The choice of the antigen in the dendritic cell-based vaccine therapy for prostate cancer

Dendritic Cells and Cancer Immunotherapy: The Adjuvant Effect

Dendritic cells (DCs) are immune specialized cells playing a critical role in promoting immune response against antigens, and may represent important targets for therapeutic interventions in cancer. DCs can be stimulated ex vivo with pro-inflammatory molecules and loaded with tumor-specific antigen(s). Protocols describing the specific details of DCs vaccination manufacturing vary widely, but regardless of the employed protocol, the DCs vaccination safety and its ability to induce antitumor responses is clearly established. Many years of studies have focused on the ability of DCs to provide overall survival benefits at least for a selection of cancer patients. Lessons learned from early trials lead to the hypothesis that, to improve the efficacy of DCs-based immunotherapy, this should be combined with other treatments. Thus, the vaccine’s ultimate role may lie in the combinatorial approaches of DCs-based immunotherapy with chemotherapy and radiotherapy, more than in monotherapy. In this review, we address some key questions regarding the integration of DCs vaccination with multimodality therapy approaches for cancer treatment paradigms.

Combination of Interleukin-15 With a STING Agonist, ADU-S100 Analog: A Potential Immunotherapy for Prostate Cancer

Prostate cancer is the second most commonly diagnosed cancer in men with mortality rates, overtaking those for breast cancer in the last 2 years in the UK. Despite advances in prostate cancer treatments, over 25% of men do not survive over 5 years with advanced disease. Due to the success of immunotherapies in treating other cancers, this treatment modality has been investigated for Prostate cancer, however, the sole FDA approved immunotherapy so far (Provenge™) only extends life by a few months. Therefore, finding immunotherapeutic agents to treat prostate cancer is of major interest. Our group has previously shown that Interleukin-15 (IL-15), unlike other therapeutic cytokines such as IL-2 and IL-12, can stimulate expansion and activity of CD8 T cells and NK cells in vitro when they are exposed to prostate cancer cells, while studies in mice have shown a 50% reduction in tumor size with no apparent toxicity. In this study, we aim to examine potencies of IL-15 in combination with a cyclic dinucleotide (CDN) that activates the Stimulator of Interferon-Gene (STING) receptor. Selected CDNs (also known as STING agonists) have previously been shown to activate both T cells and dendritic cells through STING. We hypothesize that the combination of STING agonists and IL-15 can additively increase NK and T cell activity as they act to increase type I interferons (IFNs) through STING activation and IFN-γ through IL-15. In prostate cancer-lymphocyte co-cultures we now show that combination of IL-15 and the STING agonist ADU-S100 analog induces a marked killing of cancer cells above that seen with IL-15 or ADU-S100 alone. We show that this is related to a potent activation of NK cells resulting in increased perforin and CD69 expression, and up to a 13-fold increase in IFNγ secretion in the co-cultures. NK cells are responsible for killing of the cancer cells, as shown by a lack of cytotoxicity in NK depleted lymphocyte-tumor cell co-cultures, or in co-cultures of B and T cells with tumor cells. In summary, we propose that the combination of IL-15 and the sting agonist ADU-S100 analog may be potently effective in treatment of prostate cancer.

Identification and Design of a Next-Generation Multi Epitopes Bases Peptide Vaccine Candidate Against Prostate Cancer: An In Silico Approach

Prostate cancer (PCa) is the second most diagnosed cancer in men and ranked fifth in overall cancer diagnosis. During the past decades, it has arisen as a significant life-threatening disease in men at an older age. At the early onset of illness when it is in localized form, radiation and surgical treatments are applied against this disease. In case of adverse situations androgen deprivation therapy, chemotherapy, hormonal therapy, etc. are widely used as a therapeutic element. However, studies found the occurrences of several side effects after applying these therapies. In current work, several immunoinformatic techniques were applied to formulate a multi-epitopic vaccine from the overexpressed antigenic proteins of PCa. A total of 13 epitopes were identified from the five prostatic antigenic proteins (PSA, PSMA, PSCA, STEAP, and PAP), after validation with several in silico tools. These epitopes were fused to form a vaccine element by (GGGGS)3 peptide linker. Afterward, 5, 6-dimethylxanthenone-4-acetic acid (DMXAA) was used as an adjuvant to initiate and induce STING-mediated cytotoxic cascade. In addition, molecular docking was performed between the vaccine element and HLA class I antigen with the low ACE value of -251 kcal/mol which showed a significant binding. Molecular simulation using normal mode analysis (NMA) illustrated the docking complex as a stable one. Therefore, this observation strongly indicated that our multi epitopes bases peptide vaccine molecule will be an effective candidate for the treatment of the PCa.

Targeting Prostate Cancer Using Intratumoral Cytotopically Modified Interleukin-15 Immunotherapy in a Syngeneic Murine Model

Background

The prostate cancer microenvironment is highly immunosuppressive; immune cells stimulated in the periphery by systemic immunotherapies will be rendered inactive once entering this environment. Immunotherapies for prostate cancer need to break this immune tolerance. We have previously identified interleukin-15 (IL-15) as the only cytokine tested that activates and expands immune cells in the presence of prostate cancer cells. In the current study, we aimed to identify a method of boosting the efficacy of IL-15 in prostate cancer.

Methods

We engineered, by conjugation to a myristoylated peptide, a membrane-localising form of IL-15 (cyto-IL-15) and the checkpoint inhibitor antibodies cytotoxic T lymphocyte antigen 4 (CTLA-4) and programmed death ligand 1 (PD-L1) (cyto-abs) to enable them to bind to cell surfaces by non-specific anchoring to the phospholipid bilayer. The efficacy of these agents was investigated by intratumoral administration either alone (cyto-IL-15 or cyto-abs) or in combination (cyto-combo) in subcutaneous TRAMP-C2 prostate tumors in C57BL/6J mice and compared with their non-modified equivalents in vivo. Following the survival endpoint, histological analyses and RNA sequencing were performed on the tumors.

Results

Intratumoral injection of cyto-IL-15 or cyto-combo delayed tumor growth by 50% and increased median survival to 28 and 25 days, respectively, compared with vehicle (17 days), whereas non-modified IL-15 or antibodies alone had no significant effects on tumor growth or survival. Histological analysis showed that cyto-IL-15 and cyto-combo increased necrosis and infiltration of natural killer (NK) cells and CD8 T cells in the tumors compared with vehicle and non-modified agents. Overall, the efficacy of cyto-combo was not superior to that of cyto-IL-15 alone.

Conclusion

We have demonstrated that intratumoral injection of cyto-IL-15 leads to prostate cancer growth delay, induces tumor necrosis and increases survival. Hence, cytotopic modification in combination with intratumoral injection appears to be a promising novel approach for prostate cancer immunotherapy.

Offsetting Expression Profiles of Prognostic Markers in Prostate Tumor vs. Its Microenvironment

Diagnosis of the presence of tumors and subsequent prognosis based on tumor microenvironment becomes more clinically practical because tumor-adjacent tissues are easy to collect and they are more genetically homogeneous. The purpose of this study was to identify new prognostic markers in prostate stroma that are near the tumor. We have demonstrated the prognostic features of FGFR1, FRS2, S6K1, LDHB, MYPT1, and P-LDHA in prostate tumors using tissue microarrays (TMAs) which consist of 241 patient samples from Massachusetts General Hospital (MGH). In this study, we investigated these six markers in the tumor microenvironment using an Aperio Imagescope system in the same TMAs. The joint prognostic power of markers was further evaluated and classified using a new algorithm named Weighted Dichotomizing. The classifier was verified via rigorous 10-fold cross validation. Statistical analysis of the protein expression indicated that in tumor-adjacent stroma FGFR1 and MYPT1 were significantly correlated with patient outcomes and LDHB showed the outcome-association tendency. More interestingly, these correlations were completely opposite regarding tumor tissue as previously reported. The results suggest that prognostic testing should utilize either tumor-enriched tissue or stroma with distinct signature profiles rather than using mixture of both tissue types. The new classifier based on stroma tissue has potential value in the clinical management of prostate cancer patients.

Immunotherapy as a Promising Treatment for Prostate Cancer: A Systematic Review

Prostate cancer treatment is currently based on surgical removal, radiotherapy, and hormone therapy. In recent years, another therapeutic method has emerged—immunological treatment. Immunotherapy modulates and strengthens one's immune responses against cancer. Neoplastic cells naturally escape from the control of the immune system, and the main goal of immune therapy is to bring the control back. Satisfying outcomes after treatment of advanced melanoma and lung cancer suggest a great potential of immunotherapy as an approach for other tumors' treatment, especially in patients primarily introduced to palliative care. After initial clinical trials, immunotherapy seems to have different side effects than chemotherapy. Prostate cancer was the first neoplasm in which a specific vaccine significantly improved survival. There is a tremendous potential for synergistic combinations of immunotherapy with conventional cancer treatments. A combination of several drugs or methods can be a key in radical treatment of metastatic prostate cancer as demonstrated by preliminary studies.

Prostate cancer immunotherapy, particularly in combination with androgen deprivation or radiation treatment. Customized pharmacogenomic approaches to overcome immunotherapy cancer resistance

Conventional therapeutic approaches for advanced prostate cancer - such as androgen deprivation, chemotherapy, radiation - come up often against lack of effectiveness because of possible arising of correlative cancer cell resistance and/or inadequate anti-tumor immune conditions. Whence the timeliness of resorting to immune-based treatment strategies including either therapeutic vaccination-based active immunotherapy or anti-tumor monoclonal antibody-mediated passive immunotherapy. Particularly attractive, as for research studies and clinical applications, results to be the cytotoxic T-lymphocyte check point blockade by the use of anti-CTLA-4 and PD-1 monoclonal antibodies, particularly when combined with androgen deprivation therapy or radiation. Unlike afore said immune check point inhibitors, both cell-based (by the use of prostate specific antigen carriers autologous dendritic cells or even whole cancer cells) and recombinant viral vector vaccines are able to induce immune-mediated focused killing of specific antigen-presenting prostate cancer cells. Such vaccines, either used alone or concurrently/sequentially combined with above-mentioned conventional therapies, led to generally reach, in the field of various clinical trials, reasonable results particularly as regards the patient's overall survival. Adoptive trasferred T-cells, as adoptive T-cell passive immunotherapy, and monoclonal antibodies against specific antigen-endowed prostate cancer cells can improve immune micro-environmental conditions. On the basis of a preliminary survey about various immunotherapy strategies, are here also outlined their effects when combined with androgen deprivation therapy or radiation. What's more, as regard the immune-based treatment effectiveness, it has to be pointed out that suitable personalized epigenetic/gene profile-achieved pharmacogenomic approaches to target identified gene aberrations, may lead to overcome - as well as for conventional therapies - possible prostate cancer resistance to immunotherapy.

Amplification and overexpression of PSCA at 8q24 in invasive micropapillary carcinoma of breast

PURPOSE

Invasive micropapillary carcinoma (IMPC) of the breast has distinct histological features and molecular genetic profiles. Gains/amplifications of 8q24 are found associated with IMPC. Although the prostate stem cell antigen (PSCA) gene is located at chromosome 8q24, and found over-expressed in prior studies, its prognostic values and biological significance in IMPC have not been well studied.

METHODS

Fluorescence in situ hybridization (FISH) was used to assess the frequencies of PSCA copy number gains in IMPC, invasive ductal carcinoma of no special type (IDC-NST), and invasive lobular carcinoma (ILC) samples. The protein expression levels of PSCA were examined in 56 IMPC, 72 IDC-NST, and 56 ILC samples using immunohistochemical analysis.

RESULTS

PSCA gene amplification was detected in 45.2% (14/31) of the IMPC, 28.1% (9/32) of the IDC-NST, and none (0/25) of the ILC. PSCA protein expression was observed in 58.9% (33/56), 40.3% (29/72), and 3.6% (2/56) of IMPC, IDC-NST, and ILC samples, respectively. The concordant rate of the immunohistochemistry and FISH data was 85.2%. PSCA gene amplification highly correlated with its protein overexpression (rs = 0.687, P < 0.001), suggesting that gene amplification is an important mechanism involved in PSCA overexpression. Our univariate analysis showed that the patients with PSCA-positive IMPC had a decreased disease-free survival (DFS) compared to PSCA-negative IMPC patients (P = 0.003). Our multivariate analysis confirmed the worse DFS in PSCA-positive IMPC patients (P = 0.022).

CONCLUSIONS

Our results indicate that PSCA may be an attractive target in the 8q24 amplicon and that it may serve as a molecular marker of metastasis and recurrence in IMPC. The differential expression of PSCA may be associated with cell adhesion. Detection of PSCA protein and gene amplification may help manage and predict the prognosis of IMPC patients.

A Perspective of Immunotherapy for Prostate Cancer

In cancer patients, the immune system is often altered with an excess of inhibitory factors, such as immunosuppressive cytokines, produced by regulatory T cells (Treg) or myeloid-derived suppressor cells (MDSC). The manipulation of the immune system has emerged as one of new promising therapies for cancer treatment, and also represents an attractive strategy to control prostate cancer (PCa). Therapeutic cancer vaccines and immune checkpoint inhibitors have been the most investigated in clinical trials. Many trials are ongoing to define the effects of immune therapy with established treatments: androgen deprivation therapy (ADT) and chemotherapy (CT) or radiotherapy (RT). This article discusses some of these approaches in the context of future treatments for PCa.

Negatively Charged Magnetite Nanoparticle Clusters as Efficient MRI Probes for Dendritic Cell Labeling and In Vivo Tracking

Cell labeling and tracking via magnetic resonance imaging (MRI) has drawn much attention for its noninvasive property and longitudinal monitoring functionality. Employing of imaging probes with high labeling efficiency and good biocompatibility is one of the essential factors that determine the outcome of tracking. In this study, negatively charged superparamagnetic iron oxide (PAsp‐PCL/SPIO) nanoclusters are developed for dendritic cell (DC) labeling and tracking in vivo. PAsp‐PCL/SPIO has a diameter of 124 ± 41 nm in DLS, negatively charged surface (zeta potential = −27 mV), and presents highT2relaxivity (335.6 Fe mm−1s−1) and good DC labeling efficiency. Labeled DCs are unaffected in their viability, proliferation, and differentiation capacity, and have an excellent MR imaging sensitivity in vitro. To monitor the migration of DCs into lymphoid tissues in vivo, which will be related to the final immunotherapy results,T2‐wighted andT2‐map imaging of popliteal nodes at different points in time are acquired under a clinical 3 T scanner after subcutaneous injection of a certain number of labeled DCs at hindleg footpads of mice. The signal intensities decreasing andT2values shortening of ipsilateral popliteal nodes are significant and display a time‐ and dose‐dependence, showing DCs' migration to the draining lymph nodes.

A vaccine strategy with multiple prostatic acid phosphatase-fused cytokines for prostate cancer treatment

Immunotherapy is one of the attractive treatment strategies for advanced prostate cancer. The US Food and Drug Administration (FDA) previously approved the therapeutic vaccine, sipuleucel-T, which is composed of autologous antigen-presenting cells cultured with a fusion protein [prostatic acid phosphatase (PAP) and granulocyte-macrophage colony-stimulating factor (GMCSF)]. Although sipuleucel-T has been shown to prolong the median survival of patients for 4.1 months, more robust therapeutic effects may be expected by modifying the vaccination protocol. In the present study, we aimed to develop and validate a novel vaccination strategy using multiple PAP-fused cytokines for prostate cancer treatment. Using a super gene expression (SGE) system that we previously established to amplify the production of a recombinant protein, significant amounts of PAP-fused cytokines [human GMCSF, interleukin-2 (IL2), IL4, IL7 and mouse GMCSF and IL4] were obtained. We examined the activity of the fusion proteins in vitro to validate their cytokine functions. A significant upregulation of dendritic cell differentiation from monocytes was achieved by PAP-GMCSF when used with the other PAP-fused cytokines. The PAP-fused human IL2 significantly increased the proliferation of lymphocytes, as determined by flow cytometry. We also investigated the in vivo therapeutic effects of multiple PAP-fused cytokines in a mouse prostate cancer model bearing prostate-specific antigen (PSA)- and PAP-expressing tumors. The simultaneous intraperitoneal administration of PAP-GMCSF, -IL2, -IL4 and -IL7 significantly prevented tumor induction and inhibited the tumor growth in the PAP-expressing tumors, yet not in the PSA-expressing tumors. The in vivo therapeutic effects with the multiple PAP-fused cytokines were superior to the effects of PAP-GMCSF alone. We thus demonstrated the advantages of the combined use of multiple PAP-fused cytokines including PAP-GMCSF, and propose a promising prostatic antigen-vaccination strategy to enhance the therapeutic effects.

Experimental evaluation of combined immunotherapy for tumors

The minimal vaccination dose of tumor cells was determined on experimental models. The effectiveness of antitumor immunotherapy with activated natural killer cells or dendritic cell vaccine (monotherapy or combined treatment) was evaluated in vivo. The inhibition of tumor growth was more pronounced after combination therapy with activated natural killer cells and dendritic cell-based vaccine. Our results indicate that the effectiveness of antitumor immunotherapy increases in simultaneous modulation of both immune components (innate and adaptive immunity).

Immunotherapy for prostate cancer: lessons from responses to tumor-associated antigens

Prostate cancer (PCa) is the most common cancer in men and the second most common cause of cancer-related death in men. In recent years, novel therapeutic options for PCa have been developed and studied extensively in clinical trials. Sipuleucel-T is the first cell-based immunotherapeutic vaccine for treatment of cancer. This vaccine consists of autologous mononuclear cells stimulated and loaded with an immunostimulatory fusion protein containing the prostate tumor antigen prostate acid posphatase. The choice of antigen might be key for the efficiency of cell-based immunotherapy. Depending on the treatment strategy, target antigens should be immunogenic, abundantly expressed by tumor cells, and preferably functionally important for the tumor to prevent loss of antigen expression. Autoimmune responses have been reported against several antigens expressed in the prostate, indicating that PCa is a suitable target for immunotherapy. In this review, we will discuss PCa antigens that exhibit immunogenic features and/or have been targeted in immunotherapeutic settings with promising results, and we highlight the hurdles and opportunities for cancer immunotherapy.

Specific Dioscorea Phytoextracts Enhance Potency of TCL-Loaded DC-Based Cancer Vaccines

Dioscorea tuber phytoextracts can confer immunomodulatory activities ex vivo and improve regeneration of bone marrow cells in vivo. In present study, we evaluated specific Dioscorea phytoextracts for use ex vivo as a bone-marrow-derived dendritic cell- (DC-) based vaccine adjuvant for cancer immunotherapy. Fractionated Dioscorea extracts (DsII) were assayed for their effect on maturation and functions of DC ex vivo and antimelanoma activity of DC-based vaccine in vivo. The phytoextract from 50–75% ethanol-precipitated fraction of Dioscorea alata var. purpurea Tainung no. 5 tuber, designated as DsII-TN5, showed a strong augmentation of tumor cell lysate- (TCL-) loaded DC-mediated activation of T-cell proliferation. DsII-TN5 stimulated the expression of CD40, CD80, CD86, and IL-1β in TCL-loaded DCs and downregulated the expression of TGF-β1. DC vaccines prepared by a specific schema (TCL (2 h) + LPS (22 h)) showed the strongest antitumor activity. DsII-TN5 as a DC vaccine adjuvant showed strong antimelanoma activity and reduced myeloid-derived suppressor cell (MDSC) population in tested mice. DsII-TN5 can also activate DCs to enhance Th1- and Th17-related cytokine expressions. Biochemical analysis showed that DsII-TN5 consists mainly of polysaccharides containing a high level (53%) of mannose residues. We suggest that DsII-TN5 may have potential for future application as a potent, cost-effective adjuvant for DC-based cancer vaccines.

Generation of potent cytotoxic T lymphocytes against castration-resistant prostate cancer cells by dendritic cells loaded with dying allogeneic prostate cancer cells

To induce a potent cytotoxic T lymphocyte (CTL) response in dendritic cell (DC)-based immunotherapy against prostate cancer, various tumour antigens should be loaded onto DCs. The aim of this study was to establish a method of immunotherapy for castration-resistant prostate cancer (CRPC) using prostate cancer-specific CTLs generated in vitro by DCs. Monocyte-derived DCs from patients with CRPC were induced to mature using a standard cytokine cocktail (in IL-1β, TNF-α, IL-6 and PGE(2) : standard DCs, sDCs) or using an α-type 1-polarized DC (αDC1) cocktail (in IL-1β, TNF-α, IFN-α, IFN-γ and polyinosinic:polycytidylic acid) and loaded with the UVB-irradiated CRPC cell line PC-3. Antigen-loaded DCs were evaluated by morphological and functional assays. The αDC1s significantly increased the expression of several molecules related to DC maturation, regardless of whether the αDC1s were loaded with tumour antigens or not, compared to sDCs. The αDC1s showed a higher production of interleukin-12 both during maturation and after subsequent stimulation with CD40L, which was not significantly affected by loading with tumour antigens, as compared to standard DCs (sDCs). Prostate cancer-specific CTLs against autologous CRPC cells were successfully induced by αDC1s loaded with dying PC-3 cells. Autologous αDC1s loaded with an allogeneic CRPC cell line can generate greater CRPC-specific CTL responses as compared to sDCs and may provide a novel source of DC-based vaccines that can be used for the development of immunotherapy in patients with CRPC.

Immune system targeting by biodegradable nanoparticles for cancer vaccines

The concept of therapeutic cancer vaccines is based on the activation of the immune system against tumor cells after the presentation of tumor antigens. Nanoparticles (NPs) have shown great potential as delivery systems for cancer vaccines as they potentiate the co-delivery of tumor-associated antigens and adjuvants to dendritic cells (DCs), insuring effective activation of the immune system against tumor cells. In this review, the immunological mechanisms behind cancer vaccines, including the role of DCs in the stimulation of T lymphocytes and the use of Toll-like receptor (TLR) ligands as adjuvants will be discussed. An overview of each of the three essential components of a therapeutic cancer vaccine - antigen, adjuvant and delivery system - will be provided with special emphasis on the potential of particulate delivery systems for cancer vaccines, in particular those made of biodegradable aliphatic polyesters, such as poly(lactic-co-glycolic acid) (PLGA) and poly-ε-caprolactone (PCL). Some of the factors that can influence NP uptake by DCs, including size, surface charge, surface functionalization and route of administration, will also be considered.

Maturation of morphology, phenotype and functions of murine bone marrow-derived dendritic cells (DCs) induced by polysaccharide Kureha (PSK)

The aim of this work was to evaluate the influence of protein-bound polysaccharide Kureha(PSK) on murine dendritic cells (DCs). These impacts of PSK on DCs from bone marrow derived DCs(BMDCs) were assessed with inverted phase contrast microscope, conventional scanning electron microscopy (SEM), transmission electron microscopy (TEM) for morphology, fluorescence activated cell sorting (FACS) analysis, cytochemistry assay for key surface molecules, FITC-dextran for phagocytosis, bio-assay and enzyme linked immunosorbent assay (ELISA) for cytokine production. We found that under the influence of PSK, immature DCs changed into mature DCs with decrease of antigens up-taking, simultaneously high expression of key surface molecules of the MHC classII,CD40, CD80, CD86 and CD83 as well as more production of IL-12p70 and tumor necrosis factor α (TNF-α). These data indicate that PSK could markedly promote maturation of DCs and this adjuvant-like activity may have potential therapeutic value in vaccine preparation.

A molecular imaging primer: modalities, imaging agents, and applications

Molecular imaging is revolutionizing the way we study the inner workings of the human body, diagnose diseases, approach drug design, and assess therapies. The field as a whole is making possible the visualization of complex biochemical processes involved in normal physiology and disease states, in real time, in living cells, tissues, and intact subjects. In this review, we focus specifically on molecular imaging of intact living subjects. We provide a basic primer for those who are new to molecular imaging, and a resource for those involved in the field. We begin by describing classical molecular imaging techniques together with their key strengths and limitations, after which we introduce some of the latest emerging imaging modalities. We provide an overview of the main classes of molecular imaging agents (i.e., small molecules, peptides, aptamers, engineered proteins, and nanoparticles) and cite examples of how molecular imaging is being applied in oncology, neuroscience, cardiology, gene therapy, cell tracking, and theranostics (therapy combined with diagnostics). A step-by-step guide to answering biological and/or clinical questions using the tools of molecular imaging is also provided. We conclude by discussing the grand challenges of the field, its future directions, and enormous potential for further impacting how we approach research and medicine.

Engineered T cells for pancreatic cancer treatment

OBJECTIVE

Conventional chemotherapy and radiotherapy produce marginal survival benefits in pancreatic cancer, underscoring the need for novel therapies. The aim of this study is to develop an adoptive T cell transfer approach to target tumours expressing prostate stem cell antigen (PSCA), a tumour-associated antigen that is frequently expressed by pancreatic cancer cells.

METHODS

Expression of PSCA on cell lines and primary tumour samples was confirmed by immunohistochemistry. Healthy donor- and patient-derived T cells were isolated, activated in vitro using CD3/CD28, and transduced with a retroviral vector encoding a chimeric antigen receptor (CAR) targeting PSCA. The ability of these cells to kill tumour cells was analysed by chromium-51 (Cr(51)) release.

RESULTS

Prostate stem cell antigen was expressed on >70% of the primary tumour samples screened. Activated, CAR-modified T cells could be readily generated in clinically relevant numbers and were specifically able to kill PSCA-expressing pancreatic cancer cell lines with no non-specific killing of PSCA-negative target cells, thus indicating the potential efficacy and safety of this approach.

CONCLUSIONS

Prostate stem cell antigen is frequently expressed on pancreatic cancer cells and can be targeted for immune-mediated destruction using CAR-modified, adoptively transferred T cells. The safety and efficacy of this approach indicate that it deserves further study and may represent a promising novel treatment for patients with pancreatic cancer.

Prostatectomy restores the maturation competence of blood dendritic cell precursors and reverses the abnormal expansion of regulatory T lymphocytes

OBJECTIVE

To verify the presence of deviated dendritic cell (DC) precursors and of suppressor lymphocytes (Treg) in tumor bearing prostate cancer (PCa) patients and to monitor the corrective effect of tumor ablation.

METHODS

Monocytes isolated from the blood of patients before and 1 month after prostatectomy were allowed to reach complete maturation (mDC) ex vivo in a clinical grade two-step process. T-regulatory cells were identified in the lymphocyte cell fraction by the CD4(+)CD25(high)FoxP3(+)/CD4(+)CD25(high)CD127(low/-) phenotype.

RESULTS

Despite loss of the monocytes marker CD14, cytokine-matured DCs of tumor bearing patients expressed lower levels of the costimulatory molecule CD80 and of the maturation markers CD83 and CCR7 compared to mDC of normal subjects (NS, P = 0.001, 0.001, and 0.008, respectively). Prostatectomy restored CD80, CD83, and CCR7 expression to values not different from those of NS (P = 0.15, 0.60, and 0.71) and significantly higher than those of the pre-surgery state (CD83, P = 0.0003 and CCR7, P = 0.002). The frequency of Tregs, identified as either CD4 + CD25(high)FoxP3(+) or CD4(+)CD25(high)CD127(low/-), was significantly higher in pre-surgery patients than in NS (P = 0.0001 and 0.0003) and significant recovery of the CD4(+)CD25(high)CD127(low/-) (P = 0.0005) was observed after surgery.

CONCLUSIONS

The presence of defective DC precursors and suppressor lymphocytes in the tumor-bearing, but not tumor-free stage, positions the latter as the ideal setting for clinical success of PCa vaccine therapy.

Prostate stem cell antigen: a Jekyll and Hyde molecule?

Prostate stem cell antigen (PSCA) is a glycosylphosphatidylinositol (GPI)-anchored cell surface protein. Although PSCA is thought to be involved in intracellular signaling, much remains unknown about its physiological function and regulatory mechanism in normal and cancer cells. It is up-regulated in several major cancers including prostate, bladder, and pancreatic cancers. The expression of PSCA is positively correlated with advanced clinical stage and metastasis in prostate cancers and is also associated with malignant progression of premalignant prostate lesions. Therefore, PSCA has been proposed as a biomarker of diagnosis and prognosis, as well as a target of therapy for these cancers. In addition, PSCA has also shown clinical potential in immunotherapy as a prostate-specific antigen, which, when presented by dendritic cells, may elicit strong tumor-specific immunity. In contrast, PSCA is down-regulated in esophageal and gastric cancer and may have a tumor-suppressing function in the gastric epithelium. Recent exciting findings that genetic variations of PSCA conferred increased risks of gastric cancer and bladder cancer have opened up a new avenue of research about the pathological function of PSCA. PSCA seems to be a Jekyll and Hyde molecule that plays differential roles, tumor promoting or suppressing, depending on the cellular context.