Dendritic cells transduced with a PSMA-encoding adenovirus and cocultured with autologous cytokine-induced lymphocytes induce a specific and strong immune response against prostate cancer cells

Adoptive Cell Transfer: Is it a Promising Immunotherapy for Colorectal Cancer?

The last decade has witnessed significant advances in the adoptive cell transfer (ACT) technique, which has been appreciated as one of the most promising treatments for patients with cancer. Utilization of ACT can enhance the function of the immune system or improve the specificity and persistence of transferred cells. Various immune cells including T lymphocytes, natural killer cells, dendritic cells, and even stem cells can be used in the ACT despite their different functional mechanisms. Colorectal cancer (CRC) is among the most common malignancies and causes millions of deaths worldwide every year. In this review, we discuss the status and perspective of the ACT in the treatment of CRC.

Dual Functional Capability of Dendritic Cells - Cytokine-Induced Killer Cells in Improving Side Effects of Colorectal Cancer Therapy

The aim of cancer therapy is to eradicate cancer without affecting healthy tissues. Current options available for treating colorectal cancer (CRC), including surgery, chemotherapy or radiotherapy, usually elicit multiple adverse effects and frequently fail to completely remove the tumor cells. Thus, there is a constant need for seeking cancer cell-specific therapeutics to improve the course of cancer therapy and reduce the risk of relapse. In this review we elaborate on the mechanisms underlying the immunotherapy with dendritic cells (DCs) and cytokine-induced killer (CIK) cells, and summarize their effectiveness and tolerability available clinical studies. Finally, we discuss the up-to-date combinatorial adoptive anti-cancer immunotherapy with CIK cells co-cultured with DCs that recently showed encouraging efficacy and usefulness in treating malignant disease, including CRC.

Prostate-specific membrane antigen can promote in vivo osseous metastasis of prostate cancer cells in mice

Reports remain insufficient on whether and how prostate-specific membrane antigen (PSMA) can influence in vivo osseous metastasis of prostate cancer (PCa). In the present study, the authors induced stable expression of PSMA in mouse PCa cell line RM-1. In vivo osseous metastasis was induced in 37 6-week-old female C57BL/6 mice weighing 22.45 ± 0.456 g. RM-1 cells were actively injected into the femoral bone cavity, leading to bilateral dissymmetry of bone density in the femoral bone. Tumor cells were also detected in bone tissue by pathological examination. The impact on bone density was demonstrated by the significant difference between animals injected with RM-PSMA cells (0.0738 ± 0.0185 g/cm²) and animals injected with RM-empty plasmid cells (0.0895 ± 0.0241 g/cm²). The lytic bone lesion of the RM-PSMA group (68.4%) was higher than that of the control group (27.8%). Immunohistochemistry showed that the expression of both vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) was distinctly higher in the RM-PSMA group than in the control group, while ELISA and Western blot assay indicated that VEGF and MMP-9 were higher in the RM-PSMA group compared to the control group (in vitro). Thus, the present study proposed and then confirmed for the first time that PSMA can promote in vivo osseous metastasis of PCa by increasing sclerotic destruction of PCa cells. Further analyses also suggested that PSMA functions positively on the invasive ability of RM-1 by increasing the expression of MMP-9 and VEGF by osseous metastases in vivo.

Natural killer T cells subsets in cancer, functional defects in prostate cancer and implications for immunotherapy

Natural killer T cells are T lymphocytes with unique activation and effector properties. The majority of NKT cells, termed type-I or iNKT cells, recognize lipid antigens presented on MHC-like CD1d molecules. Type-I NKT cells have the capacity to rapidly secrete various cytokines upon activation, thereby regulate immune responses exerts dominant anti-tumor and anti-microbial effector functions. Specific activation of type-I NKT cells in mouse models boosts immunity and prevents metastasis, which has led to a number of phase I-II clinical trials. Since the discovery of NKT cells other subsets with different specificities and effector functions have been described. This article briefly reviews the physiological functions of NKT cell subsets, their implications in cancer and the attempts that have been made to employ NKT cells for immune therapy of cancer.

A changing world for DCvax: a PSMA loaded autologous dendritic cell vaccine for prostate cancer

BACKGROUND

Northwest Therapeutics' DCvax-prostate consists of autologous dendritic cells (DCs) loaded with prostate-specific membrane antigen (PSMA) peptides, administered intravenously. Phase I-II testing, a decade ago, showed clinical benefit and immunological response in some patients. More recently DCvax brain, a product using a similar DC platform showed encouraging Phase I-II results and sipleucel-T, a prostatic acid phosphatase (PAP)-directed DC immunotherapy had positive Phase III results.

OBJECTIVE

Features of the clinical setting into which a new immunotherapy could be introduced are discussed, to refine a perspective on DCvax-prostate in the context of evolving prostate cancer therapeutics. PSMA-directed therapeutics and immune anticancer technologies are reviewed, and the clinical and immunological correlative testing of DCvax-prostate is discussed.

METHODS

Clinical and preclinical data from peer-reviewed literature, meetings proceedings and manufacturer-provided information are considered.

CONCLUSION

DCvax-prostate had encouraging early-phase trial results, but development and testing had stalled. As a more detailed understanding of patient-selection for capacity for anticancer immune response, the quantitation of immunological correlates, and the changing marketplace develop, it is appealing to consider a well tolerated, PSMA-directed autologous dendritic cell therapeutic product. Further clinical trial development of DCvax-prostate is warranted, and required if it is to find a relevant clinical application.

Binding of prostate-specific membrane antigen to dendritic cells: a critical step in vaccine preparation

BACKGROUND AIMS

Dendritic cell (DC)-based vaccines hold promise as a safe therapy for prostate cancer (PCa), and prostate-specific membrane antigen (PSMA) fulfils the requirements for a tumor-associated antigen (TAA) to be clinically effective. We evaluated the actual binding of selected HLA-A2-restricted PSMA peptides to HLA class I molecules on ex vivo-generated mature (m) DC.

METHODS

mDC were generated from peripheral monocytes of HLA-A2 normal donors. The PSMA peptides PSMA(711) (ALFDIESKV), PSMA(27) (VLAGGFFLL) and PSMA(663) (MMNDQLMFL) were selected based on computer-assisted prediction programs, documented CTL epitope activity or previous use in clinical trials. The model cell line T2 and the clinical grade (CD83+ CCR7+) mDC were pulsed with fluorescein (FL)-conjugated peptides and an anti-HLA-A2 monoclonal antibody (MAb) and analyzed.

RESULTS

Flow cytometry analysis showed best binding efficiency to be by PSMA(27.) Confocal microscopy confirmed coincident fluorescence emission of HLA-A2 MAb and FL-PSMA(27). Virtual co-localization of PSMA(27) and HLA class I molecules was supported further by fluorescence resonance energy transfer (FRET) analysis. The clinical relevance of our findings has to be validated in vivo.

CONCLUSIONS

The present report is the first to score selected PSMA peptides based on their detectable binding to mDC. It identifies PSMA(27) as the choice candidate among other PSMA peptides and it should be included in developing DC vaccine protocols for HLA-A2 PCa patients.

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

Tumor antigens (TA) are promising candidates for targeted treatment of prostate cancer (PCa). Critical issues in the preparation of dendritic cell (DC)-based TA vaccines are the DC maturation state and the appropriateness of the TA. Prostate-specific antigen (PSA) and prostate acide pshosphatase (PAP) presented by DC have produced encouraging results and PAP-loaded DCs are at late-stage development for PCa patients. TAs indispensable for tumor survival and propagation are now emerging as first choice TAs for future vaccines. The increased expression and enzymatic activity of prostate specific membrane antigen (PSMA) and prostate stem cell antigen (PSCA) by aggressive prostate tumors is indicative of a unique, selective advantage on the part of cells expressing them. Human telomerase reverse transcriptase (hTERT) and survivin are both involved in tumor cell survival and considered universal TAs. The T cell epitope potential of peptides derived from these TAs has been defined by computer-assisted prediction programs and has been tested in vitro and in vivo in terms of their ability to recruit cytotoxic T lymphocytes (CTL) and to be recognised as CTL targets. Results, reviewed here, show that anti-tumor immunity can be induced in vivo by DC loaded with both whole TAs and TA peptides. The promising, but still limited clinical success suggests further exploration of this immune therapy in the more appropriate setting of minimal disease. In advanced stages, vaccine can still be effective when combined with systemic or local cytoreductive therapies, which may overcome antigen specific tolerance and subvert the tumor immunosuppressive environment.