Turning 'Cold' tumors 'Hot': immunotherapies in sarcoma

Challenges and hope: latest research trends in the clinical treatment and prognosis of liposarcoma

Liposarcoma, as a complex disease, is characterized by intricate interactions between distinct histopathological subtypes and corresponding clinical outcomes, emphasizing the necessity of personalized approaches in diagnosis and treatment strategies. This malignant tumor originating from adipose tissue is classified into different subtypes with specific molecular markers, which not only distinguish them but also guide treatment directions. The main approach for treating liposarcoma is surgical resection, with the aim of complete excision and achieving clean margins (R0 resection) to minimize the risk of recurrence. This surgical principle emphasizes the critical need for precise preoperative planning, and in certain cases, the integration of neoadjuvant therapy may be needed to reduce the tumor to a surgically manageable size. In addition to surgery, systemic therapy plays a key role in the advanced stages of the disease, especially when resistance to traditional treatment arises. The emergence of novel systemic therapies, including chemotherapy, targeted therapy, and immunotherapy, has opened new avenues for treating this challenging malignancy. These systemic therapies are selected on the basis of the specific molecular features of the tumor, highlighting the importance of detailed molecular diagnostics. As our understanding of the molecular basis of liposarcoma deepens, integrating clinical and molecular features is crucial for optimizing treatment outcomes. This comprehensive approach, which combines surgical precision with systemic therapy innovations, will change the treatment landscape for patients with liposarcoma, advancing toward more personalized and effective treatment strategies.

Potential Mechanisms for Immunotherapy Resistance in Adult Soft-Tissue Sarcoma

Soft-tissue sarcomas represent a diverse group of rare malignancies originating from mesenchymal tissue, accounting for less than 1% of adult cancers in the USA. With over 13,000 new cases and around 5350 deaths annually, patients with metastatic soft-tissue sarcomas face limited therapeutic options and an estimated median overall survival of 18 months. While immunotherapy has demonstrated effectiveness in several cancers, its application in soft-tissue sarcomas remains challenging owing to the tumors' largely "cold" immunological environment, characterized by low levels of tumor-infiltrating lymphocytes and a lack of soft-tissue sarcoma-specific biomarkers. This review examines potential mechanisms underlying immunotherapy resistance in soft-tissue sarcomas, including the complex interplay between innate and adaptive immunity, the tumor microenvironment, and the role of immune-related genes. Despite preliminary findings suggesting correlations between immune profiles and histological subtypes, consistent biomarkers for predicting immunotherapeutic responses across soft-tissue sarcoma types are absent. Emerging strategies focus on converting "cold" tumors to "hot" tumors, enhancing their susceptibility to immunologic activation. While research is ongoing, personalized treatment approaches may offer hope for overcoming the inherent heterogeneity and resistance seen in soft-tissue sarcomas, ultimately aiming to improve outcomes for affected patients.

Review of Adoptive Cellular Therapies for the Treatment of Sarcoma

Sarcomas are a heterogeneous group of malignancies with limited therapeutic options, particularly in the metastatic setting. Adoptive cellular therapies (ACTs), including tumor-infiltrating lymphocyte (TIL) therapy, chimeric antigen receptor (CAR) T-cell therapy, and T-cell receptor (TCR) gene-modified T-cell therapy, offer promising novel approaches for these refractory tumors. TIL-based therapy has demonstrated early efficacy in melanoma and myeloma, with ongoing trials exploring its role in sarcoma. CAR T-cell strategies targeting HER2, GD2, and B7-H3 antigens are in development, though challenges such as tumor microenvironment-mediated resistance and antigen escape remain significant. Engineered TCRs, particularly those targeting MAGE-A4 and NY-ESO-1, have shown promising clinical results in synovial sarcoma (SS) and myxoid/round cell liposarcoma (MRCLS), leading to the recent FDA approval of afamitresgene autoleucel (afami-cel) and letetresgene autoleucel (lete-cel). Despite encouraging preliminary data, ACT implementation faces barriers including limited antigen specificity, off-tumor toxicity, immune evasion, and manufacturing scalability. Future research will focus on optimizing lymphodepleting regimens, mitigating toxicity, enhancing in vivo persistence, and combining ACT with other therapeutic agents. As clinical trials expand, ACT holds the potential to revolutionize sarcoma treatment by offering durable, targeted therapies for previously refractory disease.

Targeting myeloid-derived suppressor cells in the tumor microenvironment: potential therapeutic approaches for osteosarcoma

Osteosarcoma is a bone malignancy characterized by strong invasiveness and rapid disease progression. The tumor microenvironment of osteosarcoma contains various types of immune cells, including myeloid-derived suppressor cells, macrophages, T cells, and B cells. Imbalances of these immune cells can promote the proliferation and metastasis of osteosarcoma. Recent studies have indicated a substantial increase in the levels of myeloid-derived suppressor cells, an immune cell associated with immunosuppressive and pro-cancer effects, in the peripheral blood of patients with osteosarcoma. Moreover, the levels of the pro-inflammatory cytokine interleukin 18 are positively correlated with those of myeloid-derived suppressor cells in the peripheral blood of animal models of osteosarcoma. In this review, we explore the function of myeloid-derived suppressor cells in osteosarcoma based on the clinical diagnoses of patients with osteosarcoma and discuss future therapeutic approaches for targeting osteosarcoma. Targeting myeloid-derived suppressor cells represents a promising approach to improving the prognosis and survival rates of patients with osteosarcoma.

Efficacy and safety of the combination of anlotinib and envafolimab in the treatment of unresectable or metastatic liposarcoma: findings from a single-center retrospective study

Objective

To evaluate the efficacy and safety of anlotinib combined with envafolimab in the treatment of unresectable or metastatic liposarcoma.

Methods

This single-center, retrospective study enrolled 15 patients with unresectable or metastatic liposarcoma, who were treated at the Retroperitoneal Tumor Surgery Research Center of Qingdao University Affiliated Hospital between April 2022 and November 2023. The treatment regimen consisted of anlotinib combined with envafolimab. Treatment efficacy was evaluated using the Response Evaluation Criteria in Solid Tumors version 1.1. Treatment-related adverse events (TRAEs) were assessed using Common Terminology Criteria for Adverse Events version 5.0.

Results

A total of 15 patients with unresectable or metastatic liposarcoma were included; among them, seven were male (46.7%) and eight were female (53.3%), with a median age of 55 years. The pathological subtype distribution was as follows: three (20.0%) patients with well-differentiated liposarcoma, 11 (73.3%) patients with dedifferentiated liposarcoma, and one (6.7%) patient with myxoid liposarcoma. At 12 weeks post-diagnosis, none of the patients achieved a complete response. The objective response rate was 6.7%, with one patient (6.7%) achieving a partial response. Disease stability was observed in 10 (66.6%) patients, which corresponded to a disease control rate of 73.3%. Disease progression occurred in four (26.7%) patients. The median follow-up time was 16.9 months and the median progression-free survival time was 14.2 months. Seven patients experienced TRAEs, of whom three (42.2%) had grade 3-4 TRAEs. The most common TRAEs were liver function abnormalities, hypertension, and fatigue.

Conclusion

Anlotinib combined with envafolimab demonstrates promising efficacy and manageable safety in treating unresectable or metastatic liposarcoma.

T-cell Clonality in Pleomorphic Dermal Sarcoma in Male Veterans: A Report of 2 Cases and a Review of the Literature

ABSTRACT

The standard treatment of choice for pleomorphic dermal sarcoma (PDS), a relatively uncommon soft tissue sarcoma and 1 morphologically similar to atypical fibroxanthoma, is wide local excision with close clinical follow-up. Studies regarding management of advanced/metastatic PDS with immune checkpoint inhibitors are limited as most STSs have historically been viewed as being immunologically inert. Contradicting this belief, in this report, we describe 2 cases of PDS with a robust host response. Histopathology of both cases revealed a dermal neoplasm comprising mitotically active, pleomorphic, spindled-to-ovoid cells, which were immunohistochemically negative for keratinocytic, melanocytic, and smooth muscle markers. An unusual feature in both cases was the presence of a brisk host response. Additional workup of the infiltrating lymphocyte population revealed an abnormal CD4:CD8 ratio in both cases, with the proportion of CD8 + lymphocytes surpassing (case 1) and equaling (case 2) that of the CD4 + T-lymphocyte population. The increased proportion of CD8 + lymphocytes prompted the additional workup of TCR gene rearrangement, which revealed a clonal population of T lymphocytes in both cases. The robust and clonal T-lymphocyte host response in both of our cases suggests that PDS appears to fit the classic model of an inflammatory-type tumor and may be a candidate for checkpoint inhibition. Future work includes additional reports of cases of PDS with an infiltrating clonal T-lymphocyte population and detailing the function and specificity of the infiltrating T lymphocytes to ascertain whether they have the potential to recognize and lyse the tumors they colonize.

Targeted immunotherapy and nanomedicine for rhabdomyosarcoma: The way of the future

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood. Histology separates two main subtypes: embryonal RMS (eRMS; 60%-70%) and alveolar RMS (aRMS; 20%-30%). The aggressive aRMS carry one of two characteristic chromosomal translocations that result in the expression of a PAX3::FOXO1 or PAX7::FOXO1 fusion transcription factor; therefore, aRMS are now classified as fusion-positive (FP) RMS. Embryonal RMS have a better prognosis and are clinically indistinguishable from fusion-negative (FN) RMS. Next to histology and molecular characteristics, RMS risk groupings are now available defining low risk tumors with excellent outcomes and advanced stage disease with poor prognosis, with an overall survival of about only 20% despite intensified multimodal treatment. Therefore, development of novel effective targeted strategies to increase survival and to decrease long-term side effects is urgently needed. Recently, immunotherapies and nanomedicine have been emerging for potent and effective tumor treatments with minimal side effects, raising hopes for effective and safe cures for RMS patients. This review aims to describe the most relevant preclinical and clinical studies in immunotherapy and targeted nanomedicine performed so far in RMS and to provide an insight in future developments.

Dissecting transposable elements and endogenous retroviruses upregulation by HDAC inhibitors in leiomyosarcoma cells: Implications for the interferon response

Transposable elements (TEs) are of interest as immunomodulators for cancer therapies. TEs can fold into dsRNAs that trigger the interferon response. Here, we investigated the effect of different HDAC inhibitors (HDACIs) on the expression of TEs in leiomyosarcoma cells. Our data show that endogenous retroviruses (ERVs), especially ERV1 elements, are upregulated after treatment with HDAC1/2/3-specific inhibitors. Surprisingly, the interferon response was not activated. We observed an increase in A-to-I editing of upregulated ERV1. This could have an impact on the stability of dsRNAs and the activation of the interferon response. We also found that H3K27ac levels are increased in the LTR12 subfamilies, which could be regulatory elements controlling the expression of proapoptotic genes such as TNFRSF10B. In summary, we provide a detailed characterization of TEs modulation in response to HDACIs and suggest the use of HDACIs in combination with ADAR inhibitors to induce cell death and support immunotherapy in cancer.

Intratumoural immunotherapy plus focal thermal ablation for localized prostate cancer

Major advances have been made in the use of immunotherapy for the treatment of solid tumours, including the use of intratumourally injected immunotherapy instead of systemically delivered immunotherapy. The success of immunotherapy in prostate cancer treatment has been limited to specific populations with advanced disease, which is thought to be a result of prostate cancer being an immunologically 'cold' cancer. Accordingly, combining intratumoural immunotherapy with other treatments that would increase the immunological heat of prostate cancer is of interest. Thermal ablation therapy is currently one of the main strategies used for the treatment of localized prostate cancer and it causes immunological activation against prostate tissue. The use of intratumoural immunotherapy as an adjunct to thermal ablation offers the potential to elicit a systemic and lasting adaptive immune response to cancer-specific antigens, leading to a synergistic effect of combination therapy. The combination of thermal ablation and immunotherapy is currently in the early stages of investigation for the treatment of multiple solid tumour types, and the potential for this combination therapy to also offer benefit to prostate cancer patients is exciting.

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.

Pharmacological EZH2 inhibition combined with retinoic acid treatment promotes differentiation and apoptosis in rhabdomyosarcoma cells

BACKGROUND

Rhabdomyosarcomas (RMS) are predominantly paediatric sarcomas thought to originate from muscle precursor cells due to impaired myogenic differentiation. Despite intensive treatment, 5-year survival for patients with advanced disease remains low (< 30%), highlighting a need for novel therapies to improve outcomes. Differentiation therapeutics are agents that induce differentiation of cancer cells from malignant to benign. The histone methyltransferase, Enhancer of Zeste Homolog 2 (EZH2) suppresses normal skeletal muscle differentiation and is highly expressed in RMS tumours.

RESULTS

We demonstrate combining inhibition of the epigenetic modulator EZH2 with the differentiating agent retinoic acid (RA) is more effective at reducing cell proliferation in RMS cell lines than single agents alone. In PAX3-FOXO1 positive RMS cells this is due to an RA-driven induction of the interferon pathway resulting in apoptosis. In fusion negative RMS, combination therapy led to an EZH2i-driven upregulation of myogenic signalling resulting in differentiation. In both subtypes, EZH2 is significantly associated with enrichment of trimethylated lysine 27 on histone 3 (H3K27me3) in genes that are downregulated in untreated RMS cells and upregulated with EZH2 inhibitor treatment. These results provide insight into the mechanism that drives the anti-cancer effect of the EZH2/RA single agent and combination treatment and indicate that the reduction of EZH2 activity combined with the induction of RA signalling represents a potential novel therapeutic strategy to treat both subtypes of RMS.

CONCLUSIONS

The results of this study demonstrate the potential utility of combining EZH2 inhibitors with differentiation agents for the treatment of paediatric rhabdomyosarcomas. As EZH2 inhibitors are currently undergoing clinical trials for adult and paediatric solid tumours and retinoic acid differentiation agents are already in clinical use this presents a readily translatable potential therapeutic strategy. Moreover, as inhibition of EZH2 in the poor prognosis FPRMS subtype results in an inflammatory response, it is conceivable that this strategy may also synergise with immunotherapies for a more effective treatment in these patients.

PD-1, PD-L1, IDO, CD70 and microsatellite instability as potential targets to prevent immune evasion in sarcomas

Background: Soft tissue and bone sarcomas are rare entities, hence, standardized therapeutic strategies are difficult to assess. Materials & methods: Immunohistochemistry was performed on 68 sarcoma samples to assess the expression of PD-1, PD-L1, IDO and CD70 in different tumor compartments and molecular analysis was performed to assess microsatellite instability status. Results: PD-1/PD-L1, IDO and CD70 pathways are at play in the immune evasion of sarcomas in general. Soft tissue sarcomas more often show an inflamed phenotype compared with bone sarcomas. Specific histologic sarcoma types show high expression levels of different markers. Finally, this is the first presentation of a microsatellite instability-high Kaposi sarcoma. Discussion/conclusion: Immune evasion occurs in sarcomas. Specific histologic types might benefit from immunotherapy, for which further investigation is needed.

The interplay between neoantigens and immune cells in sarcomas treated with checkpoint inhibition

Introduction

Sarcomas are comprised of diverse bone and connective tissue tumors with few effective therapeutic options for locally advanced unresectable and/or metastatic disease. Recent advances in immunotherapy, in particular immune checkpoint inhibition (ICI), have shown promising outcomes in several cancer indications. Unfortunately, ICI therapy has provided only modest clinical responses and seems moderately effective in a subset of the diverse subtypes.

Methods

To explore the immune parameters governing ICI therapy resistance or immune escape, we performed whole exome sequencing (WES) on tumors and their matched normal blood, in addition to RNA-seq from tumors of 31 sarcoma patients treated with pembrolizumab. We used advanced computational methods to investigate key immune properties, such as neoantigens and immune cell composition in the tumor microenvironment (TME).

Results

A multifactorial analysis suggested that expression of high quality neoantigens in the context of specific immune cells in the TME are key prognostic markers of progression-free survival (PFS). The presence of several types of immune cells, including T cells, B cells and macrophages, in the TME were associated with improved PFS. Importantly, we also found the presence of both CD8+ T cells and neoantigens together was associated with improved survival compared to the presence of CD8+ T cells or neoantigens alone. Interestingly, this trend was not identified with the combined presence of CD8+ T cells and TMB; suggesting that a combined CD8+ T cell and neoantigen effect on PFS was important.

Discussion

The outcome of this study may inform future trials that may lead to improved outcomes for sarcoma patients treated with ICI.

Argon-helium knife cryoablation plus programmed cell death protein 1 inhibitor in the treatment of advanced soft tissue sarcomas: there is no evidence of the synergistic effects of this combination therapy

Background

Effective treatment for advanced soft tissue sarcomas (STSs) is necessary for improved outcomes. Previous studies have suggested that cryoablation can have a synergistic effect with programmed cell death protein-1 (PD-1) inhibitor in the treatment of malignancy. This study aimed to clarify the efficacy and safety of argon-helium knife cryoablation in combination with PD-1 inhibitor in the treatment of STSs.

Methods

Retrospectively collected and analyzed the clinical data of patients with advanced STS who underwent cryoablation and PD-1 inhibitor between March 2018 and December 2021.

Results

This study included 27 patients with advanced STS. In terms of target lesions treated with cryoablation, 1 patient achieved complete response, 15 patients had partial response (PR), 10 patients had stable disease, and 1 patient had progressive disease. This corresponded to an overall response rate of 59.3% and a disease control rate of 96.3%. In terms of distant target lesions untreated with cryoablation, only two patients had a PR compared to the diameter of the lesion before ablation. The combination therapy was relatively well tolerated. None of the patients experienced treatment-related death or delayed treatment due to adverse events.

Conclusion

Cryoablation combined with PD-1 inhibitors in the therapy of advanced STS is safe and can effectively shrink the cryoablation-target lesion. However, there is no evidence of the synergistic effects of this combination therapy.

Integrative analyses of bulk microarray data to discover genes, pathways, and immune infiltration characteristics associated with targeting of Ewing sarcoma

PURPOSE

To explore transcriptome and immunological features of patients with Ewing sarcoma (ES) using all publicly available microarray data.

METHODS

Data of 479 ES tissues were integrated and normalized. Gene expression, immune infiltration, and cancer-specific pathways were analyzed. Genes of interest were knocked down, followed by cell proliferation and colony formation assays.

RESULTS

Consistent with the previous reports of differential expressed genes (DEGs) in ES, our analysis identified CCND1, HMCN1, and NKX2-2 were among the most highly expressed, while TWNC1, MYBPC1, and CKM were among the lowest expressed genes. GO, KEGG, and GSEA enrichment analysis identified that the DEGs related to bone and muscle functioning, those that contributed to crucial cellular, and metabolism pathways such as actin binding, apoptosis, TCA cycle, and cell cycle were also significantly enriched. Immune infiltration analysis discovered that many T cell subsets including CD4T, CD8 T, and Gamma delta T cells were highly infiltrated, while monocytes and B cells were less infiltrated in tumors. A total of 138 genes were both significantly up-regulated in tumors and associated with decreased survival, while 38 significantly down-regulated genes were associated with increased survival, many of which were previously reported as oncogenes and tumor suppressors in ES and other cancers. Silencing of four newly identified top ranked up-regulated genes with decreased survivals in ES inhibited proliferation and colony formation of ES cells.

CONCLUSION

This study may provide a clear representative transcriptome profile of ES, providing diagnostic biomarkers, pathways, and immune infiltrative characteristics targets for ES.

Breaking down the tumor immune infiltration within pediatric sarcomas

Immunotherapies are a promising therapeutic option, yet for a variety of reasons, these treatments have achieved limited success against sarcomas. The immunosuppressive tumor microenvironment (TME) of sarcomas as well as lack of predictive biomarkers, decreased T-cell clonal frequency, and high expression of immunosuppressive infiltrating cells has thus far prevented major success using immunotherapies. By breaking down the TME into its individual components and understanding how the various cell types interact with each other as well as in the context of the complex immune microenvironment, can lead to effective therapeutic immunotherapy treatments, potentially improving outcomes for those with metastatic disease.

The Midwest Sarcoma Trials Partnership: Bridging Academic and Community Networks in a Collaborative Approach to Sarcoma

The treatment of sarcoma necessitates a collaborative approach, given its rarity and complex management. At a single institution, multidisciplinary teams of specialists determine and execute treatment plans involving surgical, radiation, and medical management. Treatment guidelines for systemic therapies in advanced or nonresectable soft tissue sarcoma have advanced in recent years as new immunotherapies and targeted therapies become available. Collaboration between institutions is necessary to facilitate accrual to clinical trials. Here, we describe the success of the Midwest Sarcoma Trials Partnership (MWSTP) in creating a network encompassing large academic centers and local community sites. We propose a new model utilizing online platforms to expand the reach of clinical expertise for the treatment of advanced soft tissue sarcoma.

The combination of eddy thermal effect of biodegradable magnesium with immune checkpoint blockade shows enhanced efficacy against osteosarcoma

Osteosarcoma (OS) patients have a poor prognosis due to its high degree of heterogeneity and high rate of metastasis. Magnetic hyperthermia therapy (MHT) combined with immunotherapy is an effective strategy to treat solid and metastatic tumors. Here, we combined biodegradable magnesium (Mg) macroscale rods, which acted as an eddy thermo-magnetic agent under a low external alternating magnetic field, and immunotherapy to achieve a radical cure for OS. The eddy thermal effect (ETE) of the Mg rods (MgR) showed outstanding cytotoxic effects and enhanced the maturation of dendritic cells (DCs), and the mild MHT induced the immunogenic cell death (ICD) in the OS cells. Combined with immune checkpoint blockade (ICB) therapy, we obtained an excellent curative effect against OS, and a further evaluation demonstrated that the local MHT induced by the MgR increased T cells infiltration and the polarization of M1 macrophages. Interestingly, the biodegradable MgR also promoted bone osteogenesis. Our work highlighted the uneven ETE mediated by the biodegradable MgR induced a comprehensive immunologic activation in the OS tumor microenvironment (TME), which would inspire the application of MHT for the effective treatment of OS.

Targeting cyclin-dependent kinases in sarcoma treatment: Current perspectives and future directions

Effective treatment of advanced/metastatic bone and soft tissue sarcomas still represents an unmet medical need. Recent advances in targeted therapies have highlighted the potential of cyclin-dependent kinases (CDK) inhibitors in several cancer types, including sarcomas. CDKs are master regulators of the cell cycle; their dysregulation is listed among the "hallmarks of cancer" and sarcomas are no exception to the rule. In this review, we report both the molecular basis, and the potential therapeutic implications for the use of CDK inhibitors in sarcoma treatment. What is more, we describe and discuss the possibility and biological rationale for combination therapies with conventional treatments, target therapy and immunotherapy, highlighting potential avenues for future research to integrate CDK inhibition in sarcoma treatment.

Synovial Sarcoma Preclinical Modeling: Integrating Transgenic Mouse Models and Patient-Derived Models for Translational Research

Synovial sarcomas (SyS) are rare malignant tumors predominantly affecting children, adolescents, and young adults. The genetic hallmark of SyS is the t(X;18) translocation encoding the SS18-SSX fusion gene. The fusion protein interacts with both the BAF enhancer and polycomb repressor complexes, and either activates or represses target gene transcription, resulting in genome-wide epigenetic perturbations and altered gene expression. Several experimental in in vivo models, including conditional transgenic mouse models expressing the SS18-SSX fusion protein and spontaneously developing SyS, are available. In addition, patient-derived xenografts have been estab-lished in immunodeficient mice, faithfully reproducing the complex clinical heterogeneity. This review focuses on the main molecular features of SyS and the related preclinical in vivo and in vitro models. We will analyze the different conditional SyS mouse models that, after combination with some of the few other recurrent alterations, such as gains in BCL2, Wnt-β-catenin signaling, FGFR family, or loss of PTEN and SMARCB1, have provided additional insight into the mechanisms of synovial sarcomagenesis. The recent advancements in the understanding of SyS biology and improvements in preclinical modeling pave the way to the development of new epigenetic drugs and immunotherapeutic approaches conducive to new treatment options.

Radioresistance in rhabdomyosarcomas: Much more than a question of dose

Management of rhabdomyosarcoma (RMS), the most common soft tissue sarcoma in children, frequently accounting the genitourinary tract is complex and requires a multimodal therapy. In particular, as a consequence of the advancement in dose conformity technology, radiation therapy (RT) has now become the standard therapeutic option for patients with RMS. In the clinical practice, dose and timing of RT are adjusted on the basis of patients' risk stratification to reduce late toxicity and side effects on normal tissues. However, despite the substantial improvement in cure rates, local failure and recurrence frequently occur. In this review, we summarize the general principles of the treatment of RMS, focusing on RT, and the main molecular pathways and specific proteins involved into radioresistance in RMS tumors. Specifically, we focused on DNA damage/repair, reactive oxygen species, cancer stem cells, and epigenetic modifications that have been reported in the context of RMS neoplasia in both in vitro and in vivo studies. The precise elucidation of the radioresistance-related molecular mechanisms is of pivotal importance to set up new more effective and tolerable combined therapeutic approaches that can radiosensitize cancer cells to finally ameliorate the overall survival of patients with RMS, especially for the most aggressive subtypes.

Sarcoma Common MHC-I Haplotype Restricts Tumor-Specific CD8+ T Cell Response

Simple Summary

Immunotherapy targeting immune checkpoint pathways have recently attracted great attention in cancer treatment, but better strategies are needed to identify patients likely to benefit from it. The major histocompatibility complex (MHC) class I expression in cancer cells greatly influences the outcome of T cell-mediated immunotherapy. Here, we determined the prevalent HLA class I allelic variants in a sarcoma population. We characterized patient CD8+ T-cells and demonstrated low cytolysis to autologous tumor cells. Moreover, we used a co-culture model of autologous T-cells and PD-L1-deficient or positive biopsies of rare sarcomas to determine whether HLA-I influences tumor survival.

Abstract

The major histocompatibility complex (MHC) class I expression in cancer cells has a crucial impact on the outcome of T cell-mediated cancer immunotherapy. We now determined the HLA class I allelic variants and their expression in PD-L1-deficient and positive rare sarcoma tissues. Tumor tissues were HLA-I classified based on HLA-A and -B alleles, and for class II, the HLA-DR-B by Taqman genomic PCRs. The HLA-A24*:10-B73*:01 haplotype was the most common. A general down-regulation or deletion of HLA-B mRNA and HLA-A was observed, compared to HLA-DR-B. HLA-I was almost too low to be detectable by immunohistochemistry and 32% of grade III cases were positive to PD-L1. Functional cytotoxic assays co-culturing patient biopsies with autologous T cells were used to assess their ability to kill matched tumor cells. These results establish that deletion of HLA-I loci together with their down-regulation in individual patient restrict the autologous lymphocyte cytotoxic activity, even in the presence of the immune checkpoint blocking antibody, Nivolumab. Additionally, the proposed cytotoxic test suggests a strategy to assess the sensitivity of tumor cells to T cell-mediated attack at the level of the individual patient.

Oncogenic transcription factors and neogenes: New opportunities for cancer immunotherapy?

Vibert et al. (2022) demonstrate that oncogenic transcription factor fusion proteins bind otherwise silent genomic regions, producing RNAs that can be spliced, exported, and translated. These "neogenes" represent possible targets for immunotherapy and may even be universal byproducts of altered transcription in cancer.

Identification of Tumor Antigens and Immune Subtypes for the Development of mRNA Vaccines and Individualized Immunotherapy in Soft Tissue Sarcoma

Soft tissue sarcomas (STS) are a rare disease with high recurrence rates and poor prognosis. Missing therapy options together with the high heterogeneity of this tumor type gives impetus to the development of individualized treatment approaches. This study identifies potential tumor antigens for the development of mRNA tumor vaccines for STS and explores potential immune subtypes, stratifying patients for immunotherapy. RNA-sequencing data and clinical information were extracted from 189 STS samples from The Cancer Genome Atlas (TCGA) and microarray data were extracted from 103 STS samples from the Gene Expression Omnibus (GEO). Potential tumor antigens were identified using cBioportal, the Oncomine database, and prognostic analyses. Consensus clustering was used to define immune subtypes and immune gene modules, and graph learning-based dimensionality reduction analysis was used to depict the immune landscape. Finally, four potential tumor antigens were identified, each related to prognosis and antigen-presenting cell infiltration in STS: HLTF, ITGA10, PLCG1, and TTC3. Six immune subtypes and six gene modules were defined and validated in an independent cohort. The different immune subtypes have different molecular, cellular, and clinical characteristics. The immune landscape of STS reveals the immunity-related distribution of patients and intra-cluster heterogeneity of immune subtypes. This study provides a theoretical framework for STS mRNA vaccine development and the selection of patients for vaccination, and provides a reference for promoting individualized immunotherapy.

Nanoparticle albumin-bound paclitaxel and PD-1 inhibitor (sintilimab) combination therapy for soft tissue sarcoma: a retrospective study

Background

There is increasing evidence that combination therapy with nanoparticle albumin-bound paclitaxel (nab-paclitaxel) and programmed cell death protein 1 (PD-1) inhibitor is safe and efficacious in treating many types of malignant tumors. However, clinical data demonstrating the effect of this treatment combination for patients with metastatic soft tissue sarcoma (STS) are currently limited.

Methods

The clinical data of patients with metastatic STS who received nab-paclitaxel plus PD-1 inhibitor (sintilimab) therapy between January 2019 and February 2021 were retrospectively analyzed. The effectiveness and safety of the combined treatment were evaluated in terms of the median progression-free survival (PFS), estimated using the Kaplan–Meier method. The univariate Cox proportional hazards model was used to analyze the relationship between clinicopathological parameters and PFS. All statistical analyses were two-sided; P < 0.05 was considered statistically significant.

Results

A total of 28 patients treated with nab-paclitaxel plus sintilimab were enrolled in this study. The objective response rate was 25%, the disease control rate was 50%, and the median PFS was 2.25 months (95% CI = 1.8–3.0 months). The most common grade 1 or 2 adverse events (AEs) were alopecia (89.3%; 25/28), leukopenia (25.0%; 7/28), fatigue (21.4%; 6/28), anemia (21.4%; 6/28), and nausea (21.4%; 6/28). The most common grade 3 AEs were neutropenia (10.7%; 3/28) and peripheral neuropathy (10.7%; 3/28). No grade 4 AEs were observed. Among the present study cohort, patients with angiosarcoma (n = 5) had significantly longer PFS (P = 0.012) than patients with other pathological subtypes, including undifferentiated pleomorphic sarcoma (n = 7), epithelioid sarcoma (n = 5), fibrosarcoma (n = 4), synovial sarcoma (n = 3), leiomyosarcoma (n = 2), pleomorphic liposarcoma (n = 1), and rhabdomyosarcoma (n = 1); those who experienced three or more AEs had significantly longer median PFS than those who experienced less than three AEs (P = 0.018).

Conclusion

Nab-paclitaxel plus PD-1 inhibitor is a promising treatment regimen for advanced STS. Randomized controlled clinical trials are required to further demonstrate its efficacy and optimal application scenario.

Chemokines in the Landscape of Cancer Immunotherapy: How They and Their Receptors Can Be Used to Turn Cold Tumors into Hot Ones?

Over the last decade, monoclonal antibodies to immune checkpoint inhibitors (ICI), also known as immune checkpoint blockers (ICB), have been the most successful approach for cancer therapy. Starting with mAb to cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors in metastatic melanoma and continuing with blockers of the interactions between program cell death 1 (PD-1) and its ligand program cell death ligand 1 (PDL-1) or program cell death ligand 2 (PDL-2), that have been approved for about 20 different indications. Yet for many cancers, ICI shows limited success. Several lines of evidence imply that the limited success in cancer immunotherapy is associated with attempts to treat patients with "cold tumors" that either lack effector T cells, or in which these cells are markedly suppressed by regulatory T cells (Tregs). Chemokines are a well-defined group of proteins that were so named due to their chemotactic properties. The current review focuses on key chemokines that not only attract leukocytes but also shape their biological properties. CXCR3 is a chemokine receptor with 3 ligands. We suggest using Ig-based fusion proteins of two of them: CXL9 and CXCL10, to enhance anti-tumor immunity and perhaps transform cold tumors into hot tumors. Potential differences between CXCL9 and CXCL10 regarding ICI are discussed. We also discuss the possibility of targeting the function or deleting a key subset of Tregs that are CCR8+ by monoclonal antibodies to CCR8. These cells are preferentially abundant in several tumors and are likely to be the key drivers in suppressing anti-cancer immune reactivity.

Undifferentiated Pleomorphic Sarcoma with Neoplastic Fever: A Retrospective Study

Background

Although the annual incidence of undifferentiated pleomorphic sarcoma (UPS) is extremely low, it can be subdivided into different subtypes. UPS with fever of unknown origin (also known as neoplastic fever) is a specific subtype of UPS, which shows certain clinical features that differentiate it from other UPS subtypes. However, no studies have focused on this rare UPS subtype. This study retrospectively analyzed the clinical data of patients with UPS to provide a reference for the diagnosis and treatment of UPS with neoplastic fever.

Methods

This study included patients with UPS who were diagnosed and treated between June 2012 and June 2018. We examined whether these patients had a history of neoplastic fever. The characteristics of patients with UPS with neoplastic fever were summarized and analyzed.

Results

We reviewed the medical records of 183 patients with UPS. Seven (3.83%) of these patients had neoplastic fever. In patients with UPS with neoplastic fever, the primary lesions were located in the extremities and across the muscle space. In these patients, magnetic resonance imaging showed necrosis within the tumor body and extensive soft tissue edema around the tumor body. Patients with UPS with neoplastic fever had a lower metastasis rate (14.29% vs 44.94%) and a higher 3-year survival rate (85.71% vs 59.55%) than those without neoplastic fever.

Conclusion

UPS with neoplastic fever is characterized by intratumoral necrosis and extensive edema of the surrounding soft tissues. Patients with UPS with neoplastic fever may have a better prognosis than those without neoplastic fever.