are the principal cytoplasmic intermediates involved in the transduction of signals from TGF-beta receptors to the nucleus. Expression of TbetaRIIDN did not affect the phenotype of transduced DCs. Phosphorylated Smad-2 was undetectable and expression of surface co-stimulatory molecules (CD80/CD86) were upregulated in TbetaRIIDN DCs after antigen and TGF-beta1 stimulation. Vaccination of C57BL/6 tumor-bearing mice with the TbetaRIIDN DC vaccine induced potent tumor-specific cytotoxic T lymphocyte responses against TRAMP-C2 tumors, increased serum IFN-gamma and IL-12 level, inhibited tumor growth and increased mouse survival. Furthermore, complete tumor regression occurred in two vaccinated mice. These results demonstrate that blocking TGF-beta signals in DC enhances the efficacy of DC-based vaccines.

Treatment of squamous carcinoma in mice with a vaccine enriched for cells that induce immunity to squamous carcinoma--a new vaccination strategy

We report a new vaccination strategy for squamous cell carcinoma (SCC). The vaccine was prepared by transfer of unfractionated DNA-fragments (25 kb) from squamous carcinoma cells (KLN205, DBA/2 origin (H-2(d))) into LM mouse fibroblasts (C3H/He origin; H-2(k)), a highly immunogenic cell line. To enhance their nonspecific immunogenic properties, the fibroblasts were modified before DNA transfer to secrete IL-2 and to express additional allogeneic MHC class I determinants. As the transferred DNA integrates into the genome of the recipient cells, and is replicated as the cells divide, sufficient DNA to prepare the vaccine could be obtained from as few as 10(7) squamous carcinoma cells (4 mm tumor). Since only a small proportion of the transfected cell-population was expected to have incorporated genes specifying antigens associated with the squamous carcinoma cells (TAA), we devised a novel approach to enrich the vaccine for cells that induce immunity to the SCC. Aliquots of the transfected population were divided into 10 small pools (initial inoculums = 1 x 10(3)). We reasoned that if the starting inoculums were sufficiently small, then the distribution of highly immunogenic and weakly immunogenic cells in each pool would not be the same. Cells from individual pools were allowed to increase in number. A portion of the expanded cell populations were maintained frozen/viable for later recovery. The remaining portions were used to immunize naïve DBA/2 mice. Pools containing greater numbers of immunogenic cells were identified by 2 independent assays. Frozen aliquots of cells from the pool that stimulated immunity to the squamous carcinoma to the greatest extent were recovered and subdivided for additional rounds of immune selection. Enhanced immunity to squamous carcinoma mediated by CD8+ T cells was induced in tumor-bearing mice treated solely by immunization with the enriched cell-population.

Current State and Perspectives of Dendritic Cell Vaccination in Cancer Immunotherapy

Recent progress in the approach towards immunotherapy of cancer consists in molecular definition of tumor antigens, new tools for phenotypical and functional characterization of tumor-specific effector cells and clinical use of novel adjuvants for optimal stimulation of a cancer-specific immune response such as dendritic cells. In spite of these advances and immunological as well as clinical responses in selected patients, mechanisms involved in dendritic-cell-based cancer immunotherapy are still poorly understood. Therefore, a standardized study design and small pilot trials are needed to explore open scientific questions in future clinical trials. This review focuses on the different parameters of dendritic cell biology relevant to cancer immunotherapy and on innovative approaches to hopefully enhance the efficacy of dendritic cell vaccination.

Dendritic cells engineered to express CD40L continuously produce IL12 and resist negative signals from Tr1/Th3 dominated tumors

TNFalpha-matured dendritic cells (DCs) pulsed with tumor antigens are being evaluated as cancer vaccines. It has been shown that DCs produce IL12 during a limited time span and subsequently enter a stage of IL12 exhaustion. If DCs are generated ex vivo, the patient could receive IL12-exhausted DCs which may be detrimental for stimulating anti-tumor Th1 responses. Furthermore, many cancer patients exhibit a cytokine profile skewed toward IL10 and TGFbeta. This immunological profile, called the Tr1/Th3 response, is associated with the presence of regulatory T-cells. Tr1/Th3 responses potently inhibit DC maturation, thereby regulating Th1 responses. In the present study, we produced genetically engineered DCs that continuously express Th1-related cytokines such as IL12, and resist negative signals from Tr1/Th3-dominated bladder carcinoma cells. Human immature DCs were genetically engineered by adenoviral vectors to express CD40L, or were treated with TNFalpha as a positive control for maturation. The expression of different Th1/Th3 and inflammatory cytokines was monitored. IL12 and IFNgamma were expressed by CD40L-engineered DCs, while TNFalpha-matured DCs lacked IFNgamma and exhibited low IL12 expression. The addition of recombinant IL10 to genetically engineered DCs did not abolish their Th1 profile. Likewise, coculture with tumor cell lines expressing TGFbeta with or without recombinant IL10 did not revert to the engineered DCs. We further demonstrate that the resistance of CD40L-expressing DCs to TGFbeta and IL10 may be due to decreased levels of TGFbeta and IL10 receptors. Thus, CD40L-engineered DCs are robust Th1-promoting ones that are resistant to Tr1/Th3-signaling via IL10 and TGFbeta.

Efficient Generation of Canine Bone Marrow-Derived Dendritic Cells

Because of their unsurpassed potency in presenting antigens to naive T cells, dendritic cells are considered to be an important candidate in the development of immunotherapeutic strategies. Despite the high potential of dendritic cell-based immunotherapy, as a so-called dendritic cell vaccination, few clinical approaches using dendritic cell vaccination have been performed in the dog because of very limited information regarding the generation of canine dendritic cells and their functional properties. We therefore established a protocol for the efficient generation of dendritic cells from canine bone marrow cells using recombinant feline granulocyte-macrophage colony-stimulating factor and canine interleukin-4. Dendritic cells were generated efficiently: a yield of 1-9 x 10(6) cells per approximately 0.5 ml of canine bone marrow aspiration was achieved. These dendritic cells showed features shared with mouse and human dendritic cells: dendrite morphology, expression of surface markers MHC class II and CD11c, and up-regulation of molecules related to antigen presentation (MHC class II, B7-1, and B7-2) by activation with lipopolysaccharide. Moreover, the dendritic cells demonstrated phagocytic activity, processing activity of pinocytosed proteins, and activation of allogeneic T cells far more potent than that by macrophages. Our findings suggest that the bone marrow-derived dendritic cells are functional for the capturing and processing of antigens and the initiation of T cell responses.

Targeting the local tumor microenvironment with vaccinia virus expressing B7.1 for the treatment of melanoma

Immunotherapy for the treatment of metastatic melanoma remains a major clinical challenge. The melanoma microenvironment may lead to local T cell tolerance in part through downregulation of costimulatory molecules, such as B7.1 (CD80). We report the results from the first clinical trial, to our knowledge, using a recombinant vaccinia virus expressing B7.1 (rV-B7.1) for monthly intralesional vaccination of accessible melanoma lesions. A standard 2-dose-escalation phase I clinical trial was conducted with 12 patients. The approach was well tolerated with only low-grade fever, myalgias, and fatigue reported and 2 patients experiencing vitiligo. An objective partial response was observed in 1 patient and disease stabilization in 2 patients, 1 of whom is alive without disease 59 months following vaccination. All patients demonstrated an increase in postvaccination antibody and T cell responses against vaccinia virus. Systemic immunity was tested in HLA-A*0201 patients who demonstrated an increased frequency of gp100 and T cells specific to melanoma antigen recognized by T cells 1 (MART-1), also known as Melan-A, by ELISPOT assay following local rV-B7.1 vaccination. Local immunity was evaluated by quantitative real-time RT-PCR, which suggested that tumor regression was associated with increased expression of CD8 and IFN-gamma. The local delivery of vaccinia virus expressing B7.1 was well tolerated and represents an innovative strategy for altering the local tumor microenvironment in patients with melanoma.