Pembrolizumab in advanced soft-tissue sarcoma and bone sarcoma (SARC028): a multicentre, two-cohort, single-arm, open-label, phase 2 trial

Phase II study of rucaparib and nivolumab in patients with leiomyosarcoma

BACKGROUND

Objective responses to immune checkpoint inhibitors (ICI) in leiomyosarcoma (LMS) are rare. Response rates may be increased by combination with other drugs known to promote immune infiltration, such as poly(ADP-ribose) polymerase (PARP) inhibitors, which have led to benefit in BRCA-altered uterine LMS. We therefore evaluated the combination of a PARP inhibitor, rucaparib, and the anti-programmed death receptor-1 monoclonal antibody, nivolumab, in patients with advanced LMS and investigated its effects on the tumor immune microenvironment.

METHODS

This was an open-label, single-center, single-arm, phase II study in patients with advanced refractory LMS. Full protocol available Patients were treated with rucaparib 600 mg orally, two times daily, continuously and nivolumab 480 mg intravenously on day 1 of a 28-day cycle. Re-staging scans were performed every 8 weeks. Blood and tissue samples were collected at baseline and at week 8 on treatment. The primary objective was the best objective response rate by 24 weeks using Response Evaluation Criteria in Solid Tumour (RECIST V.1.1). Secondary objectives included treatment-related toxicity, progression-free survival, overall survival, and changes in immune pathways in blood and tumor.

RESULTS

20 patients with LMS were enrolled. There was one partial response (PR) (5%) in a patient with uterine LMS and a somatic BRCA deep deletion. 19 (95%) patients had a treatment-related adverse event (TRAE) and 7 (35%) had a grade 3 or higher TRAE. Interferon (IFN) α and γ hallmark pathways were more highly expressed in patients who derived benefit from treatment (at least stable disease by 16 weeks) vs those who did not in both baseline (adjusted p=0.005 for IFN-α, 0.03 for IFN-γ) and on-treatment biopsies (adjusted p=0.0002 for IFN-α, 0.0001 for IFN-γ), but the abundance of tumor immune cell populations did not differ between these groups at either time point.

CONCLUSION

The addition of a PARP inhibitor did not improve the efficacy of ICI in LMS. Adverse events, especially due to overlapping toxicities, were frequent and often led to dose delays and modifications.

Real-world data on immune checkpoint inhibitors in advanced sarcomas across multiple European institutions

BACKGROUND

Following the success of immune checkpoint inhibitors (ICI) in other cancer types, their role is being evaluated in sarcomas. They have been assessed as monotherapy, or in combination with other ICI, chemotherapeutic drugs and tyrosine kinase inhibitors (TKI) in several clinical trials. So far the results have been limited to non-selected sarcoma populations. Further work is required to select patients who will benefit from immunotherapy.

PATIENTS AND METHODS

We conducted a pooled retrospective analysis of the use of ICI in patients with advanced sarcomas in multiple European institutions. ICI-based treatments included ICI monotherapy (n = 43, 59.7%), double ICI (n = 5, 6.9%), ICI plus TKI (n = 21, 29.2%) and ICI plus chemotherapy (n = 3, 4.2%).

RESULTS

Seventy-two patients from 10 European institutions, with metastatic (87.5%) or locally advanced (12.5%) disease were included. The most common subtype was undifferentiated pleomorphic sarcoma (16.7%), followed by leiomyosarcoma (12%), liposarcoma (10%) and angiosarcoma (9.7%). The median number of prior lines of systemic therapy was 2 (0-8). The objective response rate was 34.4% and was higher in combination regimens versus ICI monotherapy. With a median follow-up of 20.7 months, median progression-free survival (PFS) was 4.6 and median overall survival (OS) 18.8 months. Line of therapy (1st/2nd vs. ≥ 3rd line) and best response to ICI was significantly associated with PFS and OS. Histological subtype was significantly associated with OS. Toxicity was in general manageable; only six (8.3%) patients discontinued therapy for AE.

INTERPRETATION

Our study provided additional real-world data on the outcome of ICI in patients with advanced sarcomas.

Phase 1, open-label, multicenter, dose escalation safety and tolerability study of oncolytic virus OVV-01 in advanced solid tumors

BACKGROUND

OVV-01 is a genetically engineered vesicular stomatitis virus oncolytic virus designed to selectively amplify in tumor cells and express tumor-associated antigen NY-ESO-1. This study was designed to evaluate the safety, tolerability, and efficacy of OVV-01 in patients with advanced solid tumors.

METHODS

This is a phase 1, first-in-human, open-label, multicenter study of OVV-01 in patients with advanced solid tumors. OVV-01 was intratumorally injected biweekly (every two weeks, Q2W), 3 weeks after the first dose for a total of six doses. Dose escalation follows a 3+3 design at four doses of 6×107 Plaue-Forming Unit (PFU), 6×108 PFU, 6×109 PFU, and 1.2×1011 PFU. The primary endpoints were safety and tolerability. The second endpoints included overall response rate (ORR) and disease control rate (DCR) of OVV-01, by investigators per Response Evaluation Criteria in Solid Tumors V.1.1.

RESULTS

18 patients were enrolled into four dose groups, among whom 6 were soft tissue sarcoma (STS). No dose-limiting toxicities and treatment-related severe adverse events were observed. 11 patients were evaluated for efficacy, and the ORR was 27.3%, and the DCR was 63.6%. Among the four evaluable patients with advanced STS, the ORR was 75%. Two patients with STS achieved CR at doses above 6.0×109 PFU.

CONCLUSIONS

The intratumor injection of OVV-01 was safe and well-tolerated in patients with advanced solid tumors. A significant response was observed in patients with STS.

TRIAL REGISTRATION NUMBER

NCT04787003.

The phosphatase CTDSPL2 promotes proliferation, invasion, metastasis and regorafenib resistance in osteosarcoma

Osteosarcoma is the most common bone malignancy in children and adolescents. Patients with metastatic and recurrent osteosarcoma have poor prognosis. Regorafenib is a multi-kinase inhibitor recommended as a complement to standard chemotherapy in the treatment of advanced osteosarcoma. The mechanisms associated with regorafenib resistance remains unclear. In this study we performed transcriptomics, proteomics and phosphorylated proteomics using regorafenib-treated osteosarcoma cell lines (MG-63, HOS-MNNG for transcriptomics, HOS-MNNG for proteomics and phosphorylated proteomics). After comprehensive multiomics and verification analyses of differentially expressed genes, essential genes for the malignancy of osteosarcoma cells were identified. The effects of essential genes on the proliferation, invasion, and migration of osteosarcoma were determined. The study also evaluated their role in the apoptosis of osteosarcoma cells. The up-regulation of essential genes was determined by immunohistochemistry assays. Using comprehensive multiomics and verification analyses we found that the CTDSPL2 gene might play a role in the malignancy and Regorafenib resistance in osteosarcoma. In vitro and clinical specimen assays demonstrated that CTDSPL2 promotes the proliferation, invasion and metastasis of osteosarcoma cells, while inhibiting tumor cell apoptosis. In conclusion CTDSPL2 was identified as an essential gene for survival of osteosarcoma cells. Knockdown of CTDSPL2 expression significantly inhibited the proliferation, invasion, and metastasis of osteosarcoma cells, suggesting that it is involved in the formation and development of osteosarcoma tumors. Our data showed that CTDSPL2 is a potential therapeutic target for patients with osteosarcoma.

Harnessing multi‑omics to revolutionize understanding and management of osteosarcoma: A pathway to precision medicine (Review)

Osteosarcoma, the most prevalent primary bone malignancy in children and adolescents, poses significant challenges due to its aggressive nature and propensity for metastasis. Despite advances in treatment, survival rates for high‑risk patients remain unsatisfactory, underscoring the urgent need for innovative approaches. This review explores the vital role of multi‑omics‑integrating genomics, transcriptomics, proteomics and metabolomics‑in unraveling the complex biological landscapes of osteosarcoma. By providing comprehensive insights into tumor heterogeneity, signaling pathways and metabolic reprogramming, multi‑omics facilitates the identification of novel biomarkers and therapeutic targets. The objective of the present study was to highlight the transformative potential of multi‑omics in enhancing the understanding and management of osteosarcoma, ultimately paving the way for personalized treatment strategies and improved patient outcomes. Through this synthesis, the study calls for a concerted effort to integrate multi‑omics into clinical practice, fostering a more precise approach to osteosarcoma care.

Rare Uterine Tumors: What to Do?

Rare uterine malignancies present treatment challenges because of their clinical and biological heterogeneity. Among the rarest of the uterine cancers are leiomyosarcomas, uterine stromal tumors, and the mesonephric-like and serous carcinomas. In this article, we review recent advancements in diagnostic precision, risk stratification, and identification of biomarker-guided therapeutic options for these rare subtypes of uterine tumors. The improved understanding of the molecular profile of these tumors has led to the development of targeted treatment approaches. Further progress will depend on a coordinated, global effort to further characterize these diseases and enroll patients on biomarker-driven clinical trials.

Comparative analysis of bone and soft tissue vs. visceral synovial sarcoma: Demographic, clinical, and survival outcomes; a retrospective population-based study

BACKGROUND

Synovial sarcoma (SS) is typically diagnoses in young adults and usually appears in the extremities and soft tissues. However, it can sometimes arise in visceral organs. This study examines the differences in patient demographics, clinical features, and survival rates between soft tissue and visceral synovial sarcoma.

METHODS

We analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database spanning 2000-2018. ANOVA (analysis of variance) was used to identify significant factors for multivariate analysis. Cox regression modeling was used to determine independent risk factors for survival.

RESULTS

Of the 2,776 SS patients included, the median age was 39.0 years, predominating male (53.0 %) and white (81.3 %). Bone and soft tissue sarcomas were more common, accounting for 86.4 % of cases (p-value<0.001), while the rest were diagnosed as visceral sarcomas. Visceral SS patients were typically older (p-value<0.001), male (56.8 %), and white (84.8 %). They also presented more frequently with distant metastasis (HR 3.8, 95 % CI, 2.4-6.1), had larger tumors on average (HR for tumors >10 cm: 2.9, 95 % CI, 2.0-4.1), and were less likely to undergo surgery (HR 0.4, 95 % CI, 0.3-0.6). Despite receiving multimodal treatments, including surgery, radiation, and/or chemotherapy, visceral SS patients exhibited poorer overall survival compared to their bone and soft tissue SS counterparts (p-value<0.001).

CONCLUSION

Visceral SS often presents in older patients with advanced-stage and larger tumor size as compared to bone and soft tissue SS, which likely contributes to poorer survival. Advanced age, regional spread, and larger tumor size were all found to worsen outcomes, while surgery and radiation were found to be protective factors.

Loss of TACC2 impairs chemokine CCL3 and CCL4 expression and reduces response to anti-PD-1 therapy in soft tissue sarcoma

BACKGROUND

Soft tissue sarcoma (STS) is a rare, heterogeneous malignancy with limited treatment options for metastatic disease. Despite advances in immunotherapy, including PD-1 inhibitors, clinical outcomes remain suboptimal, highlighting the need for novel biomarkers and therapeutic strategies. This study investigated the role of TACC2 in STS, focusing on its impact on the immune microenvironment and immunotherapy response.

METHODS

Whole-exome sequencing was performed to characterize TACC2-related genomic alterations in STS cohorts, complemented by immunohistochemistry for protein-level validation. Mechanistic insights were obtained through chromatin immunoprecipitation (ChIP) and co-immunoprecipitation assays, focusing on TACC2's interaction with the NuRD/CoREST complex. The efficacy of anti-PD-1 therapy was evaluated in TACC2-overexpressing mouse models, and clinical relevance was analyzed using patient survival and treatment response data.

RESULTS

TACC2 acted as a tumor suppressor in STS, with low expression associated with poor overall survival. Mechanistically, TACC2 enhanced CCL3 and CCL4 transcription, promoting CD8 + T cell infiltration by inhibiting NuRD/CoREST nuclear translocation. In vivo, TACC2 overexpression synergized with PD-1 blockade therapy, leading to a significant reduction in tumor volume and prolonged survival. Clinically, high TACC2 expression was associated with improved responses to immunotherapy.

CONCLUSIONS

In conclusion, TACC2 is an important regulator of the immune response in STS, functioning as a tumor suppressor and a modulator of response to PD-1 blockade. Its role in modulating chemokine expression and CD8 + T cell infiltration highlights its potential as a therapeutic target and predictive biomarker for STS immunotherapy.

Integrating Radiogenomics and Machine Learning in Musculoskeletal Oncology Care

Musculoskeletal tumors present a diagnostic challenge due to their rarity, histological diversity, and overlapping imaging features. Accurate characterization is essential for effective treatment planning and prognosis, yet current diagnostic workflows rely heavily on invasive biopsy and subjective radiologic interpretation. This review explores the evolving role of radiogenomics and machine learning in improving diagnostic accuracy for bone and soft tissue tumors. We examine integrating quantitative imaging features from MRI, CT, and PET with genomic and transcriptomic data to enable non-invasive tumor profiling. AI-powered platforms employing convolutional neural networks (CNNs) and radiomic texture analysis show promising results in tumor grading, subtype differentiation (e.g., Osteosarcoma vs. Ewing sarcoma), and predicting mutation signatures (e.g., TP53, RB1). Moreover, we highlight the use of liquid biopsy and circulating tumor DNA (ctDNA) as emerging diagnostic biomarkers, coupled with point-of-care molecular assays, to enable early and accurate detection in low-resource settings. The review concludes by discussing translational barriers, including data harmonization, regulatory challenges, and the need for multi-institutional datasets to validate AI-based diagnostic frameworks. This article synthesizes current advancements and provides a forward-looking view of precision diagnostics in musculoskeletal oncology.

Liposarcoma: Novel Approaches to Systemic Therapy and Multidisciplinary Care

Retroperitoneal well-differentiated liposarcoma (WDLPS) and dedifferentiated liposarcoma (DDLPS) are rare tumors presenting as bulky abdominal tumors requiring multidisciplinary management in high-volume centers. Surgery is the mainstay of treatment through complete en bloc resection with the goal of achieving macroscopically complete resection, with a single specimen encompassing the tumor and involved contiguous organs. Preoperative radiation therapy is not standard of care and the role of preoperative chemotherapy is under investigation. If the tumor is not resectable or metastatic, the preferred treatment is doxorubicin-based chemotherapy in the case of DDLPS, whereas WDLPS are generally thought of as chemo-resistant.

From Intensification to Optimization: Balancing Efficacy, Safety, and Costs in High-Risk Localized Soft Tissue Sarcomas

Background/Objectives: The SU2C-SARC032 randomized controlled trial (RCT) tested pembrolizumab combined with preoperative normofractionated radiotherapy as an intensified treatment for high-risk stage III resectable soft tissue sarcoma (STS), demonstrating a moderate improvement in disease-free survival (DFS) compared to preoperative radiotherapy alone, but accompanied by significantly increased toxicity, prolonged treatment durations, elevated resource source, and limited real-world applicability. To address the gap between highly controlled trial outcomes and routine clinical practice, this comparative analysis evaluated a streamlined ultra-hypofractionated preoperative radiotherapy (uhpRT) protocol using real-world data (RWD) as a potentially more balanced approach. Methods: Prospectively collected observational RWD from 54 consecutive patients with Stage III (T2 N0 M0) high-risk resectable STS treated at a single institution with uhpRT (25 Gy in 5 fractions in one week, no systemic therapy, median interval of 14 days to surgery) were analyzed. Survival endpoints (overall survival [OS], DFS, local disease-free survival [LDFS], distant disease-free survival [DDFS]), toxicity, and treatment duration were compared qualitatively with published outcomes from the SU2C-SARC032 trial's intensified pembrolizumab arm and control arm. Results: At 2 years, the optimized uhpRT protocol achieved OS (90%), DFS (66%), and DDFS (70%) comparable to the intensified pembrolizumab arm (OS: 88%, DFS: 67%, DDFS (67%)) and clearly exceeded outcomes of the control arm (OS/DFS/DDFS: 85%/52%/52%). Importantly, the uhpRT protocol markedly reduced treatment-related toxicities (0% Grade 3/4 events vs. 56% in the intensified trial arm) and total treatment duration (<1 month vs. 3-11 months). Conclusions: These findings challenge the necessity of broad treatment intensification for high-risk localized STS, strongly supporting the concept of therapeutic optimization. Given substantial real-world variability in treatment practices and feasibility highlighted by recent research, our findings advocate for treatment strategies that prioritize realistic applicability, patient safety, and value-based care principles over pure intensification.

Exploring the causal relationship between immune factors and chondrosarcoma: a Mendelian randomization study

BACKGROUND

Previous studies have investigated the potential role of immune factors in chondrosarcoma (CHS). However, the causal relationship is unknown.

METHODS

A two-sample Mendelian randomization (MR) was used to explore potential correlations between 731 immunocyte phenotypes, 91 inflammatory proteins, and CHS. The data were derived from published summary statistics of genome-wide association studies. Inverse-variance weighted was employed as the primary method. Furthermore, a range of analytical methods, including MR-Egger, weighted mode, and weighted median was used to enhance the robustness of the results. A two-step MR was used to assess the mediating effects of inflammatory proteins. Subsequently, sensitivity and MR Steiger directionality tests were performed.

RESULTS

MR analyses showed that 12 immunocyte phenotypes were positively correlated with CHS (P < 0.05, OR > 1), and 11 immunocyte phenotypes were negatively correlated with CHS (P < 0.05, OR < 1). Five inflammatory proteins were positively associated with CHS (P < 0.05, OR > 1). No heterogeneous or horizontal pleiotropy was found. The MR Steiger analysis found no statistically significant evidence of reverse causation. Mediation analysis did not identify any potential mediating effects.

CONCLUSION

Our study underscores the pivotal role of immune factors in CHS and offers insights that can inform future research.

A review of cutaneous angiosarcoma: epidemiology, diagnosis, prognosis, and treatment options

Cutaneous angiosarcoma (cAS) is a rare and aggressive malignant vascular tumor that arises from endothelial cells lining the blood vessels. It can occur in any part of the body, but most commonly, it affects the skin and soft tissues. cAS has a poor prognosis with a 5-year survival rate of only 9%. This review summarizes the current understanding of angiosarcoma pathogenesis, clinical presentation, diagnosis, and treatment approaches. Recent advances in molecular characterization have identified recurrent genetic alterations that may lead to the development of novel targeted therapies. Multidisciplinary management combining surgery, radiation, and systemic therapy remains the mainstay of treatment; however, outcomes remain poor for metastatic disease. Ongoing research into the molecular drivers of cAS and immunotherapeutic approaches offers hope for improving the outcomes of this challenging malignancy.

Current and emerging systemic treatment options for malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma

Undifferentiated pleomorphic sarcoma (UPS)/malignant fibrous histiocytoma (MFH) is the second most common soft-tissue sarcoma. The standard treatment options for UPS/MFH include tumor excision with appropriate surgical margins, radiation therapy, and chemotherapy. Preferable clinical outcomes can be expected in patients with resectable disease, whereas the clinical outcomes in patients with metastatic disease are unsatisfactory despite multidisciplinary treatment. Although patients with metastatic diseases require chemotherapy, the response rate to conventional chemotherapy has been reported to be only 27-33% in previous reports. Systemic treatment is required to eliminate metastatic disease and improve clinical outcomes in patients with UPS/MFH. Recent clinical studies have investigated the optimal period of conventional chemotherapy and the efficacy of various combinations of anticancer agents. Furthermore, molecular targeted drugs and immune checkpoint inhibitors have shown superior outcomes compared to standard treatments for various types of malignancies. Therefore, these anticancer agents are considered as new treatment options for patients with UPS/MFH. Recent clinical trials have demonstrated the safety and efficacy of these agents in patients with soft-tissue sarcomas, including UPS/MFH. In particular, a high response rate to immune checkpoint inhibitors combined with doxorubicin has been reported in recent clinical trials; however, combination therapy needs to be assessed in a large number of patients with UPS/MFH. In this review article, recent clinical studies on the systemic treatment of UPS/MFH are discussed.

Neoadjuvant Immunotherapy for Resectable Dedifferentiated Liposarcoma: A National Cohort Analysis

BACKGROUND

Neoadjuvant immunotherapy (NIT) with checkpoint blockade has been increasingly studied for soft tissue sarcomas, however, survival outcomes data are limited, and dedifferentiated liposarcoma (DDLPS) histology remains underrepresented in recent trial cohorts. We assessed the impact of NIT with or without radiation therapy (RT) on overall survival (OS) for resectable DDLPS.

METHODS

The National Cancer Database (NCDB) was used to identify patients diagnosed with nonmetastatic DDLPS who received NIT and underwent surgical resection between 2016 and 2022. Primary outcome was 5-year OS.

RESULTS

A total of 3414 patients with DDLPS met the inclusion criteria and NIT was administered to 31 (1%) patients. Factors associated with receipt of NIT were receipt of neoadjuvant RT (NRT, odds ratio [OR]: 5.75, p < 0.001) and male sex (OR: 3.33, p = 0.036). NIT was associated with a hazard ratio (HR) for mortality of 0.89 (p = 0.786). No difference was found in 5-year OS in the overall cohort (NIT 72% vs. 61% no NIT, p = 0.320) or in the propensity-matched cohort (68% vs. 65%, p = 0.848). Subanalysis between NIT with NRT versus NRT-only also did not find any significant difference in 5-year OS (88% vs. 59%, p = 0.331).

CONCLUSION

In this retrospective NCDB analysis of patients with resectable DDLPS, administration of NIT did not significantly affect OS.

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.

Mapping Knowledge Structure and Themes Trends of Ewing Sarcoma: A Text-Mining Study

BACKGROUND

Ewing sarcoma (ES) is a rare type of cancer that primarily affects children and young adults. In recent years, there have been notable advancements in the treatment of ES due to the introduction of neoadjuvant chemotherapy and targeted therapy, as well as a wealth of related studies in this field published by scholars around the world. However, there is still a lack of a comprehensive report to aid researchers in quickly understanding the knowledge structure and emerging trends of this area.

MATERIALS AND METHODS

We conducted a comprehensive search in the Web of Science Core Collection for relevant studies published from 2000 to 2023. To conduct a thorough scientometric analysis and create network visualizations, we utilized three different tools, namely, an online analysis platform, CiteSpace, and VOSviewer. These tools enabled us to examine various aspects such as annual publication output; active journals; contributions from countries, institutions, and authors; references; and keywords.

RESULTS

A total of 5163 qualified publications were included. The annual number of publications on ES showed a significant linear growth trend (R2 = 0.927). The USA stands out as the most productive country. The institution and author that contributed the largest number of papers were University of Texas System and Dirksen U., respectively. As can be seen from highly cited studies and reference analysis and application of Surveillance, Epidemiology, and End Results (SEER) database, preclinical and clinical trials of multiple combination treatment strategies, especially with different approach of immunotherapy such as CAR-T cells or anti-PD-1 antibody for ES, are the primary focus of the current study. Keyword analysis identified several research topics including immunotherapy, tumor microenvironment, microRNA, biomarkers, EWSR1, metastasis, epigenetics, epithelial mesenchymal transition, mesenchymal stem cell, and combination therapy, which have emerged as frontiers in the field and hold significant potential as ongoing research hotspots.

CONCLUSIONS

ES is a field that has continued to receive increasing attention in recent years. Harnessing current immunotherapy approaches to improve outcomes of patients with ES is an area of intense interest. This study has provided a comprehensive knowledge map, development landscape, and future directions for ES research, and offered a practical and valuable reference for scholars to obtain better understanding of the current state of research in this field.

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.

Exploration of research hotspots and evolutionary trends in osteosarcoma pulmonary metastasis: A comprehensive bibliometric analysis spanning five decades

Objective

Pulmonary metastasis frequently complicates osteosarcoma, making the investigation of its mechanisms and therapeutic strategies a focal point in both clinical medicine and biosciences. The explosive growth of the relevant literature has still not been systematically sorted out and summarized.

Methods

Bibliometric methods were used in this study, Literature was retrieved from the Web of Science Core Collection, SCOPUS, and PubMed up until July 1, 2024. Bibliometric indicators were analyzed and research trends and hotspots in the field visualized using the Bibliometrix package, VOSviewer 1.6.19 and Citespace 6.3.R1 software.

Results

A total of 1148 publications were reviewed, revealing that over the past five decades, the cumulative number of publications on pulmonary metastasis of osteosarcoma has gradually increased. China leads in the number of published papers, while the United States exhibits the most collaborative relationships with other countries. Italy is noted for the highest quality of research. Sun Yat-sen University is the most prolific institution, and the most productive author is Eugenie S. Kleinerman from the University of Texas MD Anderson Cancer Center. "Cancer" is the journal with the most publications, and Zhou Yan's 2020 paper received the highest local citations. Keywords such as "angiogenesis," "tumor microenvironment," and "surgery" appeared frequently, suggesting these topics are current research hotspots.

Conclusion

"Immunotherapy", "survival", "chemotherapy", "prognosis", "biomarkers", "metastasectomy", "microRNA", "angiogenesis", "tumor microenvironment", and "surgery" define key research areas. Current hot topics include tumor-associated macrophages and the tumor microenvironment, which may hold the key to future therapeutic breakthroughs.

Dedifferentiated liposarcomas treated with immune checkpoint blockade: the MD Anderson experience

Background

Dedifferentiated liposarcoma (DDLPS) is one of the most common types of soft tissue sarcoma (STS) characterized by liposarcomatous differentiation and a predilection for the retroperitoneum. Despite the growing number of histology-specific immune checkpoint blockade (ICB) trials in STS, it is still difficult to identify the radiographic objective response rate (ORR) for DDLPS in the real world setting. This study aimed to evaluate the ORR and survival of patients with DDLPS treated with ICB at a single center.

Methods

We conducted a retrospective study of 31 patients with pathologically confirmed DDLPS treated with ICB at MD Anderson Cancer Center between 2018 and 2023. Patient demographics, disease characteristics, treatment history, and response to ICB were analyzed. Immunohistochemical analysis was performed on tumor samples to assess immune-related markers.

Results

ORR by RECIST 1.1 was 3.2% (n=1/31). Among all patients (n=31), 6% achieved partial radiographic response, while 39% had stable disease, and 55% showed progressive disease. Median progression-free survival (PFS) was 3.5 (95%CI:1.9, 4.7) months, and overall survival (OS) after ICB initiation was 19.7 (95%CI: 8.8, not reached) months. Patients without prior systemic therapy demonstrated better OS (p=0.004). Immunohistochemistry revealed no relationship between pre- or post-ICB expression of CD8, CD20, CD21 and PDL-1 and response.

Conclusion

While the response to ICB in DDLPS remains limited, specific immune markers may influence treatment outcomes. CD20/21 post-ICB appear more important for prognosis. Further research is warranted to identify predictive factors for ICB efficacy in DDLPS.

TFCP2 Fusion-Positive Rhabdomyosarcomas: A Report of 10 Cases and a Review of the Literature

Background/Objectives: The fusion of the TFCP2 gene with either EWSR1 or FUS typically results in a spindle cell and/or epithelioid variant of rhabdomyosarcoma. This is an ultra-rare type of sarcoma, with most of our knowledge about these coming from case reports and small case series. Herein, we describe the clinical characteristics and treatment course of 10 patients with TFCP2 fusion sarcomas. Methods: We identified 10 patients in our hospital system with TFCP2 fusion sarcomas and 43 previously reported cases in the literature. We assessed primary tumor characteristics, treatment regimens, and survival rates among all cases. Results: We find that TFCP2 fusion sarcomas most commonly occur in young adults (median age: 33 years) and arise in craniofacial bones (7/10, 70%). Concomitant ALK alterations and ALK overexpression is nearly universal, and two of our patients were treated with ALK inhibitors; one patient had a near complete response before eventual progression, while the other patient had progressive disease after 2 months. For most, the prognosis was poor. The median overall survival in this cohort was 24.7 months (range: 5.9-29.7 months). Four patients were treated with upfront surgery, and all four developed recurrent disease. The median time to recurrence following upfront surgery was 2.1 months (range: 0.73-6.9 months). Five patients received systemic therapy, and the median progression-free survival from the start of treatment to progression was 1.6 months (range: 0.97-2.7). We also review the 53 total cases of TFCP2 fusion sarcomas in the literature, again highlighting the dismal outcomes in this disease. Conclusions:TFCP2 fusion sarcomas are proven to be aggressive and have poor prognosis. Additional work is needed to define the optimal treatment course for TFCP2 fusion sarcomas.

Combination of immune checkpoint inhibitors and anthracyclines as a potential first-line regimen for dedifferentiated liposarcoma: systematic review and meta-analysis

INTRODUCTION

Dedifferentiated liposarcoma (DDLPS) is a rare and aggressive subtype of soft tissue sarcoma, characterized by limited treatment options and poor prognosis. Despite surgical resection being the only potentially curative treatment for localized DDLPS, the recurrence rate remains high, and systemic chemotherapy, typically anthracycline-based, shows limited efficacy in advanced stages. While immune checkpoint inhibitors (ICIs) have shown promise in various sarcoma subtypes, including DDLPS, their role as a first-line treatment remains unclear.

METHODS

We conducted a systematic meta-analysis to evaluate the efficacy of ICIs in treating patients with DDLPS. A total of 25 studies encompassing 245 patients were included. Data on overall response rate (ORR), progression-free survival, and grade III-V treatment-related adverse events were analyzed. We assessed treatment efficacy based on the line of therapy and treatment regimens, including ICI monotherapy, dual ICI therapy, and ICI combinations with other modalities.

RESULTS

The pooled ORR for all ICI-based treatments was 7%. First-line ICI therapy yielded a significantly higher ORR of 22%, compared to 4% in later-line treatment. The combination of ICI with anthracyclines demonstrated the highest ORR of 52%. In contrast, ICI regimens combined with trabectedin or other agents showed limited efficacy. Sensitivity analysis confirmed the stability of results, and publication bias was not detected.

CONCLUSION

This meta-analysis supports the potential role of ICIs, particularly in combination with anthracyclines, as a first-line therapeutic strategy for DDLPS. These results provide a foundation for future prospective studies aimed at optimizing immunotherapy approaches for this rare and challenging malignancy.

Malignant Mesenchymal Tumors of the Breast: Current Challenges and New Perspectives on Primary Sarcomas and Malignant Phyllodes Tumors

Mesenchymal tumors of the breast constitute a rare and heterogeneous group of neoplasms, representing only 0.5% to 1% of all breast tumors. Originating from mesenchymal tissues, these tumors include various histological subtypes. They are particularly aggressive, characterized by a high propensity for local recurrence and an overall poor prognosis. The rarity of these cases has impeded the development of comprehensive clinical studies, leading to a lack of standardized diagnostic protocols and treatment guidelines. This review provides a thorough synthesis of current knowledge on breast mesenchymal tumors with a specific focus on malignant variants such as phyllodes tumors and breast sarcomas. It also addresses the diagnostic challenges faced by clinicians, evaluates current therapeutic strategies, and emphasizes the crucial role of surgical treatment. Additionally, it examines the evolving roles of chemotherapy and radiotherapy in enhancing patient outcomes.

Research progress on cancer-associated fibroblasts in osteosarcoma

Osteosarcoma (OS) is a prevalent primary bone malignancy with limited treatment options. Therefore, it is imperative to investigate and understand the mechanisms underlying OS pathogenesis. Cancer-associated fibroblasts (CAFs) are markedly abundant in tumor stromal cells and are essentially involved in the modulation of tumor occurrence and development. In recent years, CAFs have become a hotspot as researchers aim to elucidate CAF mechanisms that regulate tumor progression. However, most studies on CAFs are limited to a few common cancers, and their association with OS remains elusive. This review describes the role and current knowledge of CAFs in OS, focusing on their potential cellular origin, classification, and diverse functionality. It was found that CAFs influenced OS tumor cell signaling, proliferation, invasion, metastasis, epithelial-mesenchymal transition, stemness maintenance, angiogenesis, and the ability to modify immune system components. Furthermore, findings on other common cancers indicated that effective therapeutic strategies included the manipulation of CAF activation, targeting CAF-derived components, and depletion of CAFs by biomarkers. This review provides new insights and a theoretical basis for OS research.

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.

Undifferentiated Pleomorphic Sarcoma in Children and Young Adults: A Comprehensive Clinicopathologic, Genomic, and Epigenetic Comparison With Adult Counterparts

Undifferentiated pleomorphic sarcoma (UPS) occurs primarily in older adults and remains a diagnosis of exclusion due to its lack of differentiation and specific molecular alterations. Its occurrence in children is rare and controversial, with an unclear relationship to its adult counterpart. In this study, we aimed to investigate a cohort of 6 pediatric undifferentiated pleomorphic sarcoma (P-UPS, mean 10 years old) and 19 young-adult undifferentiated pleomorphic sarcoma (YA-UPS, mean 30 years old) cases by conducting a comprehensive comparative analysis of their clinicopathologic, genomic, and epigenetic features relative to their adult undifferentiated pleomorphic sarcoma counterparts (A-UPS, n = 100). Histologically, P-UPS and YA-UPS exhibited broad morphologic spectrum. The most frequent alterations across all groups were TP53, CDKN2A/B, and ATRX, with no significant differences among subsets. Notably, RB1 alterations were absent in P-UPS, although representing the second most common alteration in YA-UPS (32%) and A-UPS (41%). PTEN alterations were significantly more prevalent in YA-UPS (26%) compared with that in P-UPS (0%) and A-UPS (6%). Deletions in chromosomes 10, 16q, and 13q, along with amplification of 20q, were the most common across all groups. Except for a higher frequency of 17q amplification in P-UPS (33%) and YA-UPS (26%) compared with that in A-UPS (6%), no other arm-level differences were observed. P-UPS showed a lower mean fraction genome altered compared with YA-UPS and A-UPS, whereas all UPS age groups showed a low tumor mutational burden (mean <10 mut/MB). Pathogenic germline variants of high clinical significance (TP53, NF1, MLH1, CHEK2, and BARD1) were observed only in YA-UPS (31%) and A-UPS (12%) cases. By T-distributed stochastic neighborhood embedding and hierarchical clustering of DNA methylation, the majority of P-UPS and a small subset of YA-UPS grouped in a distinct cluster, characterized by a lower genomic index compared to A-UPS. In contrast, most UPS occurring in young adults genomically parallel their older adults' counterparts. P-UPS and YA-UPS cases exhibited a better disease-specific and progression-free survival, compared with A-UPS cases.

Botensilimab (Fc-enhanced anti-cytotoxic lymphocyte-association protein-4 antibody) Plus Balstilimab (anti-PD-1 antibody) in Patients With Relapsed/Refractory Metastatic Sarcomas

PURPOSE

Outcomes for patients with advanced sarcomas are poor and there is a high unmet need to develop novel therapies. The purpose of this phase I study was to define the safety and efficacy of botensilimab (BOT), an Fc-enhanced anti-cytotoxic lymphocyte-association protein-4 antibody, plus balstilimab (BAL), an anti-PD-1 antibody, in advanced sarcomas.

METHODS

BOT was administered intravenously (IV) at 1 mg/kg or 2 mg/kg once every 6 weeks in combination with BAL IV at 3 mg/kg once every 2 weeks for up to 2 years. The primary end point was to determine dose-limiting toxicities during the dose-escalation period. Secondary end points include objective response rate (ORR), duration of response (DOR), disease control rate, and progression-free survival (PFS) by RECIST 1.1. Exploratory end points include assessing patient biomarkers including tumor mutational burden, cytokines, and PD-L1 expression.

RESULTS

Overall, 64 patients with sarcoma were treated; all were evaluable for safety and 52 for efficacy. The most common treatment-related adverse event (TRAE) was diarrhea/colitis occurring in 35.9% of patients, with grade 3 in 6.3% of patients. No grade 4 or 5 TRAEs were reported. For all evaluable patients, ORR was 19.2% (95% CI, 9.6 to 32.5), and 27.8% (95% CI, 9.7 to 53.5) for evaluable patients with angiosarcoma (n = 18); 33.3% in visceral and 22.2% in cutaneous subtypes. Median PFS for evaluable patients was 4.4 months (95% CI, 2.8 to 6.1), with a 6-month PFS rate of 36% (95% CI, 22 to 50) and a median DOR of 21.7 months (95% CI, 1.9 to not reached).

CONCLUSION

The combination of BOT/BAL demonstrated promising efficacy and safety in a large cohort of heavily pretreated sarcoma patients. This encouraging activity warrants further investigation (ClinicalTrials.gov identifier: NCT03860272).

UV-induced multifocal cutaneous high-grade leiomyosarcoma

Cutaneous sarcomas almost never present as multifocal disease. We describe a case of a man in his mid-90s with history of prior squamous cell carcinomas and an atypical fibroxanthoma involving the scalp who presented with multiple focal cutaneous nodules localised to the scalp, with some >3 cm. Biopsy with histopathology confirmed high-grade desmin-positive mesenchymal malignancy, with 99% of cells expressing PD-1, consistent with leiomyosarcoma (LMS). Gene expression profiling indicated a UV gene signature. The patient was treated with radiation therapy to the affected area with significant response but then developed additional cutaneous nodules inferior to the radiation field. He was subsequently treated with pembrolizumab with almost immediate resolution of the remaining nodules. This case is unique as it highlights several unusual features of cutaneous high-grade LMSs, notably presentation of multifocal disease, a UV signature and high responsiveness to anti-PD-1 therapy.

Synergistic chemo-immunotherapy for osteosarcoma via a pH-responsive multi-component nanoparticle system

Introduction

Osteosarcoma (OS) is the most common primary malignant bone tumor in pediatric populations. Its treatment is complicated by chemotherapy-induced toxicity and limited induction of immunogenic cell death (ICD).

Methods

To address these challenges, we developed a pH-responsive, multi-component nanoparticle system designed to co-deliver doxorubicin (DOX), monophosphoryl lipid A (MPLA), and a PD-1/PD-L1-targeting peptide, integrated with the immune-modulating polymer PEG-PC7A. The system was optimized using both one-factor-at-a-time (OFAT) and Box-Behnken design (BBD).

Results

The optimized nanoparticles had a hydrodynamic size of 110 nm, high encapsulation efficiency (97.15%), and pH-sensitive drug release (91% at pH 6.5). In vitro studies showed enhanced ICD markers, including calreticulin exposure and ATP/HMGB1 release, aswell as synergistic dendritic cell maturation via dual STING/TLR4 pathway activation. In an orthotopic LM8 osteosarcoma model, the nanoparticles significantly suppressed tumor growth, promoted cytotoxic T lymphocyte infiltration, reduced regulatory T cells, and established long-term immune memory.

Discussion

The combination of ICD induction, innate immune activation, and checkpoint blockade reprogrammed the tumor microenvironment, amplifying anti-tumor immune responses. These results demonstrate the potential of this multifunctional nanoparticle platform as an effective immunochemotherapeutic strategy for osteosarcoma, offering enhanced therapeutic efficacy and reduced systemic toxicity.

Evaluation of tumorous LCP1 and ADPGK as predictive biomarker for immune-related adverse events in bone and soft tissue sarcomas treated with anti-PD-1 and anti-PD-L1 antibodies

Immune checkpoint inhibitor (ICI) have been utilized in bone and soft tissues sarcoma patients under multiple circumstances in combination with surgeries and chemotherapy. Regretfully, immune-related adverse events (irAE) increases as the usage of ICI increases. Since a large portion of bone and soft tissues sarcoma patients gain long survival times after successful removal of the tumors which makes clinicians to avoid regimens that causes adverse events, especially lifetime irAE. Hence, predicting the development of irAE are of special significance for utilizing ICI in bone and soft tissues sarcoma patients. We have retrospectively stained tumorous LCP1 and ADPGK, two biomarkers previously reported to predict ICI induced irAE, with surgical removed, formalin-fixed and parrffin-embedded samples in a cohort of 50 bone and soft tissues sarcoma patients. We observed that the most common irAE in bone and soft tissues sarcoma patients received ICI is hyperglycemia and high grade irAE happens predominately in patients over 30 years old. Immunochemistry revealed that both LCP1 and ADPGK were elevated in tumorous tissues of patients developed irAE and bivariate-model of LCP1 and ADPGK severs as a better biomarker in comparison to LCP1 or ADPGK alone in the entire cohort. In osteosarcoma, LCP1 alone exhibited an outstanding predication value with an AUC of 0.9244 (P value of 0.0013 and a 95% CI of 0.8178 to 1.000). LCP1 and ADPGK bivariate-model serves as a promising biomarker for predicting ICI induced irAE in bone and soft tissues sarcoma patients while LCP1 alone works better in bone malignancy especially in osteosarcoma.

Cytokine Profiling of Children, Adolescents, and Young Adults Newly Diagnosed with Sarcomas Demonstrates a Role for IL-1β in Osteosarcoma Metastasis

Background

Sarcomas are a heterogeneous group of mesenchymal tumors frequently diagnosed in pediatric and young adult patients. These tumors respond poorly to conventional immunotherapy, though the precise reason for this is not known. We sought to characterize the systemic immune response to sarcomas by measuring the levels of circulating cytokines in the plasma of sarcoma patients, testing the hypothesis that the natures of a patient's immune response to their tumor directly affects outcome.

Methods

Plasma was collected from newly diagnosed, treatment-naive pediatric sarcoma patients participating in an ongoing clinical trial, MCC20320. A panel of 18 cytokines was selected and cytokine levels were measured using the Luminex platform. Cytokine levels were analyzed based on clinicopathological parameters such as gender, age, stage, and survival.

Results

We found that the cytokine profile in patients newly diagnosed with sarcoma is distinct from healthy controls, but different sarcomas were not distinguishable. Patients with osteosarcoma who had elevated levels of multiple cytokines had inferior overall survival compared to those with fewer or no elevated levels. Similarly, elevated levels of individual cytokines and chemokines, including IL-24, CXCL5, and CXCL10, were associated with inferior event-free or overall survival in patients with osteosarcoma. Perhaps most significantly, elevated IL-1β at diagnosis was associated with metastatic presentation and inferior event-free survival in patients with osteosarcoma.

Conclusion

These findings suggest that pediatric sarcoma patients mount a systemic immune response that may affect event-free or overall survival. IL-1β in particular may be a valuable target for immunotherapy for osteosarcoma patients.

Case Report: Lasting complete response to pembrolizumab in mismatch repair-deficient cardiac sarcoma: a genomic characterization

Sarcomas are traditionally considered "cold" tumors with poor response to immunotherapy. However, evidence accumulating over the last years shows that immune checkpoint inhibitors (ICIs) may have a role in selected sarcoma patients according to predictive markers. Here, we report the case of a woman diagnosed with a primary cardiac undifferentiated sarcoma. Following failure of standard first line chemotherapy, high-throughput sequencing (HTS) revealed a high tumor mutational burden (TMB), pathogenic mutations in FAT1 and NOTCH2 and a microsatellite instability (MSI)-associated signature. Immunohistochemistry confirmed mismatch repair-deficiency (MMRd) and abundant CD8+ tumor-infiltrating lymphocytes (TILs), in the absence of tertiary lymphoid structures. The patient was, therefore, treated with the ICI pembrolizumab, reaching a complete response that continues to persist at last follow-up, more than seven years from initial diagnosis and nearly six years from initiation of ICI treatment. This case illustrates the importance of performing HTS in rare sarcomas given the availability of efficient therapies, such as those for tumors displaying high TMB or MMRd/MSI. In agreement with other reports, it supports the contention that MMRd/MSI status and high numbers of TILs are valuable predictive markers of response to immunotherapy in sarcomas.

PD‑1/PD‑L1 immune checkpoint in bone and soft tissue tumors (Review)

Anti-programmed cell death 1 (PD-1)/PD-1 ligand-1 (PD-L1) drugs have been used clinically, including those for skin cancer, with reasonable efficacy. Despite extensive ongoing research on bone and soft tissue sarcomas, there is a paucity of reviews that present a coherent picture. The present article is a comprehensive narrative review on the role of the PD-1/PD-L1 immune checkpoint in bone and soft tissue tumors. The review outlines the biological functions and mechanisms of action of PD-1/PD-L1 and its expression and clinical significance in various tumor types, including osteosarcoma and soft tissue sarcoma. Clinical trial results of immune checkpoint inhibitors, their association with prognosis, mechanisms of resistance to therapy, immune-related adverse events, and their potential in combination therapies, were also discussed.

The Decline and Fall of the Current Chemotherapy Paradigm in Soft Tissue Sarcoma

BACKGROUND/OBJECTIVES

Despite conventional cytotoxic chemotherapy treatments, soft tissue sarcoma continues to remain a terminal diagnosis for most patients. Numerous chemotherapeutic agents have been trialed in soft tissue sarcoma, with marginal improvement in overall survival. Novel therapeutic approaches are needed to improve outcomes for this entity.

METHODS

the literature was reviewed, including a summary of pertinent adjuvant/neoadjuvant clinical trials and trials for metastatic disease.

RESULTS

Chemotherapeutic agent use in adjuvant/neoadjuvant trials provided limited if any evidence of the benefit of chemotherapy in this space. Despite multiple trials in the metastatic space, novel chemotherapeutic agents appear to have limited long-term benefits for the management of soft tissue sarcoma. Suggestions for further research, particularly with neoadjuvant clinical trials, were made.

CONCLUSIONS

Chemotherapy remains an inadequate treatment option for soft tissue sarcoma, and novel therapies are needed. The neoadjuvant space provides an excellent opportunity to study the effects of innovative treatments in soft tissue sarcoma.

Contemporary surgical management of osteosarcoma and Ewing sarcoma

The incidence of malignant bone tumors has remained relatively stable over the past two decades between 8% and 9% per 1,000,000 in North America. Multidisciplinary treatment is paramount for optimal care combining surgical resection, chemotherapy, and rehabilitation. Surgical treatment aims for a negative margin resection of the sarcoma with a personalized reconstruction plan. Limb salvage surgery (LSS) is possible in the majority of cases; however, amputation (including rotationplasty) may be required or preferred. Reconstruction can be achieved utilizing endoprostheses, allograft, autograft, or a combination of these techniques. Emerging technologies such as 3D printing of implants and cutting guides, and intraoperative navigation have helped to improve options for LSS.

Frequent copy number gain of MCL1 is a therapeutic target for osteosarcoma

Osteosarcoma (OS) is a primary malignant bone tumor primarily affecting children and adolescents. The lack of progress in drug development for OS is partly due to unidentified actionable oncogenic drivers common to OS. In this study, we demonstrate that copy number gains of MCL1 frequently occur in OS, leading to vulnerability to therapies based on Mcl-1 inhibitors. Fluorescence in situ hybridization analysis of 41 specimens revealed MCL1 amplification in 46.3% of patients with OS. Genetic inhibition of MCL1 induced significant apoptosis in MCL1-amplified OS cells, and the pharmacological efficacy of Mcl-1 inhibitors was correlated with MCL1 copy numbers. Chromosome 1q21.2-3 region, where MCL1 is located, contains multiple genes related to the IGF-1R/PI3K pathway, including PIP5K1A, TARS2, OUTD7B, and ENSA, which also showed increased copy numbers in MCL1-amplified OS cells. Furthermore, combining Mcl-1 inhibitors with IGF-1R inhibitors resulted in synergistic cell death by overcoming drug tolerance conferred by the activation of IGF signaling and suppressed tumor growth in MCL1-amplified OS xenograft models. These results suggest that genomic amplification of MCL1 in the 1q21.2-3 region, which occurred in approximately half of OS patients, may serve as a predictive biomarker for the combination therapy with an Mcl-1 inhibitor and an IGF1R inhibitor.

Angiosarcoma: Role of Immunotherapy

OPINION STATEMENT

Recent clinical trials have investigated immune checkpoint inhibitors (ICIs) alone, in combination with tyrosine kinase inhibitors (TKIs), or with chemotherapy in angiosarcoma, yielding mixed results across subtypes. Single-agent ICI therapy, such as cemiplimab (ORR 27.8%), has shown responses primarily in UV- and radiation-associated angiosarcomas, likely due to their higher tumor mutation burden (TMB), while dual ICI therapy (SWOG S1609, ORR 25%) suggests potential benefit but remains limited in cutaneous disease. ICI-TKI combinations, such as cabozantinib plus nivolumab (Alliance A091902, second-line, ORR 59%), demonstrated significant efficacy in both cutaneous and non-cutaneous angiosarcomas, suggesting anti-angiogenic therapy may enhance ICI responses in tumors historically resistant to checkpoint blockade. ICI-chemotherapy combinations have been less consistent. The Alliance A091902 first-line trial (paclitaxel ± nivolumab) found no overall PFS benefit, though scalp/face angiosarcoma patients appeared to fare better, raising the question of whether ICI alone might be equally effective in this subset. The South Korean paclitaxel + avelumab trial (ORR 50%) showed promising response rates, but the lack of detailed subgroup analysis limits interpretation. Other chemotherapy-ICI combinations, such as doxorubicin plus pembrolizumab, have shown isolated responses but require further study in larger cohorts. Moving forward, better biomarkers are critical for identifying which patients benefit most from ICIs, and while TKI-ICI combinations appear to hold the most promise, chemotherapy-ICI strategies need further refinement to optimize sequencing and patient selection in angiosarcoma treatment.

Macrophage and osteosarcoma cell crosstalk is dependent on oxygen tension and 3D culture

Osteosarcoma (OS), the most common form of primary bone cancer in young adults, has had no improvements in clinical outcomes in 50 years. This highlights a critical need to advance mechanistic understanding of OS to further therapeutic discovery, which will only be possible with accurate models of the disease. Compared to traditional monolayer studies and preclinical models, in vitro models that better replicate the three-dimensional (3D) bone marrow microenvironment will facilitate methodical investigations of the events and factors that drive OS progression. Herein, we use fibrin-alginate interpenetrating network (FA IPN) hydrogels to model the hematological bone marrow environment. We interrogated the effects of oxygen tension, 3D culture, and macrophage phenotype on OS behavior and specifically examine the immunomodulatory crosstalk between OS and macrophages. We observe that OS is more sensitive to oxygen tension when cultured in 3D. Specifically, both highly and less metastatic OS exhibit decreased changes in DNA content over time in 3D, but then demonstrate diverging behaviors in heterotypic culture with macrophages. OS response to macrophages differs as a function of metastatic potential, where highly metastatic OS shows increased immunosuppression that varies with oxygen tension but relies on direct coculture conditions. To our knowledge, this is among the first work to report the effects of 3D culture on the interplay between OS and macrophages in a coculture microenvironment. Together, these data introduce FA IPNs as a promising platform for cancer research and emphasize the importance of novel models for the mechanistic study of OS.

An improved experimental model of osteosarcoma lung metastases to investigate innovative therapeutic interventions and sex as a biological variable

Osteosarcoma (OS) is the most common primary bone malignancy, with OS lung metastasis (OSLM) being the leading cause of death in OS patients. No curative pharmacotherapies for OSLM are available, highlighting the clinical need for new therapies. Improved and rigorous preclinical models of OSLM are key in supporting advancements in this field. We aimed to develop an immunocompetent mouse model of OSLM that allows monitoring pharmacotherapies' effect on the lung metastatic burden over time and assessing the impact of sex as a biological variable in tumor growth and response to therapy. We transformed K7M2 cells to express bioluminescence and fluorescence, enabling real-time tracking of OSLM in BALB/c mice following tail vein injection. Metastasis was confined to the lungs and exhibited exponential growth with typical downregulated Fas receptor expression. In vivo bioluminescence correlated strongly with ex vivo, suggesting its reliability for evaluating metastatic progression and therapy response. Fluorescence from tdT was stable upon tissue processing, providing unique opportunities to probe the tumor characteristics ex vivo. We also assessed the effect of local lung-delivered gemcitabine, which was well-tolerated and significantly reduced OSLM burden without causing pulmonary toxicity. However, treatment did not resolve metastatic disease. We also explored the effect of sex on tumor growth and response to therapy; while no difference was observed in tumor growth between male and female mice, females showed a better response to local gemcitabine administration. In sum, we established a robust and rigorous immunocompetent mouse model of OSLM that will facilitate exploring new pharmacotherapies for OSLM.

The outcomes and treatment strategies in metastatic soft tissue sarcoma treated with immunotherapy-based therapy: a three-center study

Background

Preclinical studies showed that cytotoxic agents and antiangiogenic agents had regulatory effects in the tumor immune microenvironment of soft tissue sarcoma (STS), and then enhance the antitumor effect of immunotherapy. This study was to investigate the efficacy and safety of immunotherapy-based therapy in metastatic STS.

Methods

We conducted a retrospective analysis in three centers where some patients received immunotherapy-based therapy consisting of immunotherapy alone or in combination with systemic agents (cytotoxic agents and/or antiangiogenic agents). The primary endpoints were median progression-free survival (mPFS) and median overall survival (mOS), and Kaplan-Meier method was used to compare survival.

Results

A total of 79 patients were included in this study. With the median follow-up of 14.2 months, the mPFS and mOS was 7.5 months and 19.5 months, respectively. The PFS (P < 0.01) and OS (P < 0.01) were significantly better in the alveolar soft part sarcoma (ASPS) group compared to the non-ASPS group. Patients who treated in ≤2 lines had longer PFS (P < 0.01) and OS (P < 0.01) compared to those in subsequent lines. Further analysis was performed according to histopathological types, in patients with ASPS, the combination of immunotherapy-based therapy resulted in a longer PFS (P < 0.01) compared to immunotherapy in monotherapy. Similarly, the patients treated in ≤2 lines had longer PFS (P=0.03) and OS (P < 0.01) compared to in subsequent lines. In patients with non-ASPS, patients with potentially sensitive sarcomas (undifferentiated pleomorphic sarcoma, dedifferentiated liposarcoma, myxofibrosarcoma, and angiosarcoma) had a longer PFS (P = 0.02) and OS (P = 0.03) compared to other subtypes. The OS (P = 0.03) for patients with potentially sensitive sarcomas treated in ≤2 lines showed a long trend compared to subsequent lines. Most adverse events reported were mild and tolerable.

Conclusions

The immunotherapy-based therapy showed promising activity in survival, especially in certain histological subtypes (undifferentiated pleomorphic sarcoma, dedifferentiated liposarcoma, myxofibrosarcoma, and angiosarcoma), as well as in combination treatment and in early lines. Prospective researches are needed to confirm the potential benefits.

Immunologic correlates in a CIC::DUX4 fusion-positive sarcoma responsive to dual immune checkpoint blockade

CIC::DUX4 sarcoma (CDS) is a rare and aggressive subtype of soft tissue sarcoma with poor prognosis and limited treatment options. Immunotherapy has not been studied in this disease. To our knowledge, response to immune checkpoint blockade (ICB) has not been previously reported. Here, we present the first case of a patient with CDS responding to dual ICB with nivolumab and relatlimab. Immunohistochemical (IHC) analysis of pre-treatment samples revealed minimal immune cell infiltration, with scarce CD3+, CD8+, and FOXP3+ T-cells and negligible expression of PD-L1 and PD-1 markers. Post-treatment tumor samples revealed a significant shift in the immune microenvironment, with increased CD8 + T-cell infiltration and co-expression of exhaustion markers PD-1 and LAG-3 following treatment. These findings suggest that doublet ICB can activate an antitumor immune response in CDS, overcoming the immune cold phenotype typically associated with this sarcoma. This case provides the first evidence of dual PD-1/LAG-3 blockade inducing an immune response in CDS. The favorable response and tolerability observed in this patient highlight the potential of dual ICB as a therapeutic option in CDS that merits further investigation.

Identification and characterization of mitochondrial autophagy-related genes in osteosarcoma and predicting clinical prognosis

Osteosarcoma (OS), the most prevalent primary malignant bone tumor, is characterized by a poor prognosis and high metastatic potential. Mitochondrial autophagy has been implicated in cancer suppression. This study aimed to identify prognostic genes associated with mitochondrial autophagy in OS. Public datasets, including TARGET-OS, GSE99671, and GSE21257, were retrieved for analysis. Differentially expressed genes (DEGs1) between OS and normal samples were identified from GSE99671. Single-sample Gene Set Enrichment Analysis (ssGSEA) was applied to quantify the enrichment scores of 29 mitochondrial autophagy-related genes (MARGs) in OS samples from TARGET-OS, categorizing them into high- and low-score groups to extract DEGs2. The intersection of DEGs1 and DEGs2 yielded mitochondrial autophagy-associated differentially expressed genes (MDGs). Prognostic genes were subsequently screened through a multi-step regression analysis, and a risk score was computed. TARGET-OS samples were stratified into high- and low-risk groups based on the optimal cutoff value of the risk score. GSEA was conducted between the two risk groups. Additionally, associations between prognostic genes and the immune microenvironment were explored. A total of 31 MDGs were identified from the overlap of 3,207 DEGs1 and 622 DEGs2. Five prognostic genes-KLK2, NRXN1, HES5, OR2W3, and HS3ST4-were further selected. Kaplan-Meier survival analysis indicated significantly reduced survival in the high-risk group. GSEA revealed enrichment in ABC transporter activity and glycolysis/gluconeogenesis pathways. Immunoanalysis demonstrated significant differences in 11 immune cell populations and three immune functions between risk groups, notably myeloid-derived suppressor cells (MDSCs) and Type 1 T helper cells. HS3ST4 exhibited the strongest positive correlation with macrophages, whereas NRXN1 showed the most pronounced negative correlation with memory B cells. Expressions of HAVCR2 and PDCD1LG2 were elevated in the low-risk group. Functional analysis indicated significant differences in dysfunction patterns between risk groups. This study identified five mitochondrial autophagy-related prognostic genes and constructed a risk model, offering novel insights into OS diagnosis and therapeutic strategies.

Methionine intervention induces PD-L1 expression to enhance the immune checkpoint therapy response in MTAP-deleted osteosarcoma

Osteosarcoma (OS), a malignant bone tumor with limited treatment options, exhibits low sensitivity to immune checkpoint therapy (ICT). Through genomics and transcriptomics analyses, we identify a subgroup of OS with methylthioadenosine phosphorylase (MTAP) deletion, which contributes to ICT resistance, leading to a "cold" tumor microenvironment. MTAP-deleted OS relies on methionine metabolism and is sensitive to methionine intervention, achieved through either dietary restriction or inhibition of methionine adenosyltransferase 2a (MAT2A), a key enzyme in methionine metabolism. We further demonstrate that methionine intervention triggers programmed death-ligand 1 (PD-L1) transcription factor IKAROS family zinc finger 1 (IKZF1) and enhances PD-L1 expression in MTAP-deleted OS cells. Methionine intervention also activates the immune-related signaling pathways in MTAP-deleted OS cells and attracts CD8+ T cells, thereby enhancing the efficacy of ICT. Combining methionine intervention with ICT provides a significant survival benefit in MTAP-deleted OS murine models, suggesting a rationale for combination regimens in OS ICT.

Emerging immunotherapies in osteosarcoma: from checkpoint blockade to cellular therapies

Osteosarcoma remains a highly aggressive bone malignancy with limited therapeutic options, necessitating novel treatment strategies. Immunotherapy has emerged as a promising approach, yet its efficacy in osteosarcoma is hindered by an immunosuppressive tumor microenvironment and resistance mechanisms. This review explores recent advancements in checkpoint blockade, cellular therapies, and combination strategies aimed at enhancing immune responses. We highlight key challenges, including tumor heterogeneity, poor immune infiltration, and the need for predictive biomarkers. By integrating immunotherapy with chemotherapy, radiotherapy, and targeted therapy, emerging approaches seek to improve treatment outcomes. This review provides a comprehensive analysis of the evolving landscape of osteosarcoma immunotherapy, offering insights into future directions and potential breakthroughs. Researchers and clinicians will benefit from understanding these developments, as they pave the way for more effective and personalized therapeutic strategies in osteosarcoma.

Monocyte-lineage tumor infiltration predicts immunoradiotherapy response in advanced pretreated soft-tissue sarcoma: phase 2 trial results

Immunoradiotherapy holds promise for improving outcomes in patients with advanced solid tumors, including in soft-tissue sarcoma (STS). However, the ideal combination of treatment modalities remains to be determined, and reliable biomarkers to predict which patients will benefit are lacking. Here, we report the results of the STS cohort of the SABR-PDL1 phase II trial that evaluated the anti-PDL1 atezolizumab combined with stereotactic body radiation therapy (SBRT) delivered concurrently with the 2nd cycle to at least one tumor site. Eligible patients received atezolizumab until progression or unmanageable toxicity, with SBRT at 45 Gy in 3 fractions). The primary endpoint was one-year progression-free survival (PFS) rate with success defined as 13 patients achieving 1-year PFS. Sixty-one heavily pretreated patients with STS (median 5 prior lines; 52% men; median age 54 years; 28% leiomyosarcoma) were enrolled across two centers (France, Spain). SBRT was delivered to 55 patients (90%), with the lung being the most commonly irradiated site (50%). After a median follow-up of 45 months, the one-year PFS rate was 8.3% [95% CI: 3.6-18.1]. Median PFS and overall survival were 2.5 and 8.6 months, respectively. Best responses included partial responses (5%) and stable disease (60%). Immune profiling revealed increased immunosuppressive tumor-associated macrophages (e.g., IL4I1, HES1) and monocyte-recruiting chemokines in non-responders. Higher monocyte/lymphocyte ratios (MonoLR) in tumor and blood correlated with progression. PD-L1 status, lymphoid infiltration, and tertiary-lymphoid structures were not predictive. Although the primary endpoint was not met, this study highlights MonoLR imbalance as a potential biomarker to identify STS patients likely to benefit from immunoradiotherapy. EudraCT No. 2015-005464-42; Clinicaltrial.gov number: NCT02992912.

Druggable upregulated proteins in EWS-FLI-driven Ewing sarcoma as emerging new therapeutic targets

Ewing sarcoma (ES) is a highly aggressive soft tissue tumor that primarily affects the long bones of children and young adults. It is distinguished by a characteristic chromosomal translocation between the Ewing sarcoma breakpoint region 1 (EWS) gene and the erythroblast transformation-specific (ETS) family of genes, most commonly resulting in the EWS-friend leukemia integration 1 (EWS-FLI1) fusion gene. This translocation is observed in approximately 80%-85% of ES cases. This fusion gene encodes a non-physiological chimeric fusion protein that plays a central role in tumorigenesis by interacting with numerous partner proteins. Several studies have demonstrated the tumorigenic potential of the EWS-FLI1 protein when transfected into non-cancer cell lines. However, targeting EWS-FLI1 directly remains a significant challenge, as no drug to date has been reported to bind to and inhibit its activity effectively. An alternative therapeutic strategy involves targeting key overexpressed protein complexes implicated in ES tumorigenesis, many of which may be downstream interacting partners of EWS-FLI1. This review explores emerging protein targets as potential therapeutic avenues in ES treatment.

Evolutionary Pressures Shape Undifferentiated Pleomorphic Sarcoma Development and Radiotherapy Response

Radiotherapy is an integral component in the treatment of many types of cancer, with approximately half of patients with cancer receiving radiotherapy. Systemic therapy applies pressure that can select for resistant tumor subpopulations, underscoring the importance of understanding how radiation impacts tumor evolution to improve treatment outcomes. We integrated temporal genomic profiling of 120 spatially distinct tumor regions from 20 patients with undifferentiated pleomorphic sarcomas (UPS), longitudinal circulating tumor DNA analysis, and evolutionary biology computational pipelines to study UPS evolution during tumorigenesis and in response to radiotherapy. Most unirradiated UPSs displayed initial linear evolution, followed by subsequent branching evolution with distinct mutational processes during early and late development. Metrics of genetic divergence between regions provided evidence of strong selection pressures during UPS development that further increased during radiotherapy. Subclone abundance changed after radiotherapy with subclone contraction tied to alterations in calcium signaling, and inhibiting calcium transporters radiosensitized sarcoma cells. Finally, circulating tumor DNA analysis accurately measured subclone abundance and enabled noninvasive monitoring of subclonal changes. These results demonstrate that radiation exerts selective pressures on UPSs and suggest that targeting radioresistant subclonal populations could improve outcomes after radiotherapy. Significance: Radiotherapy mediates tumor evolution by leading to the expansion of resistant subclonal cancer cell populations, indicating that developing approaches to target resistant subclones will be crucial to improve radiotherapy response.

Anti-CD137 agonist antibody-independent and clinically feasible preparation of tumor-infiltrating lymphocytes from soft tissue sarcoma and osteosarcoma

Background

Tumor infiltrating lymphocytes (TILs) therapy has been proved for treatment of metastatic melanoma and is under investigation for other types of solid tumors. However, these successes are threatened by discontinued supply of GMP-grade anti-CD137 agonist, a key TIL preparation reagent. Therefore, exploring a GMP-adherent method for expanding endogenous TILs without anti-CD137 agonist is urgent. Toward this end, we aimed to establish an anti-CD137-independent and clinically feasible TIL expansion protocol to prepare TILs from under investigated sarcoma tumors.

Methods

We collected resected tumors from patients and cut tissues into fragments. We used IL-2 and T-cell activator CD3/CD28 without anti-CD137 agonist to expand nonselected TILs in 2-3 weeks, then rapidly expanded them over 2 weeks. Their phenotypes were characterized using flow cytometry. Their antitumor activity was validated in vitro using cytotoxic T lymphocyte assays measuring CD107a on the TILs and the viability of tumor cells and in vivo using an autologous patient-derived xenograft (PDX) tumor model.

Results

We successfully expanded TILs in > 90% of collected samples. TILs generated preferentially increased CD8+ T cells but suppressed CD4+ T cells. A small portion of TILs were resident memory T cells. The expanded TILs reduced autologous tumor cells by 37.5% within 24 hours. Infusion of TILs in mice bearing autologous PDX tumors strongly inhibited liposarcoma growth. FDA has approved use of this GMP-feasible protocol in our clinical trial (IND 30562).

Conclusion

It is feasible to generate antitumor TILs using CD3/CD28 activator to replace the unavailable anti-CD137 agonist. Our study supports the further development of TIL-based therapy.

Systemic Treatment in Soft Tissue Sarcomas: Are We Making a Difference?

Soft tissue sarcomas [STSs] are rare tumors of mesodermal origin that arise in diverse tissues such as muscles, fat, and nerves. There are over 100 subtypes of STS, each with distinct clinical behaviors and responses to treatment. Recent advances in treatment have moved towards histology-specific approaches, emphasizing the integration of pathological, immunohistochemical, and molecular features to guide treatment. Localized STS is primarily treated with surgery, often supplemented by neoadjuvant or adjuvant radiation and/or chemotherapy. However, about half of patients with localized disease will progress to an advanced stage, which is typically managed with systemic therapies including anthracycline-based chemotherapy such as doxorubicin or epirubicin. Despite these treatments, the survival rates for most subtypes of advanced metastatic STS remain relatively low. While anthracycline-based chemotherapy remains the mainstay of treatment, ongoing research into the biology of STSs is enhancing our understanding and approach to these complex tumors with an expansion beyond chemotherapy to include targeted therapy and immunotherapy to improve response rates and survival outcomes. This review focuses on STS other than gastrointestinal stromal tumors [GISTs], examines the current systemic treatment strategies, highlights recent advances, and explores future directions in the systemic therapy of sarcoma patients.