T-cell receptor gene therapy targeting melanoma-associated antigen-A4 inhibits human tumor growth in non-obese diabetic/SCID/γcnull mice

Exploring the role and mechanisms of MAGEA4 in tumorigenesis, regulation, and immunotherapy

MAGEA4 is a member of the Melanoma-Associated Antigen (MAGE) family, characterized by high expression in various tumor tissues but low expression in normal tissues, with the exception of testis and placenta. Its expression is associated with poor prognosis in cancer. This review summarizes the mechanisms of action, regulatory functions, and immunotherapeutic applications of MAGEA4 in cancer.MAGEA4 promotes tumor initiation and progression through multiple pathways, including ubiquitination and degradation of the tumor suppressor P53, regulation of cell cycle and apoptosis, modulation of DNA damage repair, and enhancement of cancer cell survival. By forming a complex with TRIM28, MAGEA4 accelerates tumor development via P53 degradation. Factors such as TWIST1 and BORIS can upregulate MAGEA4 expression. MAGEA4 interacts with proteins including Miz-1, p53, and RAD18, participating in gene transcription regulation and DNA damage repair. By stabilizing RAD18, MAGEA4 facilitates the recruitment of Y-family DNA polymerases, enabling cells to continue replication under DNA damage conditions and thus supporting cancer cell survival. MAGEA4-based TCR-T cell therapy and cancer vaccines show clinical potential. This article comprehensively reviews the structure and function of MAGEA4, as well as recent research progress in solid tumors, providing a theoretical foundation for the clinical translation of MAGEA4 and its application in immunotherapy.

The Melanoma-Associated Antigen Family A (MAGE-A): A Promising Target for Cancer Immunotherapy?

Early efforts to identify tumor-associated antigens over the last decade have provided unique cancer epitopes for targeted cancer therapy. MAGE-A proteins are a subclass of cancer/testis (CT) antigens that are presented on the cell surface by MHC class I molecules as an immune-privileged site. This is due to their restricted expression to germline cells and a wide range of cancers, where they are associated with resistance to chemotherapy, metastasis, and cancer cells with an increasing potential for survival. This makes them an appealing candidate target for designing an effective and specific immunotherapy, thereby suggesting that targeting oncogenic MAGE-As with cancer vaccination, adoptive T-cell transfer, or a combination of therapies would be promising. In this review, we summarize and discuss previous and ongoing (pre-)clinical studies that target these antigens, while bearing in mind the benefits and drawbacks of various therapeutic strategies, in order to speculate on future directions for MAGE-A-specific immunotherapies.

Genetically Modified T Cells for Esophageal Cancer Therapy: A Promising Clinical Application

Esophageal cancer is an exceedingly aggressive and malignant cancer that imposes a substantial burden on patients and their families. It is usually treated with surgery, chemotherapy, radiotherapy, and molecular-targeted therapy. Immunotherapy is a novel treatment modality for esophageal cancer wherein genetically engineered adoptive cell therapy is utilized, which modifies immune cells to attack cancer cells. Using chimeric antigen receptor (CAR) or T cell receptor (TCR) modified T cells yielded demonstrably encouraging efficacy in patients. CAR-T cell therapy has shown robust clinical results for malignant hematological diseases, particularly in B cell-derived malignancies. Natural killer (NK) cells could serve as another reliable and safe CAR engineering platform, and CAR-NK cell therapy could be a more generalized approach for cancer immunotherapy because NK cells are histocompatibility-independent. TCR-T cells can detect a broad range of targeted antigens within subcellular compartments and hold great potential for use in cancer therapy. Numerous studies have been conducted to evaluate the efficacy and feasibility of CAR and TCR based adoptive cell therapies (ACT). A comprehensive understanding of genetically-modified T cell technologies can facilitate the clinical translation of these adoptive cell-based immunotherapies. Here, we systematically review the state-of-the-art knowledge on genetically-modified T-cell therapy and provide a summary of preclinical and clinical trials of CAR and TCR-transgenic ACT.

Adoptive T-cell immunotherapy in digestive tract malignancies: Current challenges and future perspectives

Multiple systemic treatments are currently available for advanced cancers of the digestive tract, but none of them is curative. Adoptive T-cell immunotherapy refers to the extraction, modification and re-infusion of autologous or allogenic T lymphocytes for therapeutic purposes. A number of clinical trials have investigated either non-engineered T cells (i.e., lymphokine-activated killer cells, cytokine induced killer cells, or tumor-infiltrating lymphocytes) or engineered T cells (T cell receptor-redirected T cells or chimeric antigen receptor T cells) in patients with digestive tract malignancies over the past two decades, with variable degrees of success. While the majority of completed trials have been primarily aimed at assessing the safety of T-cell transfer strategies, a new generation of studies is being designed to formally evaluate the antitumor potential of adoptive T-cell immunotherapy in both the metastatic and adjuvant settings. In this review, we provide an overview of completed and ongoing clinical trials of passive T-cell immunotherapy in patients with cancers of the digestive tract, focusing on present obstacles and future strategies for achieving potential success.

Resveratrol acts via melanoma-associated antigen A12 (MAGEA12)/protein kinase B (Akt) signaling to inhibit the proliferation of oral squamous cell carcinoma cells

The present study examined how resveratrol affects cell growth and MAGEA12/Akt signaling pathway in OSCC cells. Cal-27 cells were transiently transfected with a plasmid encoding MAGEA12, and the effects of overexpression were assessed in terms of cell viability, colony formation and the epithelial–mesenchymal transition. Cal-27 cells and MAGEA12-overexpressing cells were treated with resveratrol, then the cell viability and colony formation were also assessed by CCK8 assay and microscope, respectively. Levels of MAGEA12, p-Akt, Akt, Cyclin D1, and CDK14 genes and these proteins were analyzed using quantitative reverse-transcription polymerase-chain reaction and western blot. In the present research, we first generated and transiently transfected MAGEA12 plasmid into Cal-27 cells. Our results suggested that overexpressing MAGEA12 led to an increase in levels of phospho-Akt, which was associated with increased cell viability, colony formation. Moreover, overexpressing MAGEA12 also resulted in the up-regulation of Cyclin D1 and CDK14, indicating MAGEA12 induces the cell proliferation of Cal-27 cells. In addition, these effects were partially reversed by inhibiting Akt. Furthermore, resveratrol could inhibit the proliferation and colony in Cal-27 cells and decrease the expressions of MAGEA12 and p-Akt depending on the time and concentration. These effects were also partially reversed by MAGEA12 overexpression and Akt activation. In summary, resveratrol may suppress the growth of OSCC cells by inactivating MAGEA12/Akt signaling. These findings suggest that resveratrol may be a therapeutic drug for OSCC in clinical.

Oncogenic cancer/testis antigens are a hallmarker of cancer and a sensible target for cancer immunotherapy

Increasing evidence shows that numerous cancer-testis antigens (CTAs) are uniquely overexpressed in various types of cancer and most CTAs are oncogenic. Overexpression of oncogenic CTAs promotes carcinogenesis, cancer metastasis, and drug resistance. Oncogenic CTAs are generally associated with poor prognosis in cancer patients and are an important hallmark of cancer, making them a crucial target for cancer immunotherapy. CTAs-targeted antibodies, vaccines, and chimeric antigen receptor-modified T cells (CAR-T) have recently been used in cancer treatment and achieved promising outcomes in the preclinical and early clinical trials. However, the efficacy of current CTA-targeted therapeutics is either moderate or low in cancer therapy. CTA-targeted cancer immunotherapy is facing enormous challenges. Several critical scientific problems need to be resolved: (1) the antigen presentation function of MHC-I protein is usually deficient in cancer patients, so that very low amounts of intracellular CTA epitopes are presented to tumor cell membrane surface, leading to weak immune response and subsequent immunity to CTAs; (2) various immunosuppressive cells are rich in tumor tissues leading to diminished tumor immunity; (3) the tumor tissue microenvironment markedly reduces the efficacy of cancer immunotherapy. In the current review paper, the authors propose new strategies and approaches to overcome the barriers of CTAs-targeted immunotherapy and to develop novel potent immune therapeutics against cancer. Finally, we highlight that the oncogenic CTAs have high tumor specificity and immunogenicity, and are sensible targets for cancer immunotherapy. We predict that CTAs-targeted immunotherapy will bring about breakthroughs in cancer therapy in the near future.

Expression of cancer-testis antigens in esophageal cancer and their progress in immunotherapy

PURPOSE

Esophageal cancer is a common disease in China with low survival rate due to no obvious early symptoms and lack of effective screening strategies. Traditional treatments usually do not produce desirable results in patients with advanced esophageal cancer, so immunotherapy which relies on tumor-related antigens is needed to combat low survival rates effectively. Cancer-testis antigens (CTA), a large family of tumor-related antigens, have a strong in vivo immunogenicity and tumor-restricted expressing patterns in normal adult tissues. These two characteristics are ideal features of anticancer immunotherapy targets and, therefore, promoted the development of some studies of CTA-based therapy. To provide ideas for the role of the cancer-testis antigens MAGE-A, NY-ESO-1, LAGE-1, and TTK in esophageal cancer, we summarized their expression, prognostic value, and development in immunotherapy.

METHODS

The relevant literature from PubMed is reviewed in this study.

RESULTS

In esophageal cancer, although the relationship between expression of MAGE-A, NY-ESO-1, LAGE-1, and TTK and prognosis value is still in a controversial situation, MAGE-A, NY-ESO-1, LAGE-1, and TTK are highly expressed and can induce specific CTL cells to produce particular killing effect on tumor cells, and some clinical trials have demonstrated that immunotherapy for esophageal cancer patients is effective and safe, which provides a new therapeutic strategy for the treatment of esophageal cancer in the future.

CONCLUSION

In this review, we summarize expression and prognostic value of MAGE-A, NY-ESO-1, LAGE-1, and TTK in esophageal cancer and point out recent advances in immunotherapy about them.

Humanized Mouse Models for the Preclinical Assessment of Cancer Immunotherapy

Immunotherapy is one of the most exciting recent breakthroughs in the field of cancer treatment. Many different approaches are being developed and a number have already gained regulatory approval or are under investigation in clinical trials. However, learning from the past, preclinical animal models often insufficiently reflect the physiological situation in humans, which subsequently causes treatment failures in clinical trials. Due to species-specific differences in most parts of the immune system, the transfer of knowledge from preclinical studies to clinical trials is eminently challenging. Human tumor cell line-based or patient-derived xenografts in immunocompromised mice have been successfully applied in the preclinical testing of cytotoxic or molecularly targeted agents, but naturally these systems lack the human immune system counterpart. The co-transplantation of human peripheral blood mononuclear cells or hematopoietic stem cells is employed to overcome this limitation. This review summarizes some important aspects of the different available tumor xenograft mouse models, their history, and their implementation in drug development and personalized therapy. Moreover, recent progress, opportunities and limitations of different humanized mouse models will be discussed.

Human PBMC-transferred murine MHC class I/II-deficient NOG mice enable long-term evaluation of human immune responses

Immunodeficient mice engrafted with human peripheral blood cells are promising tools for in vivo analysis of human patient individual immune responses. However, when human peripheral blood mononuclear cells (PBMCs) are transferred into NOG (NOD/Shi-scid, IL-2rg^null) mice, severe graft versus host disease (GVHD) hinders long term detailed analysis. Administration of human PBMCs into newly developed murine MHC class I- and class II-deficient NOG (NOG-dKO; NOG- Iab, B2m-double-knockout) mice showed sufficient engraftment of human immune cells with little sign of GVHD. Immunization with influenza vaccine resulted in an increase in influenza-specific human IgG Ab, indicating induction of antigen-specific B cells in the NOG-dKO mice. Immunization with human dendritic cells pulsed with HLA-A2 restricted cytomegalovirus peptide induced specific cytotoxic T cells, indicating the induction of antigen-specific T cells in the NOG-dKO mice. Adoptive cell therapies (ACTs) using melanoma antigen recognized by T cells (MART-1)-specific TCR-transduced activated T cells showed strong tumor growth inhibition in NOG-dKO mice without any sign of GVHD accompanied by preferential expansion of the transferred MART-1-specific T cells. ACTs using cultured human melanoma infiltrating T cells also showed anti-tumor effects against autologous melanoma cells in NOG-dKO mice, in which changes in human cancer phenotypes by immune intervention, such as increased CD271 expression, could be evaluated. Therefore, NOG-dKO mice are useful tools for more detailed analysis of both the induction and effector phases of T-cell and B-cell responses for a longer period than regular NOG mice.

Adoptive immunotherapy of cancer utilizing genetically engineered lymphocytes

It is becoming increasingly clear that adoptive immunotherapy with genetically engineered T cells has the potential to control and even cure cancer in some patients. On the other hand, severe adverse events associated with efficacy have frequently been reported in clinical trials. Current and near-future challenges for the development of adoptive immunotherapy of cancer using genetically engineered T cells include minimization and prediction of adverse events; identification of new and effective targets, including patient-specific mutations; improvement in T cell functionality, persistence, and memory formation capacity; and utilization of allogeneic or cell line-based T cells.

Adoptive Transfer of MAGE-A4 T-cell Receptor Gene-Transduced Lymphocytes in Patients with Recurrent Esophageal Cancer

PURPOSE

Preparative lymphodepletion, the temporal ablation of the immune system, has been reported to promote persistence of transferred cells along with increased rates of tumor regression in patients treated with adoptive T-cell therapy. However, it remains unclear whether lymphodepletion is indispensable for immunotherapy with T-cell receptor (TCR) gene-engineered T cells.

EXPERIMENTAL DESIGN

We conducted a first-in-man clinical trial of TCR gene-transduced T-cell transfer in patients with recurrent MAGE-A4-expressing esophageal cancer. The patients were given sequential MAGE-A4 peptide vaccinations. The regimen included neither lymphocyte-depleting conditioning nor administration of IL2. Ten patients, divided into 3 dose cohorts, received T-cell transfer.

RESULTS

TCR-transduced cells were detected in the peripheral blood for 1 month at levels proportional to the dose administered, and in 5 patients they persisted for more than 5 months. The persisting cells maintained ex vivo antigen-specific tumor reactivity. Despite the long persistence of the transferred T cells, 7 patients exhibited tumor progression within 2 months after the treatment. Three patients who had minimal tumor lesions at baseline survived for more than 27 months.

CONCLUSIONS

These results suggest that TCR-engineered T cells created by relatively short-duration in vitro culture of polyclonal lymphocytes in peripheral blood retained the capacity to survive in a host. The discordance between T-cell survival and tumor regression suggests that multiple mechanisms underlie the benefits of preparative lymphodepletion in adoptive T-cell therapy.

The immune system and head and neck squamous cell carcinoma: from carcinogenesis to new therapeutic opportunities

Head and neck squamous cell carcinomas (HNSCCs) exhibit complex interactions with the host immune system that may simultaneously explain resistance to various therapeutic modalities and that may also provide opportunities for therapeutic intervention. Discoveries in immunologic research over the last decade have led to an increased understanding of these interactions as well as the development of a multitude of investigational immunotherapies. Here, we describe the interaction between HNSCC and the immune system, including a discussion of immune cells involved with tumor carcinogenesis and the role of immune-modulating factors derived from tumors. We also describe the current immunotherapeutic approaches being investigated for HNSCC, including a discussion of the successes and limitations. With this review, we hope to present HNSCC as a model to guide future research in cancer immunology.

Stimulation through very late antigen-4 and -5 improves the multifunctionality and memory formation of CD8⁺ T cells

T cells express multiple integrin molecules. The significance of signaling through these molecules on acquisition of T-cell effector functions and memory formation capacity remains largely unknown. Moreover, the impact of stimulation through these signals on the generation of T cells for adoptive immunotherapy has not been elucidated. In this study, using a recombinant fragment of fibronectin, CH-296, we demonstrated that stimulation via very late Ag (VLA)-4 and VLA-5 in human and BALB/c mouse CD8(+) T cells, in combination with TCR stimulation, enhances effector multifunctionality and in vivo memory formation. Using TCR-transgenic mouse-derived CD8(+) T cells expressing TCR specific for the syngeneic CMS5 fibrosarcoma-derived tumor Ag, we showed that stimulation by CH-296 improved the ability of tumor-specific CD8(+) T cells to inhibit CMS5 tumor growth when adoptively transferred into hosts with progressing tumors. Improved antitumor effects were associated with decreased infiltration of Foxp3(+) CD4(+) Treg cells in tumors. These results suggest that stimulation via VLA-4 and VLA-5 modulates the qualities of effector T cells and could potentially increase the efficacy of adoptive therapy against cancer.

Gene-engineered T cells for cancer therapy

T cells have the capacity to eradicate diseased cells, but tumours present considerable challenges that render T cells ineffectual. Cancer cells often make themselves almost 'invisible' to the immune system, and they sculpt a microenvironment that suppresses T cell activity, survival and migration. Genetic engineering of T cells can be used therapeutically to overcome these challenges. T cells can be taken from the blood of cancer patients and then modified with genes encoding receptors that recognize cancer-specific antigens. Additional genes can be used to enable resistance to immunosuppression, to extend survival and to facilitate the penetration of engineered T cells into tumours. Using genetic modification, highly active, self-propagating 'slayers' of cancer cells can be generated.

Harnessing autophagy for cell fate control gene therapy

We hypothesized that rapamycin, through induction of autophagy and promotion of an antiapoptotic phenotype, would permit lentiviral (LV)-based transgene delivery to human T-Rapa cells, which are being tested in phase II clinical trials in the setting of allogeneic hematopoietic cell transplantation. Manufactured T-Rapa cells were exposed to supernatant enriched for a LV vector encoding a fusion protein consisting of truncated CD19 (for cell surface marking) and DTYMK/TMPKΔ, which provides "cell-fate control" due to its ability to phosphorylate (activate) AZT prodrug. LV-transduction in rapamycin-treated T-Rapa cells: (1) resulted in mitochondrial autophagy and a resultant antiapoptotic phenotype, which was reversed by the autophagy inhibitor 3-MA; (2) yielded changes in MAP1LC3B and SQSTM1 expression, which were reversed by 3-MA; and (3) increased T-Rapa cell expression of the CD19-DTYMKΔ fusion protein, despite their reduced proliferative status. Importantly, although the transgene-expressing T-Rapa cells expressed an antiapoptotic phenotype, they were highly susceptible to cell death via AZT exposure both in vitro and in vivo (in a human-into-mouse xenogeneic transplantation model). Therefore, rapamycin induction of T cell autophagy can be used for gene therapy applications, including the CD19-DTYMKΔ cell-fate control axis to improve the safety of T cell immuno-gene therapy.

Manipulation of human early T lymphopoiesis by coculture on human bone marrow stromal cells: potential utility for adoptive immunotherapy

T cell precursors are an attractive target for adoptive immunotherapy. We examined the regulation of human early T lymphopoiesis by human bone marrow stromal cells to explore in vitro manipulation of human T cell precursors in a human-only coculture system. The generation of CD7(+)CD56(-)cyCD3(-) proT cells from human hematopoietic progenitors on telomerized human bone marrow stromal cells was enhanced by stem cell factor, flt3 ligand, and thrombopoietin, but these stimulatory effects were suppressed by interleukin 3. Expression of Notch ligands Delta-1 and -4 on stromal cells additively promoted T cell differentiation into the CD7(+)cyCD3(+) pre-T cell stage, while cell growth was strongly inhibited. By combining these coculture systems, we found that initial coculture with telomerized stromal cells in the presence of stem cell factor, flt3 ligand, and thrombopoietin, followed by coculture on Delta-1- and -4-coexpressing stromal cells led to a higher percentage and number of pre-T cells. Adoptive immunotherapy using peripheral blood T cells transduced with a tumor antigen-specific T cell receptor (TCR) is a promising strategy but has several limitations, such as the risk of forming a chimeric TCR with the endogenous TCR. We demonstrated that incubation of TCR-transduced hematopoietic progenitors with the combination of coculture systems gave rise to CD7(+)TCR(+)CD3(+)CD1a(-) T cell precursors that rapidly proliferated and differentiated under the culture condition to induce mature T cell differentiation. These data show the regulatory mechanism of early T lymphopoiesis on human stromal cells and the potential utility of engineered human stromal cells to manipulate early T cell development for clinical application.

A Promising Vector for TCR Gene Therapy: Differential Effect of siRNA, 2A Peptide, and Disulfide Bond on the Introduced TCR Expression

Adoptive immunotherapy using TCR gene-modified T-lymphocytes is an attractive strategy for targeting malignancies. However, TCR mispairings between endogenous and introduced TCR chains are a major concern, as they may induce mixed TCRs with unknown specificities and may reduce the expression of therapeutic TCRs. To overcome these problems, we have recently established a novel retroviral siTCR vector encoding small-interfering RNAs (siRNAs) to knockdown endogenous TCR genes for the efficient expression of therapeutic TCRs. In this study, to improve the efficacy of siTCR vectors, we developed 2A peptide-based siTCR vectors that could increase the expression levels of transduced TCRs compared with internal promoter-based siTCR vectors. We also evaluated the efficacy of an siTCR strategy and the addition of a new interchain disulfide bond created by cysteine modification. We found that the effect of the cysteine modification depended on TCR variations, while the siTCR strategy improved the expression of all TCRs tested. Furthermore, the combined effect of the siTCR and cysteine modification strategies was highly significant for certain TCRs. Therefore, our novel siTCR technology, in isolation or in combination with another strategy, may open the door to effective immunotherapy for cancer patients.Molecular Therapy - Nucleic Acids (2012) 1, e63. doi:10.1038/mtna.2012.52; published online 18 December 2012.

Proteomic profiling of triple-negative breast carcinomas in combination with a three-tier orthogonal technology approach identifies Mage-A4 as potential therapeutic target in estrogen receptor negative breast cancer

Breast cancer is a very heterogeneous disease, encompassing several intrinsic subtypes with various morphological and molecular features, natural history and response to therapy. Currently, molecular targeted therapies are available for estrogen receptor (ER)(-) and human epidermal growth factor receptor 2 (Her2)-positive breast tumors. However, a significant proportion of primary breast cancers are negative for ER, progesterone receptor (PgR), and Her2, comprising the triple negative breast cancer (TNBC) group. Women with TNBC have a poor prognosis because of the aggressive nature of these tumors and current lack of suitable targeted therapies. As a consequence, the identification of novel relevant protein targets for this group of patients is of great importance. Using a systematic two dimensional (2D) gel-based proteomic profiling strategy, applied to the analysis of fresh TNBC tissue biopsies, in combination with a three-tier orthogonal technology (two dimensional PAGE/silver staining coupled with MS, two dimensional Western blotting, and immunohistochemistry) approach, we aimed to identify targetable protein markers that were present in a significant fraction of samples and that could define therapy-amenable sub-groups of TNBCs. We present here our results, including a large cumulative database of proteins based on the analysis of 78 TNBCs, and the identification and validation of one specific protein, Mage-A4, which was expressed in a significant fraction of TNBC and Her2-positive/ER negative lesions. The high level expression of Mage-A4 in the tumors studied allowed the detection of the protein in the tumor interstitial fluids as well as in sera. The existence of immunotherapeutics approaches specifically targeting this protein, or Mage-A protein family members, and the fact that we were able to detect its presence in serum suggest novel management options for TNBC and human epidermal growth factor receptor 2 positive/estrogen receptor negative patients bearing Mage-A4 positive tumors.

Limited expression of cancer-testis antigens in renal cell carcinoma patients

The aim of this study was to evaluate the frequency of expression of the cancer-testis antigens (CTAs) NY-ESO-1, MAGE-A4 and SAGE, in renal cell carcinoma (RCC) patients compared to that in head and neck cancer (HNC) patients, which represent a positive control with a high incidence of CTA expression, to identify novel target antigens for immunotherapy. We prospectively examined frozen tissue samples collected from surgery or biopsy from 35 RCC and 40 HNC patients. Total RNA was extracted, and real-time reverse transcription-polymerase chain reaction (RT)-PCR was performed to determine the expression of MAGE-A4, NY-ESO-1 and SAGE. MAGE-A4 was not detected in any of the RCC samples, although a low incidence of NY-ESO-1 (5.7%; 2/35) and SAGE (2.9%; 1/35) expression was observed. No samples demonstrated co-expression of the three CTAs. By contrast, a comparatively high incidence of CTA expression was detected in squamous cell carcinoma (SCC) specimens of HNC patients. The actual incidence was 42.5% (17/40) for MAGE-A4, 20% (8/40) for NY-ESO-1 and 15% (6/40) for SAGE. The incidence of co-expression was 7.5% (3/40) for MAGE-A4 and NY-ESO-1, 7.5% (3/40) for MAGE-A4 and SAGE, 7.5% (3/40) for NY-ESO-1 and SAGE, and 2.5% (1/40) for the CTAs. The number of HNC samples positive for MAGE-A4 was significantly higher compared to that of RCC samples. The remaining two antigens, NY-ESO-1 and SAGE, were expressed at high levels in HNC compared to RCC samples. Limited frequency of CTA (NY-ESO-1, MAGE-A4 and SAGE) expression was demonstrated in RCC compared to HNC samples.

Molecular mimics of the tumour antigen MUC1

A key requirement for the development of cancer immunotherapy is the identification of tumour-associated antigens that are differentially or exclusively expressed on the tumour and recognized by the host immune system. However, immune responses to such antigens are often muted or lacking due to the antigens being recognized as "self", and further complicated by the tumour environment and regulation of immune cells within. In an effort to circumvent the lack of immune responses to tumour antigens, we have devised a strategy to develop potential synthetic immunogens. The strategy, termed mirror image phage display, is based on the concept of molecular mimicry as demonstrated by the idiotype/anti-idiotype paradigm in the immune system. Here as 'proof of principle' we have selected molecular mimics of the well-characterised tumour associated antigen, the human mucin1 protein (MUC1) from two different peptide phage display libraries. The putative mimics were compared in structure and function to that of the native antigen. Our results demonstrate that several of the mimic peptides display T-cell stimulation activity in vitro when presented by matured dendritic cells. The mimic peptides and the native MUC1 antigenic epitopes can cross-stimulate T-cells. The data also indicate that sequence homology and/or chemical properties to the original epitope are not the sole determining factors for the observed immunostimulatory activity of the mimic peptides.

Clinical significance of human leukocyte antigen loss and melanoma-associated antigen 4 expression in smokers of non-small cell lung cancer patients

BACKGROUND

Melanoma-associated antigen-A4 (MAGE-A4) is one of the candidates for a target of immunotherapy and is expressed in non-small cell lung cancer (NSCLC). However, tumors sometimes lose human leukocyte antigen (HLA) class I expression, and tumor-specific T cells cannot eliminate the tumor with loss of HLA. However, the relationship between MAGE-A4 expression and HLA loss has remained unclear.

METHODS

Among 363 NSCLC patients who consecutively underwent curative surgery, 187 cases whose material could be analyzed were reviewed. The expression of HLA class I molecules was assessed by immunohistochemical staining. The expression of MAGE-A4 was analyzed by RT-PCR.

RESULTS

Seventy-seven tumors expressed HLA normally; however, 110 tumors lost HLA. The proportion of patients with a smoking habit and expressing the MAGE-A4 gene in patients with HLA loss was higher than those with HLA expression (p = 0.04 and 0.028, respectively). Five-year overall survival (OS) rate in the patients expressing MAGE-A4 but with loss of HLA was 52.4 %, and OS was significantly poorer than their counterparts (74.0 %, p = 0.036). Multivariate analysis indicated that advanced stage or history of smoking and HLA loss was an independently poor prognostic predictor of OS in NSCLC (p < 0.01 and p = 0.04, respectively).

CONCLUSION

HLA class I loss in NSCLC was related to smoking history and MAGE-A4 expression of tumors. HLA class I loss in smokers or patients with the MAGE-A4 gene was a prognostic factors in NSCLC.

Humanized mice for immune system investigation: progress, promise and challenges

Significant advances in our understanding of the in vivo functions of human cells and tissues and the human immune system have resulted from the development of 'humanized' mouse strains that are based on severely immunodeficient mice with mutations in the interleukin-2 receptor common γ-chain locus. These mouse strains support the engraftment of a functional human immune system and permit detailed analyses of human immune biology, development and functions. In this Review, we discuss recent advances in the development and utilization of humanized mice, the lessons learnt, the remaining challenges and the promise of using humanized mice for the in vivo study of human immunology.