Development of dendritic-cell based prostate cancer vaccine

EGFR and CXCR1 expression in thyroid carcinoma in Qassim Region-Saudi Arabia: Correlation with clinicopathological parameters

AIMS

Recent evidence indicates an increased incidence of thyroid carcinoma, especially papillary thyroid carcinoma (PTC), in Saudi Arabia. EGFR and CXCR1 were reported to have increased expression in several human neoplasms. The goals of the present research was to investigate EGFR and CXCR1 expression in thyroid carcinoma and correlate the results to the established prognostic factors.

METHODS

Immunohistochemical study for both EGFR and CXCR1 was performed on formalin-fixed paraffin-embedded thyroid carcinomas tissues sections applying Labeled Streptavidin-biotin method (LSAB).

RESULTS

Remarkable high expression of EGFR and CXCR1 were observed in PTC cases (56% and 63% respectively). There was association between EGFR expression in PTC and each of histologic subtype, lymph node metastasis (LNM), distant metastasis (DM), TNM staging and tumor relapse. There was statistical significant correlation between CXCR1 expression in PTC and each of histologic subtype, LNM, and tumor relapse. A significant correlation was detected between concomitant EGFR and CXCR expression and LNM, DM, increasing stage and tumor relapse.

CONCLUSIONS

The results of the present study demonstrated, a statistically positive correlation of EGFR and CXCR1 expression in PTC compared to normal thyroid tissues and nodular hyperplasia in Qassim Region- Saudi Arabia. Concomitant high expression of both receptors were strongly correlated with LNM, DM, TNM stage and tumor relapse than did each alone. These findings suggest that EGFR and CXCR1 play crucial roles in PTC and serve as predictors of poor prognosis, biomarkers of tumor diagnosis, and potential targets of cancer therapeutics.

Application of neoantigens in malignant tumor treatment and prognosis evaluation

In the last decade, there have been an endless number of cancer therapy strategies, and the study of tumor neoantigens provides a new direction for cancer immune therapy. With the development of deep sequencing, especially whole-exome sequencing, great opportunities have been provided to precise immune therapy of malignant tumors. This article systematically summarizes the research on tumor neoantigens in the past ten years and the challenges most likely to be encountered, describes the role of neoantigens in the treatment of malignant tumors, and discusses their possible clinical applications.

Small molecule antagonists for CXCR2 and CXCR1 inhibit human colon cancer liver metastases

CXCR1 and CXCR2 are G-protein coupled receptors, that have been shown to play important role in tumor growth and metastasis, and are prime targets for the development of novel therapeutics. Here, we report that targeting CXCR2 and CXCR1 activity using orally active small molecule antagonist (SCH-527123, SCH-479833) inhibits human colon cancer liver metastasis mediated by decreased neovascularization and enhanced malignant cell apoptosis. There were no differences in primary tumor growth. These studies demonstrate the important role of CXCR2/1 in colon cancer metastasis and that inhibition of CXCR2 and CXCR1, small molecule antagonists provides a novel therapeutic strategy.

Metastatic bone disease: a 36-year single centre trend-analysis of patients admitted to a tertiary orthopaedic surgical department

BACKGROUND AND OBJECTIVES

The treatment and outcome of primary malignant bone tumours has changed with the advances in diagnostic and treatment modalities. A trend-analysis on a large cohort of patients with metastatic bone disease was performed.

METHODS

A retrospective chart review of all cases with metastatic bone disease admitted to a single tertiary orthopaedic referral centre, registered with the Vienna Bone and Soft Tissue Tumour Registry between 1968 and 2003 was conducted. For trend-analysis of frequency, survival, primary site, treatment methods, and others, the 36-year study duration was divided into four periods.

RESULTS

The study identified 601 females and 580 males (mean: 60 years) with metastatic bone disease. The most common metastases were secondary to breast cancer (n = 275; 23%) and renal cell carcinoma (n = 242; 21%) and the majority were located in the femur (n = 332; 28%) and spine (n = 348; 29%). Overall, the proportion of patients who underwent surgery decreased. At follow-up, 887 (75%) patients were verified to have died of their disease.

CONCLUSIONS

Over the 36-year period, the frequency of bone metastases has increased at our centre. Although survival increased over time, the difference was not significant; this was most likely attributable to the seriousness of cases referred to our tertiary care centre.

Prevention of human PC-346C prostate cancer growth in mice by a xenogeneic tissue vaccine

Vaccination, as an approach to prostate cancer, has largely focused on immunotherapy utilizing specific molecules or allogeneic cells. Such methods are limited by the focused antigenic menu presented to the immune system and by immunotolerance to antigens recognized as "self". To examine if a xenogeneic tissue vaccine could stimulate protective immunity in a human prostate cancer cell line, a vaccine was produced by glutaraldehyde fixation of harvested PAIII prostate cancer cells tumors (GFT cell vaccine) from Lobund-Wistar rats. Immunocompetent Ncr-Foxn1 mice were vaccinated with the GFT cell vaccine four times, 7 days apart. The control animals were either not vaccinated or vaccinated with media or glutaraldehyde-fixed PC346C human prostate cancer cells and adjuvant. About 8 days after the final boost, serum and spleens were harvested. The splenocytes were co-incubated with PC346C cells and then transplanted orthotopically into sygneneic immunodeficient nude mice. About 10 weeks later, the prostates were weighed and sampled for histolologic examination. The spleens were harvested from additional mice, and the splenocytes were cultured, either with or without pulsing by GFT cells, and the supernatants harvested 72 h later for cytokine analysis. Results showed that vaccination with GFT cells resulted in increased serum antibody to a PAIII cell lysate; reduced weight of the prostate/seminal vesicle complex and reduced incidence of prostate cancer in nude mice; increased splenocyte supernatant levels of TNF-alpha, IL-2, IFN-gamma and IL-12, cytokines associated with Th1 immunity; and increased splenocyte supernatant levels of IL-4 and IL-10, cytokines associated with Th2 immunity. In summary, the results suggest that use of a xenogeneic tissue vaccine can stimulate protective immunity against human prostate cancer cells.

Immunology and immunotherapy approaches for prostate cancer

Several mechanisms that impair the immune response to promote tumour progression are reported. These mechanisms aim to reduce the ability of antigen-presenting cells to present antigen and activate naïve T cells to support an active immune response or to create a suppressive environment that induce non-functional tumour-associated antigen-specific T cells. Prostate cancer (PC) alone accounts for 33% of incident cancer cases and about 9% of all cancer-related deaths among men in the USA during 2006. Whereas androgen deprivation has remained the first line of therapy for advanced PC, other therapies are still required due to progression to an androgen-resistant state and eventually loss of control in patients receiving hormonal therapy. Immunotherapy seems to be a promising approach to enhance tumour-specific T-cell responses in different cancers including prostate. More importantly, clinical trials in advanced PC patients have shown that immunotherapy may generate significant clinical responses. Immunology and immunotherapy aspects of PC with focus on prostate-specific antigen will be presented.

Antitumor response against myeloma cells by immunization with mouse syngenic dendritoma

In order to generate an immune response against myeloma cells in an homogenous murine model, a stable hybrid cell line (DCSp) was established through the syngenic fusion between mouse dendritic cells (DC) and mouse Sp2/0 myeloma cells. DCSp cells behaved as potent T cell stimulators and were able to induce Sp2/0 specific cytotoxicity. When mice were immunized with irradiated hybrids before SP2/0 injection, they exhibited a significantly higher rate of survival as compared with controls. When tumors were detected, their emergence was not delayed, and time elapsed between tumor clinical perception and death remained unchanged. A humoral immune response was also always associated. We assume that this stable dendritoma cell line can be considered a valuable tool for myeloma studies in an homogenous mouse model. The efficiency of dendritoma as a weapon against tumor cells and the benefit of syngeny in experimental models are discussed.

Prevention of de novo prostate cancer by immunization with tumor-derived vaccines

Since advanced prostate cancer is difficult to treat, we have chosen a very different approach: the development of vaccines to prevent initial de novo tumor formation. To test the hypothesis that prostate cancer can be prevented by vaccination, Lobund-Wistar (LW) rats were vaccinated subcutaneously with complete Freund's adjuvant (CFA) plus glutaraldehyde-fixed (GFT) whole cell or potassium thiocyanate extract (PTE) preparations derived from in vivo tumors, or with media and CFA (media-vaccinated). Rats were vaccinated each month substituting incomplete Freund's adjuvant for CFA, from age 3 to 12 months, and methylnitrosourea (30 mg/kg) was administered intravenously at 4 months of age. Groups of 30 GFT cell-vaccinated rats showed a 90% reduction, and PTE-vaccinated rats, a 50% reduction in the occurrence of de novo prostate tumors compared with media-vaccinated controls. When splenocytes from vaccinated rats were incubated with tumor cells prior to subcutaneous implantation, PTE-vaccinated rats showed a 80% reduction, and GFT cell-vaccinated rats showed a 40% reduction in the occurrence of tumors, demonstrating a role for the spleen in the protective response. The inflammatory responses in tumors from GFT cell-vaccinated rats and PTE-vaccinated rats were distinguished by an influx of eosinophils compared with the responses in tumors from media-vaccinated rats. These results demonstrate the possibility that prostate cancer can be prevented by immunization with vaccines based on whole tumor-derived vaccines.

Simultaneous expression of T-cell activating antigens in renal cell carcinoma: implications for specific immunotherapy

PURPOSE

The activation of antigen specific T cells by tumor associated antigens (TAA) might be a promising treatment strategy for patients with renal cell carcinoma (RCC). We analyzed TAA expression in patients with RCC as well as the prevalence of fitting HLA phenotypes and calculated the percent of patients eligible for peptide vaccination trials.

MATERIALS AND METHODS

A total of 41 RCC samples from primary tumors were analyzed for TAA expression by reverse transcriptase-polymerase chain reaction. Genes of interest were MAGE-1, MAGE-3, G250 and PRAME since peptides derived from these genes have been shown to activate antigen specific cytotoxic T lymphocytes. Results were combined with data on the HLA gene and haplotype frequencies in the German population as an example of a white population.

RESULTS

Tumor specific expression of at least 1 T-cell activating antigen was observed in all patients. Of the patients 80% expressed 2 or more TAAs simultaneously. HLA molecules suitable for presentation of the respective antigens were calculated to be expressed in 51% to 85% of white German patients. These results mirror with only minor variations most of the white populations in Europe and North America.

CONCLUSIONS

We noted that T-cell activating tumor associated antigens are frequently expressed in patients with RCC. Based on HLA expression analysis in a white population at least 30% of patients with RCC are eligible for monovalent specific immunotherapy and 41% are eligible for polyvalent specific immunotherapy. These data are a rational basis for future prospective vaccination trials in patients with RCC.

Successful identification of novel agents to control infectious diseases from screening mixture-based peptide combinatorial libraries in complex cell-based bioassays

Mixture-based peptide synthetic combinatorial libraries (SCLs) represent a valuable source for the development of novel agents to control infectious diseases. Indeed, a number of studies have now proven the ability of identifying active peptides from libraries composed of thousands to millions of peptides in cell-based biosystems of varying complexity. Furthermore, progressing knowledge on the importance of endogenous peptides in various immune responses lead to a regain in importance for peptides as potential therapeutic agents. This article is aimed at providing recent studies in our laboratory for the development of antimicrobial or antiviral peptides derived from mixture-based SCLs using cell-based assays, as well as a short review of the importance of such peptides in the control of infectious diseases. Furthermore, the use of positional scanning (PS) SCL-based biometrical analyses for the identification of native optimal epitopes specific to HIV-1 proteins is also presented.

Dendritic cells loaded with killed breast cancer cells induce differentiation of tumor-specific cytotoxic T lymphocytes

Background

Early clinical trials, mostly in the setting of melanoma, have shown that dendritic cells (DCs) expressing tumor antigens induce some immune responses and some clinical responses. A major difficulty is the extension to other tumors, such as breast carcinoma, for which few defined tumor-associated antigens are available. We have demonstrated, using both prostate carcinoma and melanoma as model systems, that DCs loaded with killed allogeneic tumor cell lines can induce CD8⁺ T cells to differentiate into cytotoxic T lymphocytes (CTLs) specific for shared tumor antigens.

Methods

The present study was designed to determine whether DCs would capture killed breast cancer cells and present their antigens to autologous CD4⁺ and CD8⁺ T cells.

Results

We show that killed breast cancer cells are captured by immature DCs that, after induced maturation, can efficiently present MHC class I and class II peptides to CD8⁺ and CD4⁺ T lymphocytes. The elicited CTLs are able to kill the target cells without a need for pretreatment with interferon gamma. CTLs can be obtained by culturing the DCs loaded with killed breast cancer cells with unseparated peripheral blood lymphocytes, indicating that the DCs can overcome any potential inhibitory effects of breast cancer cells.

Conclusion

Loading DCs with killed breast cancer cells may be considered a novel approach to breast cancer immunotherapy and to identification of shared breast cancer antigens.

Single injection of CD34+ progenitor-derived dendritic cell vaccine can lead to induction of T-cell immunity in patients with stage IV melanoma

There is evidence that dendritic cell (DC) vaccines induce tumor-specific immune responses that correlate with clinical responses. Little is known, however, about the kinetics of T-cell responses to antigens presented on DC vaccines. The authors vaccinated 18 HLA A*0201+ patients with stage IV melanoma with CD34 HPC-derived DCs pulsed with six antigens: influenza matrix peptide (Flu-MP), KLH, and peptides derived from the four melanoma antigens: MART-1/Melan A, gp100, tyrosinase, and MAGE-3. A single DC vaccination was sufficient for induction of KLH-specific CD4 T-cell responses in five patients and Flu-MP-specific CD8 T-cell responses in eight patients. A single DC vaccine was sufficient for induction of tumor-specific effectors to at least one melanoma antigen in five patients. Thus, a single injection of CD34 HPC-derived DCs can lead to rapid immune response to CD4 epitopes or to melanoma antigens.

T cell targeted immune enhancement yields effective T cell adjuvants

Given the critical role of cell-mediated immunity (CMI) in defense against attack from pathogens that establish chronic infections, it has become abundantly clear that current vaccine methodology will not be sufficient to develop the appropriate immune response for protection and/or clearance of infection. By extension, this logic also applies to cancer vaccines where T cell immune-mediated destruction is a critical mechanism for control of the disease. This review describes our current thoughts on the events associated with immune activation and evaluates the various approaches to achieve successful immune activation with defined or targeted antigens as opposed to using inactivated or attenuated organisms. The advantages and disadvantages of the current adjuvants for antigens that focus on mimicking the infection events via the innate immune system or antigen uptake are described in the context of generation of T cell specific responses. A central theme of the discussions is the importance of cytokines in modulating the immune response towards T cell immunity, either by adjuvant modulation or use of natural cytokine mixtures targeted towards the site of immune activation. Also discussed is the possibility that thymomimetic agents such as thymosin alpha1, levamisole and methyl inosine monophosphate (MIMP) may be useful in enhancing the T cell mediated arm of the immune response.

Tumor-specific CD8+ T lymphocytes derived from the peripheral blood of prostate cancer patients by in vitro stimulation with autologous tumor cell lines

To identify tumor-associated antigens as putative targets for developing immunotherapies against prostate cancer, we investigated the ability of T cells derived from the peripheral blood lymphocytes of prostate cancer patients to recognize autologous tumor cells. The technical challenge of growing in vitro carcinoma cell lines from small prostate cancer samples was previously addressed by immortalization of early epithelial cell cultures with the HPV16 transforming proteins E6 and E7 and by genetic characterization of the carcinoma and normal prostate cell lines. In our study, peripheral blood lymphocytes were stimulated in vitro using autologous IFNgamma-treated prostate carcinoma cells transduced with the B7.1 molecule as a source of T-cell costimulation. Tumor-specific CD8+ T lymphocytes were obtained from 3 of 6 prostate cancer patients tested and included T cells restricted by classical and nonclassical HLA molecules. In 1 case, we demonstrated that the prostate cancer-reactive T cells were TCRalpha/beta+ and recognized autologous tumor cells but not autologous normal cells in the context of HLA-B or -C molecules. These results validate the approach of in vitro stimulation of peripheral blood lymphocytes from prostate cancer patients with autologous tumor cell lines to isolate prostate cancer-specific T cells and demonstrate the existence of a functionally diverse immune response against prostate cancer.

Dendritic cells: immune regulators in health and disease

Dendritic cells (DCs) are bone marrow-derived cells of both lymphoid and myeloid stem cell origin that populate all lymphoid organs including the thymus, spleen, and lymph nodes, as well as nearly all nonlymphoid tissues and organs. Although DCs are a moderately diverse set of cells, they all have potent antigen-presenting capacity for stimulating naive, memory, and effector T cells. DCs are members of the innate immune system in that they can respond to dangers in the host environment by immediately generating protective cytokines. Most important, immature DCs respond to danger signals in the microenvironment by maturing, i.e., differentiating, and acquiring the capacity to direct the development of primary immune responses appropriate to the type of danger perceived. The powerful adjuvant activity that DCs possess in stimulating specific CD4 and CD8 T cell responses has made them targets in vaccine development strategies for the prevention and treatment of infections, allograft reactions, allergic and autoimmune diseases, and cancer. This review addresses the origins and migration of DCs to their sites of activity, their basic biology as antigen-presenting cells, their roles in important human diseases and, finally, selected strategies being pursued to harness their potent antigen-stimulating activity.

Dendritic cells and their emerging clinical applications

Dendritic cells (DC) are now recognised as a unique leukocyte type, consisting of two or more subsets. The origins and functional inter-relationships of these cells are the subject of intense basic scientific investigation. They play important roles in initiating and directing immune responses, defending the host from pathogens and maintaining self tolerance. Fundamental studies are defining new molecules and mechanisms associated with DC function. The first methods for counting these rare blood cell populations are already providing interesting new clinical data. Indeed, abnormal DC function may contribute to deficiencies in the immune response against malignancies. Phase I trial data suggests that DC-based cancer vaccination protocols may contribute an important new biological approach to cancer therapy. Manipulation of DC to facilitate allogeneic transplantation and even to manage autoimmune disease are likely developments.

Dendritic cells: their significance in health and disease

Dendritic cells (DCs) represent a heterogeneous population of professional antigen-presenting cells. Precursor cells move via the blood to peripheral tissues. These immature DCs can take up invading pathogens and then rapidly migrate to the draining secondary lymphoid organs. Converted into antigen-presenting mature DCs, these cells are able to prime naive T cells and to initiate an adoptive immune response. The extraordinary functional profile suggests that, under certain preconditions, DCs may represent an ideal vector in the immunotherapy of cancer and infectious diseases

Transcript profiling of human dendritic cells maturation-induced under defined culture conditions: comparison of the effects of tumour necrosis factor alpha, soluble CD40 ligand trimer and interferon gamma

Using cDNA arrays, we characterized patterns of gene expression in populations of human dendritic cells (DCs) produced for clinical use. Culture and maturation induction of myeloid adherent cells under serum-free conditions yielded DCs with phenotypes similar to those described in serum-based systems. Analysis of gene expression in DCs treated with tumour necrosis factor alpha, soluble CD40L trimer or interferon gamma, however, showed specific patterns for each factor examined. Our studies document the expression of several transcripts that have not hitherto been described in DCs and/or differentially regulated according to the differentiation state of the DCs, and suggest important functional differences among the DC populations examined. In addition, DC maturation directs changes in the levels of mRNA specific for transcriptional regulators that effect the production of cytokines (e.g. BCL-6, c-rel). Other changes observed, including alteration in the gene expression profile of adhesion molecules and chemokine receptors such as CD44H, CD 49B, Rantes R, CXCR5 and CD37, suggest differences in trafficking potential between the populations studied. This broad-based description of DC populations, produced under serum-free conditions, has enabled us to better define intermediate stages of DC maturation as well as the differentiation-inducing effects of cytokines on these cells.