Novel Immunotherapies for Osteosarcoma

Advances in cell therapy for orthopedic diseases: bridging immune modulation and regeneration

Orthopedic diseases pose significant challenges to public health due to their high prevalence, debilitating effects, and limited treatment options. Additionally, orthopedic tumors, such as osteosarcoma, chondrosarcoma, and Ewing sarcoma, further complicate the treatment landscape. Current therapies, including pharmacological treatments and joint replacement, address symptoms but fail to promote true tissue regeneration. Cell-based therapies, which have shown successful clinical results in cancers and other diseases, have emerged as a promising solution to repair damaged tissues and restore function in orthopedic diseases and tumors. This review discusses the advances and potential application of cell therapy for orthopedic diseases, with a particular focus on osteoarthritis, bone fractures, cartilage degeneration, and the treatment of orthopedic tumors. We explore the potential of mesenchymal stromal cells (MSCs), chondrocyte transplantation, engineered immune cells and induced pluripotent stem cells to enhance tissue regeneration by modulating the immune response and addressing inflammation. Ultimately, the integration of cutting-edge cell therapy, immune modulation, and molecular targeting strategies could revolutionize the treatment of orthopedic diseases and tumors, providing hope for patients seeking long-term solutions to debilitating conditions.

Bibliometric analysis of targeted immunotherapy for osteosarcoma-current knowledge, hotspots and future perspectives

Objective

The objective of this study is to conduct a bibliometric analysis on examining the current condition, areas of interest, and rising trends of immunotherapy for osteosarcoma (ITFOS), as well as its importance in associated research domains.

Methods

An extensive collection of academic papers on the use of ITFOS was obtained from the Web of Science between January 1, 2000 and October 20, 2023. Then, using a variety of tools like HisCite, VOSviewer, CiteSpace, and the bibliometrix package, a bibliometric study was carried out. This study included the collection of information on country, institution, author, journal, and keywords.

Results

A comprehensive analysis was undertaken on a total of 616 publications obtained from 247 journals, encompassing the contributions of 3725 authors affiliated with 831 institutes spanning across 43 countries/regions. Notably, China exhibited the highest quantity of published 277 (44.99%) articles on ITFOS. The most productive institution was Zhejiang University, with 26 (4.22%) publications. The author with the highest publication output was Tsukahara, Tomohide from Japan with 15 (2.44%) publications. The article with the most citation was "DOI: 10.1200/JCO.2014.58.0225". Frontiers in Immunology demonstrated the highest level of productivity, having published a total of 31 (5.03%) articles. The most frequently used were "osteosarcoma," "immunotherapy," and "cancer,". Meanwhile, "sequencing", "prognostic signature" and "immune microenvironment" have been identified as the research frontiers for the forthcoming years.

Conclusion

This paper provides a thorough evaluation of current research trends and advancements in ITFOS. It includes relevant research findings and emphasizes collaborative efforts among authors, institutions, and countries.

Natural product Eriocalyxin B exerts anti-tumor effects by downregulating TCEA3 expression and sensitizes immune checkpoint blockade therapy in osteosarcoma

Osteosarcoma (OS) remains the most common bone tumor and the prognosis for many patients remains stagnant due to the unsatisfactory therapeutic effect of conventional treatment regimens. This research explored the effect and mechanism of a novel natural product, Eriocalyxin B (EB), in pathogenesis and immunotherapy in OS. Cell Count Kit 8 assay, colony formation assay, and wound healing assay were employed to detect the proliferative, colony-forming, and migratory abilities of human OS cells following EB treatment. Moreover, xenograft growth assay was performed to assess the effect of EB on OS in vivo. Subcutaneous OS models constructed in immunocompetent mice were employed to evaluate the effect of EB treatment in combination with immune checkpoint blockades (ICBs) PD1ab and CTLA4ab. Immunohistochemistry (IHC) staining was utilized to detect the level of CD8+ T cells infiltration and Ki67 expression. TARGET database, RNA interference technology, and qPCR assay were employed to explore the mechanism of EB on OS. EB inhibited the proliferative, colony-forming, and migratory abilities of the human OS cells MG63 and U2OS both in vitro and in vivo. TARGET data analysis demonstrated that up-regulation of TCEA3 was significantly negatively correlated with overall survival in OS patients. EB exerted anti-tumor activity via downregulation of TCEA3. EB, in conjunction with ICBs, synergistically optimized anti-tumorigenic activity against OS in immunocompetent mice. EB may promote infiltration of CD8+ T cells and down-regulate Ki67 expression. These results signaled that EB may have a role as a candidate therapeutic or preventive agent for the treatment of OS.

A detoxified TLR4 agonist inhibits tumour growth and lung metastasis of osteosarcoma by promoting CD8+ cytotoxic lymphocyte infiltration

BACKGROUND

Osteosarcoma is the most common malignant bone tumour with limited treatment options and poor outcomes in advanced metastatic cases. Current immunotherapies show limited efficacy, highlighting the need for novel therapeutic approaches. Systemic immune activation by Toll-like receptor 4 (TLR4) immunostimulants has shown great promise; however, current TLR4 agonists' toxicity hinders this systemic approach in patients with osteosarcoma.

METHODS

We compared the antitumour effect of lipopolysaccharides (LPS) with that of an innovative chemically detoxified TLR4 agonist (Lipo-MP-LPS) in a syngeneic metastatic osteosarcoma mouse model. Lipo-MP-LPS exhibited an optimal safety and solubility profile for systemic administration at an effective dose. We evaluated tumour growth, lung metastases, and immune cell infiltration in wild-type and TLR4-mutant mice and performed selective immunodepletion.

RESULTS

Lipo-MP-LPS exhibited antitumour effects against localised osteosarcoma tumours and lung metastases, like those of natural LPS. Lipo-MP-LPS promoted CD8+ T cells and M1 macrophages infiltration in primary tumours and CD8+ T cells in metastases, with an M1-phenotype macrophage shift. The Lipo-MP-LPS antitumour effects were found to depend on TLR4 and CD8+ T cells, but not on macrophages.

CONCLUSION

Lipo-MP-LPS inhibited tumour growth and lung metastasis of osteosarcoma by promoting CD8 + T cell infiltration, indicating its therapeutic potential for advanced osteosarcoma.

New insights into the mechanisms of the immune microenvironment and immunotherapy in osteosarcoma

Osteosarcoma, a malignant bone tumor primarily affecting adolescents, is highly invasive with a poor prognosis. While surgery and chemotherapy have improved survival for localized cases, pulmonary metastasis significantly reduces survival to approximately 20%, highlighting the need for novel treatments. Immunotherapy, which leverages the immune system to target osteosarcoma cells, shows promise. This review summarizes the biological characteristics of osteosarcoma, mechanisms of pulmonary metastasis, and the tumor immune microenvironment (TME). It involves recent immunotherapy advances, including monoclonal antibodies, tumor vaccines, immune cell therapies, checkpoint inhibitors, and oncolytic viruses, and discusses combining these with standard treatments.

PD-1 interactome in osteosarcoma: identification of a novel PD-1/AXL interaction conserved between humans and dogs

The PD-1/PDL-1 immune checkpoint inhibitors revolutionized cancer treatment, yet osteosarcoma remains a therapeutic challenge. In some types of cancer, PD-1 receptor is not solely expressed by immune cells but also by cancer cells, acting either as a tumor suppressor or promoter. While well-characterized in immune cells, little is known about the role and interactome of the PD-1 pathway in cancer. We investigated PD-1 expression in human osteosarcoma cells and studied PD-1 protein-protein interactions in cancer. Using U2OS cells as a model, we confirmed PD-1 expression by western blotting and characterized its intracellular as well as surface localization through flow cytometry and immunofluorescence. High-throughput analysis of PD-1 interacting proteins was performed using a pull-down assay and quantitative mass spectrometry proteomic analysis. For validation and molecular modeling, we selected tyrosine kinase receptor AXL-a recently reported cancer therapeutic target. We confirmed the PD-1/AXL interaction by immunoblotting and proximity ligation assay (PLA). Molecular dynamics (MD) simulations uncovered binding affinities and domain-specific interactions between extracellular (ECD) and intracellular (ICD) domains of PD-1 and AXL. ECD complexes exhibited strong binding affinity, further increasing for the ICD complexes, emphasizing the role of ICDs in the interaction. PD-1 phosphorylation mutant variants (Y223F and Y248F) did not disrupt the interaction but displayed varying strengths and binding affinities. Using bemcentinib, a selective AXL inhibitor, we observed reduced binding affinity in the PD-1/AXL interaction, although it was not abrogated. To facilitate the future translation of this finding into clinical application, we sought to validate the interaction in canine osteosarcoma. Osteosarcoma spontaneously occurs at significantly higher frequency in dogs and shares close genetic and pathological similarities with humans. We confirmed endogenous expression of PD-1 and AXL in canine osteosarcoma cells, with PD-1/AXL interaction preserved in the dog cells. Also, the interacting residues remain conserved in both species, indicating an important biological function of the interaction. Our study shed light on the molecular basis of the PD-1/AXL interaction with the implication for its conservation across species, providing a foundation for future research aimed at improving immunotherapy strategies and developing novel therapeutic approaches.

Prognostic signature and immunotherapeutic relevance of Focal adhesion signaling pathway-related genes in osteosarcoma

Background

As the most common primary malignant bone tumor in children and adolescents, osteosarcoma currently lacks an effective clinical cure. Focal adhesion plays a crucial role in tumor invasion, migration, and drug resistance by mediating communication between the extracellular matrix and tumor cells. This study investigated the prognostic features and immunotherapeutic relevance of focal adhesion pathway-related genes in osteosarcoma to aid in the development of new therapeutic options.

Methods

We obtained mutational, transcriptomic, gene expression, and clinical data of osteosarcoma patients from the Gene Expression Omnibus (GEO) and Therapeutically Applicable Research to Generate Effective (TARGET) databases. Differentially expressed genes were screened, followed by the Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) analyses. Kaplan-Meier survival analysis was performed for genes related to the focal adhesion pathway, and multivariate Cox regression analysis was employed to construct a prognostic signature model. Genes such as SIGLEC15, TIGIT, CD274, HAVCR2, PDCD1, CTLA4, and LAG3 were extracted from the TARGET and CCLE databases for osteosarcoma patients and osteosarcoma cell lines, respectively，to observe the expression of immune checkpoint-related genes. Finally, qRT-PCR was used to verify the expression of these immune checkpoint-related genes in osteosarcoma cell lines.

Results

In our study, 376 samples were analyzed, including 369 osteosarcoma samples and 7 normal tissue samples. We identified 50 up-regulated and 28 down-regulated differentially expressed genes. Among these, 10 Candidate genes relative to focal Adhesion were selected， and CAV1, ZYX, and ITGA5 were found to have a significant prognostic role based on survival analysis of osteosarcoma samples from the TARGET database. A predictive signature model related to the focal adhesion signaling pathway was constructed using these genes, and the AUCs of the 1-year, 3-year, and 5-year ROC curves were 0. 647, 0. 712, and 0. 717, respectively. The overall survival (OS) rate of osteosarcoma patients with high-risk scores was poorer than those with low-risk scores. Then, samples were divided into two subgroups based on the expression of the three genes, revealing significant differences in the expression of certain immune checkpoint-related genes between the subgroups. Additionally, above three genes and immune checkpoint-related genes in osteosarcoma cell lines were extracted from the CCLE database, showing high expression levels in eight osteosarcoma cell lines. We observed that CD274 and PDCD1LG2 were highly expressed in some osteosarcoma cell lines. Finally, the expression of CAV1, ZYX, ITGA5, CD80, CD274, and PDCD1LG2 in osteosarcoma cell lines was verified by qRT-PCR.

Conclusions

Our study validated the prognostic role of three focal adhesion pathway-related genes (ZYX, CAV1, and ITGA5) in patients with osteosarcoma and constructed a prognostic signature model associated with the focal adhesion signaling pathway. We identified significant differences in the expression of multiple immune checkpoint-related genes among subgroups defined by the three genes. Additionally, CD274 and PDCD1LG2 showed higher expression in osteosarcoma cell lines characterized by these genes. These findings may aid in the selection of effective immunotherapy for specific osteosarcoma patients.

CD47 in Osteosarcoma: Correlation with Metastasis and Macrophage-Mediated Phagocytosis

CD47 is expressed on cell surfaces and acts as a "don't eat me" signal by interacting with signal-regulatory protein-α on the macrophage surface. Some cancer cells express CD47 protein and can evade macrophage phagocytosis. Herein, we evaluated the feasibility of targeting CD47 for osteosarcoma by analyzing its expression patterns, clinicopathological correlations, and immunotherapeutic potential. We performed a retrospective analysis on 24 biopsy samples from patients with osteosarcoma to investigate correlations between CD47 protein positivity and clinicopathological characteristics. CD47 protein expression was detected in 20.8% of the biopsy samples. CD47 positivity correlated with metastasis at diagnosis. Patients with CD47-positive tumors were older than those with CD47-negative tumors. However, CD47 protein expression was not associated with sex, tumor size, or histologic response to preoperative chemotherapy. In vitro, CD47 antibody (B6H12) did not affect osteosarcoma cell viability or apoptosis. In a wound-healing assay, CD47 inhibited the migration of osteosarcoma cells. Differentiated macrophages exhibited higher phagocytic activity against osteosarcoma cells when pretreated with B6H12 compared with the isotype control. Our preliminary data suggest a possible interaction between CD47 protein and macrophage phagocytosis in osteosarcoma metastasis. A better understanding of the role of CD47 is necessary to develop an innovative immunotherapeutic approach against osteosarcoma.

Osteosarcoma: A comprehensive review of model systems and experimental therapies

Osteosarcoma (OSA) is a highly malignant bone tumor for which more than 50% of patients have or will develop metastatic disease, resulting in an abysmal 5-year survival rate of <29%. Despite the advances in science and medicine, the etiology of OSA remains unclear. Similarly, the standard of care (surgery and chemotherapy) has changed little in the past 5 decades. This stagnation in treatment options is in part due to inadequate preclinical models for OSA; many of these models are oversimplified and do not account for the complexities of patient disease. Further, current treatments are harsh and invasive (e.g. high dose chemotherapy and potential limb removal) leading to a reduction in a patient's quality of life (e.g. hearing loss, infertility, neuropathy), highlighting a need for developing more effective treatment strategies. Many experimental therapies have been tested in the preclinical and preclinical setting, with varying degrees of success. In this review, we will focus on pediatric and adolescent OSA, highlighting current animal models and experimental therapies.

Neoadjuvant Chemotherapy for Adults with Osteogenic Sarcoma

OPINION STATEMENT

Osteosarcoma is the most common primary malignant bone tumor in adolescents and adults. The 5-year survival rate is 65% when localized; however, survival drops dramatically to 10-20% in cases of metastatic disease. Therapy for osteosarcoma saw its first significant advancement in the 1970-80's, with the introduction of our current standard of care, consisting of the neo/adjuvant treatment regimen methotrexate, doxorubicin (Adriamycin), and cisplatin (collectively referred to as MAP) and surgical resection. Since MAP, development of a better therapeutic approach has stalled, creating a plateau in patient outcomes that has persisted for 40 years. Despite substantial research into a variety of pathways for novel treatment options, clinical trials have not produced sizeable improvements in outcomes. In this article, we discuss our current neoadjuvant standard of care therapy, followed by a review of contemporary therapeutic options, including tyrosine kinase inhibitors (TKIs), immune checkpoint inhibitors (ICIs), monoclonal antibodies (mAbs), and chimeric antigen receptor (CAR) T cells. Lastly, we consider the challenges hindering the success of novel treatment options and future research directions.

Machine learning-based individualized survival prediction model for prognosis in osteosarcoma: Data from the SEER database

Patient outcomes of osteosarcoma vary because of tumor heterogeneity and treatment strategies. This study aimed to compare the performance of multiple machine learning (ML) models with the traditional Cox proportional hazards (CoxPH) model in predicting prognosis and explored the potential of ML models in clinical decision-making. From 2000 to 2018, 1243 patients with osteosarcoma were collected from the Surveillance, Epidemiology, and End Results (SEER) database. Three ML methods were chosen for model development (DeepSurv, neural multi-task logistic regression [NMTLR]) and random survival forest [RSF]) and compared them with the traditional CoxPH model and TNM staging systems. 871 samples were used for model training, and the rest were used for model validation. The models' overall performance and predictive accuracy for 3- and 5-year survival were assessed by several metrics, including the concordance index (C-index), the Integrated Brier Score (IBS), receiver operating characteristic curves (ROC), area under the ROC curves (AUC), calibration curves, and decision curve analysis. The efficacy of personalized recommendations by ML models was evaluated by the survival curves. The performance was highest in the DeepSurv model (C-index, 0.77; IBS, 0.14; 3-year AUC, 0.80; 5-year AUC, 0.78) compared with other methods (C-index, 0.73-0.74; IBS, 0.16-0.17; 3-year AUC, 0.73-0.78; 5-year AUC, 0.72-0.78). There are also significant differences in survival outcomes between patients who align with the treatment option recommended by the DeepSurv model and those who do not (hazard ratio, 1.88; P < .05). The DeepSurv model is available in an approachable web app format at https://survivalofosteosarcoma.streamlit.app/. We developed ML models capable of accurately predicting the survival of osteosarcoma, which can provide useful information for decision-making regarding the appropriate treatment.

FBXO22 promotes osteosarcoma progression via regulation of FOXO1 for ubiquitination and degradation

Accumulating evidence has demonstrated that F-box protein 22 (FBXO22) participates in tumour development and progression in various types of human malignancies. However, the functions and detailed molecular mechanisms of FBXO22 in osteosarcoma tumorigenesis and progression remain elusive. In this study, we aimed to determine the effects of FBXO22 on the cell proliferation, migration and invasion of osteosarcoma cells using cell counting kit-8 and Matrigel Transwell approaches. Moreover, we explored the molecular mechanisms by which FBXO22 mediated oncogenesis and progression in osteosarcoma via Western blotting, immunoprecipitation and ubiquitination. We found that FBXO22 depletion inhibited the proliferation, migration and invasion of osteosarcoma cells, whereas FBXO22 overexpression increased the proliferation and motility of osteosarcoma cells. Mechanistically, FBXO22 promoted the ubiquitination and degradation of FoxO1 in osteosarcoma cells. FBXO22 depletion reduced cell proliferation and motility via regulation of FoxO1. Taken together, our findings provide new insight into FBXO22-induced osteosarcoma tumorigenesis. The inhibition of FBXO22 could be a promising strategy for the treatment of osteosarcoma.

Predictive value of serum alkaline phosphatase, tumor-specific growth factor, and macrophage migration inhibitory factor for the efficacy of immunotargeted therapy in osteosarcoma patients

OBJECTIVE

To assess the predictive value of serum alkaline phosphatase (ALP), tumor-specific growth factor (TSGF), and macrophage migration inhibitory factor (MIF) for the efficacy of combined immunosuppressive and targeted therapy in osteosarcoma (OS).

METHODS

We retrospectively analyzed clinical data from 161 OS patients treated at Xi'an Honghui Hospital from October 2020 to October 2022. Patients received 12 weeks of therapy with interferon-α (IFN-α) and bevacizumab. Serum levels of ALP, TSGF, and MIF were measured before and after treatment. Based on treatment efficacy, patients were categorized into effective and ineffective groups. Both univariate and logistic regression analyses were utilized to evaluate the influence of these biomarkers on therapy outcomes.

RESULTS

A significant reduction in serum ALP, TSGF, and MIF levels post-treatment was found (all P<0.001). Higher pre-treatment levels of these biomarkers were associated with less effective outcomes (P<0.001).

CONCLUSION

Pre-treatment levels of ALP, TSGF, and MIF are significant independent predictors of response to immunotargeted therapy in OS patients, suggesting their potential role in guiding treatment strategies.

Precision Oncology in Pediatric Cancer Surgery

Pediatric precision oncology has provided a greater understanding of the wide range of molecular alterations in difficult-to-treat or rare tumors with the aims of increasing survival as well as decreasing toxicity and morbidity from current cytotoxic therapies. In this article, the authors discuss the current state of pediatric precision oncology which has increased access to novel targeted therapies while also providing a framework for clinical implementation in this unique population. The authors evaluate the targetable mutations currently under investigation-with a focus on pediatric solid tumors-and discuss the key surgical implications associated with novel targeted therapies.

The Development and Characterization of a Next-Generation Oncolytic Virus Armed with an Anti-PD-1 sdAb for Osteosarcoma Treatment In Vitro

Osteosarcoma (OS) is a primary bone malignancy characterized by an aggressive nature, limited treatment options, low survival rate, and poor patient prognosis. Conditionally replicative adenoviruses (CRAds) armed with immune checkpoint inhibitors hold great potential for enhanced therapeutic efficacy. The present study aims to investigate the anti-tumor efficacy of CAV2-AU-M2, a CAV2-based CRAd armed with an anti-PD-1 single-domain antibody (sdAb), against OS cell lines in vitro. The infection, conditional replication, cytopathic effects, and cytotoxicity of CAV2-AU-M2 were tested in four different OS cell lines in two-dimensional (2D) and three-dimensional (3D) cell cultures. CAV2-AU-M2 showed selective replication in the OS cells and induced efficient tumor cell lysis and death. Moreover, CAV2-AU-M2 produced an anti-PD-1 sdAb that demonstrated effective binding to the PD-1 receptors. This study demonstrated the first CRAd armed with an anti-PD-1 sdAb. This combined approach of two distinct immunotherapies is intended to enhance the anti-tumor immune response in the tumor microenvironment.

Immunotherapy Innovations in the Fight against Osteosarcoma: Emerging Strategies and Promising Progress

Immunosuppressive elements within the tumor microenvironment are the primary drivers of tumorigenesis and malignant advancement. The presence, as well as the crosstalk between myeloid-derived suppressor cells (MDSCs), osteosarcoma-associated macrophages (OS-Ms), regulatory T cells (Tregs), and endothelial cells (ECs) with osteosarcoma cells cause the poor prognosis of OS. In addition, the consequent immunosuppressive factors favor the loss of treatment potential. Nanoparticles offer a means to dynamically and locally manipulate immuno-nanoparticles, which present a promising strategy for transforming OS-TME. Additionally, chimeric antigen receptor (CAR) technology is effective in combating OS. This review summarizes the essential mechanisms of immunosuppressive cells in the OS-TME and the current immune-associated strategies. The last part highlights the limitations of existing therapies and offers insights into future research directions.

Soy isoflavones induces mitophagy to inhibit the progression of osteosarcoma by blocking the AKT/mTOR signaling pathway

BACKGROUND

Soy isoflavones (SI) is a natural bioactive substance exhibiting beneficial effects on human health. This study aims to elucidate the therapeutic potential of SI in the treatment of osteosarcoma (OS) and to investigate the underlying mechanisms, particularly focusing on mitophagy.

METHODS

The effects of SI on the proliferation, apoptosis, migration, and invasion of U2OS cells were analyzed. Mitophagy was assessed through multiple parameters: mitochondrial autophagosomes, mitochondrial membrane potential, autophagy-related proteins, reactive oxygen species (ROS), and oxygen consumption rate (OCR). Protein levels related to apoptosis, autophagy, and the AKT/mTOR pathway were analyzed using western blot. The therapeutic efficacy of SI was further identified using a mouse tumor xenograft model. Cell apoptosis and proliferation in tumor xenografts were detected by TUNEL staining and immunohistochemistry (IHC), respectively.

RESULTS

SI dose-dependently suppressed the viability, colony formation, migration, and invasion of U2OS cells, and enhanced the apoptosis. SI also dose-dependently induced mitophagy in OS cells, evidenced by an increase in autophagosomes and ROS levels, a decrease in mitochondrial membrane potential and OCR, and concomitant changes in autophagy-related proteins. Mdivi-1, an inhibitor of mitophagy, reversed the anti-tumor effects of SI on U2OS cells. In addition, SI blocked the AKT/mTOR pathway in U2OS cells. SC-79, an AKT agonist, reversed the effect of SI on inducing mitophagy. Moreover, SI also promoted cell apoptosis and mitophagy in tumor xenografts in vivo.

CONCLUSIONS

SI induces mitophagy in OS cells by blocking the AKT/mTOR pathway, contributing to the inhibition of OS.

Current status and future challenges of CAR-T cell therapy for osteosarcoma

Osteosarcoma, the most common bone malignancy in children and adolescents, poses considerable challenges in terms of prognosis, especially for patients with metastatic or recurrent disease. While surgical intervention and adjuvant chemotherapy have improved survival rates, limitations such as impractical tumor removal or chemotherapy resistance hinder the treatment outcomes. Chimeric antigen receptor (CAR)-T cell therapy, an innovative immunotherapy approach that involves targeting tumor antigens and releasing immune factors, has shown significant advancements in the treatment of hematological malignancies. However, its application in solid tumors, including osteosarcoma, is constrained by factors such as low antigen specificity, limited persistence, and the complex tumor microenvironment. Research on osteosarcoma is ongoing, and some targets have shown promising results in pre-clinical studies. This review summarizes the current status of research on CAR-T cell therapy for osteosarcoma by compiling recent literature. It also proposes future research directions to enhance the treatment of osteosarcoma.

Construction of a 5-gene prognostic signature based on oxidative stress related genes for predicting prognosis in osteosarcoma

BACKGROUND

The understanding of the complex biological scenario of osteosarcoma will open the way to identifying new strategies for its treatment. Oxidative stress is a cancer-related biological scenario. At present, it is not clear the oxidative stress genes in affecting the prognosis and progression of osteosarcoma, the underlying mechanism as well as their impact on the classification of osteosarcoma subtypes.

METHODS

We selected samples and sequencing data from TARGET data set and GSE21257 data set, and downloaded oxidative stress related-genes (OSRGs) from MsigDB. Univariate Cox analysis of OSRG was conducted using TARGET data, and the prognostic OSRG was screened to conduct unsupervised clustering analysis to identify the molecular subtypes of osteosarcoma. Through least absolute shrinkage and selection operator (LASSO) regression analysis and COX regression analysis of differentially expressed genes (DEGs) between subgroups, a risk assessment system for osteosarcoma was developed.

RESULTS

45 prognosis-related OSRGs genes were acquired, and two molecular subtypes of osteosarcoma were clustered. C2 cluster displayed prolonged overall survival (OS) accompanied with high degree of immune infiltration and enriched immune pathways. While cell cycle related pathways were enriched in C2 cluster. Based on DEGs between subgroups and Lasso analysis, 5 hub genes (ZYX, GJA5, GAL, GRAMD1B, and CKMT2) were screened to establish a robust prognostic risk model independent of clinicopathological features. High-risk group had more patients with cancer metastasis and death as well as C1 subtype with poor prognosis. Low-risk group exhibited favorable OS and high immune infiltration status. Additionally, the risk assessment system was optimized by building decision tree and nomogram.

CONCLUSIONS

This study defined two molecular subtypes of osteosarcoma with different prognosis and tumor immune microenvironment status based on the expression of OSRGs, and provided a new risk assessment system for the prognosis of osteosarcoma.

Osteoclasts in Osteosarcoma: Mechanisms, Interactions, and Therapeutic Prospects

Osteosarcoma is an extremely malignant tumor, and its pathogenesis is complex and remains incompletely understood. Most cases of osteosarcoma are accompanied by symptoms of bone loss or result in pathological fractures due to weakened bones. Enhancing the survival rate of osteosarcoma patients has proven to be a long-standing challenge. Numerous studies mentioned in this paper, including in-vitro, in-vivo, and in-situ studies have consistently indicated a close association between the symptoms of bone loss associated with osteosarcoma and the presence of osteoclasts. As the sole cells capable of bone resorption, osteoclasts participate in a malignant cycle within the osteosarcoma microenvironment. These cells interact with osteoblasts and osteosarcoma cells, secreting various factors that further influence these cells, disrupting bone homeostasis, and shifting the balance toward bone resorption, thereby promoting the onset and progression of osteosarcoma. Moreover, the interaction between osteoclasts and various other cells types, such as tumor-associated macrophages, myeloid-derived suppressor cells, DCs cells, T cells, and tumor-associated fibroblasts in the osteosarcoma microenvironment plays a crucial role in disease progression. Consequently, understanding the role of osteoclasts in osteosarcoma has sparked significant interest. This review primarily examines the physiological characteristics and functional mechanisms of osteoclasts in osteosarcoma, and briefly discusses potential therapies targeting osteoclasts for osteosarcoma treatment. These studies provide fresh ideas and directions for future research on the treatment of osteosarcoma.

Identification of the methotrexate resistance-related diagnostic markers in osteosarcoma via adaptive total variation netNMF and multi-omics datasets

Osteosarcoma is one of the most common malignant bone tumors with high chemoresistance and poor prognosis, exhibiting abnormal gene regulation and epigenetic events. Methotrexate (MTX) is often used as a primary agent in neoadjuvant chemotherapy for osteosarcoma; However, the high dosage of methotrexate and strong drug resistance limit its therapeutic efficacy and application prospects. Studies have shown that abnormal expression and dysfunction of some coding or non-coding RNAs (e.g., DNA methylation and microRNA) affect key features of osteosarcoma progression, such as proliferation, migration, invasion, and drug resistance. Comprehensive multi-omics analysis is critical to understand its chemoresistant and pathogenic mechanisms. Currently, the network analysis-based non-negative matrix factorization (netNMF) method is widely used for multi-omics data fusion analysis. However, the effects of data noise and inflexible settings of regularization parameters affect its performance, while integrating and processing different types of genetic data is also a challenge. In this study, we introduced a novel adaptive total variation netNMF (ATV-netNMF) method to identify feature modules and characteristic genes by integrating methylation and gene expression data, which can adaptively choose an anisotropic smoothing scheme to denoise or preserve feature details based on the gradient information of the data by introducing an adaptive total variation constraint in netNMF. By comparing with other similar methods, the results showed that the proposed method could extract multi-omics fusion features more effectively. Furthermore, by combining the mRNA and miRNA data of methotrexate (MTX) resistance with the extracted feature genes, four genes, Carboxypeptidase E (CPE), LIM, SH3 protein 1 (LASP1), Pyruvate Dehydrogenase Kinase 1 (PDK1) and Serine beta-lactamase-like protein (LACTB) were finally identified. The results showed that the gene signature could reliably predict the prognostic status and immune status of osteosarcoma patients.

Promise and Challenges of T Cell Immunotherapy for Osteosarcoma

The cure rate for metastatic or relapsed osteosarcoma has not substantially improved over the past decades despite the exploitation of multimodal treatment approaches, allowing long-term survival in less than 30% of cases. Patients with osteosarcoma often develop resistance to chemotherapeutic agents, where personalized targeted therapies should offer new hope. T cell immunotherapy as a complementary or alternative treatment modality is advancing rapidly in general, but its potential against osteosarcoma remains largely unexplored. Strategies incorporating immune checkpoint inhibitors (ICIs), chimeric antigen receptor (CAR) modified T cells, and T cell engaging bispecific antibodies (BsAbs) are being explored to tackle relapsed or refractory osteosarcoma. However, osteosarcoma is an inherently heterogeneous tumor, both at the intra- and inter-tumor level, with no identical driver mutations. It has a pro-tumoral microenvironment, where bone cells, stromal cells, neovasculature, suppressive immune cells, and a mineralized extracellular matrix (ECM) combine to derail T cell infiltration and its anti-tumor function. To realize the potential of T cell immunotherapy in osteosarcoma, an integrated approach targeting this complex ecosystem needs smart planning and execution. Herein, we review the current status of T cell immunotherapies for osteosarcoma, summarize the challenges encountered, and explore combination strategies to overcome these hurdles, with the ultimate goal of curing osteosarcoma with less acute and long-term side effects.

Targeting signaling pathways in osteosarcoma: Mechanisms and clinical studies

Osteosarcoma (OS) is a highly prevalent bone malignancy among adolescents, accounting for 40% of all primary malignant bone tumors. Neoadjuvant chemotherapy combined with limb-preserving surgery has effectively reduced patient disability and mortality, but pulmonary metastases and OS cells' resistance to chemotherapeutic agents are pressing challenges in the clinical management of OS. There has been an urgent need to identify new biomarkers for OS to develop specific targeted therapies. Recently, the continued advancements in genomic analysis have contributed to the identification of clinically significant molecular biomarkers for diagnosing OS, acting as therapeutic targets, and predicting prognosis. Additionally, the contemporary molecular classifications have revealed that the signaling pathways, including Wnt/β-catenin, PI3K/AKT/mTOR, JAK/STAT3, Hippo, Notch, PD-1/PD-L1, MAPK, and NF-κB, have an integral role in OS onset, progression, metastasis, and treatment response. These molecular classifications and biological markers have created new avenues for more accurate OS diagnosis and relevant treatment. We herein present a review of the recent findings for the modulatory role of signaling pathways as possible biological markers and treatment targets for OS. This review also discusses current OS therapeutic approaches, including signaling pathway-based therapies developed over the past decade. Additionally, the review covers the signaling targets involved in the curative effects of traditional Chinese medicines in the context of expression regulation of relevant genes and proteins through the signaling pathways to inhibit OS cell growth. These findings are expected to provide directions for integrating genomic, molecular, and clinical profiles to enhance OS diagnosis and treatment.

Prognostic and immunological significance of an M1 macrophage-related gene signature in osteosarcoma

As the most abundant infiltrating immune cells in the tumor microenvironment (TME), tumor-associated macrophages (TAMs) are pivotal in tumor development and treatment. The present investigation endeavors to explore the potential of M1 macrophage-related genes (MRGs) as biomarkers for assessing risk in individuals with osteosarcoma. RNA-sequence data and clinical data were derived from TCGA and GEO databases. The CIBERSORT method was utilized to discern subtypes of tumor-infiltrating immune cells. Identification of MRGs was achieved through Pearson correlation analysis. A prognostic risk model for MRGs was developed using Cox and LASSO regression analyses. A tripartite gene signature comprising CD37, GABRD, and ARHGAP25 was an independent prognostic indicator and was employed to develop a risk score model. The internal and external validation cohort confirmed the results. The area under the ROC curve (AUC) was determined for survival periods of 1 year, three years, and five years, yielding values of 0.746, 0.839, and 0.850, respectively. The C-index of the risk score was found to be superior to clinicopathological factors. GO/KEGG enrichment showed that the differences between high- and low-risk groups were predominantly associated with immune response pathways. Immune-related analysis related to proportions of immune cells, immune function, and expression levels of immune checkpoint genes all showed differences between the high- and low-risk groups. The qRT-PCR and Western blotting results indicate that CD37 expression was markedly higher in MG63 and U2OS cell lines when compared to normal osteoblast hFOB1.19. In U2OS cell line, GABRD expression levels were significantly upregulated. ARHGAP25 expression levels were elevated in both 143B and U2OS cell lines. In summary, utilizing a macrophage genes signature demonstrates efficacy in predicting both the prognosis and therapy response of OS. Additionally, immune analysis confirms a correlation between the risk score and the tumor microenvironment. Our findings, therefore, provide a cogent account for the disparate prognoses observed among patients and furnish a justification for further inquiry into biomarkers and anti-tumor treatment strategies.

Osteosarcoma of the Larynx: A Case Report and Review of Literature

The most common malignant laryngeal tumors are squamous cell carcinomas (SCCs), and other types such as sarcomas are rare. Osteosarcomas of the larynx are extremely rare within the subset of sarcomas, with very few cases reported in the literature. This cancer has a predilection for elderly males, in the sixth to eighth decades of life. Associated symptoms include hoarseness, stridor, and dyspnea. It is known to spread early and has a high rate of recurrence. We present the case of a 73-year-old male, a former smoker, who presented to the clinic with severe dyspnea and progressive hoarseness and was found to have a large exophytic mass arising from the epiglottis. A biopsy of the mass showed a poorly differentiated cancer with osteoid and new bone formation. He then underwent surgical removal of the mass, followed by radiation, and achieved clinical remission. However, a surveillance positron emission tomography (PET) scan 14 months later showed a hypermetabolic lesion in the left lung. Biopsy revealed metastatic osteosarcoma, and unfortunately, this cancer also spread to the brain. In this report, we will focus on the histological features of this rare malignancy and treatment options.

Multifunctional Zn and Ag co-doped bioactive glass nanoparticles for bone therapeutic and regeneration

Bone cancer has traditionally been treated using surgery, radiotherapy, and/or chemotherapy. The nonspecific distribution of chemotherapy and implantable infections are significant risk factors for the failure of the bone to heal. Multifunctional zinc and silver co-doped bioactive glass nanoparticles (yAg-xZn-BGNPs) with a diameter of 150 ± 30 nm were successfully synthesized using modified sol-gel and two-step post-functionalization processes, tailored to provide antibacterial and anticancer activity whilst maintaining osteogenesis ability. Co-doped BGNPs with Zn and Ag did not significantly alter physicochemical properties, including size, morphology, glass network, and amorphous nature. Apatite-like layer was observed on the surface of yAg-xZn-BGNPs and resorbed in the simulated body fluid solution, which could increase their bioactivity. Human fetal osteoblast cell line (hFOB 1.19) treated with particles showed calcified tissue formation and alkaline phosphatase activity in the absence of osteogenic supplements in vitro, especially with 0.5Ag-1Zn-BGNPs. Moreover, these particles preferentially disrupted the metabolic activity of bone cancer cells (MG-63) and had an antibacterial effect against B. subtilis, E. coli, and S. aureus via the disc diffusion method. This novel 0.5Ag-1Zn-BGNP and 1Ag-1Zn-BGNPs, with wide-ranging ability to stimulate bone regeneration, to inhibit bone cancer cell proliferation, and to prevent bacterial growth properties, may provide a feasible strategy for bone cancer treatment. The 0.5Ag-1Zn-BGNPs and 1Ag-1Zn-BGNPs can be applied for the preparation of scaffolds or filler composites using in bone tissue engineering.

Effect of stimulator of interferon genes (STING) signaling on radiation-induced chemokine expression in human osteosarcoma cells

Cancer cell-intrinsic mechanisms affecting radiation immunomodulation could be exploited to optimize systemic effects of localized radiation. Radiation-induced DNA damage is sensed by cyclic GMP-AMP synthase (cGAS), which ultimately activates stimulator of interferon (IFN) genes (STING). Resultant expression of soluble mediators such as CCL5 and CXCL10 can facilitate recruitment of dendritic cells and immune effector cells into the tumor. The primary objectives of this study were to determine the baseline expression levels of cGAS and STING in OSA cells and evaluate the dependence of OSA cells on STING signaling for eliciting radiation-induced expression of CCL5 and CXCL10. cGAS and STING expression, and CCL5/CXCL10 expression in control cells, STING-agonist treated cells, and cells treated with 5 Gy ionizing radiation were assessed utilizing RTqPCR, Western blot, and ELISA. U2OS and SAOS-2 OSA cells were deficient in STING relative to human osteoblasts (hObs), while SAOS-2-LM6 and MG63 OSA cells expressed equivalent amounts of STING compared to hObs. A dependence on baseline or induced STING expression was observed for STING-agonist, and radiation-induced, expression of CCL5 and CXCL10. This finding was confirmed by performing siRNA knockdown of STING in MG63 cells. These results show that STING signaling is necessary for radiation-induced expression of CCL5 and CXCL10 in OSA cells. Additional studies are necessary to determine whether STING expression in OSA cells in vivo alters immune cell infiltrates after radiation exposure. These data may also have implications for other potentially STING-dependent characteristics such as resistance to oncolytic virus cytotoxicity.

Isolation and Characterization of Novel Canine Osteosarcoma Cell Lines from Chemotherapy-Naïve Patients

The present study aimed to establish novel canine osteosarcoma cell lines (COS3600, COS3600B, COS4074) and characterize the recently described COS4288 cells. The established D-17 cell line served as a reference. Analyzed cell lines differed notably in their biological characteristics. Calculated doubling times were between 22 h for COS3600B and 426 h for COS4074 cells. COS3600B and COS4288 cells produced visible colonies after anchorage-independent growth in soft agar. COS4288 cells were identified as cells with the highest migratory capacity. All cells displayed the ability to invade through an artificial basement membrane matrix. Immunohistochemical analyses revealed the mesenchymal origin of all COS cell lines as well as positive staining for the osteosarcoma-relevant proteins alkaline phosphatase and karyopherin α2. Expression of p53 was confirmed in all tested cell lines. Gene expression analyses of selected genes linked to cellular immune checkpoints (CD270, CD274, CD276), kinase activity (MET, ERBB2), and metastatic potential (MMP-2, MMP-9) as well as selected long non-coding RNA (MALAT1) and microRNAs (miR-9, miR-34a, miR-93) are provided. All tested cell lines were able to grow as multicellular spheroids. In all spheroids except COS4288, calcium deposition was detected by von Kossa staining. We believe that these new cell lines serve as useful biological models for future studies.

Current State of Cold Atmospheric Plasma and Cancer-Immunity Cycle: Therapeutic Relevance and Overcoming Clinical Limitations Using Hydrogels

Cold atmospheric plasma (CAP) is a partially ionized gas that gains attention as a well-tolerated cancer treatment that can enhance anti-tumor immune responses, which are important for durable therapeutic effects. This review offers a comprehensive and critical summary on the current understanding of mechanisms in which CAP can assist anti-tumor immunity: induction of immunogenic cell death, oxidative post-translational modifications of the tumor and its microenvironment, epigenetic regulation of aberrant gene expression, and enhancement of immune cell functions. This should provide a rationale for the effective and meaningful clinical implementation of CAP. As discussed here, despite its potential, CAP faces different clinical limitations associated with the current CAP treatment modalities: direct exposure of cancerous cells to plasma, and indirect treatment through injection of plasma-treated liquids in the tumor. To this end, a novel modality is proposed: plasma-treated hydrogels (PTHs) that can not only help overcome some of the clinical limitations but also offer a convenient platform for combining CAP with existing drugs to improve therapeutic responses and contribute to the clinical translation of CAP. Finally, by integrating expertise in biomaterials and plasma medicine, practical considerations and prospective for the development of PTHs are offered.

Construction of a cuproptosis-related lncRNA signature for predicting prognosis and immune landscape in osteosarcoma patients

BACKGROUND

Long noncoding RNAs (lncRNAs) influence the onset of osteosarcoma. Cuproptosis is a novel cell death mechanism. We attempted to identify a cuproptosis-related lncRNA signature to predict the prognosis and immune landscape in osteosarcoma patients.

METHODS

Transcriptional and clinical data of 85 osteosarcoma patients were derived from the TARGET database and randomly categorized into the training and validation cohorts. We implemented the univariate and multivariate Cox regression, along with LASSO regression analyses for developing a cuproptosis-related lncRNA risk model. Kaplan-Meier curves, C-index, ROC curves, univariate and multivariate Cox regression, and nomogram were used to assess the capacity of this risk model to predict the osteosarcoma prognosis. Gene ontology, KEGG, and Gene Set Enrichment (GSEA) analyses were conducted for determining the potential functional differences existing between the high-risk and low-risk patients. We further conducted the ESTIMATE, single-smaple GSEA, and CIBERSORT analyses for identifying the different immune microenvironments and immune cells infiltrating both the risk groups.

RESULTS

We screened out four cuproptosis-related lncRNAs (AL033384.2, AL031775.1, AC110995.1, and LINC00565) to construct the risk model in the training cohort. This risk model displayed a good performance to predict the overall survival of osteosarcoma patients, which was confirmed by using the validation and the entire cohort. Further analyses showed that the low-risk patients have more immune activation and immune cells infiltrating as well as a good response to immunotherapy.

CONCLUSIONS

We developed a novel cuproptosis-related lncRNA signature with high reliability and accuracy for predicting outcome and immunotherapy response in osteosarcoma patients, which provides new insights into the personalized treatment of osteosarcoma.

Anti-Invasive and Anti-Migratory Effects of Ononin on Human Osteosarcoma Cells by Limiting the MMP2/9 and EGFR-Erk1/2 Pathway

Osteosarcoma is a common malignancy of the bone. Due to its high metastatic properties, osteosarcoma becomes the leading cause of cancer death worldwide. Ononin is an isoflavone glycoside known to have various pharmacological properties, including antioxidant and anti-inflammatory activities. In the present study, we aimed to investigate the efficacy of ononin on osteosarcoma cell migration, invasion, and the underlying mechanisms. The in vitro anti-tumorigenic and anti-migratory properties of ononin were determined by MTT, colony formation, invasion, and migration in MG-63 and U2OS osteosarcoma cell lines. The results were compared with the standard chemotherapeutic drug, doxorubicin (DOX), as a positive control. The dose-dependent manners of ononin treatment increased the expression of apoptosis and inhibition of cell proliferation through the EGFR-Erk1/2 signaling pathways. Additionally, ononin significantly inhibited the invasion and migration of human osteosarcoma cells. For consistency, we used the MG-63-xenograft mice model to confirm the in vivo anti-tumorigenic and anti-migratory efficacy of ononin by inhibiting the protein expressions of EGFR-Erk1/2 and MMP2/9. According to the histological study, ononin had no adverse effect on the liver and kidney. Overall, our findings suggested that ononin could be a potentially effective agent against the development and metastasis of osteosarcoma.

Immune checkpoint inhibitors in osteosarcoma: A hopeful and challenging future

Osteosarcoma (OS), the most common malignant tumor in the musculoskeletal system, mainly occurs in adolescents. OS results in high mortality and disability rates due to a fatal metastatic tendency and subsequent iatrogenic damage caused by surgery, radiotherapy and chemotherapy. Recently, immunotherapies have resulted in promising prognoses with reduced side effects compared with traditional therapies. Immune checkpoint inhibitors (ICIs), which are a representative immunotherapy for OS, enhance the antitumor effects of immune cells. ICIs have shown satisfactory outcomes in other kinds of malignant tumors, especially hemopoietic tumors. However, there is still a high percentage of failures or severe side effects associated with the use of ICIs to treat OS, leading to far worse outcomes. To reveal the underlying mechanisms of drug resistance and side effects, recent studies elucidated several possible reasons, including the activation of other inhibitory immune cells, low immune cell infiltration in the tumor microenvironment, different immune properties of OS subtypes, and the involvement of osteogenesis and osteolysis. According to these mechanisms, researchers have developed new methods to overcome the shortcomings of ICIs. This review summarizes the recent breakthroughs in the use of ICIs to treat OS. Although numerous issues have not been solved yet, ICIs are still the most promising treatment options to cure OS in the long run.

Construction and validation model of necroptosis-related gene signature associates with immunity for osteosarcoma patients

Osteosarcoma is the most common malignant tumor in children and adolescents and its diagnosis and treatment still need to be improved. Necroptosis has been associated with many malignancies, but its significance in diagnosing and treating osteosarcoma remains unclear. The objective is to establish a predictive model of necroptosis-related genes (NRGs) in osteosarcoma for evaluating the tumor microenvironment and new targets for immunotherapy. In this study, we download the osteosarcoma data from the TARGET and GEO websites and the average muscle tissue data from GTEx. NRGs were screened by Cox regression analysis. We constructed a prediction model through nonnegative matrix factorization (NMF) clustering and the least absolute shrinkage and selection operator (LASSO) algorithm and verified it with a validation cohort. Kaplan–Meier survival time, ROC curve, tumor invasion microenvironment and CIBERSORT were assessed. In addition, we establish nomograms for clinical indicators and verify them by calibration evaluation. The underlying mechanism was explored through the functional enrichment analysis. Eight NRGs were screened for predictive model modeling. NRGs prediction model through NMF clustering and LASSO algorithm was established. The survival, ROC and tumor microenvironment scores showed significant statistical differences among subgroups (P < 0.05). The validation model further verifies it. By nomogram and calibration, we found that metastasis and risk score were independent risk factors for the poor prognosis of osteosarcoma. GO and KEGG analyses demonstrate that the genes of osteosarcoma cluster in inflammatory, apoptotic and necroptosis signaling pathways. The significant role of the correlation between necroptosis and immunity in promoting osteosarcoma may provide a novel insight into detecting molecular mechanisms and targeted therapy.

Subtype Classification and Prognosis Signature Construction of Osteosarcoma Based on Cellular Senescence-Related Genes

Background. Cellular senescence (CS) is an alternative procedure that replaces or reinforces inadequate apoptotic responses and is used as an influencing factor for a variety of cancers. The value of CS gene in evaluating the immunotherapy response and clinical outcome of osteosarcoma (OS) has not been reported, and an accurate risk model based on CS gene has not been developed for OS patients. Methods. 279 CS genes were obtained from CellAge. Univariate Cox regression analysis was used to screen the CS gene which was significantly related to the prognosis of OS samples in TARGET data set. The prognosis, clinicopathological features, immune infiltration, gene expression at immune checkpoints, tumor immune dysfunction and exclusion (TIDE) score, and chemotherapy resistance of OS were analyzed among clusters. Least absolute shrinkage and selection operator (Lasso) Cox regression analysis to build cellular senescence-related gene signature (CSRS). Univariate and multivariate Cox regression analysis of CSRS and clinical parameters were carried out, and the parameters with independent prognostic value were used to construct nomogram. Results. Based on 30 CS genes related to OS prognosis, OS samples were divided into three clusters: C1, C2, and C3. C3 showed the lowest survival rate and metastasis rate and the highest immune score and stromal score and was more likely to respond to immune checkpoint blockade (ICB) treatment. A CSRS scoring system including four CS genes (MYC, DLX2, EPHA3, and LIMK1) was constructed, which could distinguish the survival outcome, tumor microenvironment (TME) status, and ICB treatment response of patients with different CSRS score. Nomogram constructed by CSRS score and metastatic has a high prognostic value for OS. Conclusions. Our study identified a molecular classification determined by CS-related genes and developed a new CSRS that has potential value in OS immunotherapy response and clinical outcome prediction.

Radionuclide Imaging of Cytotoxic Immune Cell Responses to Anti-Cancer Immunotherapy

Cancer immunotherapy is an evolving and promising cancer treatment that takes advantage of the body’s immune system to yield effective tumor elimination. Importantly, immunotherapy has changed the treatment landscape for many cancers, resulting in remarkable tumor responses and improvements in patient survival. However, despite impressive tumor effects and extended patient survival, only a small proportion of patients respond, and others can develop immune-related adverse events associated with these therapies, which are associated with considerable costs. Therefore, strategies to increase the proportion of patients gaining a benefit from these treatments and/or increasing the durability of immune-mediated tumor response are still urgently needed. Currently, measurement of blood or tissue biomarkers has demonstrated sampling limitations, due to intrinsic tumor heterogeneity and the latter being invasive. In addition, the unique response patterns of these therapies are not adequately captured by conventional imaging modalities. Consequently, non-invasive, sensitive, and quantitative molecular imaging techniques, such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) using specific radiotracers, have been increasingly used for longitudinal whole-body monitoring of immune responses. Immunotherapies rely on the effector function of CD8⁺ T cells and natural killer cells (NK) at tumor lesions; therefore, the monitoring of these cytotoxic immune cells is of value for therapy response assessment. Different immune cell targets have been investigated as surrogate markers of response to immunotherapy, which motivated the development of multiple imaging agents. In this review, the targets and radiotracers being investigated for monitoring the functional status of immune effector cells are summarized, and their use for imaging of immune-related responses are reviewed along their limitations and pitfalls, of which multiple have already been translated to the clinic. Finally, emerging effector immune cell imaging strategies and future directions are provided.