Identification of a gene encoding a melanoma tumor antigen recognized by HLA-A31-restricted tumor-infiltrating lymphocytes

Gut Microbiota-Based Immunotherapy: Engineered Escherichia coli Nissle 1917 for Oral Delivery of Glypican-1 in Pancreatic Cancer

Background and Objectives: The administration of oral vaccines offers a potential strategy for cancer immunotherapy; yet, the development of effective platforms continues to pose a difficulty. This study examines Escherichia coli Nissle 1917 (EcN) as a microbial vector for the precise delivery of Glypican-1 (GPC1), a tumor-associated antigen significantly overexpressed in pancreatic ductal adenocarcinoma (PDAC).To evaluate the effectiveness of EcN as a vector for the delivery of GPC1 and assess its potential as an oral vaccination platform for cancer immunotherapy. Materials and Methods: EcN was genetically modified to produce a GPC1-flagellin fusion protein (GPC1-FL) to augment antigen immunogenicity. The expression and stability of GPC1 were confirmed in modified PANC02 cells using Western blot and flow cytometry, indicating that GPC1 expression did not influence tumor cell growth. A mouse model was employed to test immunogenicity post-oral delivery, measuring systemic IgG, IL-10, IL-2, and IFN-γ levels to indicate immune activation. Results: Oral immunization with EcN GPC1-FL elicited a robust systemic immune response, demonstrated by markedly increased levels of IgG and IL-10. IL-2 and IFN-γ concentrations were elevated in vaccinated mice relative to controls; however, the differences lacked statistical significance. Western blot examination of fecal samples verified consistent antigen expression in the gastrointestinal tract, indicating effective bacterial colonization and antigen retention. No detrimental impacts were noted, hence substantiating the safety of this methodology. Conclusions: These findings confirm EcN as a feasible and patient-friendly oral vaccination platform for cancer immunotherapy. The effective production of GPC1 in tumor cells, along with continuous antigen delivery and immune activation, underscores the promise of this approach for PDAC and other cancers. This study promotes microbial-based antigen delivery as a scalable, non-invasive substitute for traditional vaccine platforms.

Firefly luciferase-based chronological measurement of effector CD8+ T-cell activity using a multi-chamber luminometer

Background: Although cell-mediated cytotoxicity has been evaluated with various protocols, methods for monitoring cytotoxicity in a time series have not been established. This work describes a method for evaluating cytotoxicity using a multi-chamber real-time luminometer. Materials & methods: The efficiency of effector CD8⁺ T-cell expansion from melanoma-bearing splenocytes was analyzed. The effect of CD8⁺ T cells on the viability of luciferase-expressing target cells was measured by bioluminescence. Results: Melanoma-specific effector CD8⁺ T cells were differentiated by in vitro coculture. The melanoma cell growth was significantly inhibited in the presence of in vitro-expanded T cells in the bioluminescence-based time-lapse analysis. Conclusion: The bioluminescence-based assay is a useful method for monitoring the time course of cell viability of target tumor cells.

Development of Cancer Immunotherapies

Cancer immunotherapy, or the utilization of components of the immune system to target and eliminate cancer, has become a highly active area of research in the past several decades and a common treatment strategy for several cancer types. The concept of harnessing the immune system for this purpose originated over 100 years ago when a physician by the name of William Coley successfully treated several of his cancer patients with a combination of live and attenuated bacteria, later known as "Coley's Toxins", after observing a subset of prior patients enter remission following their diagnosis with the common bacterial infection, erysipelas. However, it was not until late in the twentieth century that cancer immunotherapies were developed for widespread use, thereby transforming the treatment landscape of numerous cancer types. Pivotal studies elucidating molecular and cellular functions of immune cells, such as the discovery of IL-2 and production of monoclonal antibodies, fostered the development of novel techniques for studying the immune system and ultimately the development and approval of several cancer immunotherapies by the United States Food and Drug Association in the 1980s and 1990s, including the tuberculosis vaccine-Bacillus Calmette-Guérin, IL-2, and the CD20-targeting monoclonal antibody. Approval of the first therapeutic cancer vaccine, Sipuleucel-T, for the treatment of metastatic castration-resistant prostate cancer and the groundbreaking success and approval of immune checkpoint inhibitors and chimeric antigen receptor T cell therapy in the last decade, have driven an explosion of interest in and pursuit of novel cancer immunotherapy strategies. A broad range of modalities ranging from antibodies to adoptive T cell therapies is under investigation for the generalized treatment of a broad spectrum of cancers as well as personalized medicine. This chapter will focus on the recent advances, current strategies, and future outlook of immunotherapy development for the treatment of cancer.

A decade of checkpoint blockade immunotherapy in melanoma: understanding the molecular basis for immune sensitivity and resistance

Ten years since the immune checkpoint inhibitor ipilimumab was approved for advanced melanoma, it is time to reflect on the lessons learned regarding modulation of the immune system to treat cancer and on novel approaches to further extend the efficacy of current and emerging immunotherapies. Here, we review the studies that led to our current understanding of the melanoma immune microenvironment in humans and the mechanistic work supporting these observations. We discuss how this information is guiding more precise analyses of the mechanisms of action of immune checkpoint blockade and novel immunotherapeutic approaches. Lastly, we review emerging evidence supporting the negative impact of melanoma metabolic adaptation on anti-tumor immunity and discuss how to counteract such mechanisms for more successful use of immunotherapy.

Keratinocyte differentiation antigen-specific T cells in immune checkpoint inhibitor-treated NSCLC patients are associated with improved survival

Immune checkpoint inhibitors (ICIs) have improved the survival of patients with non-small cell lung cancer (NSCLC) by reinvigorating tumor-specific T cell responses. However, the specificity of such T cells and the human leukocyte antigen (HLA)-associated epitopes recognized, remain elusive. In this study, we identified NSCLC T cell epitopes of recently described NSCLC-associated antigens, termed keratinocyte differentiation antigens. Epitopes of these antigens were presented by HLA-A 03:01 and HLA-C 04:01 and were associated with responses to ICI therapy. Patients with CD8⁺ T cell responses to these epitopes had improved overall and progression-free survival. T cells specific for such epitopes could eliminate HLA class I-matched NSCLC cells ex vivo and were enriched in patient lung tumors. The identification of novel lung cancer HLA-associated epitopes that correlate with improved ICI-dependent treatment outcomes suggests that keratinocyte-specific proteins are important tumor-associated antigens in NSCLC. These findings improve our understanding of the mechanisms of ICI therapy and may help support the development of vaccination strategies to improve ICI-based treatment of these tumors.

Quantitative Detection of Disseminated Melanoma Cells by Trp-1 Transcript Analysis Reveals Stochastic Distribution of Pulmonary Metastases

A better understanding of the process of melanoma metastasis is required to underpin the development of novel therapies that will improve patient outcomes. The use of appropriate animal models is indispensable for investigating the mechanisms of melanoma metastasis. However, reliable and practicable quantification of metastases in experimental mice remains a challenge, particularly if the metastatic burden is low. Here, we describe a qRT-PCR-based protocol that employs the melanocytic marker Trp-1 for the sensitive quantification of melanoma metastases in the murine lung. Using this protocol, we were able to detect the presence of as few as 100 disseminated melanoma cells in lung tissue. This allowed us to quantify metastatic burden in a spontaneous syngeneic B16-F10 metastasis model, even in the absence of visible metastases, as well as in the autochthonous Tg(Grm1)/Cyld^−/− melanoma model. Importantly, we also observed an uneven distribution of disseminated melanoma cells amongst the five lobes of the murine lung, which varied considerably from animal to animal. Together, our findings demonstrate that the qRT-PCR-based detection of Trp-1 allows the quantification of low pulmonary metastatic burden in both transplantable and autochthonous murine melanoma models, and show that the analysis of lung metastasis in such models needs to take into account the stochastic distribution of metastatic lesions amongst the lung lobes.

Adoptive transfer of TILs plus anti-PD1 therapy: An alternative combination therapy for treating metastatic osteosarcoma

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Anti-PD1 therapy for metastatic osteosarcoma patients is limited and the identification of new strategies for these patients is urgently needed.

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TILs plus anti-PD1 therapy significantly increases ORR, mPFS and mOS of patients.

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More infusion of TIL numbers and CD8⁺TIL percentage and less infusion of CD8⁺PD1⁺ TIL percentage and CD4⁺FoxP3⁺ TIL percentage may be potential prognostic factors which can predict clinical response to combined TILs and anti-PD1 therapy.

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PD1^hi in fresh TILs is another good prognostic factor that predict PFS and OS.

Aim

We sought to investigate the efficacy of adoptive transfer of TILs plus anti-PD1 therapy in metastatic osteosarcoma patients.

Materials and methods

A total of 30 patients received anti-PD1 therapy (Group 1) while 30 patients were subjected to TILs plus anti-PD1 therapy (Group 2). Progression-free survival time (PFS) and overall survival time (OS) were analyzed using Kaplan-Meier analysis. Potential prognostic factors were analyzed using univariate and multivariate analyses.

Results

The ORR in Group 2 is 33.3%, which is significantly higher than Group1 (6.67%). In addition, we found significantly prolonged mPFS (5.4 months) and mOS (15.2 months) in Group 2 compared to those in Group 1, which recorded mPFS and mOS of 3.8 and 6.6 months, respectively. Univariate and multivariate analyses indicate that patients with more infusions of TIL numbers and CD8⁺TILs or less infusions of CD8⁺ PD1⁺TILs and CD4⁺FoxP3⁺ TILs show increased PFS and OS. Moreover, PD1^hi is another good prognostic factor that predict PFS and OS.

Conclusion

Overall, these findings indicated that TILs plus anti-PD1 therapy has significant clinical outcomes in metastatic osteosarcoma patients. However, further studies are essential to validate and characterize the therapeutic activity of TILs plus anti-PD1.

Uncovering the Tumor Antigen Landscape: What to Know about the Discovery Process

According to the latest available data, cancer is the second leading cause of death, highlighting the need for novel cancer therapeutic approaches. In this context, immunotherapy is emerging as a reliable first-line treatment for many cancers, particularly metastatic melanoma. Indeed, cancer immunotherapy has attracted great interest following the recent clinical approval of antibodies targeting immune checkpoint molecules, such as PD-1, PD-L1, and CTLA-4, that release the brakes of the immune system, thus reviving a field otherwise poorly explored. Cancer immunotherapy mainly relies on the generation and stimulation of cytotoxic CD8 T lymphocytes (CTLs) within the tumor microenvironment (TME), priming T cells and establishing efficient and durable anti-tumor immunity. Therefore, there is a clear need to define and identify immunogenic T cell epitopes to use in therapeutic cancer vaccines. Naturally presented antigens in the human leucocyte antigen-1 (HLA-I) complex on the tumor surface are the main protagonists in evocating a specific anti-tumor CD8+ T cell response. However, the methodologies for their identification have been a major bottleneck for their reliable characterization. Consequently, the field of antigen discovery has yet to improve. The current review is intended to define what are today known as tumor antigens, with a main focus on CTL antigenic peptides. We also review the techniques developed and employed to date for antigen discovery, exploring both the direct elution of HLA-I peptides and the in silico prediction of epitopes. Finally, the last part of the review analyses the future challenges and direction of the antigen discovery field.

Opportunities and Challenges for Antibodies against Intracellular Antigens

Therapeutic antibodies are one most significant advances in immunotherapy, the development of antibodies against disease-associated MHC-peptide complexes led to the introduction of TCR-like antibodies. TCR-like antibodies combine the recognition of intracellular proteins with the therapeutic potency and versatility of monoclonal antibodies (mAb), offering an unparalleled opportunity to expand the repertoire of therapeutic antibodies available to treat diseases like cancer. This review details the current state of TCR-like antibodies and describes their production, mechanisms as well as their applications. In addition, it presents an insight on the challenges that they must overcome in order to become commercially and clinically validated.

Cancer immunotherapy with lymphocytes genetically engineered with T cell receptors for solid cancers

Adoptive transfer of T cells genetically engineered with chimeric antigen receptors (CAR-T cells) have proven to be highly effective for treating CD19⁺ B cell-derived hematologic malignancies. However, due to the lack of ideal tumor surface antigens, CAR-T cell therapy has limited success in treating solid tumors. T cells genetically engineered with T cell receptors (TCR-T cells) recognize intracellular and cell-surface antigens in the context of major histocompatibility complex (MHC) presentation and thus have the potential to access much more target antigens than CAR-T cells, providing great promise in treating solid tumors. There is an increasing interest in the application of TCR-T cell therapy for solid tumors, and fifty-six clinical trials are undergoing worldwide to confirm its validity. In this review, we summarize the recent progress in clinical studies of TCR-T cell therapy, describe strategies in the preparation and characterization of TCR-T cells, focusing on antigen selection, TCR isolation and methods to further enhance the potency of adoptively transferred cells.

A Dual-Bioresponsive Drug-Delivery Depot for Combination of Epigenetic Modulation and Immune Checkpoint Blockade

Patients with advanced melanoma that is of low tumor-associated antigen (TAA) expression often respond poorly to PD-1/PD-L1 blockade therapy. Epigenetic modulators, such as hypomethylation agents (HMAs), can enhance the antitumor immune response by inducing TAA expression. Here, a dual bioresponsive gel depot that can respond to the acidic pH and reactive oxygen species (ROS) within the tumor microenvironment (TME) for codelivery of anti-PD1 antibody (aPD1) and Zebularine (Zeb), an HMA, is engineered. aPD1 is first loaded into pH-sensitive calcium carbonate nanoparticles (CaCO₃ NPs), which are then encapsulated in the ROS-responsive hydrogel together with Zeb (Zeb-aPD1-NPs-Gel). It is demonstrated that this combination therapy increases the immunogenicity of cancer cells, and also plays roles in reversing immunosuppressive TME, which contributes to inhibiting the tumor growth and prolonging the survival time of B16F10-melanoma-bearing mice.

Impact of Human Leukocyte Antigen Loci and Haplotypes on Intestinal Acute Graft-versus-host Disease after Human Leukocyte Antigen-matched Sibling Peripheral Blood Stem Cell Transplantation

Background:

Acute graft-versus-host disease (aGVHD) is a common and severe complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Some studies have found that the presence of certain specific human leukocyte antigen (HLA) loci could affect the occurrence of aGVHD. Meanwhile, the impact of HLA haplotypes on aGVHD has been rarely studied. This study aimed to investigate the effects of HLA loci and haplotypes on intestinal aGVHD.

Methods:

Totally, 345 consecutive patients undergoing first HLA-matched sibling peripheral blood stem cell transplantation (PBSCT) from February 2004 to June 2013 at Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, were enrolled in this study. HLA loci and haplotypes of recipients with frequency over 5% were searched and their effects on intestinal aGVHD were investigated. Other important factors including donor age, recipient age, donor-recipient sex combinations, and conditioning regimens were also evaluated using logistic regression. Pure upper gastrointestinal tract aGVHD without diarrhea was excluded because the histological proof was unavailable. The follow-up end-point was 6 months after HSCT.

Results:

The cumulative incidence of intestinal aGVHD was 19.4%, with 18.0% of the patients classified as classic aGVHD and 1.4% as persistent, recurrent, or late aGVHD. Multivariate analysis showed that HLA-A31 locus (odds ratio [OR] 2.893, 95% confidence interval [CI] [1.054, 7.935], P = 0.039), HLA B40-DR15 (OR 3.133, 95% CI [1.250, 7.857], P = 0.015), and HLA B46-DR9 haplotypes (OR 2.580, 95% CI [1.070, 6.220], P = 0.035), female donor for male recipient (OR 2.434, 95% CI [1.319, 4.493], P = 0.004) were risk factors for intestinal aGVHD.

Conclusion:

The presence of certain HLA loci and haplotypes may influence the occurrence of intestinal aGVHD in PBSCT with HLA-identical sibling donors.

Antigen Discovery and Therapeutic Targeting in Hematologic Malignancies

Historically, immune-based therapies have played a leading role in the treatment of hematologic malignancies, with the efficacy of stem cell transplantation largely attributable to donor immunity against malignant cells. As new and more targeted immunotherapies have developed, their role in the treatment of hematologic malignancies is evolving and expanding. Herein, we discuss approaches for antigen discovery and review known and novel tumor antigens in hematologic malignancies. We further explore the role of established and investigational immunotherapies in hematologic malignancies, with a focus on personalization of treatment modalities such as cancer vaccines and adoptive cell therapy. Finally, we identify areas of active investigation and development. Immunotherapy is at an exciting crossroads for the treatment of hematologic malignancies, with further investigation aimed at producing effective, targeted immune therapies that maximize antitumor effects while minimizing toxicity.

Immune targets and neoantigens for cancer immunotherapy and precision medicine

Harnessing the immune system to eradicate malignant cells is becoming a most powerful new approach to cancer therapy. FDA approval of the immunotherapy-based drugs, sipuleucel-T (Provenge), ipilimumab (Yervoy, anti-CTLA-4), and more recently, the programmed cell death (PD)-1 antibody (pembrolizumab, Keytruda), for the treatment of multiple types of cancer has greatly advanced research and clinical studies in the field of cancer immunotherapy. Furthermore, recent clinical trials, using NY-ESO-1-specific T cell receptor (TCR) or CD19-chimeric antigen receptor (CAR), have shown promising clinical results for patients with metastatic cancer. Current success of cancer immunotherapy is built upon the work of cancer antigens and co-inhibitory signaling molecules identified 20 years ago. Among the large numbers of target antigens, CD19 is the best target for CAR T cell therapy for blood cancer, but CAR-engineered T cell immunotherapy does not yet work in solid cancer. NY-ESO-1 is one of the best targets for TCR-based immunotherapy in solid cancer. Despite the great success of checkpoint blockade therapy, more than 50% of cancer patients fail to respond to blockade therapy. The advent of new technologies such as next-generation sequencing has enhanced our ability to search for new immune targets in onco-immunology and accelerated the development of immunotherapy with potentially broader coverage of cancer patients. In this review, we will discuss the recent progresses of cancer immunotherapy and novel strategies in the identification of new immune targets and mutation-derived antigens (neoantigens) for cancer immunotherapy and immunoprecision medicine.

The Role of Neoantigens in Naturally Occurring and Therapeutically Induced Immune Responses to Cancer

Definitive experimental evidence from mouse cancer models and strong correlative clinical data gave rise to the Cancer Immunoediting concept that explains the dual host-protective and tumor-promoting actions of immunity on developing cancers. Tumor-specific neoantigens can serve as targets of spontaneously arising adaptive immunity to cancer and thereby determine the ultimate fate of developing tumors. Tumor-specific neoantigens can also function as optimal targets of cancer immunotherapy against established tumors. These antigens are derived from nonsynonymous mutations that occur during cellular transformation and, because they are foreign to the host genome, are not subject to central tolerance. In this review, we summarize the experimental evidence indicating that cancer neoantigens are the source of both spontaneously occurring and therapeutically induced immune responses against cancer. We also review the advances in genomics, bioinformatics, and cancer immunotherapy that have facilitated identification of neoantigens and have moved personalized cancer immunotherapies into clinical trials, with the promise of providing more specific, safer, more effective, and perhaps even more generalizable treatments to cancer patients than current immunotherapies.

Current advances in T-cell-based cancer immunotherapy

Cancer is a leading cause of death worldwide; due to the lack of ideal cancer biomarkers for early detection or diagnosis, most patients present with late-stage disease at the time of diagnosis, thus limiting the potential for successful treatment. Traditional cancer treatments, including surgery, chemotherapy and radiation therapy, have demonstrated very limited efficacy for patients with late-stage disease. Therefore, innovative and effective cancer treatments are urgently needed for cancer patients with late-stage and refractory disease. Cancer immunotherapy, particularly adoptive cell transfer, has shown great promise in the treatment of patients with late-stage disease, including those who are refractory to standard therapies. In this review, we will highlight recent advances and discuss future directions in adoptive cell transfer based cancer immunotherapy.

Non-redundant requirement for CXCR3 signalling during tumoricidal T-cell trafficking across tumour vascular checkpoints

T-cell trafficking at vascular sites has emerged as a key step in antitumour immunity. Chemokines are credited with guiding the multistep recruitment of CD8(+) T cells across tumour vessels. However, the multiplicity of chemokines within tumours has obscured the contributions of individual chemokine receptor/chemokine pairs to this process. Moreover, recent studies have challenged whether T cells require chemokine receptor signalling at effector sites. Here we investigate the hierarchy of chemokine receptor requirements during T-cell trafficking to murine and human melanoma. These studies reveal a non-redundant role for Gαi-coupled CXCR3 in stabilizing intravascular adhesion and extravasation of adoptively transferred CD8(+) effectors that is indispensable for therapeutic efficacy. In contrast, functional CCR2 and CCR5 on CD8(+) effectors fail to support trafficking despite the presence of intratumoral cognate chemokines. Taken together, these studies identify CXCR3-mediated trafficking at the tumour vascular interface as a critical checkpoint to effective T-cell-based cancer immunotherapy.

How immunoglobulin G antibodies kill target cells: revisiting an old paradigm

The capacity of immunoglobulin G (IgG) antibodies to eliminate virtually any target cell has resulted in the widespread introduction of cytotoxic antibodies into the clinic in settings of cancer therapy, autoimmunity, and transplantation, for example. More recently, it has become apparent that also the protection from viral infection via IgG antibodies may require cytotoxic effector functions, suggesting that antibody-dependent cellular cytotoxicity (ADCC) directed against malignant or virally infected cells is one of the most essential effector mechanisms triggered by IgG antibodies to protect the host. A detailed understanding of the underlying molecular and cellular pathways is critical, therefore, to make full use of this antibody effector function. Several studies over the last years have provided novel insights into the effector pathways and innate immune effector cells responsible for ADCC reactions. One of the most notable outcomes of many of these reports is that cells of the mononuclear phagocytic system rather than natural killer cells are critical for removal of IgG opsonized target cells in vivo.

Exploiting the curative potential of adoptive T-cell therapy for cancer

Adoptive T-cell therapy (ACT) is a potent and flexible cancer treatment modality that can induce complete, durable regression of certain human malignancies. Long-term follow-up of patients receiving tumor-infiltrating lymphocytes (TILs) for metastatic melanoma reveals a substantial subset that experienced complete, lasting tumor regression - and may be cured. Increasing evidence points to mutated gene products as the primary immunological targets of TILs from melanomas. Recent technological advances permit rapid identification of the neoepitopes resulting from these somatic gene mutations and of T cells with reactivity against these targets. Isolation and adoptive transfer of these T cells may improve TIL therapy for melanoma and permit its broader application to non-melanoma tumors. Extension of ACT to other malignancies may also be possible through antigen receptor gene engineering. Tumor regression has been observed following transfer of T cells engineered to express chimeric antigen receptors against CD19 in B-cell malignancies or a T-cell receptor against NY-ESO-1 in synovial cell sarcoma and melanoma. Herein, we review recent clinical trials of TILs and antigen receptor gene therapy for advanced cancers. We discuss lessons from this experience and consider how they might be applied to realize the full curative potential of ACT.

TCR repertoires of intratumoral T-cell subsets

The infiltration of human tumors by T cells is a common phenomenon, and over the past decades, it has become increasingly clear that the nature of such intratumoral T-cell populations can predict disease course. Furthermore, intratumoral T cells have been utilized therapeutically in clinical studies of adoptive T-cell therapy. In this review, we describe how novel methods that are either based on T-cell receptor (TCR) sequencing or on cancer exome analysis allow the analysis of the tumor reactivity and antigen-specificity of the intratumoral TCR repertoire with unprecedented detail. Furthermore, we discuss studies that have started to utilize these techniques to probe the link between cancer exomes and the intratumoral TCR pool. Based on the observation that both the cancer epitope repertoire and intratumoral TCR repertoire appear highly individual, we outline strategies, such as 'autologous TCR gene therapy', that exploit the tumor-resident TCR repertoire for the development of personalized immunotherapy.

Ex vivo derived primary melanoma cells: implications for immunotherapeutic vaccines

Transformation of the pigment producing melanocytes into melanoma is a complex multi-step process involving the enhanced expression of various antigens considered as immunotherapeutic targets. Significant progress in melanoma research has been made over the years and has resulted in the identification of various antigens over expressed in melanoma as well as advances in immunotherapeutic treatments, which focus on modulating the immune systems response to melanoma. Despite these advances, incidences of melanoma are still on the rise thus warranting additional research in identifying new therapeutic treatments. Our focus is on developing a multivalent immunotherapeutic vaccine that targets various melanoma associated antigens. The approach focuses on the use of five primary patient derived melanoma cells (MEL-2, MEL-V, 3MM, KFM, and GLM-2, which have been characterized in this study. These cells express differential amounts of various melanoma associated antigens such as MART-1, gp100 (Pmel17), MAGE-A1 and tyrosinase as well a cell surface antigens essential for melanoma cell metastasis, such as CD146 and CD71. In addition these cells display differential in vitro migratory and invasive properties as well as have the ability to form solid tumors when implanted into BALB/c nude mice. The retention of the innate phenotype of these primary patient derived cells together with the expression of a multitude repertoire of melanoma associated antigens offers a novel opportunity to target melanoma so as to avoid immune evasion.

Molecular cancer vaccines: Tumor therapy using antigen-specific immunizations

Vaccination against tumors promises selective destruction of malignant cells by the host's immune system. Molecular cancer vaccines rely on recently identified tumor antigens as immunogens. Tumor antigens can be applied in many forms, as genes in recombinant vectors, as proteins or peptides representing T cell epitopes.Analysis of various aspects indicates some advantage for peptide-based vaccines over the other modalities. Further refinements and extensively monitored clinical trials are necessary to advance molecular cancer vaccines from concepts into powerful therapy.

Tyrosinase related protein 1 (TYRP1/gp75) in human cutaneous melanoma

Melanoma prognosis is based on specific pathological features at the primary lesion. In metastatic patients, the extent of lymph node involvement is also an important prognosis indicator. Many progression markers both in tissues and serum, including circulating tumor cells, have been studied and new molecular markers are awaited from high-throughput screenings to discriminate between clinical stages and predict disease progression. The present review focuses on human tyrosinase related protein 1 also known as gp75 glycoprotein (Tyrp1/gp75), a melanosomal protein involved in the pigmentary machinery of the melanocyte and often used as differentiation marker, with a special emphasis on its emerging roles in the malignant melanocyte and melanoma progression.

Immunotherapeutic strategies: the melanoma example

T-cell-based immunotherapy can be induced by nonspecific activation, by antigen-specific immunization, or by adoptive immunotherapy. In this review, progress in these areas is discussed as based on data from clinical trials for the treatment of metastatic melanoma. Nonspecific immunotherapy has been shown to result in low, but in some cases significant, levels of objective tumor responses, and is often associated with autoimmune reactions. Antigen-specific targeting of tumors via vaccination has only resulted in low to very low levels of objective responses, and these strategies seem to have most value when the T-cell repertoire is not affected by tolerance. Finally, adoptive immunotherapy can be applied by in vitro expansion of autologous lymphocytes that have escaped tolerance or by genetic transfer of allogeneic T-cell receptors (TCRs). Autologous adoptive T-cell transfer has resulted in a very high frequency of clinical responses when combined with chemotherapy and IL-2 administration in single-center studies. Although TCR gene transfer has, until now, only resulted in a low frequency of clinical responses, it does have a broader application potential, and optimization of this strategy is likely to improve its efficacy.

Screening of human tumor antigens for CD4 T cell epitopes by combination of HLA-transgenic mice, recombinant adenovirus and antigen peptide libraries

BACKGROUND

As tumor antigen-specific CD4+ T cells can mediate strong therapeutic anti-tumor responses in melanoma patients we set out to establish a comprehensive screening strategy for the identification of tumor-specific CD4+ T cell epitopes suitable for detection, isolation and expansion of tumor-reactive T cells from patients.

METHODS AND FINDINGS

To scan the human melanoma differentiation antigens TRP-1 and TRP-2 for HLA-DRB1*0301-restricted CD4+ T cell epitopes we applied the following methodology: Splenocytes of HLA-DRB1*0301-transgenic mice immunized with recombinant adenovirus encoding TRP-1 (Ad5.TRP-1) or TRP-2 (Ad5.TRP-2) were tested for their T cell reactivity against combinatorial TRP-1- and TRP-2-specific peptide libraries. CD4+ T cell epitopes thus identified were validated in the human system by stimulation of peripheral blood mononuclear cells (PBMC) from healthy donors and melanoma patients. Using this strategy we observed that recombinant Ad5 induced strong CD4+ T cell responses against the heterologous tumor antigens. In Ad5.TRP-2-immunized mice CD4+ T cell reactivity was detected against the known HLA-DRB1*0301-restricted TRP-2(60-74) epitope and against the new epitope TRP-2(149-163). Importantly, human T cells specifically recognizing target cells loaded with the TRP-2(149-163)-containing library peptide or infected with Ad5.TRP-2 were obtained from healthy individuals, and short term in vitro stimulation of PBMC revealed the presence of epitope-reactive CD4+ T cells in melanoma patients. Similarly, immunization of mice with Ad5.TRP-1 induced CD4+ T cell responses against TRP-1-derived peptides that turned out to be recognized also by human T cells, resulting in the identification of TRP-1(284-298) as a new HLA-DRB1*0301-restricted CD4+ T cell epitope.

CONCLUSIONS

Our screening approach identified new HLA-DRB1*0301-restricted CD4+ T cell epitopes derived from melanoma antigens. This strategy is generally applicable to target antigens of other tumor entities and to different HLA class II molecules even without prior characterization of their peptide binding motives.

Phase I clinical trial of the vaccination for the patients with metastatic melanoma using gp100-derived epitope peptide restricted to HLA-A*2402

BACKGROUND

The tumor associated antigen (TAA) gp100 was one of the first identified and has been used in clinical trials to treat melanoma patients. However, the gp100 epitope peptide restricted to HLA-A*2402 has not been extensively examined clinically due to the ethnic variations. Since it is the most common HLA Class I allele in the Japanese population, we performed a phase I clinical trial of cancer vaccination using the HLA-A*2402 gp100 peptide to treat patients with metastatic melanoma.

METHODS

The phase I clinical protocol to test a HLA-A*2402 gp100 peptide-based cancer vaccine was designed to evaluate safety as the primary endpoint and was approved by The University of Tokyo Institutional Review Board. Information related to the immunologic and antitumor responses were also collected as secondary endpoints. Patients that were HLA-A*2402 positive with stage IV melanoma were enrolled according to the criteria set by the protocol and immunized with a vaccine consisting of epitope peptide (VYFFLPDHL, gp100-in4) emulsified with incomplete Freund's adjuvant (IFA) for the total of 4 times with two week intervals. Prior to each vaccination, peripheral blood mononuclear cells (PBMCs) were separated from the blood and stored at -80°C. The stored PBMCs were thawed and examined for the frequency of the peptide specific T lymphocytes by IFN-γ- ELISPOT and MHC-Dextramer assays.

RESULTS

No related adverse events greater than grade I were observed in the six patients enrolled in this study. No clinical responses were observed in the enrolled patients although vitiligo was observed after the vaccination in two patients. Promotion of peptide specific immune responses was observed in four patients with ELISPOT assay. Furthermore, a significant increase of CD8+ gp100-in4+ CTLs was observed in all patients using the MHC-Dextramer assay. Cytotoxic T lymphocytes (CTLs) clones specific to gp100-in4 were successfully established from the PBMC of some patients and these CTL clones were capable of lysing the melanoma cell line, 888 mel, which endogenously expresses HLA-restricted gp100-in4.

CONCLUSION

Our results suggest this HLA-restricted gp100-in4 peptide vaccination protocol was well-tolerated and can induce antigen-specific T-cell responses in multiple patients. Although no objective anti-tumor effects were observed, the effectiveness of this approach can be enhanced with the appropriate modifications.

Update on vaccine development for renal cell cancer

Renal cell carcinoma (RCC) remains a significant health concern that frequently presents as metastatic disease at the time of initial diagnosis. Current first-line therapeutics for the advanced-stage RCC include antiangiogenic drugs that have yielded high rates of objective clinical response; however, these tend to be transient in nature, with many patients becoming refractory to chronic treatment with these agents. Adjuvant immunotherapies remain viable candidates to sustain disease-free and overall patient survival. In particular, vaccines designed to optimize the activation, maintenance, and recruitment of specific immunity within or into the tumor site continue to evolve. Based on the integration of increasingly refined immunomonitoring systems in both translational models and clinical trials, allowing for the improved understanding of treatment mechanism(s) of action, further refined (combinational) vaccine protocols are currently being developed and evaluated. This review provides a brief history of RCC vaccine development, discusses the successes and limitations in such approaches, and provides a rationale for developing combinational vaccine approaches that may provide improved clinical benefits to patients with RCC.

Melanoma progression despite infiltration by in vivo-primed TRP-2-specific T cells

Many antigens recognized by tumor-reactive cytotoxic CD8+ T cells are self-antigens. Tyrosinase-related protein 2 (TRP-2) is a melanogenic enzyme expressed by both melanocytes and melanomas that is reported to be a candidate melanoma rejection antigen. To study the role of self-reactive CD8+ T cells in tumor immunity and autoimmunity, we generated mice that bear a T-cell receptor transgene (TCR Tg) specific for the TRP-2(180-188) epitope. TRP-2 TCR Tg mice did not spontaneously develop depigmentation despite systemic expression of TRP-2 in the skin. Peripheral T cells from these TCR Tg mice exhibited a naive phenotype and proliferated in response to TRP-2 in vitro. In addition, transfer of in vitro-activated Tg T cells reduced B16 pulmonary tumor burden, but not subcutaneous tumors. We next sought to determine the in vivo responses of the Tg T cells to endogenous and tumor-derived TRP-2. Adoptive transfer of naive TCR Tg T cells into wild-type C57BL/6 mice, in combination with a TRP-2-pulsed dendritic cell vaccine, induced proliferation of the Tg T cells and resulted in migration of the Tg T cells into a subcutaneous B16 melanoma tumor. Although these tumor-infiltrating Tg T cells remained reactive against TRP-2, they did not reduce growth of the primary subcutaneous tumor; similarly, these in vivo-primed effector cells had no significant effect on the growth of pulmonary nodules. These data demonstrate that despite in vivo priming, tumor-infiltrating T cells may fail to reduce tumor burden. Determining the basis for the inability of the tumor microenvironment to sustain effective antitumor responses will be critical for designing newer, more potent antitumor immunotherapies.

Molecular cloning and characterization of MHC class I- and II-restricted tumor antigens recognized by T cells

T cells play a central role in cancer immunosurveillance, autoimmune, and infectious diseases. Identification of MHC class I- and II-restricted T cell peptides is a critical step for the development of effective vaccines against cancer and infectious diseases. This unit describes a cDNA expression system and a genetic targeting expression system for the cloning of genes encoding for MHC class I- and II-restricted antigens recognized by antigen-specific CD8(+) and CD4(+) T cells.

Cancer vaccines: accomplishments and challenges

Advancements in knowledge in diverse fields of science, including genetics, cell biology, molecular biology and biochemistry, have shed light on the origins of cancer and cell intrinsic properties that allow it to grow, invade and metastasize. Many therapies currently in use or under development are based on this knowledge. Advances in immunology, on the other hand, have shed light on how the host responds to these malignant properties of cancer. Based on that knowledge, immunotherapy, in particular vaccines directed at improving the host response against cancer, is being developed as an alternative therapeutic approach. In this review, we address main issues that have driven development of cancer vaccines and the challenges that have been met and/or are anticipated.

Analyses and perspectives in cancer immunotherapy

Since the last two decades, rapid progress has been made in the field of cancer immunotherapy relevant to manipulation of adaptative cytotoxic T lymphocytes (CTLs) and innate immunity natural killer (NK) cells as well as antibodies. Many possibilities are now offered for therapeutic purposes contributing to better approaches in treatment of cancer.

Regulatory T Cells and Toll-Like Receptors in Cancer Therapy: Figure 1

T regulatory (Treg) cells that suppress immune responses may limit the efficiency of cancer immunotherapy. Recent findings indicate that Toll-like receptors (TLR) directly regulate the suppressive activity of Treg cells. Linking TLR signaling to the functional control of Treg cells may offer new opportunities to improve the outcome of cancer immunotherapy by coadminstration of certain TLR ligands.

Induction of autologous CD4- and CD8-mediated T-cell responses against acute lymphocytic leukemia cell line using apoptotic tumor cell–loaded dendritic cells

OBJECTIVE

Several studies have demonstrated that dendritic cells (DCs) pulsed with tumor lysate or apoptotic tumor cells can elicit effective T-cell responses. This technique does not require the identification of the tumor antigen or HLA haplotype of the patient. We applied this approach to induce HLA class I- and class II-restricted T-cell responses directed against autologous acute lymphocytic leukemia (B-ALL) cell line NH-1.

METHODS

Autologous T cells were stimulated by apoptotic tumor cell-loaded DCs generated from a patient with ALL. The stimulated and expanded T cells were isolated into CD8(+) T-cell line and CD4(+) T-cell line, and each of them was examined as to their functions.

RESULTS

Both CD8(+) and CD4(+) T-cell lines demonstrated cytotoxicity against NH-1 in an major histocompatibility complex-dependent manner. Finally, we established two independent CD4(+) T-cell clones restricted to HLA-DR. The CD4(+) T-cell line responded strongly to autologous Epstein-Barr virus-transformed lymphoblastoid cell lines (EBV-LCL) but not to autologous normal cells. Furthermore, the T-cell clones also responded to allogeneic EBV-LCLs and B-ALL cell lines in the context of the HLA-DRB1( *)04051 molecule. Interestingly, 293T and COS-7 cells, which had been transfected with the HLA-DRB1( *)04051, were also recognized by T-cell clones.

CONCLUSION

These findings indicate that B-ALL has shared and strong immunogenic epitopes expressed on HLA class II molecules, the expression of which is limited to immortalized cells. These data suggest that vaccinations using DCs loaded with apoptotic tumor cells might be a potent strategy in the treatment of B-ALL.

Toll-like receptor 8-mediated reversal of CD4+ regulatory T cell function

CD4+ regulatory T (Treg) cells have a profound ability to suppress host immune responses, yet little is understood about how these cells are regulated. We describe a mechanism linking Toll-like receptor (TLR) 8 signaling to the control of Treg cell function, in which synthetic and natural ligands for human TLR8 can reverse Treg cell function. This effect was independent of dendritic cells but required functional TLR8-MyD88-IRAK4 signaling in Treg cells. Adoptive transfer of TLR8 ligand-stimulated Treg cells into tumor-bearing mice enhanced anti-tumor immunity. These results suggest that TLR8 signaling could play a critical role in controlling immune responses to cancer and other diseases.

The TLR7 Agonist Imiquimod Enhances the Anti-Melanoma Effects of a RecombinantListeria monocytogenesVaccine

Activation of innate immune cells through TLR triggers immunomodulating events that enhance cell-mediated immunity, raising the possibility that ligands to these receptors might act as adjuvants in conjunction with T cell activating vaccines. In this report, topical imiquimod, a synthetic TLR7 agonist, significantly enhanced the protective antitumor effects of a live, recombinant listeria vaccine against murine melanoma. This tumor protective effect was not dependent on direct application to the tumor and was associated with an increase in tumor-associated and splenic dendritic cells. Additionally, the combination of imiquimod treatment with prior vaccination led to development of localized vitiligo. These findings indicate that activation of the innate immune system with TLR ligands stimulates dendritic cell activity resulting in a bypass of peripheral tolerance and enhanced antitumor activity. The results of these studies have broad implications for future designs of immunotherapeutic vaccines against tumors and the treatment of metastatic melanoma.

Melan A (A103) is expressed in adrenocortical neoplasms but not in renal cell and hepatocellular carcinomas

Most adrenocortical neoplasms, renal cell carcinomas, and hepatocellular carcinomas are diagnosed by a combination of clinical and morphologic features. However, occasionally this histologic differential diagnosis requires additional ancillary tests, such as immunohistochemistry. The authors investigated the potential value of A103 in the differential diagnosis of these tumors. Thirty-two adrenocortical neoplasms, 86 renal cell carcinomas, and 57 hepatocellular carcinomas were evaluated by immunohistochemistry using a monoclonal antibody A103 and a standard ABC method. The adrenocortical neoplasms were 21 adenomas and 11 carcinomas. Thirty-one of the 32 adrenocortical neoplasms showed strong and diffuse granular cytoplasmic staining for Melan A. No nuclear reaction was observed. There were no differences in staining patterns between adrenocortical adenomas and carcinomas. With the exception of one clear cell renal cell carcinoma, all non-adrenocortical neoplasms were negative. The authors conclude that A103 is a useful addition to the immunohistochemical panel in the differential diagnosis of adrenocortical neoplasms from both renal cell and hepatocellular carcinomas. This marker, however, does not separate benign from malignant adrenocortical neoplasms.

IFN-gamma enables cross-presentation of exogenous protein antigen in human Langerhans cells by potentiating maturation

We compared monocyte-derived dendritic cells and transforming growth factor-beta1-induced Langerhans-like cells (LCs) for their capacity to cross-present exogenous NY-ESO-1 protein/antibody immune complexes to an NY-ESO-1-specific CD8+ T cell clone. In contrast to dendritic cells, LCs were not able to cross-present NY-ESO-1 to the T cell clone constitutively but did so after treatment with IFN-gamma. Remarkably, this IFN-gamma-inducible characteristic was due neither to enhanced antigen uptake nor to facilitated antigen processing in LCs. Rather, IFN-gamma acted at least in part by potentiating the maturation of otherwise refractory LCs, enabling in turn exogenous antigen to reach the processing machinery. This model of conditional cross-presentation establishes an original level of action for IFN-gamma as an effective immune modulator and supports the use of IFN-gamma in protein vaccination strategies targeting LCs.