Detection and induction of CTLs specific for SYT-SSX-derived peptides in HLA-A24(+) patients with synovial sarcoma

Desmoplastic small round cell tumor: from genomics to targets, potential paths to future therapeutics

Desmoplastic Small Round Cell Tumor (DSRCT) is a highly aggressive pediatric cancer caused by a reciprocal translocation between chromosomes 11 and 22, leading to the formation of the EWSR1::WT1 oncoprotein. DSRCT presents most commonly in the abdominal and pelvic peritoneum and remains refractory to current treatment regimens which include chemotherapy, radiotherapy, and surgery. As a rare cancer, sample and model availability have been a limiting factor to DSRCT research. However, the establishment of rare tumor banks and novel cell lines have recently propelled critical advances in the understanding of DSRCT biology and the identification of potentially promising targeted therapeutics. Here we review model and dataset availability, current understanding of the EWSR1::WT1 oncogenic mechanism, and promising preclinical therapeutics, some of which are now advancing to clinical trials. We discuss efforts to inhibit critical dependencies including NTRK3, EGFR, and CDK4/6 as well as novel immunotherapy strategies targeting surface markers highly expressed in DSRCT such as B7-H3 or neopeptides either derived from or driven by the fusion oncoprotein. Finally, we discuss the prospect of combination therapies and strategies for prioritizing clinical translation.

RNA vaccines for cancer: Principles to practice

Vaccines are the most impactful medicines to improve health. Though potent against pathogens, vaccines for cancer remain an unfulfilled promise. However, recent advances in RNA technology coupled with scientific and clinical breakthroughs have spurred rapid discovery and potent delivery of tumor antigens at speed and scale, transforming cancer vaccines into a tantalizing prospect. Yet, despite being at a pivotal juncture, with several randomized clinical trials maturing in upcoming years, several critical questions remain: which antigens, tumors, platforms, and hosts can trigger potent immunity with clinical impact? Here, we address these questions with a principled framework of cancer vaccination from antigen detection to delivery. With this framework, we outline features of emergent RNA technology that enable rapid, robust, real-time vaccination with somatic mutation-derived neoantigens-an emerging "ideal" antigen class-and highlight latent features that have sparked the belief that RNA could realize the enduring vision for vaccines against cancer.

State-Of-The-Art Advancements on Cancer Vaccines and Biomarkers

The origins of cancer vaccines date back to the 1800s. Since then, there have been significant efforts to generate vaccines against solid and hematologic malignancies using a variety of platforms. To date, these efforts have generally been met with minimal success. However, in the era of improved methods and technological advancements, supported by compelling preclinical and clinical data, a wave of renewed interest in the field offers the promise of discovering field-changing paradigms in the management of established and resected disease using cancer vaccines. These include novel approaches to personalized neoantigen vaccine development, as well as innovative immune-modulatory vaccines (IMVs) that facilitate activation of antiregulatory T cells to limit immunosuppression caused by regulatory immune cells. This article will introduce some of the limitations that have affected cancer vaccine development over the past several decades, followed by an introduction to the latest advancements in neoantigen vaccine and IMV therapy, and then conclude with a discussion of some of the newest technologies and progress that are occurring across the cancer vaccine space. Cancer vaccines are among the most promising frontiers for breakthrough innovations and strategies poised to make a measurable impact in the ongoing fight against cancer.

Tumor Antigens beyond the Human Exome

With the advent of immunotherapeutics, a new era in the combat against cancer has begun. Particularly promising are neo-epitope-targeted therapies as the expression of neo-antigens is tumor-specific. In turn, this allows the selective targeting and killing of cancer cells whilst healthy cells remain largely unaffected. So far, many advances have been made in the development of treatment options which are tailored to the individual neo-epitope repertoire. The next big step is the achievement of efficacious "off-the-shelf" immunotherapies. For this, shared neo-epitopes propose an optimal target. Given the tremendous potential, a thorough understanding of the underlying mechanisms which lead to the formation of neo-antigens is of fundamental importance. Here, we review the various processes which result in the formation of neo-epitopes. Broadly, the origin of neo-epitopes can be categorized into three groups: canonical, noncanonical, and viral neo-epitopes. For the canonical neo-antigens that arise in direct consequence of somatic mutations, we summarize past and recent findings. Beyond that, our main focus is put on the discussion of noncanonical and viral neo-epitopes as we believe that targeting those provides an encouraging perspective to shape the future of cancer immunotherapeutics.

Chromatin Remodelers Are Regulators of the Tumor Immune Microenvironment

Immune checkpoint inhibitors show remarkable responses in a wide range of cancers, yet patients develop adaptive resistance. This necessitates the identification of alternate therapies that synergize with immunotherapies. Epigenetic modifiers are potent mediators of tumor-intrinsic mechanisms and have been shown to regulate immune response genes, making them prime targets for therapeutic combinations with immune checkpoint inhibitors. Some success has been observed in early clinical studies that combined immunotherapy with agents targeting DNA methylation and histone modification; however, less is known about chromatin remodeler-targeted therapies. Here, we provide a discussion on the regulation of tumor immunogenicity by the chromatin remodeling SWI/SNF complex through multiple mechanisms associated with immunotherapy response that broadly include IFN signaling, DNA damage, mismatch repair, regulation of oncogenic programs, and polycomb-repressive complex antagonism. Context-dependent targeting of SWI/SNF subunits can elicit opportunities for synthetic lethality and reduce T-cell exhaustion. In summary, alongside the significance of SWI/SNF subunits in predicting immunotherapy outcomes, their ability to modulate the tumor immune landscape offers opportunities for therapeutic intervention.

Sarcoma Immunotherapy: Confronting Present Hurdles and Unveiling Upcoming Opportunities

Sarcomas are rare and heterogeneous mesenchymal neoplasms originating from the bone or soft tissues, which pose significant treatment challenges. The current standard treatment for sarcomas consists of surgical resection, often combined with chemo- and radiotherapy; however, local recurrence and metastasis remain significant concerns. Although immunotherapy has demonstrated promise in improving long-term survival rates for certain cancers, sarcomas are generally considered to be relatively less immunogenic than other tumors, presenting substantial challenges for effective immunotherapy. In this review, we examine the possible opportunities for sarcoma immunotherapy, noting cancer testis antigens expressed in sarcomas. We then cover the current status of immunotherapies in sarcomas, including progress in cancer vaccines, immune checkpoint inhibitors, and adoptive cellular therapy and their potential in combating these tumors. Furthermore, we discuss the limitations of immunotherapies in sarcomas, including a low tumor mutation burden and immunosuppressive tumor microenvironment, and explore potential strategies to tackle the immunosuppressive barriers in therapeutic interventions, shedding light on the development of effective and personalized treatments for sarcomas. Overall, this review provides a comprehensive overview of the current status and potential of immunotherapies in sarcoma treatment, highlighting the challenges and opportunities for developing effective therapies to improve the outcomes of patients with these rare malignancies.

The screening, identification, design and clinical application of tumor-specific neoantigens for TCR-T cells

Recent advances in neoantigen research have accelerated the development of tumor immunotherapies, including adoptive cell therapies (ACTs), cancer vaccines and antibody-based therapies, particularly for solid tumors. With the development of next-generation sequencing and bioinformatics technology, the rapid identification and prediction of tumor-specific antigens (TSAs) has become possible. Compared with tumor-associated antigens (TAAs), highly immunogenic TSAs provide new targets for personalized tumor immunotherapy and can be used as prospective indicators for predicting tumor patient survival, prognosis, and immune checkpoint blockade response. Here, the identification and characterization of neoantigens and the clinical application of neoantigen-based TCR-T immunotherapy strategies are summarized, and the current status, inherent challenges, and clinical translational potential of these strategies are discussed.

Current Landscape of Immunotherapy for Advanced Sarcoma

There is substantial heterogeneity between different subtypes of sarcoma regarding their biological behavior and microenvironment, which impacts their responsiveness to immunotherapy. Alveolar soft-part sarcoma, synovial sarcoma and undifferentiated pleomorphic sarcoma show higher immunogenicity and better responses to checkpoint inhibitors. Combination strategies adding immunotherapy to chemotherapy and/or tyrosine-kinase inhibitors globally seem superior to single-agent schemes. Therapeutic vaccines and different forms of adoptive cell therapy, mainly engineered TCRs, CAR-T cells and TIL therapy, are emerging as new forms of immunotherapy for advanced solid tumors. Tumor lymphocytic infiltration and other prognostic and predictive biomarkers are under research.

Specific recognition of an FGFR2 fusion by tumor infiltrating lymphocytes from a patient with metastatic cholangiocarcinoma

BACKGROUND

Metastatic cholangiocarcinoma (CC), a form of gastrointestinal cancer that originates from the bile ducts, cannot be cured by currently available therapies, and is associated with dismal prognosis. In a previous case report, adoptive transfer of autologous tumor infiltrating lymphocytes (TILs), the majority of which recognized a tumor-specific point mutation, led to a profound and durable cancer regression in a patient with metastatic CC. Thus, more effective treatment for patients with this disease may be developed by using TILs that target cancer-specific mutations, but also other genetic aberrations such as gene fusions. In this context, fusions that involve fibroblast growth factor receptor 2 (FGFR2) and function as oncogenes in a subset of patients with intrahepatic CC (ICC) represent particularly attractive targets for adoptive cell therapy. However, no study to date has explored whether FGFR2 fusions can be recognized by patients' T cells.

METHOD

To address whether FGFR2 fusions can be recognized by patients' T cells, we tested TILs from four patients with FGFR2 fusion-positive ICC for recognition of peptides and minigenes that represented the breakpoint regions of these fusions, which were unique to each of the four patients.

RESULTS

We found that CD4+ TILs from one patient specifically recognized the breakpoint region of a unique FGFR2-TDRD1 (tudor domain-containing 1) fusion, and we isolated a T-cell receptor responsible for its recognition.

CONCLUSIONS

This finding suggests that FGFR2 fusion-reactive TILs can be isolated from some patients with metastatic ICC, and thus provides a rationale for future exploration of T cell-based therapy targeting FGFR2 fusions in patients with cancer. Furthermore, it augments the rationale for extending such efforts to other types of solid tumors hallmarked by oncogenic gene fusions.

Neoantigens: promising targets for cancer therapy

Recent advances in neoantigen research have accelerated the development and regulatory approval of tumor immunotherapies, including cancer vaccines, adoptive cell therapy and antibody-based therapies, especially for solid tumors. Neoantigens are newly formed antigens generated by tumor cells as a result of various tumor-specific alterations, such as genomic mutation, dysregulated RNA splicing, disordered post-translational modification, and integrated viral open reading frames. Neoantigens are recognized as non-self and trigger an immune response that is not subject to central and peripheral tolerance. The quick identification and prediction of tumor-specific neoantigens have been made possible by the advanced development of next-generation sequencing and bioinformatic technologies. Compared to tumor-associated antigens, the highly immunogenic and tumor-specific neoantigens provide emerging targets for personalized cancer immunotherapies, and serve as prospective predictors for tumor survival prognosis and immune checkpoint blockade responses. The development of cancer therapies will be aided by understanding the mechanism underlying neoantigen-induced anti-tumor immune response and by streamlining the process of neoantigen-based immunotherapies. This review provides an overview on the identification and characterization of neoantigens and outlines the clinical applications of prospective immunotherapeutic strategies based on neoantigens. We also explore their current status, inherent challenges, and clinical translation potential.

Accurate detection of tumor-specific gene fusions reveals strongly immunogenic personal neo-antigens

Cancer-associated gene fusions are a potential source for highly immunogenic neoantigens, but the lack of computational tools for accurate, sensitive identification of personal gene fusions has limited their targeting in personalized cancer immunotherapy. Here we present EasyFuse, a machine learning computational pipeline for detecting cancer-specific gene fusions in transcriptome data obtained from human cancer samples. EasyFuse predicts personal gene fusions with high precision and sensitivity, outperforming previously described tools. By testing immunogenicity with autologous blood lymphocytes from patients with cancer, we detected pre-established CD4⁺ and CD8⁺ T cell responses for 10 of 21 (48%) and for 1 of 30 (3%) identified gene fusions, respectively. The high frequency of T cell responses detected in patients with cancer supports the relevance of individual gene fusions as neoantigens that might be targeted in personalized immunotherapies, especially for tumors with low mutation burden.

Immunotherapy in soft tissue sarcoma: current evidence and future perspectives in a variegated family of different tumour

INTRODUCTION

In the last few years steps forward in the knowledge of the biology of soft tissue sarcomas (STS) has led to the development of new therapeutic strategies, including immunotherapy.

AREAS COVERED

This review outlines the recent findings on immunological features and provides a synopsis of the results of clinical trials with different immunotherapy approaches in STS, discussing criticisms and how the efficacy of immunotherapy could be improved.

EXPERT OPINION

The heterogeneity of STS has limited generalized approaches of immunotherapy in the disease. Clinical decisions should encompass a comprehensive characterization of the tumour microenvironment (TME), marked by intra-histotype diversity. Profiling of immune cells, checkpoint molecules and antigen target/HLA expression is deemed to re-shape the classical histotype classification for a selection of the most appropriate immune-based treatment. In a synergistic view, tumour-directed treatments, designed on the genetic and epigenetic histotype make-up, should be monitored for their immunomodulant effect and applied to ensure or amplify immunotherapy response. In light of the dynamic nature of the TME, this immunomonitoring should be conducted at baseline and during treatment, for improved therapeutic decisions and rational sequence of treatment combination, pursuing an immunological marker approach by histotype guidance.

Identification of neoantigens for individualized therapeutic cancer vaccines

Somatic mutations in cancer cells can generate tumour-specific neoepitopes, which are recognized by autologous T cells in the host. As neoepitopes are not subject to central immune tolerance and are not expressed in healthy tissues, they are attractive targets for therapeutic cancer vaccines. Because the vast majority of cancer mutations are unique to the individual patient, harnessing the full potential of this rich source of targets requires individualized treatment approaches. Many computational algorithms and machine-learning tools have been developed to identify mutations in sequence data, to prioritize those that are more likely to be recognized by T cells and to design tailored vaccines for every patient. In this Review, we fill the gaps between the understanding of basic mechanisms of T cell recognition of neoantigens and the computational approaches for discovery of somatic mutations and neoantigen prediction for cancer immunotherapy. We present a new classification of neoantigens, distinguishing between guarding, restrained and ignored neoantigens, based on how they confer proficient antitumour immunity in a given clinical context. Such context-based differentiation will contribute to a framework that connects neoantigen biology to the clinical setting and medical peculiarities of cancer, and will enable future neoantigen-based therapies to provide greater clinical benefit.

Application of additively manufactured 3D scaffolds for bone cancer treatment: a review

Bone cancer is a critical health problem on a global scale, and the associated huge clinical and economic burdens are still rising. Although many clinical approaches are currently used for bone cancer treatment, these methods usually affect the normal body functions and thus present significant limitations. Meanwhile, advanced materials and additive manufacturing have opened up promising avenues for the development of new strategies targeting both bone cancer treatment and post-treatment bone regeneration. This paper presents a comprehensive review of bone cancer and its current treatment methods, particularly focusing on a number of advanced strategies such as scaffolds based on advanced functional materials, drug-loaded scaffolds, and scaffolds for photothermal/magnetothermal therapy. Finally, the main research challenges and future perspectives are elaborated.

Improving Immunotherapy Efficacy in Soft-Tissue Sarcomas: A Biomarker Driven and Histotype Tailored Review

Anti-PD-(L)1 therapies yield a disappointing response rate of 15% across soft-tissue sarcomas, even if some subtypes benefit more than others. The proportions of TAMs and TILs in their tumor microenvironment are variable, and this heterogeneity correlates to histotype. Tumors with a richer CD8+ T cell, M1 macrophage, and CD20+ cells infiltrate have a better prognosis than those infiltrated by M0/M2 macrophages and a high immune checkpoint protein expression. PD-L1 and CD8+ infiltrate seem correlated to response to immune checkpoint inhibitors (ICI), but tertiary lymphoid structures have the best predictive value and have been validated prospectively. Trials for combination therapies are ongoing and focus on the association of ICI with chemotherapy, achieving encouraging results especially with pembrolizumab and doxorubicin at an early stage, or ICI with antiangiogenics. A synergy with oncolytic viruses is seen and intratumoral talimogene laherpavec yields an impressive 35% ORR when associated to pembrolizumab. Adoptive cellular therapies are also of great interest in tumors with a high expression of cancer-testis antigens (CTA), such as synovial sarcomas or myxoid round cell liposarcomas with an ORR ranging from 20 to 50%. It seems crucial to adapt the design of clinical trials to histology. Leiomyosarcomas are characterized by complex genomics but are poorly infiltrated by immune cells and do not benefit from ICI. They should be tested with PIK3CA/AKT inhibition, IDO blockade, or treatments aiming at increasing antigenicity (radiotherapy, PARP inhibitors). DDLPS are more infiltrated and have higher PD-L1 expression, but responses to ICI remain variable across clinical studies. Combinations with MDM2 antagonists or CDK4/6 inhibitors may improve responses for DDLPS. UPS harbor the highest copy number alterations (CNA) and mutation rates, with a rich immune infiltrate containing TLS. They have a promising 15-40% ORR to ICI. Trials for ICB should focus on immune-high UPS. Association of ICI with FGFR inhibitors warrants further exploration in the immune-low group of UPS. Finally translocation-related sarcomas are heterogeneous, and although synovial sarcomas a poorly infiltrated and have a poor response rate to ICI, ASPS largely benefit from ICB monotherapy or its association with antiangiogenics agents. Targeting specific neoantigens through vaccine or adoptive cellular therapies is probably the most promising approach in synovial sarcomas.

Gene fusion neoantigens: Emerging targets for cancer immunotherapy

Tumor neoantigens play an important role in current cancer immunotherapies. The most commonly studied class of tumor neoantigens contains those derived from single-nucleotide variants (SNVs) and insertions or deletions (Indels). However, gene fusions are also ideal sources of tumor neoantigens, as they can form new open reading frames (ORFs). Compared with SNV and Indel (SNV&Indel) neoantigens, fusion gene neoantigens tend to be more immunogenic, have more targets per mutation, and are more broadly shared across different cancer types. As a result, they are an important class of tumor neoantigens and emerging targets for cancer immunotherapies, with uses as prognostic biomarkers of immune checkpoint blockade (ICB) and in the development of tumor vaccines, adoptive cell therapies and tumor immune microenvironment modulation. In this review, we introduce the chromosomal basis and characteristics of gene fusions. Then, we summarize the predictive tools, mutation burden and immunogenicity of gene fusion neoantigens. Further, we discuss applications and future improvements of gene fusion neoantigens with respect to current cancer immunotherapies and novel developments in cancer treatment.

Will Next-Generation Immunotherapy Overcome the Intrinsic Diversity and Low Immunogenicity of Sarcomas to Improve Clinical Benefit?

Sarcomas are a rare type of a heterogeneous group of tumours arising from mesenchymal cells that form connective tissues. Surgery is the most common treatment for these tumours, but additional neoadjuvant or adjuvant chemotherapy or radiation therapies may be necessary. Unfortunately, a significant proportion of patients treated with conventional therapies will develop metastatic disease that is resistant to therapies. Currently, there is an urgent need to develop more effective and durable therapies for the treatment of sarcomas. In recent years immunotherapies have revolutionised the treatment of a variety of cancers by restoring patient anti-tumour immune responses or through the adoptive infusion of immune effectors able to kill and eliminate malignant cells. The clinicopathologic and genetic heterogeneity of sarcomas, together with the generally low burden of somatic mutations potentially generating neoantigens, are currently limited to broad application of immunotherapy for patients with sarcomas. Nevertheless, a better understanding of the microenvironmental factors hampering the efficacy of immunotherapy and the identification of new and suitable therapeutic targets may help to overcome current limitations. Moreover, the recent advances in the development of immunotherapies based on the direct exploitation or targeting of T cells and/or NK cells may offer new opportunities to improve the treatment of sarcomas, particularly those showing recurrence or resistance to standard of care treatments.

Identifying and Targeting Human Tumor Antigens for T Cell-Based Immunotherapy of Solid Tumors

Cancer elimination in humans can be achieved with immunotherapy that relies on T lymphocyte-mediated recognition of tumor antigens. Several types of these antigens have been recognized based on their cellular origins and expression patterns, while their detection has been greatly facilitated by recent achievements in next-generation sequencing and immunopeptidomics. Some of them have been targeted in clinical trials with various immunotherapy approaches, while many others remain untested. Here, we discuss molecular identification of different tumor antigen types, and the clinical safety and efficacy of targeting them with immunotherapy. Additionally, we suggest strategies to increase the efficacy and availability of antigen-directed immunotherapies for treatment of patients with metastatic cancer.

Immunotherapy in soft-tissue sarcoma

Soft-tissue sarcoma (sts) is a rare mesenchymal malignancy that accounts for less than 1% of all adult tumours. Despite the successful advancement of localized therapies such as surgery and radiotherapy, these tumours can, for many, recur-often with metastatic disease. In the advanced setting, the role of systemic therapies is modest and is associated with poor survival. With the discovery of immunotherapies in other tumour types such as melanoma and lung cancer, interest has been renewed in exploring immunotherapy in sts. The biology of some stss makes them ripe for immunotherapy intervention; for example, some stss might have chromosomal translocations resulting in pathognomonic fusion products that have been shown to express cancer/testis antigens. Here, we present a targeted review of the published data and ongoing clinical trials for immunotherapies in patients with sarcoma, which comprise immune checkpoint inhibitors, adoptive cell therapies, and cancer vaccines.

Immunogenic neoantigens derived from gene fusions stimulate T cell responses

Anti-tumor immunity is driven by self versus non-self discrimination. Many immunotherapeutic approaches to cancer have taken advantage of tumor neoantigens derived from somatic mutations. Here, we demonstrate that gene fusions are a source of immunogenic neoantigens that can mediate responses to immunotherapy. We identified an exceptional responder with metastatic head and neck cancer who experienced a complete response to immune checkpoint inhibitor therapy, despite a low mutational load and minimal pre-treatment immune infiltration in the tumor. Using whole-genome sequencing and RNA sequencing, we identified a novel gene fusion and demonstrated that it produces a neoantigen that can specifically elicit a host cytotoxic T cell response. In a cohort of head and neck tumors with low mutation burden, minimal immune infiltration and prevalent gene fusions, we also identified gene fusion-derived neoantigens that generate cytotoxic T cell responses. Finally, analyzing additional datasets of fusion-positive cancers, including checkpoint-inhibitor-treated tumors, we found evidence of immune surveillance resulting in negative selective pressure against gene fusion-derived neoantigens. These findings highlight an important class of tumor-specific antigens and have implications for targeting gene fusion events in cancers that would otherwise be less poised for response to immunotherapy, including cancers with low mutational load and minimal immune infiltration.

Critical testing and parameters for consideration when manufacturing and evaluating tumor-associated antigen-specific T cells

The past year has seen remarkable translation of cellular and gene therapies, with U.S. Food and Drug Administration (FDA) approval of three chimeric antigen receptor (CAR) T-cell products, multiple gene therapy products, and the initiation of countless other pivotal clinical trials. What makes these new drugs most remarkable is their path to commercialization: they have unique requirements compared with traditional pharmaceutical drugs and require different potency assays, critical quality attributes and parameters, pharmacological and toxicological data, and in vivo efficacy testing. What's more, each biologic requires its own unique set of tests and parameters. Here we describe the unique tests associated with ex vivo-expanded tumor-associated antigen T cells (TAA-T). These tests include functional assays to determine potency, specificity, and identity; tests for pathogenic contaminants, such as bacteria and fungus as well as other contaminants such as Mycoplasma and endotoxin; tests for product characterization, tests to evaluate T-cell persistence and product efficacy; and finally, recommendations for critical quality attributes and parameters associated with the expansion of TAA-Ts.

Immunotherapy: A New (and Old) Approach to Treatment of Soft Tissue and Bone Sarcomas

Soft tissue and bone sarcomas are a rare and heterogeneous form of cancer. With standard of care treatment options including surgery, radiation, and chemotherapy, the long-term survival is still low for high-risk soft tissue sarcoma patients. New treatment strategies are needed. Immunotherapy offers a new potential treatment paradigm with great promise. Immunotherapy of soft tissue sarcomas dates back to Dr. Coley's first use of toxins in the late 1800s. A variety of strategies of immunotherapy have been tried in soft tissue and bone sarcomas, including various vaccines and cytokines, with limited success. Results of these early clinical trials with vaccines and cytokines were disappointing, but there are reasons to be optimistic. Recent advances, particularly with the use of adoptive T-cell therapy and immune checkpoint inhibitors, have led to a resurgence of this field for all cancer patients. Clinical trials utilizing adoptive T-cell therapy and immune checkpoint inhibitors in soft tissue and bone sarcomas are under way. This paper reviews the current state of evidence for the use of immunotherapy, as well as current immunotherapy strategies (vaccines, adopative T-cell therapy, and immune checkpoint blockade), in soft tissue and bone sarcomas. By understanding the tumor microenviroment of sarcomas and how it relates to their immunoresponsiveness, better immunotherapy clinical trials can be designed, hopefully with improved outcomes for soft tissue and bone sarcoma patients.

IMPLICATIONS FOR PRACTICE

Immunotherapy is a promising treatment paradigm that is gaining acceptance for the management of several cancers, including melanoma, renal cell carcinoma, prostate cancer, and lung cancer. There is a long history of immunotherapy in the treatment of soft tissue and bone sarcomas, although with little success. It is important to understand past failures to develop future immunotherapy treatment strategies with an improved possibility of success. This article reviews the history of and current state of immunotherapy research in the treatment of soft tissue and bone sarcomas, with particular regard to vaccine trials, adoptive T-cell therapy, and immune checkpoint blockade.

Current status of engineered T-cell therapy for synovial sarcoma

Synovial sarcoma is a rare soft tissue sarcoma characterized by a t(X;18) translocation, which results in a SYT-SSX gene fusion. In the metastatic setting, chemotherapy has limited, durable efficacy prompting the necessity for new therapeutic modalities. One emerging new strategy involves T-cell-directed therapy such as tumor-infiltrating lymphocytes or the development of T cells that are genetically engineered to express a T-cell receptor against a cancer testis antigen. Of these approaches, engineered T cells that recognize NY-ESO-1 are the furthest along in development. Completed and on-going clinical trials have shown promise and there are efforts to continue to optimize the current approach.

The future of immunotherapy for sarcoma

INTRODUCTION

The use of immunotherapeutic challenges for sarcoma has a long history. Despite the existence of objective responses, immunotherapy has been overshadowed by the results of chemotherapy, especially for osteosarcoma. However, the prognosis for non-responders to chemotherapy is still poor and immunotherapy is now focused on again.

AREAS COVERED

We reviewed the following types of clinical trials of immunotherapy for sarcoma: (i) vaccination with autologous tumor cells, (ii) vaccination with peptides derived from tumor-associated antigens, (iii) adoptive cell transfer using engineered T cells expressing T cell receptor directed at NY-ESO-1 and (iv) immune checkpoint inhibitors targeting CTLA-4 and PD1/PDL1.

EXPERT OPINION

The immunogenicity of sarcoma might be lower than that of melanoma. Patients with small lesions who have not received any chemotherapy are good candidates for peptide-based immunotherapy. Combining peptide vaccination and immune checkpoint inhibitors is an attractive option, and long-lived memory T cells are attracting attention. Memory T stem cells defined by CD95+ are long-lived and have the capacity for self-renewal and multidifferentiation. We also identified a novel memory T cell population, young memory T cells defined by CD73+CXCR3+. Regulation of such memory T stem cells will be useful for peptide vaccination and adoptive cell transfer.

Key Role of DAMP in Inflammation, Cancer, and Tissue Repair

PURPOSE

This review aimed to take stock of the current status of research on damage-associated molecular pattern (DAMP) protein. We discuss the Janus-faced role of DAMP molecules in inflammation, cancer, and tissue repair. The high-mobility group box (HMGB)-1 and adenosine triphosphate proteins are well-known DAMP molecules and have been primarily associated with inflammation. However, as we shall see, recent data have linked these molecules to tissue repair. HMGB1 is associated with cancer-related inflammation. It activates nuclear factor kB, which is involved in cancer regulation via its receptor for advanced glycation end-products (RAGE), Toll-like receptors 2 and 4. Proinflammatory activity and tissue repair may lead to pharmacologic intervention, by blocking DAMP RAGE and Toll like receptor 2 and 4 role in inflammation and by increasing their concentration in tissue repair, respectively.

METHODS

We conducted a MEDLINE search for articles pertaining to the various issues related to DAMP, and we discuss the most relevant articles especially (ie, not only those published in journals with a higher impact factor).

FINDINGS

A cluster of remarkable articles on DAMP have appeared in the literature in recent years. Regarding inflammation, several strategies have been proposed to target HMGB1, from antibodies to recombinant box A, which interacts with RAGE, competing with the full molecule. In tissue repair, it was reported that the overexpression of HMGB1 or the administration of exogenous HMGB1 significantly increased the number of vessels and promoted recovery in skin-wound, ischemic injury.

IMPLICATIONS

Due to the bivalent nature of DAMP, it is often difficult to explain the relative role of DAMP in inflammation versus its role in tissue repair. However, this point is crucial as DAMP-related treatments move into clinical practice.

Potential for immunotherapy in soft tissue sarcoma

Soft tissue sarcomas (STS) are rare, heterogeneous tumors of mesenchymal origin. Despite optimal treatment, a large proportion of patients will develop recurrent and metastatic disease. For these patients, current treatment options are quite limited. Significant progress has been made recently in the use of immunotherapy for the treatment of other solid tumors (e.g. prostate cancer, melanoma). There is a strong rationale for immunotherapy in STS, based on an understanding of disease biology. For example, STS frequently have chromosomal translocations which result in unique fusion proteins and specific subtypes have been shown to express cancer testis antigens. In this review, we discuss the current status of immunotherapy in STS, including data from human studies with cancer vaccines, adoptive cell therapy, and immune checkpoint blockade. Further research into STS immunology is needed to help design logical, subtype-specific immunotherapeutic strategies.

A rare synovial sarcoma of the spine in the thoracic vertebral body

INTRODUCTION

Synovial sarcomas of the spine are very rare, most rare of which was occurring in the thoracic vertebral body. The diagnosis of synovial sarcomas was very difficult. It depends on the radiological examination, immunohistochemical examination and gene examination. The best treatment to them was completely surgical resection with negative margins. Other treatments such as radiation therapy and chemotherapy were just adjuvant. The prognosis of synovial sarcomas was disappointing.

CASE PRESENTATION

A 26-year-old male patient had low back pain. The radiological examination showed bony erosion of the T7 vertebral body and no soft tissue mass around the spine. He underwent T7 resection en bloc and internal fixation with two levels above T7 and two levels below T7. Then histopathological and gene examination revealed high malignant synovial sarcoma. So he was treated by chemotherapy and external beam radiation therapy after surgery.

CONCLUSION

Primary vertebral body synovial sarcoma is very rare and difficult to diagnose and treat.

Specific targeting of a naturally presented osteosarcoma antigen, papillomavirus binding factor peptide, using an artificial monoclonal antibody

Osteosarcoma is a rare but highly malignant tumor occurring most frequently in adolescents. The prognosis of non-responders to chemotherapy is still poor, and new treatment modalities are needed. To develop peptide-based immunotherapy, we previously identified autologous cytotoxic T lymphocyte-defined osteosarcoma antigen papillomavirus binding factor (PBF) in the context of HLA-B55 and the cytotoxic T lymphocyte epitope (PBF A2.2) presented by HLA-A2. PBF and HLA class I are expressed in ∼90 and 70% of various sarcomas, respectively. However, the expression status of peptide PBF A2.2 presented by HLA-A2 on osteosarcoma cells has remained unknown because it is difficult to generate a specific probe that reacts with the HLA·peptide complex. For detection and qualification of the HLA-A*02:01·PBF A2.2 peptide complex on osteosarcoma cells, we tried to isolate a single chain variable fragment (scFv) antibody directed to the HLA-*A0201·PBF A2.2 complex using a naïve scFv phage display library. As a result, scFv clone D12 with high affinity (KD = 1.53 × 10(-9) M) was isolated. D12 could react with PBF A2.2 peptide-pulsed T2 cells and HLA-A2+PBF+ osteosarcoma cell lines and simultaneously demonstrated that the HLA·peptide complex was expressed on osteosarcoma cells. In conclusion, scFv clone D12 might be useful to select candidate patients for PBF A2.2 peptide-based immunotherapy and develop antibody-based immunotherapy.

Vaccination using peptides spanning the SYT-SSX tumor-specific translocation

Evaluation of: Kawaguchi S, Tsukahara T, Ida K et al. SYT-SSX breakpoint peptide vaccines in patients with synovial sarcoma: a study from the Japanese Musculoskeletal Oncology Group. Cancer Sci. 103(9), 1625-1630 (2012). The identification of genetic translocations as key tumor-initiating events has led to the development of novel antigen-specific vaccines targeting these tumor-specific breakpoint regions. Previous studies have evaluated vaccines targeting the breakpoints in the BCR-ABL translocation in patients with chronic myelogenous leukemia and EWS-FLI1 in patients with Ewing sarcoma. In the article under evaluation, the authors evaluated a peptide vaccine targeting the breakpoint in the SYT-SSX translocation, the genetic translocation essentially pathognomonic for synovial sarcoma. This is the second small clinical trial reported by this group using HLA-A24-binding peptides as vaccine antigens. In this four-arm trial, using a native or HLA-A24-optimized SYT-SSX peptide with or without adjuvant plus IFN-α, they immunized patients with metastatic synovial sarcoma. Immune responses were evaluated by delayed-type hypersensitivity testing and tetramer analysis. No robust evidence of immune response to the target epitope was detected. Some patients treated with peptide in adjuvant plus IFN-α had stable disease. These results suggest that future similar studies might best evaluate patients with a lower burden of disease, consider alternative immunization approaches to the SYT-SSX target antigen and consider the efficacy of IFN-α alone for the treatment of synovial sarcoma.

A Pilot Study of Anti-CTLA4 Antibody Ipilimumab in Patients with Synovial Sarcoma

Background. Patients with recurrent synovial sarcomas have few options for systemic therapy. Since they express large amounts of endogenous CT (cancer testis) antigens such as NY-ESO-1, we investigated the clinical activity of single agent anti-CTLA4 antibody ipilimumab in patients with advanced or metastatic synovial sarcoma. Methods. A Simon two-stage phase II design was used to determine if there was sufficient activity to pursue further. The primary endpoint was tumor response rate by RECIST 1.0. Patients were treated with ipilimumab 3 mg/kg intravenously every 3 weeks for three cycles and then restaged. Retreatment was possible for patients receiving an extra three-week break from therapy. Sera and peripheral blood mononuclear cells were collected before and during therapy to assess NY-ESO-1-specific immunity. Results. Six patients were enrolled and received 1–3 cycles of ipilimumab. All patients showed clinical or radiological evidence of disease progression after no more than three cycles of therapy, for a RECIST response rate of 0%. The study was stopped for slow accrual, lack of activity, and lack of immune response. There was no evidence of clinically significant either serologic or delayed type hypersensitivity responses to NY-ESO-1 before or after therapy. Conclusion. Despite high expression of CT antigens by synovial sarcomas of patients treated in this study, there was neither clinical benefit nor evidence of anti-CT antigen serological responses. Assessment of the ability of synovial sarcoma cell lines to present cancer-germ cell antigens may be useful in determining the reason for the observed lack of immunological or clinical activity.

SYT-SSX breakpoint peptide vaccines in patients with synovial sarcoma: a study from the Japanese Musculoskeletal Oncology Group

In the present study, we evaluated the safety and effectiveness of SYT-SSX-derived peptide vaccines in patients with advanced synovial sarcoma. A 9-mer peptide spanning the SYT-SSX fusion region (B peptide) and its HLA-A*2402 anchor substitute (K9I) were synthesized. In Protocols A1 and A2, vaccines with peptide alone were administered subcutaneously six times at 14-day intervals. The B peptide was used in Protocol A1, whereas the K9I peptide was used in Protocol A2. In Protocols B1 and B2, the peptide was mixed with incomplete Freund's adjuvant and then administered subcutaneously six times at 14-day intervals. In addition, interferon-α was injected subcutaneously on the same day and again 3 days after the vaccination. The B peptide and K9I peptide were used in Protocols B1 and B2, respectively. In total, 21 patients (12 men, nine women; mean age 43.6 years) were enrolled in the present study. Each patient had multiple metastatic lesions of the lung. Thirteen patients completed the six-injection vaccination schedule. One patient developed intracerebral hemorrhage after the second vaccination. Delayed-type hypersensitivity skin tests were negative in all patients. Nine patients showed a greater than twofold increase in the frequency of CTLs in tetramer analysis. Recognized disease progression occurred in all but one of the nine patients in Protocols A1 and A2. In contrast, half the 12 patients had stable disease during the vaccination period in Protocols B1 and B2. Of note, one patient showed transient shrinkage of a metastatic lesion. The response of the patients to the B protocols is encouraging and warrants further investigation.

Exploiting antitumor immunity to overcome relapse and improve remission duration

Cancer survivors often relapse due to evolving drug-resistant clones and repopulating tumor stem cells. Our preclinical study demonstrated that terminal cancer patient’s lymphocytes can be converted from tolerant bystanders in vivo into effective cytotoxic T-lymphocytes in vitro killing patient’s own tumor cells containing drug-resistant clones and tumor stem cells. We designed a clinical trial combining peginterferon α-2b with imatinib for treatment of stage III/IV gastrointestinal stromal tumor (GIST) with the rational that peginterferon α-2b serves as danger signals to promote antitumor immunity while imatinib’s effective tumor killing undermines tumor-induced tolerance and supply tumor-specific antigens in vivo without leukopenia, thus allowing for proper dendritic cell and cytotoxic T-lymphocyte differentiation toward Th1 response. Interim analysis of eight patients demonstrated significant induction of IFN-γ-producing-CD8⁺, -CD4⁺, -NK cell, and IFN-γ-producing-tumor-infiltrating-lymphocytes, signifying significant Th1 response and NK cell activation. After a median follow-up of 3.6 years, complete response (CR) + partial response (PR) = 100%, overall survival = 100%, one patient died of unrelated illness while in remission, six of seven evaluable patients are either in continuing PR/CR (5 patients) or have progression-free survival (PFS, 1 patient) exceeding the upper limit of the 95% confidence level of the genotype-specific-PFS of the phase III imatinib-monotherapy (CALGB150105/SWOGS0033), demonstrating highly promising clinical outcomes. The current trial is closed in preparation for a larger future trial. We conclude that combination of targeted therapy and immunotherapy is safe and induced significant Th1 response and NK cell activation and demonstrated highly promising clinical efficacy in GIST, thus warranting development in other tumor types.

Sarcoma immunotherapy

Much of our knowledge regarding cancer immunotherapy has been derived from sarcoma models. However, translation of preclinical findings to bedside success has been limited in this disease, though several intriguing clinical studies hint at the potential efficacy of this treatment modality. The rarity and heterogeneity of tumors of mesenchymal origin continues to be a challenge from a therapeutic standpoint. Nonetheless, sarcomas remain attractive targets for immunotherapy, as they can be characterized by specific epitopes, either from their mesenchymal origins or specific alterations in gene products. To date, standard vaccine trials have proven disappointing, likely due to mechanisms by which tumors equilibrate with and ultimately escape immune surveillance. More sophisticated approaches will likely require multimodal techniques, both by enhancing immunity, but also geared towards overcoming innate mechanisms of immunosuppression that favor tumorigenesis.

Primary cardiac synovial sarcoma: a case report and brief review of the literature

Synovial sarcoma comprises approximately 10% of all soft tissue sarcoma diagnoses; a primary synovial sarcoma of the myocardium is exceedingly rare. There have been very few cases reported in the literature thus far. With the identification of the characteristic and diagnostic chromosomal abnormality t(X;18), this may become an increasingly recognized entity. Our report adds to the limited published cases of primary cardiac synovial sarcoma with the characteristic t(X;18). Further elucidation of the effects of this translocation on the cell cycle may lead to directed therapies in the future.

Comparison of speedy PCR-ssp method and serological typing of HLA-A24 for Japanese cancer patients

Human leukocyte antigen (HLA) typing is essential to carry out HLA-class I restricted antigenic peptide-based cancer immunotherapy. To establish a one-step polymerase chain reaction-sequence-specific primer (PCR-SSP) method, we designed two novel HLA-A24-specific primer sets and determined the optimal conditions for specific amplification. Then, we performed HLA-A24 typing of two healthy donors' and 17 cancer patients' peripheral blood with serological typing and PCR-SSP typing. Eleven of the 19 cases were determined HLA-A24-positive by the PCR-SSP method precisely; however, five cases showed false positive with serological analysis. Thus, for HLA-A24 typing in the Japanese population, the PCR-SSP method is faster and more accurate than serological typing.

Phase I clinical trial of survivin-derived peptide vaccine therapy for patients with advanced or recurrent oral cancer

Survivin, a member of the inhibitor of apoptosis protein (IAP) family, is abundantly expressed in most malignancies, but is hardly detectable in normal adult tissues. Previously we have identified a human leukocyte antigen (HLA)-A24-restricted antigenic peptide, survivin-2B80-88 (AYACNTSTL), recognized by CD8(+) cytotoxic T lymphocytes (CTL). Survivin-2B80-88-specific CTL were induced efficiently from peripheral blood mononuclear cells (PBMC) of oral cancer patients after stimulation with the peptide in vitro. We conducted a phase I clinical study to evaluate the safety and the efficacy of survivin-2B80-88 peptide vaccination in HLA-A24-positive patients with advanced or recurrent oral cancer. The vaccines were given subcutaneously or intratumorally six times at 14-day intervals. Eleven patients were enrolled and 10 patients completed the vaccination protocol. No adverse events were observed in any patients. In two patients, the levels of serum squamous cell carcinoma (SCC) antigen decreased transiently during the period of vaccination. Tumor regression that was compatible with a partial response (PR) was noted in one patient. The remaining nine patients experienced progressive disease (PD). Immunologically, an increase of the peptide-specific CTL frequency was detected in six of the eight patients evaluated by HLA-A24/peptide tetramer analysis. The present clinical trial revealed that survivin-2B peptide vaccination was safe and had therapeutic potential for oral cancer patients. However, subsequent clinical trials in combination with various adjuvant drugs will be required to improve the immunological and therapeutic efficacy. This trial was registered with University Hospital Medical Information Network (UMIN) number UMIN000000976.

Phase I clinical study of anti-apoptosis protein survivin-derived peptide vaccination for patients with advanced or recurrent urothelial cancer

Survivin, a member of the inhibitor of apoptosis protein family, is expressed in many malignant tumors including urothelial cancer but is hardly detectable in normal, differentiated adult tissues. Previously we reported CD8-positive cytotoxic T-lymphocytes (CTLs) were successfully induced by stimulation with survivin-2B80-88 peptide in vitro. We started a phase I clinical study of survivin-2B80-88 peptide vaccination for advanced urothelial cancer patients to assess the safety and efficacy of this vaccination. Nine patients were received vaccination and were evaluated for immunological evaluation, adverse events, and clinical responses. A total of 46 vaccinations were carried out. There was no severe adverse event. HLA-A24/survivin-2B80-88 peptide tetramer analysis revealed a significant increase in the peptide-specific CTL frequency after the vaccination in five patients. Slight reduction of the tumor volume was observed in one patient. Survivin-2B80-88 peptide-based vaccination is safe and should be further considered for potential immune and clinical efficacy in urothelial cancer patients.

Cep55/c10orf3, a tumor antigen derived from a centrosome residing protein in breast carcinoma

Identification of tumor-associated antigens may facilitate vaccination strategies to treat patients with malignant diseases. We have found that the centrosomal protein, Cep55/c10orf3 acts as a novel breast carcinoma-associated tumor-associated antigen. Cep55/c10orf3 mRNA was detectable in a wide variety of tumor cell lines. Expression was barely detectable in normal tissues except for testis and thymus. Moreover, Cep55/c10orf3 protein could be detected by a monoclonal anti-Cep55/c10orf3 antibody (# 11-55) in 69.8% of breast carcinoma, 25% of colorectal carcinoma, and 57.8% of lung carcinoma tissues. The expression of Cep55/c10orf3 protein did not show any relationship with the hormone receptors such as estrogen receptor and progesterone receptor or expression patterns of p185 HER2/neu. We designed 11 peptides which displayed a human leukocyte antigen-A24 binding motif. One Cep55/c10orf3-peptide, Cep55/c10orf3_193(10) (VYVKGLLAKI), induced cytotoxic T lymphocytes (CTLs) in 3 of 3 patients with Cep55/c10orf3 (# 11-55)-positive breast carcinoma. A Cep55/c10orf3_193(10)-specific CTL clone could also recognize Cep55/c10orf3 (+) displayed on human leukocyte antigen-A24 (+) cancer cell lines. These data indicate that Cep55/c10orf3 peptides were naturally presented by breast cancer cells and can cause CTL clonal expansion in vivo. Monoclonal antibody # 11-55 and the Cep55/c10orf3_193(10) peptides may be useful as part of a therapeutic strategy for hormonal therapy or anti-p185 HER2/neu monoclonal antibody therapy-resistant breast carcinoma patients.

Side population cells have the characteristics of cancer stem-like cells/cancer-initiating cells in bone sarcomas

Background:

Several human cancers have been found to contain cancer stem-like cells (CSCs) having cancer-initiating ability. However, only a few reports have shown the existence of CSCs in bone and soft tissue sarcomas. In this study, we identified and characterised side population (SP) cells that showed drug-resistant features in human bone sarcoma cell lines.

Methods:

In seven osteosarcoma cell lines (OS2000, KIKU, NY, Huo9, HOS, U2OS and Saos2) and in one bone malignant fibrous histiocytoma (MFH) cell line (MFH2003), the frequency of SP cells was analysed. Tumourigenicity of SP cells was assessed in vitro and in vivo. Gene profiles of SP cells and other populations (main population; MP) of cells were characterised using cDNA microarrays.

Results:

SP cells were found in NY (0.31%) and MFH2003 (5.28%). SP cells of MFH2003 formed spherical colonies and re-populated into SP and MP cells. In an NOD/SCID mice xenograft model, 1 × 10³ sorted SP cell-induced tumourigenesis. cDNA microarray analysis showed that 23 genes were upregulated in SP cells.

Conclusions:

We showed that SP cells existed in bone sarcoma cell lines. SP cells of MFH2003 had cancer-initiating ability in vitro and in vivo. The gene profiles of SP cells could serve as candidate markers for CSCs in bone sarcomas.

Molecular genetics of sarcomas: applications to diagnoses and therapy

Sarcomas are mesenchymal cancers consisting of tumors with various clinical and pathological features. Some of them compel affected individuals to lose important musculoskeletal functions, and some of them are highly malignant and life-threatening. A great amount of genetic information for sarcomas has accumulated during the past two decades, contributing diagnoses and treatments. From the standpoint of molecular genetics, sarcomas are classified into two groups: those with defined genetic alterations and those with various genetic alterations. The genetic alterations in the first group include reciprocal translocations resulting in fusion oncoproteins and oncogenic mutations of defined genes such as those of the c-kit gene in gastrointestinal stromal tumors. The function of fusion proteins includes transcription regulator, signal transducer, chromatic remodeling factor, and growth factor, some of which are suitable targets for the molecular therapy. In tumors belonging to the second group, the number of which is far larger than those of the first group, considerable genetic heterogeneity was found even among tumors with same pathological diagnosis. The disruption of the RB and p53 pathways was frequently found, resulting in the dysregulation of cell cycle and the genomic instability. The application of molecular target therapy for tumors in this group requires novel strategies to overcome cross talk between different signal pathways. Recent evidence from in vitro and in vivo experiments has indicated that the cells of origin of sarcomas are tissue stem cells such as mesenchymal stem cells, and the application of stem cell biology holds the promise of novel treatment options.

HLA-A*0201-restricted CTL epitope of a novel osteosarcoma antigen, papillomavirus binding factor

Background

To develop peptide-based immunotherapy for osteosarcoma, we previously identified papillomavirus binding factor (PBF) as a CTL-defined osteosarcoma antigen in the context of HLA-B55. However, clinical application of PBF-based immunotherapy requires identification of naturally presented CTL epitopes in osteosarcoma cells in the context of more common HLA molecules such as HLA-A2.

Methods

Ten peptides with the HLA-A*0201 binding motif were synthesized from the amino acid sequence of PBF according to the BIMAS score and screened with an HLA class I stabilization assay. The frequency of CTLs recognizing the selected PBF-derived peptide was determined in peripheral blood of five HLA-A*0201⁺ patients with osteosarcoma using limiting dilution (LD)/mixed lymphocyte peptide culture (MLPC) followed by tetramer-based frequency analysis. Attempts were made to establish PBF-specific CTL clones from the tetramer-positive CTL pool by a combination of limiting dilution and single-cell sorting. The cytotoxicity of CTLs was assessed by ⁵¹Cr release assay.

Results

Peptide PBF A2.2 showed the highest affinity to HLA-A*0201. CD8+ T cells reacting with the PBF A2.2 peptide were detected in three of five patients at frequencies from 2 × 10^-7 to 5 × 10^-6. A tetramer-positive PBF A2.2-specific CTL line, 5A9, specifically lysed allogeneic osteosarcoma cell lines that expressed both PBF and either HLA-A*0201 or HLA-A*0206, autologous tumor cells, and T2 pulsed with PBF A2.2. Five of 12 tetramer-positive CTL clones also lysed allogeneic osteosarcoma cell lines expressing both PBF and either HLA-A*0201 or HLA-A*0206 and T2 pulsed with PBF A2.2.

Conclusion

These findings indicate that PBF A2.2 serves as a CTL epitope on osteosarcoma cells in the context of HLA-A*0201, and potentially, HLA-A*0206. This extends the availability of PBF-derived therapeutic peptide vaccines for patients with osteosarcoma.

Molecular pathological approaches to human tumor immunology

Research on human tumor immunology has greatly advanced in the past two decades. Many immunogenic tumor antigens have been identified, and some of these antigens entered in clinical trials. Consequently, it has been shown that these antigens can inhibit tumor growth in patients to some extent, indicating that they act as potent immunogenic therapeutic vaccines in cancer patients with malignancies originating from various tissues. These patients had antigen-specific cytotoxic T-lymphocyte (CTL) responses when assessed on tetramer, enzyme-linked immunospot (ELISPOT), T-cell clonotype and CTL induction efficiency. Thus, it has become clear that human tumor vaccines can evoke clinical and immunological anti-tumor responses in patients. The tumor regression effects of tumor vaccines, however, are generally low, and it is obvious that current vaccination protocols are generally too weak to provide substantial and satisfactory clinical benefits. This means that other drastic and more potent clinical and immunological protocols are required in cancer immunotherapy. To find such efficient protocols the basic immunological and biological properties of cancers must be investigated. In the present review the identification of human tumor antigens recognized on CTL and the clinical trials are introduced. Next, the most recent analysis of human cancer-initiating cell (cancer stem cell)-associated antigens is described. These antigens might be able to act as 'universal, general and fundamental' tumor antigens. Also present is the authors' recent study for increasing cross-presentation efficiency in dendritic cells and subsequent enhancement of human leukocyte antigen (HLA)-class I-restricted peptide antigenicity by using HSP90 and ORP150 molecular chaperones that act as endogenous Toll-like receptor ligands. In addition to the aforementioned manipulation of the positive loop of tumor immunity, it is necessary to regulate and intervene in the negative loop. In particular, the potential of the expression of HLA class I molecule regulation by epigenetic mechanisms will be discussed. Finally, the type of basic and clinical tumor immunology research highly required currently, and in the very near future, are described.

Comparative study on the immunogenicity between an HLA-A24-restricted cytotoxic T-cell epitope derived from survivin and that from its splice variant survivin-2B in oral cancer patients

BACKGROUND

We previously reported an HLA-A24-restricted cytotoxic T-cell epitope, Survivin-2B80-88, derived from a splice variant of survivin, survivin-2B. In this report, we show a novel HLA-A24-restricted T-cell epitope, Survivin-C58, derived from a wild type survivin, and compared their immunogenicity in oral cancer patients.

METHODS

By stimulating peripheral blood lymphocytes of HLA-A24-positive cancer patients with Survivin-C58 peptide in vitro, the peptide-specific CTLs were induced. In order to compare the immunogenic potential between C58 peptide and 2B80-88 peptide, peripheral blood T-cells from thirteen HLA-A24-positive oral cancer patients were stimulated with either or both of these two peptides.

RESULTS

Survivin-2B80-88 peptide-specific CTLs were induced from four patients, and C58 peptide-specific CTLs were induced from three out of eight patients with over stage II progression. The CTLs exerted cytotoxicity against HLA-A24-positive tumor cells. In contrast, CTL induction failed from a healthy volunteer and all four patients with cancer stage I.

CONCLUSION

It was indicated that a splicing variant-derived peptide and wild type survivin-derived peptide might have a comparable potency of CTL induction, and survivin targeting immunotherapy using survivin-2B80-88 and C58 peptide cocktail should be suitable for HLA-A24+ oral cancer patients.

Identification of an immunogenic CTL epitope of HIFPH3 for immunotherapy of renal cell carcinoma

PURPOSE

CD8(+) CTLs have an essential role in immune response against tumor. Although tumor-associated antigens have been identified in renal cell carcinoma (RCC), few of these are commonly shared and investigated as therapeutic targets in the clinical medicine. In this report, we show that HIFPH3, a member of prolyl hydroxylases that function as oxygen sensor, is a novel tumor antigen and HIFPH3-specific CTLs are induced from peripheral blood lymphocytes of RCC patients.

EXPERIMENTAL DESIGN

Expression of HIFPH3 was examined by reverse transcription-PCR and immunostaining with anti-HIFPH3 antibody. To identify HLA-A24-restricted T-cell epitopes of HIFPH3, eight peptides were selected from the amino acid sequence of this protein and screened for their binding affinity to HLA-A24. Peptide-specific CTLs were induced by stimulating peripheral blood lymphocytes of HLA-A24-positive RCC patients with these peptides in vitro. HLA-A24-restricted cytotoxicity of the CTLs against HIFPH3(+) RCC lines was assessed by chromium release assay.

RESULTS

HIFPH3 was overexpressed in many RCC cell lines and primary RCC tissues, whereas it was not detectable in normal adult tissues by reverse transcription-PCR. Of the eight peptides that contained HLA-A24-binding motif, HIFPH3-8 peptide (amino acid sequence, RYAMTVWYF) could induce the peptide-specific CTLs from 3 of 6 patients with HIFPH3-positive RCC. Furthermore, HIFPH3-8 peptide-specific CTLs showed cytotoxicity against HIFPH3(+) RCC cell lines in a HLA-A24-restricted manner.

CONCLUSIONS

HIFPH3 may be a target antigen in immunotherapy for RCC and HIFPH3-8 peptide could be used as a peptide vaccine for HLA-A*2402(+)/HIFPH3(+) RCC patients.

Synovial sarcoma: from genetics to genetic-based animal modeling

Synovial sarcomas are highly aggressive mesenchymal cancers that show modest response to conventional cytotoxic chemotherapy, suggesting a definite need for improved biotargeted agents. Progress has been hampered by the lack of insight into pathogenesis of this deadly disease. The presence of a specific diagnostic t(X;18) translocation leading to expression of the unique SYT-SSX fusion protein in effectively all cases of synovial sarcoma suggests a role in the etiology. Other nonspecific anomalies such as overexpression of Bcl-2, HER-2/neu, and EGFR have been reported, but their role in the pathogenesis remains unclear. Using gene targeting, we recently generated mice conditionally expressing the human SYT-SSX2 fusion gene from mouse endogenous ROSA26 promoter in chosen tissue types in the presence of Cre recombinase. These mice develop synovial sarcoma when SYT-SSX2 is expressed within myoblasts, thereby identifying a source of this enigmatic tumor and establishing a mouse model of this disease that recapitulates the clinical, histologic, immunohistochemical, and transcriptional profile of human synovial sarcomas. We review the genetics of synovial sarcoma and discuss the usefulness of genetics-based mouse models as a valuable research tool in the hunt for key molecular determinants of this lethal disease as well as a preclinical platform for designing and evaluating novel treatment strategies.

Clonal T-cell response against autologous pleomorphic malignant fibrous histiocytoma antigen presented by retrieved HLA-A*0206

Towards the goal of identifying tumor-rejection antigens on eradicated tumors in bone and soft tissue sarcomas, we evaluated the immune response against antigens presented by lost HLA class I molecules. Tumor specimens and peripheral blood samples were obtained from a 70-year-old woman with pleomorphic malignant fibrous histiocytoma. Over 1-year culture, a tumor cell line (MFH2004) was established. A B-cell line infected with Epstein-Barr virus (B2004-EBV) was developed from the blood samples. HLA genotypes of B2004-EBVcells were A*0206/2402, B*4006/4601, and C*0102/0801, whereas MFH2004 cells were defective for A*0206, B*4006, and C*0102. Loss of HLA-A2 expression was also proved immunohistochemically in the primary tumor tissues. Lost HLA-A2 in MFH2004 cells was retrieved by transfection of HLA-A*0206 cDNA to develop MFH2004-A2. Attempts to induce CTLs by mixed culture with autologous T cells and MFH2004 cells resulted in failure. In contrast, those with MFH2004-A2 induced CTL clones CTL2004-c6 and CTL2004-c17. These CTL clones specifically killed MFH2004-A2 but not MFH2004 or B2004-EBV in an HLA-A2-restricted manner. These findings suggest that CTL2004-c6 and CTL2004-c17 recognize autologous tumor-rejection antigens presented by HLA-A*0206, which may have been expressed by tumor cells that had been eradicated by the host's immunosurveillance system.

Prognostic impact and immunogenicity of a novel osteosarcoma antigen, papillomavirus binding factor, in patients with osteosarcoma

To develop peptide-based immunotherapy for osteosarcoma, we previously identified papillomavirus binding factor (PBF) as a cytotoxic T lymphocytes (CTL)-defined osteosarcoma antigen in the context of human leukocyte antigen (HLA)-B55. In the present study, we analyzed the distribution profile of PBF in 83 biopsy specimens of osteosarcomas and also the prognostic impact of PBF expression in 78 patients with osteosarcoma who had completed the standard treatment protocols. Next, we determined the antigenic peptides from PBF that react with peripheral T lymphocytes of HLA-A24(+) patients with osteosarcoma. Immunohistochemical analysis revealed that 92% of biopsy specimens of osteosarcoma expressed PBF. PBF-positive osteosarcoma conferred significantly poorer prognosis than those with negative expression of PBF (P = 0.025). In accordance with the Bioinformatics and Molecular Analysis Section score, we synthesized 10 peptides from the PBF sequence. Subsequent screening with an HLA class I stabilization assay revealed that peptide PBF A24.2 had the highest affinity to HLA-A24. CD8(+) T cells reacting with a PBF A24.2 peptide were detected in eight of nine HLA-A24-positive patients with osteosarcoma at the frequency from 5 x 10(-7) to 7 x 10(-6) using limiting dilution/mixed lymphocyte peptide culture followed by tetramer-based frequency analysis. PBF A24.2 peptide induced CTL lines from an HLA-A24-positive patient, which specifically killed an osteosarcoma cell line that expresses both PBF and HLA-A24. These findings suggested prognostic significance and immunodominancy of PBF in patients with osteosarcoma. PBF is the candidate target for immunotherapy in patients with osteosarcoma.

Molecular target therapy for synovial sarcoma

Although the specific chromosomal translocation and fusion gene SYT-SSX in synovial sarcoma (SS) has been identified, the molecular mechanism of its tumorigenesis is largely unknown. Recent gene-expression profiles of soft-tissue tumors using cDNA microarray demonstrated that SS has the distinct gene-expression pattern from other sarcomas and has a similar pattern to that of malignant peripheral nerve sheath tumors, indicating that the origin of SS is likely to be the neural crest cells. Through this analysis, several genes were found to be specifically upregulated in SS and considered to play an important role in the proliferation of SS cells. Among them, Frizzled homolog 10 was identified as a good candidate molecule for the development of novel therapies to treat SS patients.