Vaccination of hormone-refractory prostate cancer patients with peptide cocktail-loaded dendritic cells: results of a phase I clinical trial

Immune mediated support of metastasis: Implication for bone invasion

Bone is a common organ affected by metastasis in various advanced cancers, including lung, breast, prostate, colorectal, and melanoma. Once a patient is diagnosed with bone metastasis, the patient's quality of life and overall survival are significantly reduced owing to a wide range of morbidities and the increasing difficulty of treatment. Many studies have shown that bone metastasis is closely related to bone microenvironment, especially bone immune microenvironment. However, the effects of various immune cells in the bone microenvironment on bone metastasis remain unclear. Here, we described the changes in various immune cells during bone metastasis and discussed their related mechanisms. Osteoblasts, adipocytes, and other non-immune cells closely related to bone metastasis were also included. This review also summarized the existing treatment methods and potential therapeutic targets, and provided insights for future studies of cancer bone metastasis.

Potential of Personalized Dendritic Cell-Based Immunohybridoma Vaccines to Treat Prostate Cancer

Prostate cancer (PCa) is the most commonly diagnosed cancer and the second most common cause of death due to cancer. About 30% of patients with PCa who have been castrated develop a castration-resistant form of the disease (CRPC), which is incurable. In the last decade, new treatments that control the disease have emerged, slowing progression and spread and prolonging survival while maintaining the quality of life. These include immunotherapies; however, we do not yet know the optimal combination and sequence of these therapies with the standard ones. All therapies are not always suitable for every patient due to co-morbidities or adverse effects of therapies or both, so there is an urgent need for further work on new therapeutic options. Advances in cancer immunotherapy with an immune checkpoint inhibition mechanism (e.g., ipilimumab, an anti-CTLA-4 inhibitor) have not shown a survival benefit in patients with CRPC. Other immunological approaches have also not given clear results, which has indirectly prevented breakthrough for this type of therapeutic strategy into clinical use. Currently, the only approved form of immunotherapy for patients with CRPC is a cell-based medicine, but it is only available to patients in some parts of the world. Based on what was gained from recently completed clinical research on immunotherapy with dendritic cell-based immunohybridomas, the aHyC dendritic cell vaccine for patients with CRPC, we highlight the current status and possible alternatives that should be considered in the future.

Vaccination against RhoC induces long-lasting immune responses in patients with prostate cancer: results from a phase I/II clinical trial

Background

Peptide-based vaccination is a rational option for immunotherapy of prostate cancer. In this first-in-man phase I/II study, we assessed the safety, tolerability and immunological impact of a synthetic long peptide vaccine targeting Ras homolog gene family member C (RhoC) in patients with prostate cancer. RhoC is a small GTPase overexpressed in advanced solid cancers, metastases and cancer stem cells.

Methods

Twenty-two patients who had previously undergone radical prostatectomy received subcutaneous injections of 0.1 mg of a single RhoC-derived 20mer peptide emulsified in Montanide ISA-51 every 2 weeks for the first six times, then five times every 4 weeks for a total treatment time of 30 weeks. The drug safety and vaccine-specific immune responses were assessed during treatment and thereafter within a 13-month follow-up period. Serum level of prostate-specific antigen was measured up to 26 months postvaccination.

Results

Most patients (18 of 21 evaluable) developed a strong CD4 T cell response against the vaccine, which lasted at least 10 months following the last vaccination. Three promiscuouslypresented HLA-class II epitopes were identified. Vaccine-specific CD4 T cells were polyfunctional and effector memory T cells that stably expressed PD-1 (CD279) and OX-40 (CD134), but not LAG-3 (CD223). One CD8 T cell response was detected in addition. The vaccine was well tolerated and no treatment-related adverse events of grade ≥3 were observed.

Conclusion

Targeting of RhoC induced a potent and long-lasting T cell immunity in the majority of the patients. The study demonstrates an excellent safety and tolerability profile. Vaccination against RhoC could potentially delay or prevent tumor recurrence and metastasis formation.

Trial registration number

NCT03199872.

Moving on From Sipuleucel-T: New Dendritic Cell Vaccine Strategies for Prostate Cancer

Tumors evade the immune system though a myriad of mechanisms. Using checkpoint inhibitors to help reprime T cells to recognize tumor has had great success in malignancies including melanoma, lung, and renal cell carcinoma. Many tumors including prostate cancer are resistant to such treatment. However, Sipuleucel-T, a dendritic cell (DC) based immunotherapy, improved overall survival (OS) in prostate cancer. Despite this initial success, further DC vaccines have failed to progress and there has been limited uptake of Sipuleucel-T in the clinic. We know in prostate cancer (PCa) that both the adaptive and the innate arms of the immune system contribute to the immunosuppressive environment. This is at least in part due to dysfunction of DC that play a crucial role in the initiation of an immune response. We also know that there is a paucity of DC in PCa, and that those there are immature, creating a tolerogenic environment. These attributes make PCa a good candidate for a DC based immunotherapy. Ultimately, the knowledge gained by much research into antigen processing and presentation needs to translate from bench to bedside. In this review we will analyze why newer vaccine strategies using monocyte derived DC (MoDC) have failed to deliver clinical benefit, particularly in PCa, and highlight the emerging antigen loading and presentation technologies such as nanoparticles, antibody-antigen conjugates and virus co-delivery systems that can be used to improve efficacy. Lastly, we will assess combination strategies that can help overcome the immunosuppressive microenvironment of PCa.

Oncolytic Adenovirus Type 3 Coding for CD40L Facilitates Dendritic Cell Therapy of Prostate Cancer in Humanized Mice and Patient Samples

Dendritic cell (DC)-based vaccines have shown some degree of success for the treatment of prostate cancer (PC). However, the highly immunosuppressive tumor microenvironment leads to DC dysfunction, which has limited the effectiveness of these vaccines. We hypothesized that use of a fully serotype 3 oncolytic adenovirus (Ad3-hTERT-CMV-hCD40L; TILT-234) could stimulate DCs in the prostate tumor microenvironment by expressing CD40L. Activated DCs would then activate cytotoxic T cells against the tumor, resulting in therapeutic immune responses. Oncolytic cell killing due to cancer cell-specific virus replication adds to antitumor effects but also enhances the immunological effect by releasing tumor epitopes for sampling by DC, in the presence of danger signals. In this study, we evaluated the companion effect of Ad3-hTERT-CMV-hCD40L and DC-therapy in a humanized mouse model and PC histocultures. Treatment with Ad3-hTERT-CMV-hCD40L and DC resulted in enhanced antitumor responses in vivo. Treatment of established histocultures with Ad3-hTERT-CMV-hCD40L induced DC maturation and notable increase in proinflammatory cytokines. In conclusion, Ad3-hTERT-CMV-hCD40L is able to modulate an immunosuppressive prostate tumor microenvironment and improve the effectiveness of DC vaccination in PC models and patient histocultures, setting the stage for clinical translation.

Inhibition of melanoma by survivin-specific lymphocytes combined with CCL17 and granulocyte-macrophage colony-stimulating factor in a mouse syngeneic model

As a new generation of treatment, tumor immunotherapy targeting tumor-associated antigens (TAA) has attracted widespread attention. The survivin antigen belongs to TAA. It is a key inhibitor of apoptosis and a key regulator of cell cycle progression; furthermore, it may be a candidate target for tumor therapy. In addition, studies have confirmed that granulocyte-macrophage colony-stimulating factor (GM-CSF) and CCL17 significantly affect local anti-tumor immunity in the tumor microenvironment. The mouse survivin gene was screened by BIMAS and SYFPEITHI to obtain the highest scored mouse survivin epitope peptide, which was synthesized into a peptide vaccine to immunize normal mice. Subsequently, spleen lymphocytes were isolated to induce survivin-specific cytotoxic T lymphocytes (CTL). Next, genetic engineering was used to construct the B16F10 cell line that stably expressed CCL17 and GM-CSF genes. A mouse melanoma model was used to observe the effects of the combination of the three on tumor volume and tumor weight. In-vitro survivin-specific CTL combined with CCL17 gene had a stronger inhibitory effect on B16F10 cells, while combined GM-CSF gene did not enhance the inhibitory effect of CTL on B16F10 cells. In-vivo experiments demonstrated that survivin-specific CTL combined with GM-CSF and CCL17 genes can inhibit the growth of mouse melanoma. HE staining and immunohistochemistry showed that the tumor had more necrotic cells and more infiltrating lymphocytes. The results showed that survivin-specific CTL combined with CCL17 and GM-CSF genes could inhibit tumor growth better.

Transient Receptor Potential Cation Channels in Cancer Therapy

In mammals, the transient receptor potential (TRP) channels family consists of six different families, namely TRPC (canonical), TRPV (vanilloid), TRPM (melastatin), TRPML (mucolipin), TRPP (polycystin), and TRPA (ankyrin), that are strictly connected with cancer cell proliferation, differentiation, cell death, angiogenesis, migration, and invasion. Changes in TRP channels' expression and function have been found to regulate cell proliferation and resistance or sensitivity of cancer cells to apoptotic-induced cell death, resulting in cancer-promoting effects or resistance to chemotherapy treatments. This review summarizes the data reported so far on the effect of targeting TRP channels in different types of cancer by using multiple TRP-specific agonists, antagonists alone, or in combination with classic chemotherapeutic agents, microRNA specifically targeting the TRP channels, and so forth, and the in vitro and in vivo feasibility evaluated in experimental models and in cancer patients. Considerable efforts have been made to fight cancer cells, and therapies targeting TRP channels seem to be the most promising strategy. However, more in-depth investigations are required to completely understand the role of TRP channels in cancer in order to design new, more specific, and valuable pharmacological tools.

Dendritic cells pulsed with prostate-specific membrane antigen in metastatic castration-resistant prostate cancer patients: a systematic review and meta-analysis

BACKGROUND

Dendritic cells (DCs) are used in many malignancies as vaccines to induce immunity against specific cancer antigens. The role of DCs in metastatic castration-resistant prostate cancer (mCRPC) is not determined. In this study, the proportion of mCRPC patients with clinically significant response to targeted therapy by DCs pulsed with prostate-specific membrane antigen was evaluated, and the possible adverse effects of this modality were investigated.

METHODS

Major databases were searched up to Feb 2017, to identify studies in which the antitumor efficacy of DCs pulsed with the extracellular portion of PSMA was studied for the treatment of mCRPC. Data were collected by two reviewers and analyzed using Comprehensive Meta-Analysis software, version 2.0.

FINDINGS

Our study consisted of 6 nonrandomized prospective (cohort) trials, overall reporting on 153 mCRPC patients. The event rate that is the representative of fraction of patients showing antitumor response was 0.43 (95% confidence interval = 0.355-0.512; P = 0.097). No significant between-study heterogeneity or inconsistency was detected (I2 = 5.47; Q = 5; P = 0.382). Our study failed to demonstrate a significant therapeutic efficacy for DCs in mCRPC. However, no significant adverse effects were seen.

Dendritic cells as cancer therapeutics

The ability of immune therapies to control cancer has recently generated intense interest. This therapeutic outcome is reliant on T cell recognition of tumour cells. The natural function of dendritic cells (DC) is to generate adaptive responses, by presenting antigen to T cells, hence they are a logical target to generate specific anti-tumour immunity. Our understanding of the biology of DC is expanding, and they are now known to be a family of related subsets with variable features and function. Most clinical experience to date with DC vaccination has been using monocyte-derived DC vaccines. There is now growing experience with alternative blood-derived DC derived vaccines, as well as with multiple forms of tumour antigen and its loading, a wide range of adjuvants and different modes of vaccine delivery. Key insights from pre-clinical studies, and lessons learned from early clinical testing drive progress towards improved vaccines. The potential to fortify responses with other modalities of immunotherapy makes clinically effective "second generation" DC vaccination strategies a priority for cancer immune therapists.

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.

Dendritic cell vaccination in combination with docetaxel for patients with metastatic castration-resistant prostate cancer: A randomized phase II study

BACKGROUND AIMS

We investigated whether the addition of an autologous dendritic cell-based cancer vaccine (DCvac) induces an immune response in patients with metastatic castration-resistant prostate cancer treated with docetaxel.

METHODS

Forty-three patients were randomized 1:1 to receive up to 10 cycles of docetaxel alone, 75 mg/m² every 3 weeks or in combination with DCvac. Monocytes were harvested following a leukapheresis procedure, matured ex vivo and subsequently transfected with messenger RNA encoding multiple tumor-associated antigens (TAAs). DCvac was administered intradermally twice through treatment cycles 1-4 and once through treatment cycles 5-10. Immune cell composition and antigen-specific responses were analyzed using flow cytometry, ELISpot and delayed type hypersensitivity (DTH) tests. Toxicity was graded according to Common Terminology Criteria for Adverse Events version 3.0. Progression-free survival (PFS) and disease-specific survival (DSS) was calculated using the Kaplan-Meier method.

RESULTS

Prostate-specific antigen responses were similar in patients treated with docetaxel alone and combination therapy (58% versus 38%; P = 0.21). PFS and DSS were comparable: 5.5 versus 5.7 months (P = 0.62, log rank) and 21.9 versus 25.1 months (P = 0.60, log rank). Nine (50%) and 14 (78%) patients treated with docetaxel and DCvac had a TAA-specific or vaccine-specific immune response in the ELISpot and DTH analysis, respectively. Vaccine induced toxicity was limited to local reactions. Decline in myeloid-derived suppressor cells at the third treatment cycle was found to be an independent predictor of DSS.

CONCLUSIONS

The addition of DCvac was safe. Immune responses were detected in approximately half of the patients investigated.

The therapeutic and diagnostic potential of the prostate specific membrane antigen/glutamate carboxypeptidase II (PSMA/GCPII) in cancer and neurological disease

Prostate specific membrane antigen (PSMA) otherwise known as glutamate carboxypeptidase II (GCPII) is a membrane bound protein that is highly expressed in prostate cancer and in the neovasculature of a wide variety of tumours including glioblastomas, breast and bladder cancers. This protein is also involved in a variety of neurological diseases including schizophrenia and ALS. In recent years, there has been a surge in the development of both diagnostics and therapeutics that take advantage of the expression and activity of PSMA/GCPII. These include gene therapy, immunotherapy, chemotherapy and radiotherapy. In this review, we discuss the biological roles that PSMA/GCPII plays, both in normal and diseased tissues, and the current therapies exploiting its activity that are at the preclinical stage. We conclude by giving an expert opinion on the future direction of PSMA/GCPII based therapies and diagnostics and hurdles that need to be overcome to make them effective and viable.

Identification of a Novel Autoimmune Peptide Epitope of Prostein in Prostate Cancer

There is a demand for novel targets and approaches to diagnose and treat prostate cancer (PCA). In this context, serum and plasma samples from a total of 609 individuals from two independent patient cohorts were screened for IgG reactivity against a sum of 3833 human protein fragments. Starting from planar protein arrays with 3786 protein fragments to screen 80 patients with and without PCA diagnosis, 161 fragments (4%) were chosen for further analysis based on their reactivity profiles. Adding 71 antigens from literature, the selection of antigens was corroborated for their reactivity in a set of 550 samples using suspension bead arrays. The antigens prostein (SLC45A3), TATA-box binding protein (TBP), and insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2) showed higher reactivity in PCA patients with late disease compared with early disease. Because of its prostate tissue specificity, we focused on prostein and continued with mapping epitopes of the 66-mer protein fragment using patient samples. Using bead-based assays and 15-mer peptides, a minimal peptide epitope was identified and refined by alanine scanning to the KPxAPFP. Further sequence alignment of this motif revealed homology to transmembrane protein 79 (TMEM79) and TGF-beta-induced factor 2 (TGIF2), thus providing a reasoning for cross-reactivity found in females. A comprehensive workflow to discover and validate IgG reactivity against prostein and homologous targets in human serum and plasma was applied. This study provides useful information when searching for novel biomarkers or drug targets that are guided by the reactivity of the immune system against autoantigens.

Tn-MUC1 DC Vaccination of Rhesus Macaques and a Phase I/II Trial in Patients with Nonmetastatic Castrate-Resistant Prostate Cancer

MUC1 is a glycoprotein expressed on the apical surface of ductal epithelial cells. Malignant transformation results in loss of polarization and overexpression of hypoglycosylated MUC1 carrying truncated carbohydrates known as T or Tn tumor antigens. Tumor MUC1 bearing Tn carbohydrates (Tn-MUC1) represent a potential target for immunotherapy. We evaluated the Tn-MUC1 glycopeptide in a human phase I/II clinical trial for safety that followed a preclinical study of different glycosylation forms of MUC1 in rhesus macaques, whose MUC1 is highly homologous to human MUC1. Either unglycosylated rhesus macaque MUC1 peptide (rmMUC1) or Tn-rmMUC1 glycopeptide was mixed with an adjuvant or loaded on autologous dendritic cells (DC), and responses were compared. Unglycosylated rmMUC1 peptide induced negligible humoral or cellular responses compared with the Tn-rmMUC1 glycopeptide. Tn-rmMUC1 loaded on DCs induced the highest anti-rmMUC1 T-cell responses and no clinical toxicity. In the phase I/II clinical study, 17 patients with nonmetastatic castrate-resistant prostate cancer (nmCRPC) were tested with a Tn-MUC1 glycopeptide-DC vaccine. Patients were treated with multiple intradermal and intranodal doses of autologous DCs, which were loaded with the Tn-MUC1 glycopeptide (and KLH as a positive control for immune reactivity). PSA doubling time (PSADT) improved significantly in 11 of 16 evaluable patients (P = 0.037). Immune response analyses detected significant Tn-MUC1-specific CD4⁺ and/or CD8⁺ T-cell intracellular cytokine responses in 5 out of 7 patients evaluated. In conclusion, vaccination with Tn-MUC1-loaded DCs in nmCRPC patients appears to be safe, able to induce significant T-cell responses, and have biological activity as measured by the increase in PSADT following vaccination. Cancer Immunol Res; 4(10); 881-92. ©2016 AACR.

An Investigation on a Novel Anti-tumor Fusion Peptide of FSH33-53-IIKK

A novel fusion peptide FSH_33-53-IIKK was designed and expected to combine the follicle stimulating hormone receptor (FSHR) targeting and tumor toxicity. In vitro and in vivo study showed the anti-tumor activity of FSH_33-53-IIKK was enhanced compared to that of IIKK only. FSH_33-53-IIKK could inhibit the growth of tumor via apoptosis and autophagy pathways. In summary, combining the tumor marker-target peptide and anti-tumor peptide together may be an efficient way to search for better anti-tumor candidates.

TRPM8 channel as a novel molecular target in androgen-regulated prostate cancer cells

The cold and menthol receptor TRPM8 is highly expressed in prostate and prostate cancer (PC). Recently, we identified that TRPM8 is as an ionotropic testosterone receptor. The TRPM8 mRNA is expressed in early prostate tumors with high androgen levels, while anti-androgen therapy greatly reduces its expression. Here, from the chromatin-immunoprecipitation (ChIP) analysis, we found that an androgen response element (ARE) mediates androgen regulation of trpm8. Furthermore, using immunofluorescence, calcium-imaging and planar lipid bilayers, we identified that TRPM8 channel is functionally regulated by androgens in the prostate. Although TRPM8 mRNA is expressed at high levels, we found that the TRPM8 protein undergoes ubiquitination and degradation in PC cells. The mass-spectrometry analysis of TRPM8, immunoprecipitated from LNCaP cells identified ubiquitin-like modifier-activating enzyme 1 (UBA1). PYR-41, a potent inhibitor of initial enzyme in the ubiquitination cascade, UBA1, increased TRPM8 activity on the plasma membrane (PM) of LNCaP cells. Furthermore, PYR-41-mediated _PMTRPM8 activity was accompanied by enhanced activation of p53 and Caspase-9. Interestingly, we found that the trpm8 promoter possesses putative binding sites for p53 and that the overexpression of p53 increased the TRPM8 mRNA levels. In addition to the genomic regulation of TRPM8 by AR and p53, our findings indicate that the testosterone-induced _PMTRPM8 activity elicits Ca²⁺ uptake, subsequently causing apoptotic cell death. These findings support the strategy of rescuing _PMTRPM8 expression as a new therapeutic application through the regulation of PC cell growth and proliferation.

Tissue-resident dendritic cells and diseases involving dendritic cell malfunction

Dendritic cells (DCs) control immune responses and are central to the development of immune memory and tolerance. DCs initiate and orchestrate immune responses in a manner that depends on signals they receive from microbes and cellular environment. Although DCs consist mainly of bone marrow-derived and resident populations, a third tissue-derived population resides the spleen and lymph nodes (LNs), different subsets of tissue-derived DCs have been identified in the blood, spleen, lymph nodes, skin, lung, liver, gut and kidney to maintain the tolerance and control immune responses. Tissue-resident DCs express different receptors for microbe-associated molecular patterns (MAMPs) and damage-associated molecular patterns (DAMPs), which were activated to promote the production of pro- or anti-inflammatory cytokines. Malfunction of DCs contributes to diseases such as autoimmunity, allergy, and cancer. It is therefore important to update the knowledge about resident DC subsets and diseases associated with DC malfunction.

Survivin and PSMA Loaded Dendritic Cell Vaccine for the Treatment of Prostate Cancer

Dendritic cell (DC)-based vaccines are a promising therapeutic modality for cancer. Results from recent trials and approval of the first DC vaccine by the U.S. Food and Drugs Administration for prostate cancer have paved the way for DC-based vaccines. A total of 21 hormone refractory prostate cancer (HRPC) patients with a life expectancy >3 months were randomised into two groups. DC loaded with recombinant Prostate Specific Membrane Antigen (rPSMA) and recombinant Survivin (rSurvivin) peptides was administered as an subcutaneous (s.c.) injection (5×10(6) cells). Docetaxel (75 mg/m(2) intravenous (i.v.)) and prednisone (5 mg, bis in die (b.i.d.)) served as control. Clinical and immunological responses were evaluated. Primary endpoints were safety and feasibility; secondary endpoint was overall survival. Responses were evaluated on day 15, day 30, day 60, and day 90. DC vaccination was well tolerated with no signs of grade 2 toxicity. DC vaccination induced delayed-type hypersensitivity reactivity and an immune response in all patients. Objective Response Rate (ORR) by Response Evaluation Criteria in Solid Tumours (RECIST) was 72.7% (8/11) versus 45.4 (5/11) in the docetaxel arm and immune related response criteria (irRC) was 54.5% (6/11) compared with 27.2% (3/11) in the control arm. The DC arm showed stable disease (SD) in 6 patients, progressive disease (PD) in 3 patients, and partial remission (PR) in two patients compared to SD in 5 patients, PD in 6 patients, and PR in none in the docetaxel arm. There was a cellular response, disease stabilization, no adverse events, and partial remission with the rPSMA and rSurvivin primed DC vaccine.

Clinical outcomes of a novel therapeutic vaccine with Tax peptide-pulsed dendritic cells for adult T cell leukaemia/lymphoma in a pilot study

Adult T cell leukaemia/lymphoma (ATL) is a human T cell leukaemia virus type-I (HTLV-I)-infected T cell malignancy with poor prognosis. We herein developed a novel therapeutic vaccine designed to augment an HTLV-I Tax-specific cytotoxic T lymphocyte (CTL) response that has been implicated in anti-ATL effects, and conducted a pilot study to investigate its safety and efficacy. Three previously treated ATL patients, classified as intermediate- to high-risk, were subcutaneously administered with the vaccine, consisting of autologous dendritic cells (DCs) pulsed with Tax peptides corresponding to the CTL epitopes. In all patients, the performance status improved after vaccination without severe adverse events, and Tax-specific CTL responses were observed with peaks at 16-20 weeks. Two patients achieved partial remission in the first 8 weeks, one of whom later achieved complete remission, maintaining their remission status without any additional chemotherapy 24 and 19 months after vaccination, respectively. The third patient, whose tumour cells lacked the ability to express Tax at biopsy, obtained stable disease in the first 8 weeks and later developed slowly progressive disease although additional therapy was not required for 14 months. The clinical outcomes of this pilot study indicate that the Tax peptide-pulsed DC vaccine is a safe and promising immunotherapy for ATL.

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.

Survivin as a preferential target for cancer therapy

Cancer is typically a consequence of imbalance between cell death and proliferation in a way favorable to cell proliferation and survival. Most conventional cancer therapies are based on targeting rapidly growing cancerous cells to block growth or enhance cell death, thereby, restoring the balance between these processes. In many instances, malignancies that develop resistance to current treatment modalities, such as chemotherapy, immunotherapy, and radiotherapy often present the greatest challenge in subsequent management of the patient. Studies have shown that under normal circumstances, cells utilize different death mechanisms, such as apoptosis (programmed cell death), autophagy, mitotic catastrophe, and necrosis to maintain homeostasis and physiological integrity of the organism, but these processes often appear to be altered in cancer. Thus, in recent years developing various strategies for administration of cytotoxic chemotherapeutics in combination with apoptosis-sensitizing reagents is receiving more emphasis. Here, we review the properties of the anti-apoptotic protein, survivin, a member of the inhibitor of apoptosis protein (IAP) family and the clinical feasibility and anti-cancer potential of drugs targeting this protein. We also discuss some key points and concerns that should be taken into consideration while developing drugs that target apoptotic proteins, such as survivin.

Ion channels in cancer: future perspectives and clinical potential

Ion transport across the cell membrane mediated by channels and carriers participate in the regulation of tumour cell survival, death and motility. Moreover, the altered regulation of channels and carriers is part of neoplastic transformation. Experimental modification of channel and transporter activity impacts tumour cell survival, proliferation, malignant progression, invasive behaviour or therapy resistance of tumour cells. A wide variety of distinct Ca(2+) permeable channels, K(+) channels, Na(+) channels and anion channels have been implicated in tumour growth and metastasis. Further experimental information is, however, needed to define the specific role of individual channel isoforms critically important for malignancy. Compelling experimental evidence supports the assumption that the pharmacological inhibition of ion channels or their regulators may be attractive targets to counteract tumour growth, prevent metastasis and overcome therapy resistance of tumour cells. This short review discusses the role of Ca(2+) permeable channels, K(+) channels, Na(+) channels and anion channels in tumour growth and metastasis and the therapeutic potential of respective inhibitors.

Glioma-specific antigens for immune tumor therapy

This review describes glioma-specific antigens important in immunotherapy of glioma tumors. The structure and function of these antigens and recent immunotherapy data are summarized. Also, some important aspects of tumor formation are outlined. The roles of neuronal precursor cells and tumor stroma cells are discussed. The stroma cells of the tumor may be of interest as a target for tumor therapy, especially since they are less heterogeneous than the tumor cells. To date, the clinical benefit of immunotherapy has been very limited. Immunotherapy is, however, still an extremely promising approach to tumor therapy and it will most likely be implemented as a future treatment option for many types of tumors. The current shortcomings of immunotherapy will probably diminish as we start to understand and are able to modulate tumor-induced immunosuppression. There is also a need for a continued search for new tumor-specific antigens and to optimize protocols for vaccine administration.

Generation of multiple peptide cocktail-pulsed dendritic cells as a cancer vaccine

Cancer immunotherapy based on dendritic cell (DC) vaccination has promising alternatives for the treatment of cancer. A central tenet of DC-based cancer immunotherapy is the generation of antigen-specific cytotoxic T lymphocyte (CTL) response. Tumor-associated antigens (TAA) and DC play pivotal roles in this process. DCs are well known to be the most potent antigen-presenting cells and have the most powerful antigen-presenting capacity. DCs pulsed with various TAA have been shown to be effective in producing specific antitumor effects both in vitro and in vivo. Several types of tumor antigens have been applied in cancer treatment including tumor RNA, lysates, apoptotic bodies, heat shock protein, peptides from TAA, and allogeneic tumor cells. Among them, the use of immunogenic HLA-A*0201-specific epitopes from multiple TAA enhances induction of antigen-specific CTL and associated therapeutic efficacy in HLA-A*0201(+) cancer patients. The current chapter provides a detailed protocol of generating multiple peptide cocktail-pulsed DC to elicit CTL with a broad spectrum of immune responses against the related tumor antigens.

Entry of a cationic lytic-type peptide into the cytoplasm via endocytosis-dependent and -independent pathways in human glioma U251 cells

Cationic lytic-type peptides have been studied for clinical application in various infections and cancers. This study aimed to determine the functions of our specially designed lytic peptide. To investigate the functional mechanism at the cell membrane level, we used giant unilayer vesicles (GUVs) mimicking cell membranes. In GUVs treated with FITC-labeled lytic peptide (lytic-FITC), fluorescence increased in a time-dependent manner. However, no inner fluorescence was detected in GUVs treated with lytic peptide and calcein. Next, distribution of lytic-FITC peptide on the cell membrane and in the cytoplasm was examined in a living human glioma U251 cell line. In the immunocytochemical study, some lytic peptide stains colocalized with early endosome antigen protein 1 (EEA-1). In cells treated with lytic peptide, the immunofluorescence intensity of lytic peptide increased in a concentration and treatment time-dependent manner. Cytotoxic activity of lytic peptide decreased after pretreatment with the endocytosis inhibitors cytochalasin D, chlorpromazine and amiloride. These findings suggest that lytic peptide exerts cytotoxic activity after cellular uptake via an endocytosis pathway. In conclusion, the influx mechanism of lytic peptide was shown to include not only disintegration and pore formation at the cell membrane, but also cell entry via endocytosis dependent and independent pathways.

Tumour cell lysate-loaded dendritic cell vaccine induces biochemical and memory immune response in castration-resistant prostate cancer patients

Background:

Recently, we produced a tumour antigen-presenting cells (TAPCells) vaccine using a melanoma cell lysate, called TRIMEL, as an antigen source and an activation factor. Tumour antigen-presenting cells induced immunological responses and increased melanoma patient survival. Herein, we investigated the effect of TAPCells loaded with prostate cancer cell lysates (PCCL) as an antigen source, and TRIMEL as a dendritic cell (DC) activation factor; which were co-injected with the Concholepas concholepas haemocyanin (CCH) as an adjuvant on castration-resistant prostate cancer (CRPC) patients.

Methods:

The lysate mix capacity, for inducing T-cell activation, was analysed by flow cytometry and Elispot. Delayed-type hypersensitivity (DTH) reaction against PCCL, frequency of CD8⁺ memory T cells (Tm) in blood and prostate-specific antigen (PSA) levels in serum were measured in treated patients.

Results:

The lysate mix induced functional mature DCs that were capable of activating PCCL-specific T cells. No relevant adverse reactions were observed. Six out of 14 patients showed a significant decrease in levels of PSA. DTH⁺ patients showed a prolonged PSA doubling-time after treatment. Expansion of functional central and effector CD8⁺ Tm were detected.

Conclusion:

Treatment of CRPC patients with lysate-loaded TAPCells and CCH as an adjuvant is safe: generating biochemical and memory immune responses. However, the limited number of cases requires confirmation in a phase II clinical trial.

Ionizing radiation, ion transports, and radioresistance of cancer cells

The standard treatment of many tumor entities comprises fractionated radiation therapy which applies ionizing radiation to the tumor-bearing target volume. Ionizing radiation causes double-strand breaks in the DNA backbone that result in cell death if the number of DNA double-strand breaks exceeds the DNA repair capacity of the tumor cell. Ionizing radiation reportedly does not only act on the DNA in the nucleus but also on the plasma membrane. In particular, ionizing radiation-induced modifications of ion channels and transporters have been reported. Importantly, these altered transports seem to contribute to the survival of the irradiated tumor cells. The present review article summarizes our current knowledge on the underlying mechanisms and introduces strategies to radiosensitize tumor cells by targeting plasma membrane ion transports.

Tumor-associated autoantibodies as diagnostic and prognostic biomarkers

In the process of tumorigenesis, normal cells are remodeled to cancer cells and protein expression patterns are changed to those of tumor cells. A newly formed tumor microenvironment elicits the immune system and, as a result, a humoral immune response takes place. Although the tumor antigens are undetectable in sera at the early stage of tumorigenesis, the nature of an antibody amplification response to antigens makes tumor-associated autoantibodies as promising early biomarkers in cancer diagnosis. Moreover, the recent development of proteomic techniques that make neo-epitopes of tumor-associated autoantigens discovered concomitantly has opened a new area of ‘immuno-proteomics’, which presents tumor-associated autoantibody signatures and confers information to redefine the process of tumorigenesis. In this article, the strategies recently used to identify and validate serum autoantibodies are outlined and tumor-associated antigens suggested until now as diagnostic/prognostic biomarkers in various tumor types are reviewed. Also, the meaning of autoantibody signatures and their clinical utility in personalized medicine are discussed. [BMB Reports 2012; 45(12): 677-685]

The immunological response and post-treatment survival of DC-vaccinated melanoma patients are associated with increased Th1/Th17 and reduced Th3 cytokine responses

INTRODUCTION

Immunization with autologous dendritic cells (DCs) loaded with a heat shock-conditioned allogeneic melanoma cell lysate caused lysate-specific delayed type hypersensitivity (DTH) reactions in a number of patients. These responses correlated with a threefold prolonged long-term survival of DTH(+) with respect to DTH(-) unresponsive patients. Herein, we investigated whether the immunological reactions associated with prolonged survival were related to dissimilar cellular and cytokine responses in blood.

MATERIALS AND METHODS

Healthy donors and melanoma patient's lymphocytes obtained from blood before and after vaccinations and from DTH biopsies were analyzed for T cell population distribution and cytokine release.

RESULTS/DISCUSSION

Peripheral blood lymphocytes from melanoma patients have an increased proportion of Th3 (CD4(+) TGF-β(+)) regulatory T lymphocytes compared with healthy donors. Notably, DTH(+) patients showed a threefold reduction of Th3 cells compared with DTH(-) patients after DCs vaccine treatment. Furthermore, DCs vaccination resulted in a threefold augment of the proportion of IFN-γ releasing Th1 cells and in a twofold increase of the IL-17-producing Th17 population in DTH(+) with respect to DTH(-) patients. Increased Th1 and Th17 cell populations in both blood and DTH-derived tissues suggest that these profiles may be related to a more effective anti-melanoma response.

CONCLUSIONS

Our results indicate that increased proinflammatory cytokine profiles are related to detectable immunological responses in vivo (DTH) and to prolonged patient survival. Our study contributes to the understanding of immunological responses produced by DCs vaccines and to the identification of follow-up markers for patient outcome that may allow a closer individual monitoring of patients.

Identification of a novel HLA-A2-restricted mutated Survivin epitope and induction of specific anti-HCC CTLs that could effectively cross-recognize wild-type Survivin antigen

Peptide vaccine based on tumor-associated antigen (TAA), which usually belongs to self-antigen with poor immunogenicity, has been considered as an attractive option for treatment of malignant tumors. The ideal TAA epitopes should have stable affinity to major histocompatibility complex (MHC) molecules and elicit strong anti-tumor immune response. Although point-mutation technology of TAA peptide may increase the binding capability to MHC molecules, some previous studies have revealed that part of the variant peptides results in lymphocyte not to effectively cross-recognize and kill the target tumor expressed wild-type TAA. Here, we designed a novel HLA-A2-restricted mutated TAA Survivin epitope nonapeptide Sur79L2 (KLSSGCAFL) that showed higher binding ability compared to wild-type peptide Sur79 (KHSSGCAFL) in T2-binding assays. To investigate whether Sur79L2 can induce Survivin-specific anti-hepatocellular carcinoma (HCC) response, we stimulated tumor-associated lymphocytes from a HCC patient with Sur79L2 in vitro. IFN-γ release and cytotoxicity assays showed Sur79L2 could effectively cross-recognize and lysis T2 cell plus peptide Sur79 and HCC cell lines (expression of wild-type Survivin antigen) in an HLA-A2-restricted manner. In contrast, peptide Sur95 (ELTLGEFLKL) that has been reported as a very promising anti-tumor epitope in a variety of tumors except HCC were not able to generate detectable cytotoxic immune responses against HCC in this study. Our results suggest that point-mutated peptide Sur79L2 is a new HLA-A2-restricted CTL epitope and may be useful for the immunotherapy for patients with HCC.

HER2-targeted hybrid peptide that blocks HER2 tyrosine kinase disintegrates cancer cell membrane and inhibits tumor growth in vivo

HER2 is a transmembrane oncoprotein encoded by the HER2/neu gene and is overexpressed in approximately 20% to 30% of breast cancers. We have recently designed a novel class of drug, the hybrid peptide, which is chemically synthesized and is composed of a target-binding peptide and a lytic peptide containing cationic-rich amino acid components that disintegrate the cell membrane, leading to cancer cell death via membrane lysis. In this study, we designed a HER2-binding peptide linked to this novel lytic peptide, which we termed the HER2-lytic hybrid peptide and assessed the cytotoxic activity of this hybrid peptide in vitro and in vivo. The HER2-lytic hybrid peptide showed high cytotoxic activity against all ovarian and breast cancer cell lines, even trastuzumab- and/or lapatinib-resistant cells, but not against normal cells. Competition assays using anti-HER2 antibody and knockdown of this receptor by siRNA confirmed the specificity of the HER2-lytic hybrid peptide. In addition, it was shown that the HER2-lytic hybrid peptide can disintegrate the cancer cell membrane of HER2-overexpressing SK-BR-3 cancer cells in only 5 minutes, but not normal cells, and block HER2 signaling. Intravenous administration of the HER2-lytic peptide in the athymic mouse implanted with BT-474 and MDA-MB-453 cells significantly inhibited tumor progression. The HER2-lytic hybrid peptide was effective even in breast cancer cell lines that are resistant to trastuzumab and/or lapatinib in vitro and in vivo. Therefore, this hybrid peptide may provide a potent treatment option for patients with cancer.

Immunogenicity and toxicity of transferrin receptor-targeted hybrid peptide as a potent anticancer agent

PURPOSE

Transferrin receptor (TfR) is a cell membrane-associated glycoprotein involved in the cellular uptake of iron and the regulation of cell growth. Recent studies have shown elevated expression levels of TfR on cancer cells compared with normal cells. We previously designed a TfR-lytic hybrid peptide, which combines the TfR-binding peptide and a lytic peptide, and reported that it bound specifically to TfR and selectively killed cancer cells. Furthermore, the intravenous administration of TfR-lytic peptide in an athymic mouse model significantly inhibited tumor progression. To evaluate the immunogenicity of this peptide as a novel and potent anticancer agent, we investigated whether TfR-lytic hybrid peptide elicits cellular and humoral immune responses to produce antibodies. We also examined the toxicity of this peptide in syngeneic mice.

METHODS

We performed hematologic and blood chemistry test and histological analysis and assessed hemolytic activity to check toxicity. To evaluate the immunogenicity, measurement of murine interferon-gamma and detection of TfR-lytic-specific antibody by ELISA were demonstrated.

RESULTS

No T cell immune response or antibodies were detected in the group treated with TfR-lytic hybrid peptide. No hematologic toxicity, except for a decrease in leukocytes, was observed, and no remarkable influence on metabolic parameters and organs (liver, kidney, and spleen) was noted.

CONCLUSIONS

Therefore, TfR-lytic hybrid peptide might provide an alternative therapeutic option for patients with cancer.

TRPM8 ion channels differentially modulate proliferation and cell cycle distribution of normal and cancer prostate cells

Overexpression of the cation-permeable channel TRPM8 in prostate cancers might represent a novel opportunity for their treatment. Inhibitors of TRPM8 reduce the growth of prostate cancer cells. We have used two recently described and highly specific blockers, AMTB and JNJ41876666, and RNAi to determine the relevance of TRPM8 expression in the proliferation of non-tumor and tumor cells. Inhibition of the expression or function of the channel reduces proliferation rates and proliferative fraction in all tumor cells tested, but not of non-tumor prostate cells. We observed no consistent acceleration of growth after stimulation of the channel with menthol or icilin, indicating that basal TRPM8 expression is enough to sustain growth of prostate cancer cells.

Dendritic cell based PSMA immunotherapy for prostate cancer using a CD40-targeted adenovirus vector

Human prostate tumor vaccine and gene therapy trials using ex vivo methods to prime dendritic cells (DCs) with prostate specific membrane antigen (PSMA) have been somewhat successful, but to date the lengthy ex vivo manipulation of DCs has limited the widespread clinical utility of this approach. Our goal was to improve upon cancer vaccination with tumor antigens by delivering PSMA via a CD40-targeted adenovirus vector directly to DCs as an efficient means for activation and antigen presentation to T-cells. To test this approach, we developed a mouse model of prostate cancer by generating clonal derivatives of the mouse RM-1 prostate cancer cell line expressing human PSMA (RM-1-PSMA cells). To maximize antigen presentation in target cells, both MHC class I and TAP protein expression was induced in RM-1 cells by transduction with an Ad vector expressing interferon-gamma (Ad5-IFNγ). Administering DCs infected ex vivo with CD40-targeted Ad5-huPSMA, as well as direct intraperitoneal injection of the vector, resulted in high levels of tumor-specific CTL responses against RM-1-PSMA cells pretreated with Ad5-IFNγ as target cells. CD40 targeting significantly improved the therapeutic antitumor efficacy of Ad5-huPSMA encoding PSMA when combined with Ad5-IFNγ in the RM-1-PSMA model. These results suggest that a CD-targeted adenovirus delivering PSMA may be effective clinically for prostate cancer immunotherapy.

DNA and adenovirus tumor vaccine expressing truncated survivin generates specific immune responses and anti-tumor effects in a murine melanoma model

Survivin is overexpressed in major types of cancer and is considered an ideal "universal" tumor-associated antigen that can be targeted by immunotherapeutic vaccines. However, its anti-apoptosis function raises certain safety concerns. Here, a new truncated human survivin, devoid of the anti-apoptosis function, was generated as a candidate tumor vaccine. Interleukin 2 (IL-2) has been widely used as an adjuvant for vaccination against various diseases. Meanwhile, the DNA prime and recombinant adenovirus (rAd) boost heterologous immunization strategy has been proven to be highly effective in enhancing immune responses. Therefore, the efficacy of a new cancer vaccine based on a truncated form of survivin, combined with IL-2, DNA prime, and rAd boost, was tested. As prophylaxis, immunization with the DNA vaccine alone resulted in a weak immune response and modest anti-tumor effect, whereas the tumor inhibition ratio with the DNA vaccine administered with IL-2 increased to 89 % and was further increased to nearly 100 % by rAd boosting. Moreover, complete tumor rejection was observed in 5 of 15 mice. Efficacy of the vaccine administered therapeutically was enhanced by nearly 300 % when combined with carboplatin. These results indicated that vaccination with a truncated survivin vaccine using DNA prime-rAd boost combined with IL-2 adjuvant and carboplatin represents an attractive strategy to overcoming immune tolerance to tumors and has potential therapeutic benefits in melanoma cancer.

Promiscuous survivin peptide induces robust CD4+ T-cell responses in the majority of vaccinated cancer patients

CD4(+) T cells have been shown to be crucial for the induction and maintenance of cytotoxic T cell responses and to be also capable of mediating direct tumor rejection. Therefore, the anticancer therapeutic efficacy of peptide-based vaccines may be improved by addition of HLA class II epitopes to stimulate T helper cells. Survivin is an apoptosis inhibiting protein frequently overexpressed in tumors. Here we describe the first immunological evaluation of a survivin-derived CD4(+) T cell epitope in a multipeptide immunotherapy trial for prostate carcinoma patients. The survivin peptide is promiscuously presented by several human HLA-DRB1 molecules and, most importantly, is naturally processed by dendritic cells. In vaccinated patients, it was able to induce frequent, robust and multifunctional CD4(+) T cell responses, as monitored by IFN-γ ELISPOT and intracellular cytokine staining. Thus, this HLA-DR restricted epitope is broadly immunogenic and should be valuable for stimulating T helper cells in patients suffering from a wide range of tumors.

A novel transferrin receptor-targeted hybrid peptide disintegrates cancer cell membrane to induce rapid killing of cancer cells

Background

Transferrin receptor (TfR) is a cell membrane-associated glycoprotein involved in the cellular uptake of iron and the regulation of cell growth. Recent studies have shown the elevated expression levels of TfR on cancer cells compared with normal cells. The elevated expression levels of this receptor in malignancies, which is the accessible extracellular protein, can be a fascinating target for the treatment of cancer. We have recently designed novel type of immunotoxin, termed "hybrid peptide", which is chemically synthesized and is composed of target-binding peptide and lytic peptide containing cationic-rich amino acids components that disintegrates the cell membrane for the cancer cell killing. The lytic peptide is newly designed to induce rapid killing of cancer cells due to conformational change. In this study, we designed TfR binding peptide connected with this novel lytic peptide and assessed the cytotoxic activity in vitro and in vivo.

Methods

In vitro: We assessed the cytotoxicity of TfR-lytic hybrid peptide for 12 cancer and 2 normal cell lines. The specificity for TfR is demonstrated by competitive assay using TfR antibody and siRNA. In addition, we performed analysis of confocal fluorescence microscopy and apoptosis assay by Annexin-V binding, caspase activity, and JC-1 staining to assess the change in mitochondria membrane potential. In vivo: TfR-lytic was administered intravenously in an athymic mice model with MDA-MB-231 cells. After three weeks tumor sections were histologically analyzed.

Results

The TfR-lytic hybrid peptide showed cytotoxic activity in 12 cancer cell lines, with IC₅₀ values as low as 4.0-9.3 μM. Normal cells were less sensitive to this molecule, with IC₅₀ values > 50 μM. Competition assay using TfR antibody and knockdown of this receptor by siRNA confirmed the specificity of the TfR-lytic hybrid peptide. In addition, it was revealed that this molecule can disintegrate the cell membrane of T47D cancer cells just in 10 min, to effectively kill these cells and induce approximately 80% apoptotic cell death but not in normal cells. The intravenous administration of TfR-lytic peptide in the athymic mice model significantly inhibited tumor progression.

Conclusions

TfR-lytic peptide might provide a potent and selective anticancer therapy for patients.

Enhanced antitumor effects by the coculture of allotumor RNA-pulsed dendritic cells with autologous cytokine-induced killer cells on hormone-refractory prostate cancer

In this study, we evaluated antitumor effects of allotumour RNA-transfected dendritic cells (DCs) cocultured with autologous cytokine-induced killer cells (CIKs) on hormone-refractory prostate cancer. The cocultured cells enhanced prostate cancer cytolysis from 26% (CIKs-induced cytolysis) to 80.8%. They also increased the productions of CD4(+) Th1 (IFN-γ(+)IL-4(-), 55.52%) and CD8(+) T (IFN-γ(+), 69.59%) cells determined by intracellular cytokines IFN-γ /IL-4 staining and reduced the rate of CD4(+) CD25(+) cells from 18.72% (in CIKs) to 9.72%. The cocultured cells significantly inhibited tumor growth in SCID mouse and induced cancer cells necrosis and apoptosis. Our study indicates that tumor RNA-pulsed DCs cocultured with autologous CIKs significantly enhance antitumor immunity, which can be induced by increased CD4(+) Th1 and CD8(+) T cells and decreased CD4(+)CD25(+) regulatory T (T(reg)) cells. This provides a potential immunotherapy strategy for HRPC.

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

BACKGROUND

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

METHODOLOGY/PRINCIPAL FINDINGS

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

CONCLUSIONS/SIGNIFICANCE

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

Characterization of antilytic peptide antibody: application for the detection of lytic-based hybrid peptide in serum samples

We previously reported that a novel targeted drug termed hybrid epidermal growth factor receptor (EGFR)-lytic peptide, made by chemical conjugation of targeted binding peptide and cell-killing, lytic-peptide components, has selective cytotoxic activity that allows it to discriminate between normal and cancer cells. In addition, in vivo analysis revealed that this hybrid peptide displays significant antitumor activity in a xenograft model of human breast and pancreatic cancer in mice. Here, we characterized antilytic peptide antibody, which was raised from rabbit serum using the antigen of lytic peptide conjugated with keyhole limpet hemocyanin. It was found that antilytic peptide antibody is specific to the lytic peptide as assessed by both ELISA and surface plasmon resonance analysis and can also bind to EGFR-lytic peptide. Epitope mapping analysis using Biacore showed that two successive lysine regions in the lytic-peptide sequence are significant for recognition by this antibody. In addition, it was shown that this antibody can detect lytic-based hybrid peptide in serum samples from mouse blood and also in cultured breast cancer MDA-MB-231 cell samples by immunocytochemical staining experiments. It was found that the maximum concentrations of this peptide in serum were reached within 15-30 min of i.v. administration of EGFR-lytic peptide to mice. These results indicate that this antibody will be a useful tool for the detection of lytic-based peptides to investigate their in vivo stability and pharmacokinetics.

Altered decamer and nonamer from an HLA-A0201-restricted epitope of Survivin differentially stimulate T-cell responses in different individuals

Survivin is a universal tumor antigen that is being currently targeted in vaccine approaches against cancer. Our study here examined the immunogenicity of a novel variant of an HLA-A0201-binding decamer peptide from region 95 to 104 of Survivin (ELMLGEFLKL) with a T→M modification at position 3 in the peptide. We found that this new modified 10-mer peptide had enhanced HLA-A0201 binding and induced a stronger T-cell response over its wild type counterpart peptide (ELTLGEFLKL) in select HLA-A0201(+) normal donors. In addition, when compared to the previously characterized altered 96-104 peptide (LMLGEFLKL) from the same region of Survivin currently used in vaccine trials, we found that both peptides had similar immunogenicity, but donor T cells preferentially reacted strongly to either one or the other, but not strongly to both. These results suggest that these two closely related Survivin peptides yield distinct T-cell responses and that most individuals dominantly respond to one or the other altered peptide. We also found a novel association between positive reactivity to the new altered decamer Survivin peptide in some individuals and their expression of the HLA-C0701 allele along with HLA-A0201. Thus, vaccinating with both the 10-mer and 9-mer peptides would be required to immunize a maximum number of individuals in the HLA-A0201(+) population and could lead to more consistent T-cell responses against this region of Survivin.

Dendritic cell-based immunotherapy for prostate cancer

Dendritic cells (DCs) are professional antigen-presenting cells (APCs), which display an extraordinary capacity to induce, sustain, and regulate T-cell responses providing the opportunity of DC-based cancer vaccination strategies. Thus, clinical trials enrolling prostate cancer patients were conducted, which were based on the administration of DCs loaded with tumor-associated antigens. These clinical trials revealed that DC-based immunotherapeutic strategies represent safe and feasible concepts for the induction of immunological and clinical responses in prostate cancer patients. In this context, the administration of the vaccine sipuleucel-T consisting of autologous peripheral blood mononuclear cells including APCs, which were pre-exposed in vitro to the fusion protein PA2024, resulted in a prolonged overall survival among patients with metastatic castration-resistent prostate cancer. In April 2010, sipuleucel-T was approved by the United States Food and Drug Administration for prostate cancer therapy.

Advances in cellular therapy for the treatment of thyroid cancer

Up to now, there are no curative therapies available for the subset of metastasized undifferentiated/anaplastic thyroid carcinomas. This review describes the possible use of immunocompetent cells which may help to restore the antitumor immune recognition for treating an existing tumor or preventing its recurrence. The most prominent experimental strategy is the use of dendritic cells (DCs) which are highly potent in presenting tumor antigens. Activated DCs subsequently migrate to draining lymph nodes where they present antigens to naïve lymphocytes and induce cytotoxic T cells (CTL). Alternatively to DC therapy, adoptive cell transfer may be performed by either using natural killer cells or ex vivo maturated CTLs. Within this review article we will focus on recent advances in the understanding of anti-tumor immune responses, for example, in thyroid carcinomas including the advances which have been made for the identification of potential tumor antigens in thyroid malignancies.