Dendritic cell based vaccines: progress in immunotherapy studies for prostate cancer

The Blood-prostate Barrier: An Obstacle to Drug Delivery into the Prostate

The blood-prostate barrier (BPB), a non-static physical barrier, stands as an obstacle between the prostate stroma and the lumen of the prostate gland tube. The barrier has the ability to dynamically regulate and strictly control the mass exchange between the blood and the prostate, thereby limiting drug penetration into the prostate. The basement membrane, fibrous stromal layer, capillary endothelial cell, prostatic ductal epithelial cell, lipid layer, etc., have been confirmed to be involved in the composition of the barrier structure and altered membrane permeability mainly by regulating the size of paracellular ion pores. Various studies have been conducted to improve the efficiency of drug therapy for prostate diseases by changing the administration approaches, improving barrier permeability and increasing drug penetration. To gain a full understanding of BPB, the composition of BPB, the methodology for evaluating the permeability of BPB and alterations in barrier function under pathological conditions are summarized in this review. To find a shortcut for drug delivery across BPB, the biodistribution of drugs in the prostate and different methods of improving drug penetration across BPB are outlined. This review offers an applied perspective on recent advances in drug delivery across BPB.

In vitro induction of anti‑lung cancer immune response by the A549 lung cancer stem cell lysate‑sensitized dendritic cell vaccine

Lung adenocarcinoma is one of the most fatal types of cancer worldwide, with non-small cell lung cancer being the most common subtype. Therefore, there is need for improved treatment approaches. Tumor growth results from the proliferation of a very small number of tumor stem cells, giving rise to the theory of cancer stem cells (CSCs). Lung CSCs are associated with lung cancer development, and although chemotherapy drugs can inhibit the proliferation of lung cancer cells, they have difficulty acting on lung CSCs. Even if the tumor appears to have disappeared after chemotherapy, the presence of a small number of residual tumor stem cells can lead to cancer recurrence and metastasis. Hence, targeting and eliminating lung CSCs is of significant therapeutic importance. In this study, we cultured A549 cells in sphere-forming conditions using B27, EGF, and bFGF, isolated peripheral blood mononuclear cells (PBMCs), and induced and characterized dendritic cells (DCs). We also isolated and expanded T lymphocytes. DC vaccines were prepared using A549 stem cell lysate or A549 cell lysate for sensitization and compared with non-sensitized DC vaccines. The content of IFN-γ in the supernatant of cultures with vaccines and T cells was measured by ELISA. The cytotoxic effects of the vaccines on A549 cells and stem cells were assessed using the Cytotox96 assay, and the impact of the vaccines on A549 cell migration and apoptosis was evaluated using Transwell assays and flow cytometry. DC vaccines sensitized with human lung CSC lysates induced significant in vitro cytotoxic effects on A549 lung cancer cells and CSCs by T lymphocytes, while not producing immune cytotoxic effects on human airway epithelial cells. Moreover, the immune-killing effect induced by DC vaccines sensitized with lung CSC lysates was superior to that of DC vaccines sensitized with lung cancer cells.

The potential of TRP channels as new prognostic and therapeutic targets against prostate cancer progression

Prostate cancer (PCa) is the second deadliest cancer among men worldwide. Particularly critical is its development towards metastatic androgen-independent forms for which the current therapies are ineffective. Indeed, the 5-year relative survival for PCa drops dramatically to 34 % in the presence of metastases. The superfamily of Transient Receptor Potential (TRP) channels could answer the urgent request to identify new prognostic and therapeutic tools against metastatic PCa. Indeed, this class of ion channels revealed an appealing de-regulation during PCa development and its progression towards aggressive forms. Altered expression and/or functionality of several TRPs have been associated with the PCa metastatic cascade by significantly impacting tumor growth, invasiveness, and angiogenesis. In this review, we will dissect the contribution of TRP channels in such hallmarks of PCa and then discuss their applicability as new prognostic and therapeutic agents in the fight against metastatic PCa. In particular, the great potential of TRPM8, TRPV6, and TRPA1 in opening the way to new treatment perspectives will be highlighted.

Alloreactive cytotoxic T lymphocyte immunotherapy treatment of a patient with metastatic prostate cancer: A case report

RATIONALE

Cytotoxic T lymphocyte (CTL) immunotherapy is an autologous cellular immune therapy that has been approved for treating patients with malignant tumors. However, there is still limited information regarding the impact of CTL on metastatic prostate cancer (PC) patients with bone metastatic lesions.

PATIENT CONCERNS

An 82-year-old male patient complained of interrupted urination, urination pain, and significant dysuria on November 24, 2014. Transurethral resection of the prostate (TURP) and postoperative pathological examination showed prostatic adenocarcinoma, and a SPECT/CT scan demonstrated multiple bone metastases. In addition, prostate specific antigen (PSA) and free PSA (FPSA) levels were 54.54 μg/mL and 2.63 μg/mL, respectively, at the beginning of treatment.

DIAGNOSES

The man was diagnosed with prostatic adenocarcinoma and multiple bone metastases.

INTERVENTIONS

The patient received 30 cycles of alloreactive CTL (ACTL) immunotherapy regularly.

OUTCOMES

Over the course of the 2-year treatment, the PC patient exhibited diminished bone metastasis accompanied by a marked reduction of serum PSA and FPSA from 54.54 and 2.63 μg/ml to 0.003 and <0.006 μg/ml, respectively.

LESSONS

Our clinical observations demonstrate that CTL immunotherapy is a viable treatment option for PC patients, particularly those with bone metastatic lesions and high serum levels of PSA and FPSA.

Reference-free deconvolution of DNA methylation data and mediation by cell composition effects

Background

Recent interest in reference-free deconvolution of DNA methylation data has led to several supervised methods, but these methods do not easily permit the interpretation of underlying cell types.

Results

We propose a simple method for reference-free deconvolution that provides both proportions of putative cell types defined by their underlying methylomes, the number of these constituent cell types, as well as a method for evaluating the extent to which the underlying methylomes reflect specific types of cells. We demonstrate these methods in an analysis of 23 Infinium data sets from 13 distinct data collection efforts; these empirical evaluations show that our algorithm can reasonably estimate the number of constituent types, return cell proportion estimates that demonstrate anticipated associations with underlying phenotypic data; and methylomes that reflect the underlying biology of constituent cell types.

Conclusions

Our methodology permits an explicit quantitation of the mediation of phenotypic associations with DNA methylation by cell composition effects. Although more work is needed to investigate functional information related to estimated methylomes, our proposed method provides a novel and useful foundation for conducting DNA methylation studies on heterogeneous tissues lacking reference data.

Electronic supplementary material

The online version of this article (doi:10.1186/s12859-016-1140-4) contains supplementary material, which is available to authorized users.

Dendritic cell based immunotherapy using tumor stem cells mediates potent antitumor immune responses

Cancer stem cells (CSCs) are demonstrated to be usually less sensitive to conventional methods of cancer therapies, resulting in tumor relapse. It is well-known that an ideal treatment would be able to selectively target and kill CSCs, so as to avoid the tumor reversion. The aim of our present study was to evaluate the effectiveness of a dendritic cell (DC) based vaccine against CSCs in a mouse model of malignant melanoma. C57BL/6 mouse bone marrow derived DCs pulsed with a murine melanoma cell line (B16F10) or CSC lysates were used as a vaccine. Immunization of mice with CSC lysate-pulsed DCs was able to induce a significant prophylactic effect by a higher increase in lifespan and obvious depression of tumor growth in tumor bearing mice. The mice vaccinated with DCs loaded with CSC-lysate were revealed to produce specific cytotoxic responses to CSCs. The proliferation assay and cytokine (IFN-γ and IL-4) secretion of mice vaccinated with CSC lysate-pulsed DCs also showed more favorable results, when compared to those receiving B16F10 lysate-pulsed DCs. These findings suggest a potential strategy to improve the efficacy of DC-based immunotherapy of cancers.

Effect of thymosin α₁ on the phenotypic and functional maturation of dendritic cells from children with acute lymphoblastic leukemia

To determine the effect of thymosin α1 (Tα1) on the phenotypic and functional maturation of HL‑60 cells, freeze‑thaw antigen‑loaded dendritic cells (DCs) were derived from peripheral blood mononuclear cells (PBMCs) of children with acute lymphoblastic leukemia (ALL). The DCs were generated from the PBMC samples that were collected from the PB of 10 consecutive ALL children. On day 3 of culturing, the cells in the antigen + no Tα1 (AN) and antigen + Tα1 (AT) groups were incubated with 100 µl lysates obtained from freeze‑thaw cycling. After 5 days of incubation, the AT group was administered with 100 ng/ml Tα1. On day 8, the DCs were stained with fluorescein isothiocyanate‑conjugated cluster of differentiation (CD)1a, CD83 and HLA‑DR antibodies and analyzed by flow cytometry. In addition, the killing activity of cytotoxic T lymphocytes (CTLs) from the different groups on wild‑type leukemia cells was measured. The DCs in the AT group exhibited more apparent, characteristic dendritic morphologies than the control and AN group DCs. Furthermore, the lowest expression level of CD1a, and the highest expression of CD83 and HLA‑DR were observed in the AT group when compared with the AN and control groups (P<0.05). The lactate dehydrogenase release assay demonstrated that the killing rate of CTL in the AT group was significantly higher than that in the control and AN groups (P<0.01). Thus, Tα1 may markedly promote the phenotypic and functional maturation of DCs, and may serve as a suitable immunomodulator of DC‑based immunotherapy for treatment of hematological malignancies.

Immune response, safety, and survival and quality of life outcomes for advanced colorectal cancer patients treated with dendritic cell vaccine and cytokine-induced killer cell therapy

Purpose. To determine the immune response after dendritic cell (DC) vaccine and cytokine-induced killer cells (CIK) therapy and assess its associated toxicity, survival benefit, and changes in the quality of life (QOL) of advanced colorectal cancer (CRC) patients. Methods. We recruited 100 patients with unresectable CRC orrelapsed CRC after surgery who received DC vaccine and CIK cells (group immunotherapy, group I), and, as a control, 251 patients who had similar characteristics and underwent similar treatments, except for this immunotherapy (group nonimmunotherapy, group NI). After a follow-up period of 489.2 ± 160.4 days, overall survival (OS) of the two groups was compared using the Kaplan-Meier method. Results. In group I, 62% of patients developed a positive delayed type hypersensitivity response, and most patients showed an improvement in physical strength (75.2%), appetite (74.2%), sleeping (72.1%), and body weight (70.1%). Adverse events were fever (29.5%), insomnia (19.2%), anorexia (9.1%), sore joints (5.4%), and skin rash (1.0%). No toxicity was observed in patients treated with DC vaccine and CIK therapy. OS was significantly longer in group I than in group NI (P = 0.043). Conclusion. DC vaccine and CIK therapy were safe and could induce an immune response against CRC, thereby improving QOL and prolonging OS.

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

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

Reduced expression of NGEP is associated with high-grade prostate cancers: a tissue microarray analysis

New gene expressed in prostate (NGEP) is a newly diagnosed prostate-specific gene that is expressed only in normal prostate and prostate cancer cells. Discovery of tissue-specific markers may promote the development of novel targets for immunotherapy of prostate cancer. In the present study, the staining pattern and clinical significance of NGEP were evaluated in a series of prostate tissues composed of 123 prostate cancer, 19 high-grade prostatic intraepithelial neoplasia and 44 samples of benign prostate tissue included in tissue microarrays using immunohistochemistry. Our study demonstrated that NGEP localized mainly in the apical and lateral membranes and was also partially distributed in the cytoplasm of epithelial cells of normal prostate tissue. All of the examined prostate tissues expressed NGEP with a variety of intensities; the level of expression was significantly more in the benign prostate tissues compared to malignant prostate samples (P value <0.001). Among prostate adenocarcinoma samples, a significant and inverse correlation was observed between the intensity of NGEP expression and increased Gleason score (P = 0.007). Taken together, we found that NGEP protein is widely expressed in low-grade to high-grade prostate adenocarcinomas as well as benign prostate tissues, and the intensity of expression is inversely proportional to the level of malignancy. NGEP could be an attractive target for immune-based therapy of prostate cancer patients as an alternative to the conventional therapies particularly in indolent patients.

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

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

Immunotherapy of prostate cancer: should we be targeting stem cells and EMT?

Cancer stem cells have been implicated in a number of solid malignancies including prostate cancer. In the case of localised prostate cancer, patients are often treated with surgery (radical prostatectomy) and/or radiotherapy. However, disease recurrence is an issue in about 30% of patients, who will then go on to receive hormone ablation therapy. Hormone ablation therapy is often palliative in a vast proportion of individuals, and for hormone-refractory patients, there are several immunotherapies targeting a number of prostate tumour antigens which are currently in development. However, clinical responses in this setting are inconsistent, and it is believed that the failure to achieve full and permanent tumour eradication is due to a small, resistant population of cells known as 'cancer stem cells' (CSCs). The stochastic and clonal evolution models are among several models used to describe cancer development. The general consensus is that cancer may arise in any cell as a result of genetic mutations in oncogenes and tumour suppressor genes, which consequently result in uncontrolled cell growth. The cancer stem cell theory, however, challenges previous opinion and proposes that like normal tissues, tumours are hierarchical and only the rare subpopulation of cells at the top of the hierarchy possess the biological properties required to initiate tumourigenesis. Furthermore, where most cancer models infer that every cell within a tumour is equally malignant, i.e. equally capable of reconstituting new tumours, the cancer stem cell theory suggests that only the rare cancer stem cell component possess tumour-initiating capabilities. Hence, according to this model, cancer stem cells are implicated in both tumour initiation and progression. In recent years, the role of epithelial--mesenchymal transition (EMT) in the advancement of prostate cancer has become apparent. Therefore, CSCs and EMT are both likely to play critical roles in prostate cancer tumourigenesis. This review summarises the current immunotherapeutic strategies targeting prostate tumour antigens taking into account the need to consider treatments that target cancer stem cells and cells involved in epithelial--mesenchymal transition.

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.

Development of an effective method for dendritic cell immunotherapy of mouse melanoma

Dendritic cell (DC) immunotherapy is a strong candidate for the treatment of incurable cancers especially malignant melanoma. Nevertheless, the proper guideline of DC immunotherapy does not exist. The absence of the guideline is also an obstacle to clinical trials of DC immunotherapy. So we conducted this study in order to develop an effective DC preparation method for immunotherapy in mouse malignant melanoma. Mouse bone marrow-derived DC were stimulated with tumour antigen alone or tumour antigen plus a cocktail (anti-CD40 antibody +TNF-alpha+ IL-1beta) for 8, 24 or 48 h and the characteristics of these DC, such as surface molecules (CD40, CD80, CD86, MHC class II, CCR7), cytokines(IL-12, IFN-gamma, and IL-10), DC-induced T cell proliferation in vitro, and the production of IFN-gamma by those cells, were evaluated. Mice with melanoma were then treated with DC stimulated with tumour antigen alone and tumour antigen plus cocktail for 8 or 48 h. The tumour size and survival rate of these mice were then evaluated. (1) Beneficial clinical effects such as a reduction of tumour size and an increased survival rate were best observed in the group treated with DC stimulated for 8 h with tumour antigen plus cocktail. (2) The single prominent characteristic of DC stimulated for 8 h with tumour antigen plus cocktail was an elevated IL-12 secretion. The cytokine IL-12 was not secreted by other DC. Consequently, proper production of IL-12 was found to be an important requirement for DC used in immunotherapy of mouse melanoma.

Novel multi-peptide vaccination in Hla-A2+ hormone sensitive patients with biochemical relapse of prostate cancer

BACKGROUND

A phase I/II trial was conducted to assess feasibility and tolerability of tumor associated antigen peptide vaccination in hormone sensitive prostate carcinoma (PC) patients with biochemical recurrence after primary surgical treatment.

METHODS

Nineteen HLA-A2 positive patients with rising PSA without detectable metastatic disease or local recurrence received 11 HLA-A*0201-restricted and two HLA class II synthetic peptides derived from PC tumor antigens subcutaneously for 18 months or until PSA progression. The vaccine was emulgated in montanide ISA51 and combined with imiquimod, GM-CSF, mucin-1-mRNA/protamine complex, local hyperthermia or no adjuvant. PSA was assessed, geometric mean doubling times (DT) calculated and clinical performance monitored.

RESULTS

PSA DT of 4 out of 19 patients (21%) increased from 4.9 to 25.8 months during vaccination. Out of these, two patients (11%) exhibited PSA stability for 28 and 31 months which were still continuing at data cut-off. One patient showed no change of PSA DT during vaccination but decline after the therapy. Three patients had an interim PSA decline or DT increase followed by DT decrease compared to baseline PSA DT. Three of the responding patients received imiquimod and one the mucin-1-mRNA/protamine complex as adjuvant; both are Toll-like receptor-7 agonists. Eleven (58%) patients had progressive PSA values. The vaccine was well tolerated, and no grade III or IV toxicity occurred.

CONCLUSION

Multi-peptide vaccination stabilized or slowed down PSA progress in four of 19 cases. The vaccination approach is promising with moderate adverse events. Long-term stability delayed androgen deprivation up to 31 months. TLR-7 co-activation seems to be beneficial.

Androgen ablation augments prostate cancer vaccine immunogenicity only when applied after immunization

BACKGROUND

Androgen ablation (AA) causes apoptosis of normal and neoplastic prostate cells. It is a standard treatment for advanced prostate cancer. Androgen ablation-mediated immunological effects include bone marrow hyperplasia, thymic regeneration, T and B cell lymphopoeisis and restoration of age-related peripheral T cell dysfunction. Androgens also regulate the transcription of several cytokines. Dendritic cells (DC) are the most potent antigen presenting cells that can activate antigen-specific naïve T cells. Despite myriad clinical trials involving DC-based prostate cancer immunotherapies, the effects of AA on DC function remain largely uncharacterized. Therefore, we investigated the effects of AA on DC and whether it could improve the efficacy of prostate cancer immunotherapy.

METHODS

Cytokine expression changes due to AA were quantified by multiplex ELISA. Flow cytometry was used to assess AA-mediated effects on DC maturation and expression of costimulatory markers. Mixed leukocyte reactions and cell-mediated lysis assays elucidated the role of androgens in DC function. The effect of AA on the efficacy of vaccination against a prostate tumor-associated antigen was tested using Elispot assays.

RESULTS

Androgen ablation increased dendritic cell maturation and costimulatory marker expression, but had no effect on DC costimulatory function. However, DC isolated from castrated mice increased the expression of key cytokines by antigen-experienced T cells while decreasing their expression in naïve cells. Finally, androgen ablation improved immune responses to vaccination only when applied after immunization.

CONCLUSION

Androgen ablation causes differential effects of DC on primary and secondary T cell responses, thus augmenting vaccine immunogenicity only when applied after immunization.

Grundlagen der systemischen Therapie

Die Einführung sog. »zielgerichteter Medikamente« hat einen Paradigmenwechsel in der Systemtherapic maligner Erkrankungen ausgelöst. Voraussetzung hierfür waren die in den letzten 25 Jahren gesammelten Erkenntnisse der molekularbiologischen, molekulargenetischen und immunologischen Grundlagenforschung, die ein besseres Verständnis der pathogenetischen Prozesse im Rahmen der malignen Transformation und Tumorprogression sowie die Identifikation strategischer Zielstrukturen (»Targets«) ermöglichen. Auf diese Weise wurde ein neuer Ansatz der Entwicklung antineoplastischer Therapeutika angestoßen, der auf die Wirkung an spezifischen Molekülaktivitäten und nicht primär auf zelluläre Endpunkte (Wachstumshemmung, Zelltod) ausgerichtet ist.

Chemotherapy followed by syngeneic dendritic cell injection in the mouse: findings and implications for human treatment

A growing number of studies have described an apparent synergy between systemic chemotherapy administration and the intratumoral injection of dendritic cells (DCs) in the successful treatment of murine tumors. A review of several of these studies is undertaken here and possible combinations of DC therapy and conventional cancer therapies are discussed with the goal of contemplating the exploitation of current findings and theory toward the treatment of human patients with cancer. The methods and results of several murine studies are described in detail and additional reference is made to other relevant murine studies. Hypothetical routes of synergy between DC therapy, chemotherapy, and ablative therapies are explored, and the potentially significant role played by the regulatory immune system is discussed. Given the results of preclinical studies and the current understanding of cancer immunity, it is possible to consider a human treatment that calls for focal ablation of cancer followed by intratumoral DC injection, in the setting of chemotherapy-based regulatory T-cell depletion.

Generation of robust cytotoxic T lymphocytes against prostate specific antigen by transduction of dendritic cells using protein and recombinant adeno-associated virus

Prostate cancer is the most common male cancer and there is an urgent need for adjuvant therapy such as immunotherapy. Recombinant adeno-associated virus type 2 (rAAV) vectors are useful for antigen gene-loading of human dendritic cells (DC) and for the rapid generation of cytotoxic T lymphocytes (CTL). In this study, we report a protocol for AAV-loading of DC with the AAV-loading of self-antigen prostate specific antigen (PSA) resulting in generation of CTL. PSA and cytokine expression, Cell surface marker analysis of DC and CTL cells were done using a FACScalibur flow cytometer. Chromium-51 release assay was used to analyze the killing activity of CTL. It was found that AAV-loading of DC with the PSA gene is superior to PSA protein loading of the same antigen for generating effective CTL. AAV/PSA-loading of DC was found to result in: (1) strong, rapid PSA-specific, MHC Class I-restricted CTL, (2) PSA expression in DC, (3) high CD80, CD83, and CD86 expression on DC, (4) high level of IL-12 and low level of IL-10 in DC, (5) T cell populations with significant interferon gamma (IFNgamma) expression, but low IL-4 expression, (6) high proliferation of T cell populations, (7) high CD8:CD4 and CD8:CD56 T cell ratios. The reason for generation of robust CTL is partly explained by the characteristics of DC and CTL described. This protocol may be useful for adoptive immunotherapy against self antigens such as PSA for prostate cancer.

Targeting human {gamma}delta} T cells with zoledronate and interleukin-2 for immunotherapy of hormone-refractory prostate cancer

The increasing evidence that gammadelta T cells have potent antitumor activity suggests their value in immunotherapy, particularly in areas of unmet need such as metastatic carcinoma. To this end, we initiated a phase I clinical trial in metastatic hormone-refractory prostate cancer to examine the feasibility and consequences of using the gammadelta T-cell agonist zoledronate, either alone or in combination with low-dose interleukin 2 (IL-2), to activate peripheral blood gammadelta cells. Nine patients were enlisted to each arm. Neither treatment showed appreciable toxicity. Most patients were treated with zoledronate + IL-2, but conversely only two treated with zoledronate displayed a significant long-term shift of peripheral gammadelta cells toward an activated effector-memory-like state (T(EM)), producing IFN-gamma and perforin. These patients also maintained serum levels of tumor necrosis factor-related apoptosis inducing ligand (TRAIL), consistent with a parallel microarray analysis showing that TRAIL is produced by gammadelta cells activated via the T-cell receptor and IL-2. Moreover, the numbers of T(EM) gammadelta cells showed a statistically significant correlation with declining prostate-specific antigen levels and objective clinical outcomes that comprised three instances of partial remission and five of stable disease. By contrast, most patients treated only with zoledronate failed to sustain either gammadelta cell numbers or serum TRAIL, and showed progressive clinical deterioration. Thus, zoledronate + IL-2 represents a novel, safe, and feasible approach to induce immunologic and clinical responses in patients with metastatic carcinomas, potentially providing a substantially increased window for specific approaches to be administered. Moreover, gammadelta cell phenotypes and possibly serum TRAIL may constitute novel biomarkers of prognosis upon therapy with zoledronate + IL-2 in metastatic carcinoma.

Advances in preclinical investigation of prostate cancer gene therapy

Treating recurrent prostate cancer poses a great challenge to clinicians. Research efforts in the last decade have shown that adenoviral vector-based gene therapy is a promising approach that could expand the arsenal against prostate cancer. This maturing field is at the stage of being able to translate many preclinical discoveries into clinical practices. At this juncture, it is important to highlight the promising strategies including prostate-targeted gene expression, the use of oncolytic vectors, therapy coupled to reporter gene imaging, and combined treatment modalities. In fact, the early stages of clinical investigation employing combined, multimodal gene therapy focused on loco-regional tumor eradication and showed promising results. Clinicians and scientists should seize the momentum of progress to push forward to improve the therapeutic outcome for the patients.

Hepatitis B virus (HBV) antigen-pulsed monocyte-derived dendritic cells from HBV-associated hepatocellular carcinoma patients significantly enhance specific T cell responses in vitro

To investigate whether hepatitis B virus (HBV) antigen-pulsed monocyte-derived dendritic cells (MoDC) could mount a T cell response in hepatocellular carcinoma (HCC) patients associated with chronic HBV infection, peripheral blood mononuclear cells (PBMCs) from 36 HBV-associated HCC patients were induced into MoDC and pulsed with hepatitis B core antigen (HBcAg) and hepatitis B surface antigen (HBsAg), alone and in combination. Co-stimulatory molecules CD80, CD86 and CD40, as well as human leucocyte antigens D-related (HLA-DR) were found to express at the highest level on MoDC pulsed with HBcAg or HBsAg + HBcAg, at a median level on MoDC pulsed with HBcAg or HBsAg alone, and at the lowest level on non-antigen-pulsed MoDC. Interleukin (IL)-10 and IL-12 cytokines were released by antigen-pulsed MoDC at increased levels in the order: no-antigen < HBsAg < HBcAg < HBcAg + HBsAg. MoDC pulsed with HBcAg or HBsAg + HBcAg also had the strongest ability to stimulate autologous T cell proliferation and intracellular interferon (IFN)-gamma production. HBcAg- or HBsAg + HBcAg-pulsed MoDC could also induce HBV core peptide-specific CD8(+) T cell proliferation determined by tetramer staining. In addition, the antigen-pulsed MoDC were found to have a stronger capacity to produce IL-12 and induce T cell response in vitro for patients with higher alanine transaminase (ALT) levels than those with lower ALT levels, indicating that antigen pulse could substantially reverse the impaired function of MoDC in primary HCC patients with active chronic hepatitis B. In conclusion, HBV antigen-pulsed MoDC from HCC patients with chronic hepatitis B could induce HBV-specific T cell response in vitro.

Characterization of circulating blood dendritic cell subsets DC123+ (lymphoid) and DC11C+ (myeloid) in prostate adenocarcinoma patients

PURPOSE

We verified whether prostate adenocarcinoma produces specific modifications in DC subsets count.

METHODS

Twenty-one untreated prostate adenocarcinomas were divided on the basis of clinical stage in localized and metastatic disease. As control we used a population of 18 healthy male subjects. For DCs enumeration, peripheral blood (PB) samples were obtained in all cases. A single-platform flow cytometric assay based on Tru-COUNT was used for the enumeration of the two DCs subsets, myeloid (mDCs) and plasmacytoid (pDCs).

RESULTS

We showed a statistically significant reduction in pDCs count in prostate cancer population when compared to healthy controls (P = 0.002). Comparing each clinical stage with healthy controls, significant differences were found between controls and the metastatic group in both pDCs and mDCs (P = 0.005 and P = 0.023 respectively) but not between controls and the localized group (P = 0.055 and P = 0.829 respectively).

CONCLUSIONS

We showed that DCs count in PB is significantly affected by prostate adenocarcinoma progression in a metastatic disease.

Inhibition of dendritic cell generation and function by serum from prostate cancer patients: correlation with serum-free PSA

Tumor produces a number of immunosuppressive factors that block maturation of dendritic cells (DCs). Here, we demonstrated that endogenous factors presented in the serum of patients with prostate cancer (CaP) inhibited the generation of functionally active DCs from CD14+ monocytes in vitro. We have shown a significant inhibitory potential of serum obtained from patients with CaP and benign prostate hyperplasia benign prostatic hyperplasia (BPH) when compared with serum from healthy volunteers. As assessed by flow cytometry, expression of CD83, CD86, and CD40 molecules was strongly inhibited by CaP and BPH serum. In addition, these DCs were weak stimulators of allogeneic T cell proliferation when compared with DCs produced in the presence of healthy volunteer serum. Statistical analysis of the results revealed a positive relationship between the inhibition of expression of DC markers CD83 and CD80 and the levels of serum-free prostate-specific antigen (PSA). These data suggest that the DC system may be impaired in CaP patients.

In vitro assessment of dendritic cells pulsed with apoptotic tumor cells as a vaccine for ovarian cancer patients

Surgery and chemotherapy are standard treatments in ovarian cancer, but patients have a high rate of relapse. Dendritic cell (DC)-based vaccines are a new treatment option for elimination of residual tumor disease. We aim to explore the feasibility and immunogenicity of DC vaccines pulsed with autologous irradiated tumor cells from ovarian cancer patients. Monocyte-derived DC were generated and pulsed with autologous tumor-derived bodies, matured and subsequently cocultured with autologous lymphocytes. The ability of DC to activate lymphocytes was evaluated by proliferation and IFN-gamma ELISPOT. Induction of tumor cell apoptosis was optimal at 24 h, and DC pulsing optimal at 4 h. Maturation of DC and proliferation of lymphocytes were achieved in 75% of patients tested. Lymphocyte IFN-gamma production increased in response to tumor antigen-pulsed DC. We show the feasibility of preparing individual DC-based vaccines in ovarian cancer patients and the potential for induction of lymphocyte responses.

Larger numbers of immature dendritic cells augment an anti-tumor effect against established murine melanoma cells

The dendritic cell (DC) is a potentially promising tool for cancer immunotherapy. To date, however, DC-based immunotherapy has not yielded data with which firm conclusions can be drawn. In the present study, we tested the dose-dependant enhancement of the anti-tumor effect induced by DCs. When large numbers of DCs were used, tumor growth was suppressed up to 41% when compared to control mice. Survival of the animals was prolonged to 54 days compared to the 33-day survival the control mice. The delayed-type hypersensitivity (DTH) response induced was 26-fold higher than in the controls. Larger numbers of DCs also led to higher expansion of IFN-gamma-secreting-CD8(+) T cells. Furthermore, the secretion of IL-12p70 and IFN-gamma by spleen cells were enhanced in proportion to the dosage. However, the level of IL-4 secreted from spleen cells was negligible compared to the level of IFN-gamma that was released. These results indicate that DCs induce Th1-dominant immune response and that more DCs could lead to better immunological results, a finding which was consistent with our therapeutic results.

Dendritic cell-based multi-epitope immunotherapy of hormone-refractory prostate carcinoma

BACKGROUND

Dendritic cell (DC)-based immunotherapy is a promising approach to augment tumor antigen-specific T cell responses in cancer patients. However, tumor escape with down-regulation or complete loss of target antigens may limit the susceptibility of tumor cells to the immune attack. Concomitant generation of T cell responses against several immunodominant antigens may circumvent this potential drawback. In this trial, we determined the immunostimulatory capacity of autologous DC pulsed with multiple T cell epitopes derived from four different prostate-specific antigens in patients with advanced hormone-refractory prostate cancer.

PATIENTS AND METHODS

Autologous DC of HLA-A*0201(+) patients with hormone-refractory prostate cancer were loaded with antigenic peptides derived from prostate stem cell antigen (PSCA(14-22)), prostatic acid phosphatase (PAP(299-307)), prostate-specific membrane antigen (PSMA(4-12)), and prostate-specific antigen (PSA(154-163)). DC were intradermally applied six times at biweekly intervals followed-in the case of an enhanced immune response-by monthly booster injections. Immune monitoring during the time of ongoing vaccinations (12-59 weeks) included ex vivo ELISPOT measurements, MHC tetramer analysis and in vitro cytotoxicity assays.

RESULTS

Of the initial six patients, three qualified for long-term multi-epitope DC vaccination. This regime was tolerated well by all three patients. The vaccination elicited significant cytotoxic T cell responses against all prostate-specific antigens tested. In addition, memory T cell responses against the control peptides derived from influenza matrix protein and tetanus toxoid were efficiently boosted. Clinically, the long-term DC vaccination was associated with an increase in PSA doubling time.

CONCLUSIONS

DC-based multi-epitope immunotherapy with repeated boosting in men with hormone-refractory prostate carcinoma is feasible and generates efficient cellular antitumor responses.

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

BACKGROUND

Immunotherapies might represent promising alternatives for the treatment of patients with hormone-refractory prostate cancer (HRPC). In a Phase I clinical trial, we evaluated a vaccination with dendritic cells (DCs) loaded with a cocktail consisting of HLA-A*0201-restricted peptides derived from five different prostate cancer-associated antigens [prostate-specific antigen (PSA), prostate-specific membrane antigen (PSMA), survivin, prostein, transient receptor potential p8 (trp-p8)].

METHODS

Eight HRPC patients received a total of four vaccinations every other week. Clinical and immunological responses were monitored by the determination of the serum PSA levels and by enzyme linked immunospot (ELISPOT) analyses, respectively.

RESULTS

Apart from local skin reactions no side effects were noted. One patient displayed a partial response (PR; PSA decrease >50%) and three other patients showed stable PSA values or decelerated PSA increases. In ELISPOT analyses, three of four PSA responders also showed antigen-specific CD8+ T-cell activation against prostein, survivin, and PSMA.

CONCLUSIONS

The described protocol represents a safe and feasible concept for the induction of clinical and immunological responses. The application of a peptide cocktail-derived from different antigens as a novel treatment modality is supposed to allow for the genetic and biologic heterogeneity of PCa.

Therapeutic Vaccines for Prostate Cancer

Prostate cancer is the most common, noncutaneous cancer for men in the U.S., leading to more than 30,000 deaths a year. Vaccines for prostate cancer, which for several years have been shown to generate immunologic responses, are beginning to show significant clinical promise. At present, numerous therapeutic options are being investigated, including autologous and allogeneic whole-tumor cell vaccines, dendritic cell vaccines, and poxvirus-based vaccines. Advances in basic immunology have translated into new, more complex therapeutic strategies. The findings from current trials and the demonstrated potential to combine vaccines with conventional therapies herald a promising future for the treatment of prostate cancer. This review highlights recent advances and clinical trials in immunotherapy for prostate cancer, along with current thoughts on immunologic and clinical monitoring of these trials.

Enhanced antitumor effect of dendritic cell based immunotherapy after intratumoral injection of radionuclide Ho-166 against B16 melanoma

Internal radiotherapy with the intratumoral injection of the beta-emitting radionuclide, Holmium (Ho)-166, into B16 melanoma resulted in a reduction in size and growth rate; however, complete remission was not always achieved. Therefore, additional dendritic cell (DC) therapy was investigated to determine whether it could improve therapeutic results. Malignant melanoma was induced in mice by inoculating B16F10 cell line subcutaneously. Fifty-four mice were divided into four groups: (1) non-treated (group I, n = 11), (2) treated with Ho-166 (group II, n = 16), (3) treated with immature DCs (group III, n = 8), and (4) treated with immature DCs after Ho-166 injection (group IV, n = 19). Changes in tumor size, survival rates, and immunologic profiles were observed. Nineteen days after Ho-166 or PBS injection, mean tumor sizes in the four groups were 6044 +/- 1046, 1658 +/- 523, 3871 +/- 921, and 444 +/- 167 mm(3), respectively. We observed a significant decrease in tumor size (P < 0.05) and an increase in survival in group IV. When the B16F10 cell line was reinjected into the contralateral backs of survivors, much slower growth was observed in group IV (P < 0.05). Both tumor-specific CTL and natural killer cell activities and the infiltration of inflammatory cells into tumor tissues were found to be elevated in group IV. In addition, strong immune responses as determined by in vitro T cell proliferation, ELISA and ELISPOT assay were induced in group IV. Our results suggest that a combination of internal radiotherapy using Ho-166 and immature DCs could be used either to treat unresectable melanoma or as an adjuvant therapy after surgery.

Numerical and functional assessment of blood dendritic cells in prostate cancer patients

BACKGROUND

Prostate cancer is one of the leading causes of cancer deaths in males and there are currently no effective treatments available for metastatic disease. Although recent clinical trials using dendritic cell (DC) based immunotherapy treatments have demonstrated safety, immunological responses, and some clinical efficacy, better vaccine delivery strategies need to be developed. We have undertaken the first detailed analysis of blood DC (BDC) subsets and their function in prostate cancer patients, with a view to utilizing immunoselected BDC for immunotherapy.

METHODS

We enumerated the CD11c+CD1c+, CD11c+CD16+, and CD11c-CD123+ BDC subsets in whole blood of prostate cancer patients using a single platform TruCOUNT assay. These subsets were identified and purified using flow cytometry and immunomagnetic selection, and their functional capacity analyzed by costimulatory molecule expression, cytokine secretion, and antigen presenting ability.

RESULTS

There were no significant differences in the number or composition of these subsets compared to healthy donors and these cells could be purified with equal efficiency from both groups. The prostate cancer patients BDC had similar levels of key costimulatory molecules and cytokine expression profiles, compared to healthy donors, and these were upregulated to the same extent, in response to exogenous stimuli. BDC from both groups were capable of eliciting allogeneic proliferative responses and inducing autologous CD4+ responses to naïve and recall antigens, and antigen-specific CD8+ responses to influenza matrix protein and prostate specific antigen.

CONCLUSIONS

These results indicate that an immunoselected CD1c+ BDC preparation could provide a suitable vaccine delivery vehicle for future prostate cancer immunotherapy trials.

Update on cancer vaccines

PURPOSE OF REVIEW

Vaccination against cancer has had a variable history, with claims of success often fading into disappointment. The reasons for this include poor vaccine design, inadequate understanding of the nature of the immune response, and a lack of objective measures to evaluate performance. The impact of genetic technology has changed everything. We now have multiple strategies to identify candidate tumor antigens, and we understand more about activation and regulation of immunity against cancer. There are novel vaccine strategies to activate specific attack on tumor cells. We also have modern assays using surrogate markers of performance to correlate with clinical effects. It is timely to select significant relevant papers to illustrate the growing potential for patients with cancer.

RECENT FINDINGS

Recent findings include tumor antigen discovery and vaccine formulation, relevant knowledge concerning mechanisms of induction of effective immunity from preclinical models, and translation into clinical trials with objective evaluation of performance.

SUMMARY

The ability of the immune response to dispose of cancer cells is clear. Passive transfer of antibody or immune cells is already clinically successful. We are now in a position to harness new gene-based information to design vaccines capable of inducing effective and long-lasting immunity. Safe vaccines could be used either in patients or in transplant donors. Pilot clinical trials are the means of testing performance, with continuing vaccine design modification to target specific antigens in different cancers.

Vaccine strategies to treat lymphoproliferative disorders

Lymphoproliferative disorders, including follicular lymphoma (FL), multiple myeloma (MM) and chronic lymphatic leukaemia (CLL), are slowly progressive malignancies which remain incurable despite advances in therapy. Harnessing the immune system to recognise and destroy tumours is a promising new approach to treating these diseases. Dendritic cells (DC) are unique antigen-presenting cells that play a central role in the initiation and direction of immune responses. DC loaded ex vivo with tumour-associated antigens and administered as a vaccine have already shown promise in early clinical trials for a number of lymphoproliferative disorders, but the need for improvement is widely agreed. Recent advances in the understanding of basic DC biology and lessons from early clinical trials have provided exciting new insights into the generation of anti-tumour immune responses and the design of vaccine strategies. In this review we provide an overview of our current understanding of DC biology and their function in patients with lymphoproliferative disorders. We discuss the current status of clinical trials and new approaches to exploit the antigen presenting capacity of DC to design vaccines of the future.