Immunotherapeutic approaches to sarcoma

Prognosis and Immune Infiltration of Chromobox Family Genes in Sarcoma

Background

Chromobox family genes (CBXs) are known to play roles in numerous modifications of the chromatin in order to inhibit the transcription of target genes. CBXs have been shown to be expressed at high levels in many types of cancer and can also serve as a target gene for therapeutic purposes. However, little is known about the expression and prognostic value of CBXs in human sarcomas.

Methods

The transcription level of CBXs was analyzed using the Oncomine dataset, and the differential expression of CBXs in sarcoma was reported by the Gene Expression Profiling Interactive Analysis (GEPIA) dataset. We also used the CCLE dataset to evaluate the expression of CBXs in a sarcoma cell line. The prognostic value of CBXs was analyzed using GEPIA and Kaplan–Meier analysis. In addition, the corrections between CBXs and their co-expressed genes were reported using Oncomine and GEPIA datasets. DAVID was used to perform GO function enrichment analysis for the CBXs and their co-expression genes. Finally, TIMER was used to analyze the immune cell infiltration of CBXs in patients with sarcoma.

Results

HP1-α/β/γ (CBX1/3/5) and CBX4/6/8 were found to be overexpressed in human sarcoma, and CBXs were upregulated in almost all the sarcoma cell line. The expression levels of HP1-α/β/γ (CBX1/3/5) and CBX7 were associated with overall survival (OS) in patients with sarcoma, while high expression levels of CBX7 were related to disease-free survival (DFS). In addition, the expression levels of CBX2/6/7 were related to recurrence-free survival (RFS). We also found that the CBX family was positively correlated with the infiltration of immune cells, including CD8⁺ T cells, CD4⁺ T cells, B cells, macrophages, neutrophils, and dendritic cells, in sarcoma.

Conclusions

The results from the present study indicated that CBXs were significantly associated with prognosis and immunological status in sarcoma. These data suggest that CBXs could serve as potential biomarkers for prognosis and immune infiltration in human sarcoma.

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.

Intraperitoneal immunotherapy: historical perspectives and modern therapy

Intraperitoneal immunotherapy represents a novel strategy for the management of peritoneal metastases (PM). Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) has remained the gold standard of treatment for patients with PM, yet despite optimal treatment, recurrence rates remain high and long-term survival poor. From Coley's toxins to immune checkpoint inhibitors, the wide variety of anticancer immunotherapeutic strategies are now garnering attention for control of regional disease of the peritoneal cavity. Early studies with vaccine-based therapies, adoptive cell transfer, immune checkpoint inhibitors, and chimeric T cells with tumor-specific antigen receptors (CAR-T cells) are being performed, showing promise for control of peritoneal spread and induction of lasting anticancer immunity. In addition, catumaxomab, a trifunctional antibody, has been approved for intraperitoneal immunotherapy in Europe for the control of malignant ascites in patients with epithelial cell adhesion molecule positive cancers. We review a brief history of immunotherapy and current modalities under investigation for intraperitoneal use in the treatment of PM.

Prognostic implications of PD-L1 expression in patients with soft tissue sarcoma

Background

The PD-1/PD-L1 axis plays a paramount role in the immune escape of tumor cells by negative regulation of T-cell functions. The aim of the present study was to characterize the PD-L1 expression pattern and its clinical implication in soft-tissue sarcomas (STS).

Methods

We analyzed PD-L1 expression in 82 STS patients with 5 subtypes: rhabdomyosarcoma, synovial sarcoma, Ewing sarcoma, epithelioid sarcoma, and mesenchymal chondrosarcoma.

Results

The median age at diagnosis was 26 (range: 1–78) and the male to female ratio was 1.6. The majority (80 %) of patients showed locoregional disease rather than metastatic disease at diagnosis. Thirty-five cases (43 %) showed PD-L1 expression and the proportion of PD-L1 expression was significantly different according to histologic subtypes (P = 0.004); highest in epithelioid sarcoma (100 %, 7/7), followed by synovial sarcoma (53 %, 10/19), rhabdomyosarcoma (38 %, 12/32), and Ewing sarcoma (33 %, 6/18), while it was not expressed in mesenchymal chondrosarcoma (0 %, 0/6). STS patients with PD-L1 expression had worse overall survival compared with those without PD-L1 expression (5-year survival rate: 48 % vs. 68 %, P = 0.015). The Cox proportional hazard model adjusted for histologic subtype, initial metastasis, and PD-L1 expression showed that PD-L1 expression was significantly associated with shorter overall survival (P = 0.037, HR 2.57, 95 % CI 1.060–6.231).

Conclusion

We have confirmed PD-L1 expression in various STS of young population and demonstrated its independent negative prognostic role, thereby suggesting the PD-1/PD-L1 axis as a potential therapeutic target for the treatment of young STS patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2451-6) contains supplementary material, which is available to authorized users.

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.

Dendritic cell immunotherapy in soft tissue sarcoma

Soft tissue sarcomas represent a rare but diverse family of tumors affecting patients of all ages. Conventional chemotherapy rarely eradicates metastatic disease and newer targeted agents are successful in only very specific histologic subgroups. Therefore, scientists and clinicians are investigating immunotherapy techniques, primarily involving cellular immunity focused on the T-cell response to tumor antigens. In both animal models and human sarcoma trials, dendritic cells have been shown to induce an effective antitumor immune response. Radiotherapy, particularly when delivered in a hypofractionated manner prior to sarcoma excision, may potentiate the function of the dendritic cells through the induction of apoptosis. The synergistic effect may carry over to other cancer types and warrants further multidisciplinary investigation.

Molecular approaches to sarcoma therapy

Soft tissue sarcomas comprise a heterogeneous group of aggressive tumors that have a relatively poor prognosis. Although conventional therapeutic regimens can effectively cytoreduce the overall tumor mass, they fail to consistently achieve a curative outcome. Alternative gene-based approaches that counteract the underlying neoplastic process by eliminating the clonal aberrations that potentiate malignant behavior have been proposed. As compared to the accumulation of gene alterations associated with epithelial carcinomas, sarcomas are frequently characterized by the unique presence of a single chromosomal translocation in each histological subtype. Similar to the Philadelphia chromosome associated with CML, these clonal abnormalities result in the fusion of two independent unrelated genes to generate a unique chimeric protein that displays aberrant activity believed to initiate cellular transformation. Secondary gene mutations may provide an additional growth advantage that further contributes to malignant progression. The recent clinical success of the tyrosine kinase inhibitor, STI571, suggests that therapeutic approaches specifically directed against essential survival factors in sarcoma cells may be effective. This review summarizes published approaches targeting a specific molecular mechanism associated with sarcomagenesis. The strategy and significance of published translational studies in six distinct areas are presented. These include: (1) the disruption of chimeric transcription factor activity; (2) inhibition of growth stimulatory post-translational modifications; (3) restoration of tumor suppressor function; (4) interference with angiogenesis; (5) induction of apoptotic pathways; and (6) introduction of toxic gene products. The potential for improving outcomes in sarcoma patients and the conceptual obstacles to be overcome are discussed.

HLA-restricted specific tumor cytolysis by autologous T-lymphocytes infiltrating metastatic bone malignant fibrous histiocytoma of lymph node

Malignant fibrous histiocytoma (MFH) of the bone is a high-grade sarcoma characterized histologically by the composition of fibroblasts and pleomorphic cells with a prominent storiform pattern. Despite institution of multi-modality treatments, the prognosis for patients with this tumor remains unsatisfactory. In the present study, towards the goal of developing active immunotherapy for those affected, we established four cell lines from a 53-year-old woman who suffered from MFH of the humerus with lymph node metastases. MFH2003 and MFH2003-B7.1 were the primary lesion-derived cell line and its B7.1-transfectant, respectively. B2003-EBV and TIL2003 were a B cell line established from peripheral blood lymphocytes and a T cell line established from tumor-invaded lymph nodes, respectively. MFH2003 cells could be maintained over a period of 1 year in vitro, and could be xenotransplanted into nude mice. The phenotype of cells analyzed by immunostaining was similar to the original tumor. TIL2003 cells were all CD8+ and specifically recognized MFH2003 cells and MFH2003-B7.1 cells, but not B2003-EBV cells. An anti-HLA-class I monoclonal antibody completely blocked the anti-MFH2003 response of TILs2003. These findings indicate the existence of an anti-MFH specific immune response in the microenvironment of metastatic lymph nodes. The present autologous cell lines provide the basis for identification of novel tumor-associated antigens and may be helpful in the establishment of immunotherapy for patients with MFH of the bone.

A quest for therapeutic antigens in bone and soft tissue sarcoma

Over the past three decades, there have been remarkable advances in the treatment of bone and soft tissue sarcomas. These include the introduction of adjuvant chemotherapy, establishment of guidelines for adequate surgical margins, and the development of post-excision reconstruction. There have also been advances in the field of immunotherapy against bone and soft tissue sarcomas, which, unfortunately, have received less attention. However, lack of progress in chemotherapy-based treatments for bone and soft tissue sarcomas has reignited interest in immunotherapeutic approaches. Here we summarize current progress in the immunotherapy of bone and soft tissue sarcomas including the strategies utilized to identify tumor-associated antigens, and the design of clinical trials.

Experimental approaches to treatment of soft tissue sarcoma

The experimental approaches described in this article represent potential new approaches for targeted therapy. Thus far, none of the preclinical data have demonstrated a cure for sarcomas; however, the antitumor effects of many of these new agents seem to be enhanced when the agents are combined with chemotherapeutic agents. The combination of novel therapeutics with conventional chemotherapy may be the most effective strategy in terms of maximization of tumor killing and minimization of toxicity and the risk of drug resistance. Not only are new drugs being developed for treatment of sarcomas but new ways of delivering drugs are also being investigated. The angiogenic, or metronomic, schedule of drug delivery may be preferable to conventional schedules in achieving optimal tumor inhibition. In addition, isolated limb perfusion is a unique approach to delivery of drugs, such as TNF and melphalan, for sarcomas and melanomas [137, 138]. The advantages of this method of drug delivery include the ability to administer therapeutic agents in high concentrations to a specific region of the body without systemic toxicity. Further advances in the understanding of the biology of sarcomas along with novel approaches to delivery of drugs are crucial to the development of new and effective therapies.

Ewing's sarcoma: diagnostic, prognostic, and therapeutic implications of molecular abnormalities

The identification of the non-random chromosome rearrangements between the EWS gene on chromosome 22q12 and members of the ETS gene family in Ewing's sarcoma, peripheral primitive neuroectodermal tumour, Askin tumour, and neuroepithelioma has been a key advance in understanding their common histogenesis and defining the Ewing's sarcoma family of tumours (ESFT). In addition to improvements in diagnosis and potentially the stratification of patients for risk, biological investigations of these gene fusions may define targets for much needed therapeutic strategies to eliminate minimal residual disease or metastatic disease. Insight into their relation with other oncogenic events in ESFT will advance risk group analysis and ultimately may improve clinical management and survival for patients with this disease.

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

To investigate the immunogenic property of peptides derived from the synovial sarcoma-specific SYT-SSX fusion gene, we synthesized four peptides according to the binding motif for HLA-A24. The peptides, SS391 (PYGYDQIMPK) and SS393 (GYDQIMPKK), were derived from the breakpoint of SYT-SSX, and SS449a (AWTHRLRER) and SS449b (AWTHRLRERK) were from the SSX region. These peptides were tested for their reactivity with CTL precursors (CTLps) in 16 synovial sarcoma patients using HLA-A24/SYT-SSX peptide tetramers and also for induction of specific CTLs from four HLA-A24(+) synovial sarcoma patients. Tetramer analysis indicated that the increased CTLp frequency to the SYT-SSX was associated with pulmonary metastasis in synovial sarcoma patients (p < 0.03). CTLs were induced from PBLs of two synovial sarcoma patients using the peptide mixture of SS391 and SS393, which lysed HLA-A24(+) synovial sarcoma cells expressing SYT-SSX as well as the peptide-pulsed target cells in an HLA class I-restricted manner. These findings suggest that aberrantly expressed SYT-SSX gene products have primed SYT-SSX-specific CTLps in vivo and increased their frequency in synovial sarcoma patients. The identification of SYT-SSX peptides may offer an opportunity to design peptide-based immunotherapeutic approaches for HLA-A24(+) patients with synovial sarcoma.

Diagnosis of soft tissue tumors by fine-needle aspiration with combined cytopathology and ancillary techniques

The diagnosis of mesenchymal neoplasm by fine-needle aspiration biopsy (FNAB) has presented a diagnostic challenge. Most reports claim an accuracy approaching 95%, but while they distinguish benign and malignant lesions, the most problematic group, the intermediary malignant group, is omitted. The purpose of this study was to determine whether rapid cytologic diagnosis of soft-tissue tumors could guide surgeons in therapeutic decisions without the need for a tissue biopsy. Ninety-four FNA cytologic specimens were examined by the National Soft Tissue Consortium of Hungary and compared with the corresponding histology. Ordinary lipomas were excluded. Morphologic evaluation was supplemented by ancillary techniques such as fluorescence in situ hybridization (FISH), DNA cytometry, and immunocytochemistry. From a practical clinicopathological point of view, the cases were grouped in the following categories: 1) tumors with definitive diagnosis: a) high-grade malignant neoplasms (high-grade sarcomas, metastatic carcinomas, lymphoma), b) tumors with precise histogenetic origin by cytogenetics, c) benign tumors; 2) tumors of questionable nature. In the first group there were 74 tumors: 22 high-grade sarcomas, six metastatic carcinomas, one malignant lymphoma, 16 malignant tumors in which the precise histogenetic origin could be established by cytogenetic studies, and 29 benign soft-tissue tumors other than lipomas. In the second group there were 20 tumors comprising benign and malignant soft tissue tumors of low grade, wherein the precise nature of the neoplasm could not be established with confidence on cytologic study, even using ancillary techniques. FNAB of soft-tissue tumors combined with ancillary techniques should be considered a viable diagnostic technique for therapeutic protocols. Although the second group is fairly large, we have reliable, well-characterized categories which provide great freedom for preoperative and surgical treatment, thus providing the best chance for healing.

Soft tissue sarcoma as a model disease to examine cancer immunotherapy

Immunotherapy is in its infancy for many diseases, whether they are neoplastic or autoimmune. The major issues for cancer immunotherapy today involve the definition of molecular targets and the generation of effector mechanisms to attack the targets of interest. Soft tissue sarcomas provide a unique opportunity to examine the immune response against defined antigens. Many types of sarcomas contain tumor-specific chromosomal translocations encoding fusion proteins, which are attractive targets for immunotherapy. Our understanding of the immune system is also coming into clearer focus with the discovery of dendritic cells as powerful natural adjuvants and the teasing out of mechanisms leading to immunity versus tolerance as examples. It is hoped that the intersection of cellular immunology and sarcoma molecular biology will lead to new modalities of therapy for this group of patients with this heterogeneous group of diseases.

Eradication of established tumors by CD8+ T cell adoptive immunotherapy

We generated the DUC18 T cell receptor transgenic mouse expressing an H-2Kd -restricted transgenic T cell receptor specific for the syngeneic CMS5 fibrosarcoma rejection antigen mutated ERK2(136-144). DUC18 mice were capable of specifically eliminating lethal CMS5 tumor challenges, and transfer of DUC18 splenocytes to naive nontransgenic recipients conferred protection from subsequent and established CMS5 tumor burdens. Eradication of established tumor burdens by adoptive transfer of DUC18 splenocytes was dose and time dependent. Transferred tumor-specific T cells remained functional in vivo and capable of rejecting small tumors even in the presence of large, established tumor burdens. These findings highlight the kinetic battle between tumor growth and the production of a tumor-specific response and have critical implications for effective adoptive immunotherapy.