Intratumoral injection of dendritic cells in combination with local hyperthermia induces systemic antitumor effect in patients with advanced melanoma

Polymersome-based protein drug delivery - quo vadis?

Protein-based therapeutics are an attractive alternative to established therapeutic approaches and represent one of the fastest growing families of drugs. While many of these proteins can be delivered using established formulations, the intrinsic sensitivity of proteins to denaturation sometimes calls for a protective carrier to allow administration. Historically, lipid-based self-assembled structures, notably liposomes, have performed this function. After the discovery of polymersome-based targeted drug-delivery systems, which offer manifold advantages over lipid-based structures, the scientific community expected that such systems would take the therapeutic world by storm. However, no polymersome formulations have been commercialised. In this review article, we discuss key obstacles for the sluggish translation of polymersome-based protein nanocarriers into approved pharmaceuticals, which include limitations imparted by the use of non-degradable polymers, the intricacies of polymersome production methods, and the complexity of the in vivo journey of polymersomes across various biological barriers. Considering this complex subject from a polymer chemist's point of view, we highlight key areas that are worthy to explore in order to advance polymersomes to a level at which clinical trials become worthwhile and translation into pharmaceutical and nanomedical applications is realistic.

Local Destruction of Tumors and Systemic Immune Effects

Current immune-based therapies signify a major advancement in cancer therapy; yet, they are not effective in the majority of patients. Physically based local destruction techniques have been shown to induce immunologic effects and are increasingly used in order to improve the outcome of immunotherapies. The various local destruction methods have different modes of action and there is considerable variation between the different techniques with respect to the ability and frequency to create a systemic anti-tumor immunologic effect. Since the abscopal effect is considered to be the best indicator of a relevant immunologic effect, the present review focused on the tissue changes associated with this effect in order to find determinants for a strong immunologic response, both when local destruction is used alone and combined with immunotherapy. In addition to the T cell-inflammation that was induced by all methods, the analysis indicated that it was important for an optimal outcome that the released antigens were not destroyed, tumor cell death was necrotic and tumor tissue perfusion was at least partially preserved allowing for antigen presentation, immune cell trafficking and reduction of hypoxia. Local treatment with controlled low level hyperthermia met these requisites and was especially prone to result in abscopal immune activity on its own.

Tackling cancer cell dormancy: Insights from immune models, and transplantation

Disseminated non-dividing (dormant) cancer cells as well as those in equilibrium with the immune response remain the major challenge for successful treatment of cancer. The equilibrium between disseminated dormant cancer cells and the immune system is reminiscent of states that can occur during infection or allogeneic tissue and cell transplantation. We discuss here the major competing models of how the immune system achieves a self nonself discrimination (pathogen/danger patterns, quorum, and coinhibition/tuning models), and suggest that taking advantage of a combination of the proposed mechanisms in each model may lead to increased efficacy in tackling cancer cell dormancy.

Synergic effects of nanoparticles-mediated hyperthermia in radiotherapy/chemotherapy of cancer

The conventional cancer treatment modalities such as radiotherapy and chemotherapy suffer from several limitations; hence, their efficiency needs to be improved with other complementary modalities. Hyperthermia, as an adjuvant therapeutic modality for cancer, can result in a synergistic effect on radiotherapy (radiosensitizer) and chemotherapy (chemosensitizer). Conventional hyperthermia methods affect both tumoral and healthy tissues and have low specificity. In addition, a temperature gradient generates in the tissues situated along the path of the heat source, which is a more serious for deep-seated tumors. Nanoparticles (NPs)-induced hyperthermia can resolve these drawbacks through localization around/within tumoral tissue and generating local hyperthermia. Although there are several review articles dealing with NPs-induced hyperthermia, lack of a paper discussing the combination of NPs-induced hyperthermia with the conventional chemotherapy or radiotherapy is tangible. Accordingly, the main focus of the current paper is to summarize the principles of NPs-induced hyperthermia and more importantly its synergic effects on the conventional chemotherapy or radiotherapy. The heat-producing nanostructures such as gold NPs, iron oxide NPs, and carbon NPs, as well as the non-heat-producing nanostructures, such as lipid-based, polymeric, and silica-based NPs, as the carrier for heat-producing NPs, are discussed and their pros and cons highlighted.

Combination Therapy of Pulsed-Wave Ultrasound Hyperthermia and Immunostimulant OK-432 Enhances Systemic Antitumor Immunity for Cancer Treatment

PURPOSE

In this study, we hypothesized that systemic antitumor immunity might be enhanced by combining pulsed-wave ultrasound hyperthermia (pUSHT) with OK-432 and that the induced antitumor immunity could confer protection against tumorigenesis. These hypotheses were tested in bilateral and rechallenged tumor models.

METHODS AND MATERIALS

Bilateral and rechallenged tumor models were applied in the studies. In the bilateral tumor model, BALB/c mice were inoculated in both flanks with CT26-luc tumor cells. The tumors in the right flank were treated with 4 courses of pUSHT with or without OK-432. In the rechallenged tumor model, tumor cells were implanted into the right flank. Once formed, the tumors were treated with pUSHT with OK-432, followed by surgical resection. New tumor cells were then implanted into the contralateral flank. The antitumor response was evaluated via infiltrated immune cells and the severity of necrosis/apoptosis in tumors.

RESULTS

In the bilateral tumor model, the tumor growth rate and growth activity of both treated (100% reduction) and untreated tumors (90.5% reduction) were significantly inhibited with the combination treatment compared with the sham control group, and the systemic antitumor effect was prolonged. The survival rate was significantly enhanced (sham control, 8 days; OK plus pUSHT, >20 days). IFNγ⁺ CD4 (treated tumor, 8.6-fold; untreated tumor, 4-fold), IFNγ⁺ CD8 (treated tumor, 6.7-fold; untreated tumor, 2.6-fold), and T cell and NK cell (treated tumor, 4-fold; untreated tumor, 2.5-fold) infiltration was increased in the combination group compared with the control group. In the rechallenged tumor model, new tumors failed to form with the combination treatment.

CONCLUSION

This experimental study combining pUSHT and OK-432 explored a new therapeutic strategy for controlling colon cancer metastasis. The results show that the combination treatment may produce an effective antitumor immune response.

Dendritic Cells and Immunogenic Cancer Cell Death: A Combination for Improving Antitumor Immunity

The safety and feasibility of dendritic cell (DC)-based immunotherapies in cancer management have been well documented after more than twenty-five years of experimentation, and, by now, undeniably accepted. On the other hand, it is equally evident that DC-based vaccination as monotherapy did not achieve the clinical benefits that were predicted in a number of promising preclinical studies. The current availability of several immune modulatory and targeting approaches opens the way to many potential therapeutic combinations. In particular, the evidence that the immune-related effects that are elicited by immunogenic cell death (ICD)-inducing therapies are strictly associated with DC engagement and activation strongly support the combination of ICD-inducing and DC-based immunotherapies. In this review, we examine the data in recent studies employing tumor cells, killed through ICD induction, in the formulation of anticancer DC-based vaccines. In addition, we discuss the opportunity to combine pharmacologic or physical therapeutic approaches that can promote ICD in vivo with in situ DC vaccination.

In situ Vaccination by Direct Dendritic Cell Inoculation: The Coming of Age of an Old Idea?

For more than 25 years, dendritic cell (DC) based vaccination has flashily held promises to represent a therapeutic approach for cancer treatment. While the vast majority of studies has focused on the use of antigen loaded DC, the intratumoral delivery of unloaded DC aiming at in situ vaccination has gained much less attention. Such approach grounds on the ability of inoculated DC to internalize and process antigens directly released by tumor (usually in combination with cell-death-inducing agents) to activate broad patient-specific antitumor T cell response. In this review, we highlight the recent studies in both solid and hematological tumors showing promising clinical results and discuss the main pitfalls and advantages of this approach for endogenous cancer vaccination. Lastly, we discuss how in situ vaccination by DC inoculation may fit with current immunotherapy approaches to expand and prolong patient response.

Intralesional rose bengal in melanoma elicits tumor immunity via activation of dendritic cells by the release of high mobility group box 1

Intralesional (IL) therapy is under investigation to treat dermal and subcutaneous metastatic cancer. Rose bengal (RB) is a staining agent that was originally used by ophthalmologists and in liver function studies. IL injection of RB has been shown to induce regression of injected and uninjected tumors in murine models and clinical trials. In this study, we have shown a mechanism of tumor-specific immune response induced by IL RB. In melanoma-bearing mice, IL RB induced regression of injected tumor and inhibited the growth of bystander lesions mediated by CD8⁺ T cells. IL RB resulted in necrosis of tumor cells and the release of High Mobility Group Box 1 (HMGB1), with increased dendritic cell (DC) infiltration into draining lymph nodes and the activation of tumor-specific T cells. Treatment of DC with tumor supernatants increased the ability of DCs to stimulate T cell proliferation, and blockade of HMGB1 in the supernatants suppressed DC activity. Additionally, increased HMGB1 levels were measured in the sera of melanoma patients treated with IL RB. These results support the role of IL RB to activate dendritic cells at the site of tumor necrosis for the induction of a systemic anti-tumor immune response.

Propofol promotes apoptosis and suppresses the HOTAIR-mediated mTOR/p70S6K signaling pathway in melanoma cells

Propofol is an intravenous anesthetic, which is widely used in clinical anesthesia induction and maintenance and is critical in the sedation of patients. However, the functions and mechanisms of propofol on apoptosis of melanoma cells remain unclear. The present study investigated whether propofol promotes cell apoptosis and suppresses the HOX transcript antisense RNA (HOTAIR)-mediated mechanistic target of rapamycin (mTOR) pathway in melanoma cells. B16F10 cells were cultured with different concentrations (0-10 µM) of propofol for 24 or 48 h. Proliferation and apoptosis of B16F10 cells were detected using MTT assay and flow cytometry. The pcDNA 3.1(-)-HOTAIR and pcDNA 3.1(-)-control plasmids were transfected into B16F10 cells using Lipofectamine 2000. In the present study, treatment with propofol significantly reduced viability, and induced apoptosis and caspase-3 activity in melanoma cells. Propofol treatment significantly inhibited HOTAIR expression and the expression of phosphorylated (p)-mTOR and p- p70S6K protein in melanoma cells. Overexpression of HOTAIR significantly increased viability of melanoma cells, and increased HOTAIR, p-mTOR and p-p70S6K protein expression in melanoma cells. These results indicated that propofol promotes apoptosis and suppresses the HOTAIR-mediated mTOR signaling pathway in melanoma cells.

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.

The cryo-thermal therapy eradicated melanoma in mice by eliciting CD4+ T-cell-mediated antitumor memory immune response

Tumor metastasis is a major concern in tumor therapy. In our previous studies, a novel tumor therapeutic modality of the cryo-thermal therapy has been presented, highlighting its effect on the suppression of distal metastasis and leading to long-term survival in 4T1 murine mammary carcinoma model. To demonstrate the therapeutic efficacy in other aggressive tumor models and further investigate the mechanism of long-term survival induced, in this study, spontaneous metastatic murine B16F10 melanoma model was used. The cryo-thermal therapy induced regression of implanted melanoma and prolonged long-term survival while inhibiting lung metastasis. It also promoted the activation of CD4⁺ CD25⁻ conventional T cells, while reduced the percentage of CD4⁺ CD25⁺ regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) in the spleen, lung and blood. Furthermore, the cryo-thermal therapy enhanced the cytolytic function of CD8⁺ T cells and induced differentiation of CD8⁺ T cells into memory stem T cell (T_SCM), and differentiation of CD4⁺ T cells into dominant CD4-CTL, Th1 and Tfh subsets in the spleen for 90 days after the treatment. It was found that good therapeutic effect was mainly dependent on CD4⁺ T cells providing a durable memory antitumor immune response. At the same time, significant increase of serum IFN-γ was also observed to provide an ideal microenvironment of antitumor immunity. Further study showed that the rejection of re-challenge of B16F10 but not GL261 tumor in the treated mice in 45 or 60 days after the treatment, implied a strong systemic and melanoma-specific memory antitumor immunity induced by the treatment. Thus the cryo-thermal therapy would be considered as a new therapeutic strategy to prevent tumor recurrence and metastasis with potential clinical applications in the near future.

In situ vaccination for the treatment of cancer

Vaccination has had a tremendous impact on human health by harnessing the immune system to prevent and eradicate infectious diseases and this same approach might be used in cancer therapy. Cancer vaccine development has been slowed hindered by the paucity of universal tumor-associated antigens and the difficulty in isolating and preparing individualized vaccines ex vivo. Another approach has been to initiate or stimulate an immune response in situ (at the tumor site) and thus exploit the potentially numerous tumor-associated antigens there. Here, we review the many approaches that have attempted to accomplish effective in situ vaccination, using intratumoral administration of immunomodulators to increase the numbers or activation state of either antigen present cells or T cells within the tumor.

Use of Cell-Penetrating Peptides in Dendritic Cell-Based Vaccination

Cell-penetrating peptides (CPPs) are short amino acids that have been widely used to deliver macromolecules such as proteins, peptides, DNA, or RNA, to control cellular behavior for therapeutic purposes. CPPs have been used to treat immunological diseases through the delivery of immune modulatory molecules in vivo. Their intracellular delivery efficiency is highly synergistic with the cellular characteristics of the dendritic cells (DCs), which actively uptake foreign antigens. DC-based vaccines are primarily generated by pulsing DCs ex vivo with various immunomodulatory antigens. CPP conjugation to antigens would increase DC uptake as well as antigen processing and presentation on both MHC class II and MHC class I molecules, leading to antigen specific CD4(+) and CD8(+) T cell responses. CPP-antigen based DC vaccination is considered a promising tool for cancer immunotherapy due to the enhanced CTL response. In this review, we discuss the various applications of CPPs in immune modulation and DC vaccination, and highlight the advantages and limitations of the current CPP-based DC vaccination.

Antitumor dendritic cell-based vaccines: lessons from 20 years of clinical trials and future perspectives

Dendritic cells (DCs) are versatile elements of the immune system and are best known for their unparalleled ability to initiate and modulate adaptive immune responses. During the past few decades, DCs have been the subject of numerous studies seeking new immunotherapeutic strategies against cancer. Despite the initial enthusiasm, disappointing results from early studies raised some doubts regarding the true clinical value of these approaches. However, our expanding knowledge of DC immunobiology and the definition of the optimal characteristics for antitumor immune responses have allowed a more rational development of DC-based immunotherapies in recent years. Here, after a brief overview of DC immunobiology, we sought to systematize the knowledge provided by 20 years of clinical trials, with a special emphasis on the diversity of approaches used to manipulate DCs and their consequent impact on vaccine effectiveness. We also address how new therapeutic concepts, namely the combination of DC vaccines with other anticancer therapies, are being implemented and are leveraging clinical outcomes. Finally, optimization strategies, new insights, and future perspectives on the field are also highlighted.

In situ vaccination: Cancer immunotherapy both personalized and off-the-shelf

As cancer immunotherapy continues to benefit from novel approaches which cut immune 'brake pedals' (e.g. anti-PD1 and anti-CTLA4 antibodies) and push immune cell gas pedals (e.g. IL2, and IFNα) there will be increasing need to develop immune 'steering wheels' such as vaccines to guide the immune system specifically toward tumor associated antigens. Two primary hurdles in cancer vaccines have been: identification of universal antigens to be used in 'off-the-shelf' vaccines for common cancers, and 2) logistical hurdles of ex vivo production of individualized whole tumor cell vaccines. Here we summarize approaches using 'in situ vaccination' in which intratumoral administration of off-the-shelf immunomodulators have been developed to specifically induce (or amplify) T cell responses to each patient's individual tumor. Clinical studies have confirmed the induction of systemic immune and clinical responses to such approaches and preclinical models have suggested ways to further potentiate the translation of in situ vaccine trials for our patients.

Fever and the thermal regulation of immunity: the immune system feels the heat

Fever is a cardinal response to infection that has been conserved in warm-blooded and cold-blooded vertebrates for more than 600 million years of evolution. The fever response is executed by integrated physiological and neuronal circuitry and confers a survival benefit during infection. In this Review, we discuss our current understanding of how the inflammatory cues delivered by the thermal element of fever stimulate innate and adaptive immune responses. We further highlight the unexpected multiplicity of roles of the pyrogenic cytokine interleukin-6 (IL-6), both during fever induction and during the mobilization of lymphocytes to the lymphoid organs that are the staging ground for immune defence. We also discuss the emerging evidence suggesting that the adrenergic signalling pathways associated with thermogenesis shape immune cell function.

Vitiligo-like depigmentation in patients with stage III-IV melanoma receiving immunotherapy and its association with survival: a systematic review and meta-analysis

PURPOSE

Vitiligo-like depigmentation in patients with melanoma may be associated with more favorable clinical outcome. We conducted a systematic review of patients with stage III to IV melanoma treated with immunotherapy to determine the cumulative incidence of vitiligo-like depigmentation and the prognostic value of vitiligo development on survival.

METHODS

We systemically searched and selected all studies on melanoma immunotherapy that reported on autoimmune toxicity and/or vitiligo between 1995 and 2013. Methodologic quality of each study was appraised using adapted criteria for systematic reviews in prognostic studies. Random-effect models were used to calculate summary estimates of the cumulative incidence of vitiligo-like depigmentation across studies. The prognostic value of vitiligo-like depigmentation on survival outcome was assessed using random-effects Cox regression survival analyses.

RESULTS

One hundred thirty-seven studies were identified comprising 139 treatment arms (11 general immune stimulation, 84 vaccine, 28 antibody-based, and 16 adoptive transfer) including a total of 5,737 patients. The overall cumulative incidence of vitiligo was 3.4% (95% CI, 2.5% to 4.5%). In 27 studies reporting individual patient data, vitiligo development was significantly associated with both progression-free-survival (hazard ratio [HR], 0.51; 95% CI, 0.32 to 0.82; P < .005) and overall survival (HR, 0.25; 95% CI, 0.10 to 0.61; P < .003), indicating that these patients have two to four times less risk of disease progression and death, respectively, compared with patients without vitiligo development.

CONCLUSION

Although vitiligo occurs only in a low percentage of patients with melanoma treated with immunotherapy, our findings suggest clear survival benefit in these patients. Awareness of vitiligo induction in patients with melanoma is important as an indicator of robust antimelanoma immunity and associated improved survival.

Intralesional therapy for metastatic melanoma

INTRODUCTION

Intralesional therapy for metastatic melanoma has some advantages over systemic therapy. Local drug administration allows for delivery of an increased concentration of the agent and reduced systemic exposure, thereby increasing local efficacy and limiting toxicity. Moreover, since in vivo tumor nodules contain the tumor antigens, this tumor tissue may serve as an autologous vaccine to induce systemic immunity. This so-called 'bystander effect', where uninjected distant lesions exhibit a response, has been reported in select intralesional therapy trials.

AREAS COVERED

This review will give an overview of the working mechanisms, clinical evidence and side effects for available intralesional and topical therapies and summarize the most recent developments in this field.

EXPERT OPINION

The ideal treatment approach for locoregionally advanced melanoma should be multidisciplinary and tailored to the patient, taking into consideration patient-related, tumor-related factors (such as location, tumor burden, mutation status) and previous treatments received. It will likely not be a single therapy, but rather a combination of injectable treatments, regional perfusions and systemic therapies.

FoxP3 and indoleamine 2,3-dioxygenase immunoreactivity in sentinel nodes from melanoma patients

OBJECTIVE

1) Assess FoxP3/indoleamine 2,3-dioxygenase immunoreactivity in head and neck melanoma sentinel lymph nodes and 2) correlate FoxP3/indoleamine 2,3-dioxygenase with sentinel lymph node metastasis and clinical recurrence.

STUDY DESIGN

Retrospective cohort study.

METHODS

Patients with sentinel lymph node biopsy for head and neck melanoma between 2004 and 2011 were identified. FoxP3/indoleamine 2,3-dioxygenase prevalence and intensity were determined from the nodes. Poor outcome was defined as local, regional or distant recurrence. The overall immunoreactivity score was correlated with clinical recurrence and sentinel lymph node metastasis using the chi-square test for trend.

RESULTS

Fifty-six sentinel lymph nodes were reviewed, with 47 negative and 9 positive for melanoma. Patients with poor outcomes had a statistically significant trend for higher immunoreactivity scores (p=0.03). Positive nodes compared to negative nodes also had a statistically significant trend for higher immunoreactivity scores (p=0.03). Among the negative nodes, there was a statistically significant trend for a poor outcome with higher immunoreactivity scores (p=0.02).

CONCLUSION

FoxP3/indoleamine 2,3-dioxygenase immunoreactivity correlates with sentinel lymph node positivity and poor outcome. Even in negative nodes, higher immunoreactivity correlated with poor outcome. Therefore higher immunoreactivity may portend a worse prognosis even without metastasis in the sentinel lymph node. This could identify a subset of patients that may benefit from future trials and treatment for melanoma through Treg and IDO suppression.

Trial watch: Dendritic cell-based interventions for cancer therapy

Dendritic cells (DCs) occupy a central position in the immune system, orchestrating a wide repertoire of responses that span from the development of self-tolerance to the elicitation of potent cellular and humoral immunity. Accordingly, DCs are involved in the etiology of conditions as diverse as infectious diseases, allergic and autoimmune disorders, graft rejection and cancer. During the last decade, several methods have been developed to load DCs with tumor-associated antigens, ex vivo or in vivo, in the attempt to use them as therapeutic anticancer vaccines that would elicit clinically relevant immune responses. While this has not always been the case, several clinical studies have demonstrated that DC-based anticancer vaccines are capable of activating tumor-specific immune responses that increase overall survival, at least in a subset of patients. In 2010, this branch of clinical research has culminated with the approval by FDA of a DC-based therapeutic vaccine (sipuleucel-T, Provenge^®) for use in patients with asymptomatic or minimally symptomatic metastatic hormone-refractory prostate cancer. Intense research efforts are currently dedicated to the identification of the immunological features of patients that best respond to DC-based anticancer vaccines. This knowledge may indeed lead to personalized combination strategies that would extend the benefit of DC-based immunotherapy to a larger patient population. In addition, widespread enthusiasm has been generated by the results of the first clinical trials based on in vivo DC targeting, an approach that holds great promises for the future of DC-based immunotherapy. In this Trial Watch, we will summarize the results of recently completed clinical trials and discuss the progress of ongoing studies that have evaluated/are evaluating DC-based interventions for cancer therapy.

Intralesional injection of rose bengal induces a systemic tumor-specific immune response in murine models of melanoma and breast cancer

Intralesional (IL) injection of PV-10 has shown to induce regression of both injected and non-injected lesions in patients with melanoma. To determine an underlying immune mechanism, the murine B16 melanoma model and the MT-901 breast cancer model were utilized. In BALB/c mice bearing MT-901 breast cancer, injection of PV-10 led to regression of injected and untreated contralateral subcutaneous lesions. In a murine model of melanoma, B16 cells were injected into C57BL/6 mice to establish one subcutaneous tumor and multiple lung lesions. Treatment of the subcutaneous lesion with a single injection of IL PV-10 led to regression of the injected lesion as well as the distant B16 melanoma lung metastases. Anti-tumor immune responses were measured in splenocytes collected from mice treated with IL PBS or PV-10. Splenocytes isolated from tumor bearing mice treated with IL PV-10 demonstrated enhanced tumor-specific IFN-gamma production compared to splenocytes from PBS-treated mice in both models. In addition, a significant increase in lysis of B16 cells by T cells isolated after PV-10 treatment was observed. Transfer of T cells isolated from tumor-bearing mice treated with IL PV-10 led to tumor regression in mice bearing B16 melanoma. These studies establish that IL PV-10 therapy induces tumor-specific T cell-mediated immunity in multiple histologic subtypes and support the concept of combining IL PV10 with immunotherapy for advanced malignancies.

Old and new facts about hyperthermia-induced modulations of the immune system

Hyperthermia (HT) is a potent sensitiser for radiotherapy (RT) and chemotherapy (CT) and has been proven to modulate directly or indirectly cells of the innate and adaptive immune system. We will focus in this article on how anti-tumour immunity can be induced by HT. In contrast to some in vitro assays, in vivo examinations showed that natural killer cells and phagocytes like granulocytes are directly activated against the tumour by HT. Since heat also activates dendritic cells (DCs), HT should be combined with further death stimuli (RT, CT or immune therapy) to allocate tumour antigen, derived from, for example, necrotic tumour cells, for uptake by DCs. We will outline that induction of immunogenic tumour cells and direct tumour cell killing by HT in combination with other therapies contributes to immune activation against the tumour. Studies will be presented showing that non-beneficial effects of HT on immune cells are mostly timely restricted. A special focus is set on immune activation mediated by extracellular present heat shock proteins (HSPs) carrying tumour antigens and further danger signals released by dying tumour cells. Local HT treatment in addition to further stress stimuli exerts abscopal effects and might be considered as in situ tumour vaccination. An increased natural killer (NK) cell activity, lymphocyte infiltration and HSP-mediated induction of immunogenic tumour cells have been observed in patients. Treatments with the addition of HT therefore can be considered as a personalised cancer treatment approach by specifically activating the immune system against the individual unique tumour.

Effector CD8+ T cell IFN-γ production and cytotoxicity are enhanced by mild hyperthermia

PURPOSE

Clinical trials combining hyperthermia with radiation and/or chemotherapy for cancer treatment have resulted in improved overall survival and control of local recurrences. The contribution of thermally enhanced anti-immune function in these effects is of considerable interest, but not understood; studies on the fundamental effects of elevated temperature on immune effector cells are needed. The goal of this study is to investigate the potential of mild hyperthermia to impact tumour antigen-specific (Ag) effector CD8+ T cell functions.

METHOD

Pmel-1 Ag-specific CD8+ T cells were exposed to mild hyperthermia and tested for changes in IFN-γ production and cytotoxicity. Additionally, overall plasma membrane organisation and the phosphorylation of signalling proteins were also investigated following heat treatment.

RESULTS

Exposing effector Pmel-1-specific CD8+ T cells to mild hyperthermia (39.5°C) resulted in significantly enhanced Ag-specific IFN-γ production and tumour target cell killing compared to that seen using lower temperatures (33° and 37°C). Further, inhibition of protein synthesis during hyperthermia did not reduce subsequent Ag-induced IFN-γ production by CD8+ T cells. Correlated with these effects, we observed a distinct clustering of GM1(+) lipid microdomains at the plasma membrane and enhanced phosphorylation of LAT and PKCθ which may be related to an observed enhancement of Ag-specific effector CD8+ T cell IFN-γ gene transcription following mild hyperthermia. However, mitogen-mediated production of IFN-γ, which bypasses T cell receptor activation with antigen, was not enhanced.

CONCLUSIONS

Antigen-dependent effector T cell activity is enhanced following mild hyperthermia. These effects could potentially occur in patients being treated with thermal therapies. These data also provide support for the use of thermal therapy as an adjuvant for immunotherapies to improve CD8+ effector cell function.

Inhibition of B16 murine melanoma metastasis and enhancement of immunity by fever-range whole body hyperthermia

PURPOSE

Whole body hyperthermia (WBH) has been regarded as a promising alternative therapy to cure late stage cancer with metastasis. As the final biological and therapeutic effects are dependent on the specific protocol, the potential of using a microwave-based WBH approach for metastasis inhibition is established and its typical results are discussed.

MATERIALS AND METHODS

The effectiveness of a 30-min whole body hyperthermia (WH) on animals, raised to a rectal temperature of 40.2° ± 0.3°C for 30  min followed by 84 h observation by 2450 MHz microwave irradiation, were evaluated. In an experimental lung metastasis model by injection of B16-F10 melanoma, lungs were removed from sacrificed mice 16 days after tumour implantation, and the expression of heat shock protein, inter-cellular adhesion molecule 1 (ICAM-1), proliferating cell nuclear antigen (PCNA) and cyclin D(1) was examined. CD4(+), CD8(+) and NK cell subpopulation in peripheral blood were measured by flow cytometry before and after the last treatment.

RESULTS

The best therapeutic effect was obtained when the mice were treated with WBH in combination with the initial chemotherapy with cis-diaminodichloroplatinum (CDDP) and dacarbazine (DTIC) (p < 0.05). The WBH alone has an advantage of reduced toxicity and lower cost. Heat shock protein (HSP) expression increased in the hyperthermia groups. Reduction of PCNA and cyclin D(1) was observed in the mice treated with WH alone or in combination with chemotherapy. In the hyperthermia groups, CD4(+)/CD8(+) decreased while the NK increased slightly.

CONCLUSIONS

The whole body hyperthermia protocol described in this work inhibits B16 tumour metastasis by inhibiting cell proliferation, neovascularisation and stimulating favourable immune responses. It demonstrated that WBH treatment benefits therapy of metastasis cancers.

Re-inventing intratumoral immunotherapy for melanoma

Immunotherapeutics have been applied intratumorally to manage accessible lesions and to induce systemic immunity in malignant melanoma. Intratumoral bacillus Calmette-Guérin (BCG) has been used for 40 years, and intratumoral BCG, IL-2, IFN-α and imiquimod are recommended as treatment options for patients with in-transit melanoma metastases. Regression of cutaneous metastases can be achieved. Subcutaneous metastases are more refractory, and regression of uninjected, visceral metastases is infrequent. Other microbial products, cytokines, chemicals, immune cells, antibody and viral and plasmid vectors expressing immunologically active molecules have been tested. Antitumor activity has not been demonstrated to be superior to that of intratumoral BCG. There are few controlled trials, and whether survival is impacted with any approach has not yet been established. The immunotherapeutics applied and the intratumoral administration procedure itself can activate responses that are immune inhibitory. More rigorous clinical testing and improved understanding and modulation of regulatory immune responses are necessary.

Therapeutic response in patients with advanced malignancies treated with combined dendritic cell-activated T cell based immunotherapy and intensity-modulated radiotherapy

Successful cancer immunotherapy is confounded by the magnitude of the tumor burden and the presence of immunoregulatory elements that suppress an immune response. To approach these issues, 26 patients with advanced treatment refractory cancer were enrolled in a safety/feasibility study wherein a conventional treatment modality, intensity modulated radiotherapy (IMRT), was combined with dendritic cell-based immunotherapy. We hypothesized that radiation would lower the tumor burdens, decrease the number/function of regulatory cells in the tumor environment, and release products of tumor cells that could be acquired by intratumoral injected immature dendritic cells (iDC). Metastatic lesions identified by CT (computed tomography) were injected with autologous iDC combined with a cytokine-based adjuvant and KLH (keyhole limpet hemocyanin), followed 24 h later by IV-infused T-cells expanded with anti-CD3 and IL-2 (AT). After three to five days, each of the injected lesions was treated with fractionated doses of IMRT followed by another injection of intratumoral iDC and IV-infused AT. No toxicity was observed with cell infusion while radiation-related toxicity was observed in seven patients. Five patients had progressive disease, eight demonstrated complete resolution at treated sites but developed recurrent disease at other sites, and 13 showed complete response at various follow-up times with an overall estimated Kaplan-Meier disease-free survival of 345 days. Most patients developed KLH antibodies supporting our hypothesis that the co-injected iDC are functional with the capacity to acquire antigens from their environment and generate an adaptive immune response. These results demonstrate the safety and effectiveness of this multimodality strategy combining immunotherapy and IMRT in patients with advanced malignancies.

Genetically modified dendritic cells in cancer immunotherapy: a better tomorrow?

IMPORTANCE OF THE FIELD

Dendritic cells (DC) are powerful antigen-presenting cells that induce and maintain primary cytotoxic T lymphocyte (CTL) responses directed against tumor antigens. Consequently, there has been much interest in their application as antitumor vaccines.

AREAS COVERED IN THIS REVIEW

A large number of DC-based vaccine trials targeting a variety of cancers have been conducted; however, the rate of reported clinically significant responses remains low. Modification of DC to express tumor antigens or immunostimulatory molecules through the transfer of genes or mRNA transfection offers a logical alternative with potential advantages over peptide- or protein antigen-loaded DC. In this article, we review the current results and future prospects for genetically modified DC vaccines for the treatment of cancer.

WHAT THE READER WILL GAIN

Genetically-modified dendritic cell-based vaccines represent a powerful tool for cancer therapy. Numerous preclinical and clinical studies have demonstrated the potential of dendritic cell vaccines alone or in combination with other therapeutic modalities.

TAKE HOME MESSAGE

Genetically modified DC-based anti-cancer vaccination holds promise, perhaps being best employed in the adjuvant setting with minimal residual disease after primary therapy, or in combination with other antitumor or immune-enhancing therapies.

Carcinoma-derived interleukin-8 disorients dendritic cell migration without impairing T-cell stimulation

Background

Interleukin-8 (IL-8, CXCL8) is readily produced by human malignant cells. Dendritic cells (DC) both produce IL-8 and express the IL-8 functional receptors CXCR1 and CXCR2. Most human colon carcinomas produce IL-8. IL-8 importance in malignancies has been ascribed to angiogeneis promotion.

Principal Findings

IL-8 effects on human monocyte-derived DC biology were explored upon DC exposure to recombinant IL-8 and with the help of an IL-8 neutralizing mAb. In vivo experiments were performed in immunodeficient mice xenografted with IL-8-producing human colon carcinomas and comparatively with cell lines that do not produce IL-8. Allogenic T lymphocyte stimulation by DC was explored under the influence of IL-8. DC and neutrophil chemotaxis were measured by transwell-migration assays. Sera from tumor-xenografted mice contained increasing concentrations of IL-8 as the tumors progress. IL-8 production by carcinoma cells can be modulated by low doses of cyclophosphamide at the transcription level. If human DC are injected into HT29 or CaCo2 xenografted tumors, DC are retained intratumorally in an IL-8-dependent fashion. However, IL-8 did not modify the ability of DC to stimulate T cells. Interestingly, pre-exposure of DC to IL-8 desensitizes such cells for IL-8-mediated in vitro or in vivo chemoattraction. Thereby DC become disoriented to subsequently follow IL-8 chemotactic gradients towards malignant or inflamed tissue.

Conclusions

IL-8 as produced by carcinoma cells changes DC migration cues, without directly interfering with DC-mediated T-cell stimulation.

Preliminary safety and efficacy results of laser immunotherapy for the treatment of metastatic breast cancer patients

We report our preliminary results of a pilot clinical trial of late-stage breast cancer patients treated by laser immunotherapy (LIT), a local intervention using an 805 nm laser for non-invasive irradiation, indocyanine green for selective thermal effect, and immunoadjuvant (glycated chitosan) for immunological stimulation. Ten breast cancer patients were enrolled in this study; all patients were considered to be out of other available treatment options. Toxicity was individually evaluated through physical exams and laboratory tests. Adverse reactions only occurred in the area of treatment due to photothermal injury and local administration of immunoadjuvant. No grade 3 or 4 side effects were observed. Treatment efficacy of LIT was also evaluated by physical examination and tomography. In 8 patients available for evaluation, the objective response rate was 62.5% and the clinical beneficial response rate was 75%. While the study is still ongoing, the initial outcomes of this clinical trial show that LIT is well tolerated and is promising in the treatment of metastatic breast cancer.

Mild hyperthermia enhances human monocyte-derived dendritic cell functions and offers potential for applications in vaccination strategies

Dendritic cell (DC)-based immunotherapy has been shown to be a promising strategy for anti-cancer therapy. Nevertheless, only a low overall clinical response rate has been observed in vaccinated patients with advanced cancer and therefore methods to improve DC immuno-stimulatory functions are currently under intense investigation. In this respect, we exposed human monocyte-derived DCs to a physiological temperature stress of 40°C for up to 24 h followed by analysis for (i) expression of different heat shock proteins, (ii) survival, (iii) cell surface maturation markers, (iv) cytokine secretion, and (v) migratory capacity. Furthermore, we examined the ability of heat-shocked DCs to prime naïve CD8(+) T cells after loading with MelanA peptide, by transfection with MelanA RNA, or by transduction with MelanA by an adenovirus vector. The results clearly indicate that in comparison to control DCs, which remained at 37°C, heat-treated cells revealed no differences concerning the survival rate or their migratory capacity. However, DCs exposed to thermal stress showed a time-dependent enhanced expression of the immune-chaperone heat shock protein 70A and both an up-regulation of co-stimulatory molecules such as CD80, CD83, and CD86 and of the inflammatory cytokine TNF-α. Moreover, these cells had a markedly improved capacity to prime autologous naïve CD8(+) T cells in vitro in an antigen-specific manner, independent of the method of antigen-loading. Thus, our strategy of heat treatment of DCs offers a promising means to improve DC functions during immune activation which, as a physical method, facilitates straight-forward applications in clinical DC vaccination protocols.

Long-term effect on EMT6 tumors in mice induced by combination of laser immunotherapy and surgery

Laser immunotherapy (LI) has been demonstrated to be a promising modality for cancer treatment. The present study was designed to further investigate the impact of LI combined with surgery. LI consists of a near-infrared laser, a light-absorbing dye (indocyanine green, ICG), and an immunostimulant (glycated chitosan, GC). ICG and GC were intratumorally injected, followed by laser irradiation. Female BALB/c mice bearing EMT6 tumor cells were divided into 4 groups: control, LI, LI followed by immediate surgery resection of residual tumor (LI + S(0wk)), and LI followed by surgical removal of residual tumor after 1 week (LI + S(1wk)). Successfully treated mice from all treatment groups were rechallenged twice with 10(5) and 5 × 10(5) EMT6 cells, respectively. The LI + S(1wk) group had the highest survival rate (72%) after 90 days, whereas the mice survival rates of the LI + S(0wk), LI, and control groups were 50%, 46%, 0%, respectively. The median survival times of control, LI, LI + S(0wk), and LI + S(1wk) groups were 32, 66, 74, and 90 days, respectively. Survival rates of the treated mice after the first and second tumor rechallenges, ranging from 73% to 95%, were not significantly different among the 4 groups (P > .05). The results show that LI is a useful tool for the treatment of tumor-bearing mice. Long-term antitumor effect can be induced by LI. They also indicate that combination of LI with surgery can further improve the therapeutic efficiency of LI.

Intra-tumoral dendritic cells increase efficacy of peripheral vaccination by modulation of glioma microenvironment

Pilot data showed that adding intratumoral (IT) injection of dendritic cells (DCs) prolongs survival of patients affected by glioblastoma multiforme (GBM) treated by subcutaneous (SC) delivery of DCs. Using a murine model resembling GBM, we investigated the immunological mechanisms underlying this effect. C57BL6/N mice received brain injections of GL261 glioma cells. Seven days later, mice were treated by 3 SC injections of DCs with or without 1 IT injection of DCs. DC maturation, induced by pulsing with GL261 lysates, was necessary to develop effective immune responses. IT injection of pulsed (pDC), but not unpulsed DCs (uDC), increased significantly the survival, either per se or in combination with SC-pDC (P < .001 vs controls). Mice treated by IT-pDC plus SC-pDC survived longer than mice treated by SC-pDC only (P = .03). Injected pDC were detectable in tumor parenchyma, but not in cervical lymph nodes. In gliomas injected with IT-pDC, CD8+ cells were significantly more abundant and Foxp3+ cells were significantly less abundant than in other groups. Using real-time polymerase chain reaction, we also found enhanced expression of IFN-gamma and TNF-alpha and decreased expression of transforming growth factor-beta (TGF-beta) and Foxp3 in mice treated with SC-pDC and IT-pDC. In vitro, pDC produced more TNF-alpha than uDC: addition of TNF-alpha to the medium decreased the proliferation of glioma cells. Overall, the results suggest that IT-pDC potentiates the anti-tumor immune response elicited by SC-pDC by pro-immune modulation of cytokines in the tumor microenvironment, decrease of Treg cells, and direct inhibition of tumor proliferation by TNF-alpha.

Heat shock protein 70, released from heat-stressed tumor cells, initiates antitumor immunity by inducing tumor cell chemokine production and activating dendritic cells via TLR4 pathway

Extracellular heat shock proteins (HSP) can activate dendritic cells (DC) and monocytes/macrophages, and HSP derived from tumor cells have been regarded as potent adjuvant facilitating presentation of tumor Ags and induction of antitumor immunity. However, the roles and the underlying mechanisms of releasable HSP in the induction of antitumor immunity have not been fully elucidated. In this study, we report that heat stress can induce the release of various HSP from tumor cells, which, in turn, activate tumor cells to produce chemokines for chemoattraction of DC and T cells via TLR4 signaling pathway. In vivo, we find that the infiltration and function of DC and T cells within tumor after local hyperthermia are increased significantly. We also provide evidence that HSP70 proteins released by tumor cells and TLR4 expressed by tumor cells/DC are essential for the chemoattraction of DC/T cells and for the subsequent induction of tumor-specific antitumor immunity. Therefore, our study suggests that heat stress-induced releasable HSP70 proteins from tumor cells play important roles in the initiation of antitumor immunity by inducing tumor cell production of chemokines and by activating the chemoattracted DC via TLR4 pathway.

Use of antibodies and immunoconjugates for the therapy of more accessible cancers

There are currently 6 unconjugated antibodies and 3 immunoconjugates approved for use in the United States in a variety of cancers, with a considerable number of new agents in clinical testing and preclinical development. Unconjugated antibodies alone can be effective, but more often, antibodies need to be combined with chemotherapy, which enhances the efficacy of the standard treatment. Immunoconjugates tend to be more effective than their unconjugated counterparts, but their increased toxicity often restricts when and how they are used. In order to improve efficacy, a number of immunoconjugates are being examined in settings where the disease is more easily accessible, such as leukemias, or within compartments that allow easier and more direct access to the tumor, such as in the peritoneal cavity or brain, or both locally and systemically, in adjuvant situations, where the disease burden has been reduced by some other means, and with the main goal of these treatments being to kill residual disease.

Local Effects of Retrovirally Transduced Endostatin-Expressing Human Umbilical Cord Blood CD34+ Cells on Transplanted Malignancy in a Mouse Model of Hepatic Cancer

Antiangiogenesis has been exploited as an effective approach to inhibit the growth of solid tumors. This technique has been evaluated using various vectors in several xenograft animal models to demonstrate the efficacy of endostatin gene therapy against cancer growth. However, previous studies have not examined the use of cord blood CD34+ cells as endostatin-producing cells for gene therapy against hepatoma. This exploratory study was done to investigate the local effects of CD34+ cells transduced with the endostatin gene on a mouse xenograft tumor model. The human endostatin gene was transferred into CD34+ cells using the recombinant retrovirus plasmid, pLncx/endo. Expression was verified by RT-PCR and Western blot analyses, confirming the stable expression and secretion of endostatin from the transferred CD34+ cells. The proliferation of vascular endothelial cells was evaluated by MTT assay and found to decrease by about 59.9% when treated with the supernatant of cultured transfected CD34+ cells in vitro. These genetically modified cord blood CD34+ cells were implanted intratumorally and tumor regression was evaluated after 2 weeks. The average size of a xenograft tumor in the CD34+/endo group was reduced 31.39% compared to that in the untreated mice or those transplanted with CD34+ cells transduced with a control vector. The microvascular density of the tumor decreased 62.45% in the treated group. The expression of proliferation cell nuclear antigen (PCNA) also decreased significantly in the treated group. Moreover, the apoptotic index (AI) of tumors, as evaluated by TUNEL staining, was significantly enhanced in the treatment group. Our findings indicate that angiogenesis of the xenograft tumor in mice may be inhibited by local administration of genetically modified CD34+ cells expressing the endostatin gene. This novel approach may lead to a new direction of cell-based gene therapy for malignancy.

Hyperthermia on immune regulation: a temperature's story

Over the last decade the linkage between hyperthermia, heat shock proteins and fever with the body's immune system has been well investigated. The immunomodulatory function of hyperthermia has been found to be quite sensitively regulated by temperature, as different levels of heating can bring different modulatory effect on different sensitive targets. Understanding these intrinsic mechanisms could bring new inspirations on the design of clinical trials combining local tumor hyperthermia with immunotherapy in cancer patients. This review will attempt to tell the story about the effect of temperature on immune regulation, with special emphasis on the clinical application of hyperthermia and the feasibility of combining it with immunotherapy in the clinic.

Immune cell recruitment and cell-based system for cancer therapy

Immune cells, such as cytotoxic T lymphocytes, natural killer cells, B cells, and dendritic cells, have a central role in cancer immunotherapy. Conventional studies of cancer immunotherapy have focused mainly on the search for an efficient means to prime/activate tumor-associated antigen-specific immunity. A systematic understanding of the molecular basis of the trafficking and biodistribution of immune cells, however, is important for the development of more efficacious cancer immunotherapies. It is well established that the basis and premise of immunotherapy is the accumulation of effective immune cells in tumor tissues. Therefore, it is crucial to control the distribution of immune cells to optimize cancer immunotherapy. Recent characterization of various chemokines and chemokine receptors in the immune system has increased our knowledge of the regulatory mechanisms of the immune response and tolerance based on immune cell localization. Here, we review the immune cell recruitment and cell-based systems that can potentially control the systemic pharmacokinetics of immune cells and, in particular, focus on cell migrating molecules, i.e., chemokines, and their receptors, and their use in cancer immunotherapy.

Primary immune surveillance: some like it hot

The thermal element of fever has been found to be beneficial in models of infectious disease. The contributions of fever-range temperatures to the efficacy of the adaptive immune response have only begun to be delineated. There is accumulating evidence that fever-range thermal stress bolsters primary immune surveillance of lymph nodes and Peyer patches by augmenting lymphocyte extravasation across specialized vessels termed high endothelial venules. Molecular mechanisms have recently come to light by which the thermal component of fever alone may promote lymphocyte trafficking, and thereby the probability of mounting a defense against microbial infection. Acquired knowledge of the molecular changes associated with thermal stress may allow for the development of novel therapies for a variety of disease processes.