Anti-PD-1 antibody decreases tumour-infiltrating regulatory T cells

KAT7 serves as an oncogenic gene and regulates CCL3 expression via STAT1 signaling in osteosarcoma

Osteosarcoma, considered as the primary cause of malignant bone tumors in children, necessitates novel therapeutic strategies to enhance overall survival rates. KAT7, a histone acetyltransferase, exerts pivotal functions in gene transcription and immune modulation. In light of this, our study identified a significant upregulation of KAT7 in the mRNA and protein levels in human osteosarcoma, boosting cell proliferation in vivo and in vitro. In addition, KAT7-mediated H3K14ac activation induced MMP14 transcription, leading to increased expression and facilitation of osteosarcoma cell metastasis. Subsequent bioinformatics analyses highlighted a correlation between KAT7 and adaptive immune responses, indicating CCL3 as a downstream target of KAT7. Mechanistically, STAT1 was found to transcriptionally upregulate CCL3 expression. Furthermore, overexpression of KAT7 suppressed CCL3 secretions, whereas knockdown of KAT7 enhanced its release. Overall, these findings underscore the oncogenic role of KAT7 in regulating immune responses for osteosarcoma treatment.

Chimeric antigen receptor T cells in the treatment of osteosarcoma (Review)

Osteosarcoma (OS) is a frequently occurring primary bone tumor, mostly affecting children, adolescents and young adults. Before 1970, surgical resection was the main treatment method for OS, but the clinical results were not promising. Subsequently, the advent of chemotherapy has improved the prognosis of patients with OS. However, there is still a high incidence of metastasis or recurrence, and chemotherapy has several side effects, thus making the 5‑year survival rate markedly low. Recently, chimeric antigen receptor T (CAR‑T) cell therapy represents an alternative immunotherapy approach with significant potential for hematologic malignancies. Nevertheless, the application of CAR‑T cells in the treatment of OS faces numerous challenges. The present review focused on the advances in the development of CAR‑T cells to improve their clinical efficacy, and discussed ways to overcome the difficulties faced by CAR T‑cell therapy for OS.

Osteosarcoma-Associated Immune Genes as Potential Immunotherapy and Prognosis Biomarkers

Immune-modulating therapies exhibit abundant promise compared to traditional treatment for osteosarcoma. We aim to establish an immune-related prognostic signatures in osteosarcoma. We identified the differentially expressed genes in osteosarcoma compared with normal controls using the GEO dataset. The intersection with immune-related genes was considered as differentially expressed immune genes. Potential prognosis-related differentially expressed genes were first analyzed with the multifactor Cox regression and then the step function performed the iteration. The best model was finally chosen as the immunological risk score signature model. And finally, we evaluated the correlation of genes in the prognostic model with immune cells, common immune checkpoints, and immune checkpoint blockade responses. We identified 1527 significantly upregulated and 2407 significantly downregulated genes in osteosarcoma compared to normal samples. In the 258 differentially expressed immune genes, 20 genes with independent prognostic significance were included in the step function. Finally, we constructed a prognostic signature for overall survival based on five immune genes (JAG2, PLXNB1, CMKLR1, NUDT6, and PSMC4) in osteosarcoma. These five genes are closely related to immune infiltration. Osteosarcoma with high JAG2 expression or low CMKLR1 expression may be associated with better immune checkpoint blockade response. JAG2 overexpression or CMKLR1 inhibition induced sensitivity to PD-1 antibody in osteosarcoma cells. We constructed a prognosis prediction signature containing five immune-related genes (JAG2, PLXNB1, CMKLR1, NUDT6, and PSMC4) with a significant prognostic value in osteosarcoma. Significant differences in immune infiltration and immunotherapy responses were identified between groups with different levels of these genes.

Current approaches in tissue engineering-based nanotherapeutics for osteosarcoma treatment

Osteosarcoma (OS) is a malignant bone neoplasm plagued by poor prognosis. Major treatment strategies include chemotherapy, radiotherapy, and surgery. Chemotherapy to treat OS has severe adverse effects due to systemic toxicity to healthy cells. A possible way to overcome the limitation is to utilize nanotechnology. Nanotherapeutics is an emerging approach in treating OS using nanoparticulate drug delivery systems. Surgical resection of OS leaves a critical bone defect requiring medical intervention. Recently, tissue engineered scaffolds have been reported to provide physical support to bone defects and aid multimodal treatment of OS. These scaffolds loaded with nanoparticulate delivery systems could also actively repress tumor growth and aid new bone formation. The rapid developments in nanotherapeutics and bone tissue engineering have paved the way for improved treatment efficacy for OS-related bone defects. This review focuses on current bifunctional nanomaterials-based tissue engineered (NTE) scaffolds that use novel approaches such as magnetic hyperthermia, photodynamic therapy, photothermal therapy, bioceramic and polymeric nanotherapeutics against OS. With further optimization and screening, NTE scaffolds could meet clinical applications for treating OS patients.

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.

Systemic Delivery of Paclitaxel by Find-Me Nanoparticles Activates Antitumor Immunity and Eliminates Tumors

Local delivery of immune-activating agents has shown promise in overcoming an immunosuppressive tumor microenvironment (TME) and stimulating antitumor immune responses in tumors. However, systemic therapy is ultimately needed to treat tumors that are not readily locatable or accessible. To enable systemic delivery of immune-activating agents, we employ poly(lactic-co-glycolide) (PLGA) nanoparticles (NPs) with a track record in systemic application. The surface of PLGA NPs is decorated with adenosine triphosphate (ATP), a damage-associated molecular pattern to recruit antigen-presenting cells (APCs). The ATP-conjugated PLGA NPs (NPpD-ATP) are loaded with paclitaxel (PTX), a chemotherapeutic agent inducing immunogenic cell death to generate tumor antigens in situ. We show that the NPpD-ATP retains ATP activity in hostile TME and provides a stable "find-me" signal to recruit APCs. Therefore, the PTX-loaded NPpD-ATP helps populate antitumor immune cells in TME and attenuate the growth of CT26 and B16F10 tumors better than a mixture of PTX-loaded NPpD and ATP. Combined with anti-PD-1 antibody, PTX-loaded NPpD-ATP achieves complete regression of CT26 tumors followed by antitumor immune memory. This study demonstrates the feasibility of systemic immunotherapy using a PLGA NP formulation that delivers ICD-inducing chemotherapy and an immunostimulatory signal.

Evaluation of regulatory T-cells in cancer immunotherapy: therapeutic relevance of immune checkpoint inhibition

The evolution of the complex immune system is equipped to defend against perilous intruders and concurrently negatively regulate the deleterious effect of immune-mediated inflammation caused by self and nonself antigens. Regulatory T-cells (Tregs) are specialized cells that minimize immune-mediated inflammation, but in malignancies, this feature has been exploited toward cancer progression by keeping the antitumor immune response in check. The modulation of Treg cell infiltration and their induction in the TME (tumor microenvironment) alongside associated inhibitory molecules, both soluble or membranes tethered in the TME, have proven clinically beneficial in boosting the tumoricidal activity of the immune system. Moreover, Treg-associated immune checkpoints pose a greater obstruction in cancer immunotherapy. Inhibiting or blocking active immune checkpoint signaling in combination with other therapies has proven clinically beneficial. This review summarizes the ontogeny of Treg cells and their migration, stability, and function in the TME. We also elucidate the Treg-associated checkpoint moieties that impede effective antitumor activity and harness these molecules for effective and targeted immunotherapy against cancer nuisance.

C-C Motif Chemokine Ligand 5 (CCL5): A Potential Biomarker and Immunotherapy Target for Osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common primary malignant tumor of bone tissue, which has an insidious onset and is difficult to detect early, and few early diagnostic markers with high specificity and sensitivity. Therefore, this study aims to identify potential biomarkers that can help diagnose OS in its early stages and improve the prognosis of patients.

METHODS

The data sets of GSE12789, GSE28424, GSE33382 and GSE36001 were combined and normalized to identify Differentially Expressed Genes (DEGs). The data were analyzed by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genome (KEGG) and Disease Ontology (DO). The hub gene was selected based on the common DEG that was obtained by applying two regression methods: the Least Absolute Shrinkage and Selection Operator (LASSO) and Support vVector Machine (SVM). Then the diagnostic value of the hub gene was evaluated in the GSE42572 data set. Finally, the correlation between immunocyte infiltration and key genes was analyzed by CIBERSORT.

RESULTS

The regression analysis results of LASSO and SVM are the following three DEGs: FK501 binding protein 51 (FKBP5), C-C motif chemokine ligand 5 (CCL5), complement component 1 Q subcomponent B chain (C1QB). We evaluated the diagnostic performance of three biomarkers (FKBP5, CCL5 and C1QB) for osteosarcoma using receiver operating characteristic (ROC) analysis. In the training group, the area under the curve (AUC) of FKBP5, CCL5 and C1QB was 0.907, 0.874 and 0.676, respectively. In the validation group, the AUC of FKBP5, CCL5 and C1QB was 0.618, 0.932 and 0.895, respectively. It is noteworthy that these genes were more expressed in tumor tissues than in normal tissues by various immune cell types, such as plasma cells, CD8+ T cells, T regulatory cells (Tregs), activated NK cells, activated dendritic cells and activated mast cells. These immune cell types are also associated with the expression levels of the three diagnostic genes that we identified.

CONCLUSION

We found that CCL5 can be considered an early diagnostic gene of osteosarcoma, and CCL5 interacts with immune cells to influence tumor occurrence and development. These findings have important implications for the early detection of osteosarcoma and the identification of novel therapeutic targets.

Efficacy of Nivolumab in Pediatric Cancers with High Mutation Burden and Mismatch Repair Deficiency

PURPOSE

Checkpoint inhibitors have limited efficacy for children with unselected solid and brain tumors. We report the first prospective pediatric trial (NCT02992964) using nivolumab exclusively for refractory nonhematologic cancers harboring tumor mutation burden (TMB) ≥5 mutations/megabase (mut/Mb) and/or mismatch repair deficiency (MMRD).

PATIENTS AND METHODS

Twenty patients were screened, and 10 were ultimately included in the response cohort of whom nine had TMB >10 mut/Mb (three initially eligible based on MMRD) and one patient had TMB between 5 and 10 mut/Mb.

RESULTS

Delayed immune responses contributed to best overall response of 50%, improving on initial objective responses (20%) and leading to 2-year overall survival (OS) of 50% [95% confidence interval (CI), 27-93]. Four children, including three with refractory malignant gliomas are in complete remission at a median follow-up of 37 months (range, 32.4-60), culminating in 2-year OS of 43% (95% CI, 18.2-100). Biomarker analyses confirmed benefit in children with germline MMRD, microsatellite instability, higher activated and lower regulatory circulating T cells. Stochastic mutation accumulation driven by underlying germline MMRD impacted the tumor microenvironment, contributing to delayed responses. No benefit was observed in the single patient with an MMR-proficient tumor and TMB 7.4 mut/Mb.

CONCLUSIONS

Nivolumab resulted in durable responses and prolonged survival for the first time in a pediatric trial of refractory hypermutated cancers including malignant gliomas. Novel biomarkers identified here need to be translated rapidly to clinical care to identify children who can benefit from checkpoint inhibitors, including upfront management of cancer. See related commentary by Mardis, p. 4701.

Frequency of peripheral PD-1+regulatory T cells is associated with treatment responses to PARP inhibitor maintenance in patients with epithelial ovarian cancer

BACKGROUND

Poly (adenosine diphosphate [ADP]-ribose) polymerase inhibitors (PARPis) are becoming the standard of care for epithelial ovarian cancer (EOC). Recently, clinical trials of triple maintenance therapy (PARPi+anti-angiogenic agent+anti-PD-1/L1) are actively ongoing. Here, we investigated the immunological effects of PARPi or triple maintenance therapy on T cells and their impact on clinical responses.

METHODS

We collected serial blood from EOC patients receiving PARPi therapy (cohort 1: PARPi, n = 49; cohort 2: olaparib+bevacizumab+pembrolizumab, n = 31). Peripheral T cells were analyzed using flow cytometry and compared according to the PARPi response. Progression-free survival (PFS) was assessed according to prognostic biomarkers identified in a comparative analysis.

RESULTS

Regulatory T cells (Tregs) were suppressed by PARPi therapy, whereas PD-1 was not significantly changed. Short PFS group exhibited a higher percentage of baseline PD-1+Tregs than long PFS group, and the patients with high percentage of PD-1+Tregs before treatment showed poor PFS in cohort 1. However, the expression of PD-1 on Tregs significantly decreased after receiving triple maintenance therapy, and the reduction in PD-1+Tregs was associated with superior PFS in cohort 2 (P = 0.0078).

CONCLUSION

PARPi suppresses Tregs, but does not affect PD-1 expression. Adding anti-PD-1 to PARPi decreases PD-1+Tregs, which have negative prognostic value for PARPi monotherapy.

Targeting post-translational modifications of Foxp3: a new paradigm for regulatory T cell-specific therapy

A healthy immune system is pivotal for the hosts to resist external pathogens and maintain homeostasis; however, the immunosuppressive tumor microenvironment (TME) damages the anti-tumor immunity and promotes tumor progression, invasion, and metastasis. Recently, many studies have found that Foxp3+ regulatory T (Treg) cells are the major immunosuppressive cells that facilitate the formation of TME by promoting the development of various tumor-associated cells and suppressing the activity of effector immune cells. Considering the role of Tregs in tumor progression, it is pivotal to identify new therapeutic drugs to target and deplete Tregs in tumors. Although several studies have developed strategies for targeted deletion of Treg to reduce the TME and support the accumulation of effector T cells in tumors, Treg-targeted therapy systematically affects the Treg population and may lead to the progression of autoimmune diseases. It has been understood that, nevertheless, in disease conditions, Foxp3 undergoes several definite post-translational modifications (PTMs), including acetylation, glycosylation, phosphorylation, ubiquitylation, and methylation. These PTMs not only elevate or mitigate the transcriptional activity of Foxp3 but also affect the stability and immunosuppressive function of Tregs. Various studies have shown that pharmacological targeting of enzymes involved in PTMs can significantly influence the PTMs of Foxp3; thus, it may influence the progression of cancers and/or autoimmune diseases. Overall, this review will help researchers to understand the advances in the immune-suppressive mechanisms of Tregs, the post-translational regulations of Foxp3, and the potential therapeutic targets and strategies to target the Tregs in TME to improve anti-tumor immunity.

Ferroptosis-related lncRNAs guiding osteosarcoma prognosis and immune microenvironment

OBJECTIVE

To investigate the ferroptosis-related long non-coding RNAs (FRLncs) implicated in influencing the prognostic and immune microenvironment in osteosarcoma (OS), and to establish a foundational framework for informing clinical decision making pertaining to OS management.

METHODS

Transcriptome data and clinical data pertaining to 86 cases of OS, the GSE19276, GSE16088 and GSE33382 datasets, and a list of ferroptosis-related genes (FRGs) were used to establish a risk prognostic model through comprehensive analysis. The identification of OS-related differentially expressed FRGs was achieved through an integrated analysis encompassing the aforementioned 86 OS transcriptome data and the GSE19276, GSE16088 and GSE33382 datasets. Concurrently, OS-related FRLncs were ascertained via co-expression analysis. To establish a risk prognostic model for OS, Univariate Cox regression analysis and Lasso Cox regression analysis were employed. Subsequently, a comprehensive evaluation was conducted, comprising risk curve analysis, survival analysis, receiver operating characteristic curve analysis and independent prognosis analysis. Model validation with distinct clinical subgroups was performed to assess the applicability of the risk prognostic model to diverse patient categories. Moreover, single sample gene set enrichment analysis (ssGSEA) was conducted to investigate variations in immune cell populations and immune functions within the context of the risk prognostic model. Furthermore, an analysis of immune checkpoint differentials yielded insights into immune checkpoint-related genes linked to OS prognosis. Finally, the risk prognosis model was verified by dividing the samples into train group and test group.

RESULTS

We identified a set of seven FRLncs that exhibit potential as prognostic markers and influence factors of the immune microenvironment in the context of OS. This ensemble encompasses three high-risk FRLncs, denoted as APTR, AC105914.2 and AL139246.5, alongside four low-risk FRLncs, designated as DSCR8, LOH12CR2, AC027307.2 and AC025048.2. Furthermore, our analysis revealed notable down-regulation in the high-risk group across four distinct immune cell types, namely neutrophils, natural killer cells, plasmacytoid dendritic cells and tumor-infiltrating lymphocytes. This down-regulation was also reflected in four key immune functions, antigen-presenting cell (APC)-co-stimulation, checkpoint, cytolytic activity and T cell co-inhibition. Additionally, we identified seven immune checkpoint-associated genes with significant implications for OS prognosis, including CD200R1, HAVCR2, LGALS9, CD27, LAIR1, LAG3 and TNFSF4.

CONCLUSION

The findings of this study have identified FRLncs capable of influencing OS prognosis and immune microenvironment, as well as immune checkpoint-related genes that are linked to OS prognosis. These discoveries establish a substantive foundation for further investigations into OS survival and offer valuable insights for informing clinical decision making in this context.

Radiotherapy remodels the tumor microenvironment for enhancing immunotherapeutic sensitivity

Cancer immunotherapy has transformed traditional treatments, with immune checkpoint blockade being particularly prominent. However, immunotherapy has minimal benefit for patients in most types of cancer and is largely ineffective in some cancers (such as pancreatic cancer and glioma). A synergistic anti-tumor response may be produced through the combined application with traditional tumor treatment methods. Radiotherapy (RT) not only kills tumor cells but also triggers the pro-inflammatory molecules' release and immune cell infiltration, which remodel the tumor microenvironment (TME). Therefore, the combination of RT and immunotherapy is expected to achieve improved efficacy. In this review, we summarize the effects of RT on cellular components of the TME, including T cell receptor repertoires, different T cell subsets, metabolism, tumor-associated macrophages and other myeloid cells (dendritic cells, myeloid-derived suppressor cells, neutrophils and eosinophils). Meanwhile, non-cellular components such as lactate and extracellular vesicles are also elaborated. In addition, we discuss the impact of different RT modalities on tumor immunity and issues related to the clinical practice of combination therapy.

Glycolysis-cholesterol metabolic axis in immuno-oncology microenvironment: emerging role in immune cells and immunosuppressive signaling

Cell proliferation and function require nutrients, energy, and biosynthesis activity to duplicate repertoires for each daughter. It is therefore not surprising that tumor microenvironment (TME) metabolic reprogramming primarily orchestrates the interaction between tumor and immune cells. Tumor metabolic reprogramming affords bioenergetic, signaling intermediates, and biosynthesis requirements for both malignant and immune cells. Different immune cell subsets are recruited into the TME, and these manifestations have distinct effects on tumor progression and therapeutic outcomes, especially the mutual contribution of glycolysis and cholesterol metabolism. In particularly, glycolysis-cholesterol metabolic axis interconnection plays a critical role in the TME modulation, and their changes in tumor metabolism appear to be a double-edged sword in regulating various immune cell responses and immunotherapy efficacy. Hence, we discussed the signature manifestation of the glycolysis-cholesterol metabolic axis and its pivotal role in tumor immune regulation. We also highlight how hypothetical combinations of immunotherapy and glycolysis/cholesterol-related metabolic interventions unleash the potential of anti-tumor immunotherapies, as well as developing more effective personalized treatment strategies.

Progresses in biomarkers for cancer immunotherapy

Currently, checkpoint inhibitor-based immunotherapy has emerged as prevailing treatment modality for diverse cancers. However, immunotherapy as a first-line therapy has not consistently yielded durable responses. Moreover, the risk of immune-related adverse events increases with combination regimens. Thus, the development of predictive biomarkers is needed to optimize individuals benefit, minimize risk of toxicities, and guide combination approaches. The greatest focus has been on tumor programmed cell death-ligand 1 (PD-L1), microsatellite instability (MSI), and tumor mutational burden (TMB). However, there remains a subject of debate due to thresholds variability and significant heterogeneity. Major unmet challenges in immunotherapy are the discovery and validation of predictive biomarkers. Here, we show the status of tumor PD-L1, MSI, TMB, and emerging data on novel biomarker strategies with oncogenic signaling and epigenetic regulation. Considering the exploration of peripheral and intestinal immunity has served as noninvasive alternative in predicting immunotherapy, this review also summarizes current data in systemic immunity, encompassing solute PD-L1 and TMB, circulating tumor DNA and infiltrating lymphocytes, routine emerging inflammatory markers and cytokines, as well as gut microbiota. This review provides up-to-date information on the evolving field of currently available biomarkers in predicting immunotherapy. Future exploration of novel biomarkers is warranted.

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.

Metabolism and senescence in the immune microenvironment of osteosarcoma: focus on new therapeutic strategies

Osteosarcoma is a highly aggressive and metastatic malignant tumor. It has the highest incidence of all malignant bone tumors and is one of the most common solid tumors in children and adolescents. Osteosarcoma tissues are often richly infiltrated with inflammatory cells, including tumor-associated macrophages, lymphocytes, and dendritic cells, forming a complex immune microenvironment. The expression of immune checkpoint molecules is also high in osteosarcoma tissues, which may be involved in the mechanism of anti-tumor immune escape. Metabolism and senescence are closely related to the immune microenvironment, and disturbances in metabolism and senescence may have important effects on the immune microenvironment, thereby affecting immune cell function and immune responses. Metabolic modulation and anti-senescence therapy are gaining the attention of researchers as emerging immunotherapeutic strategies for tumors. Through an in-depth study of the interconnection of metabolism and anti- senescence in the tumor immune microenvironment and its regulatory mechanism on immune cell function and immune response, more precise therapeutic strategies can be developed. Combined with the screening and application of biomarkers, personalized treatment can be achieved to improve therapeutic efficacy and provide a scientific basis for clinical decision-making. Metabolic modulation and anti- senescence therapy can also be combined with other immunotherapy approaches, such as immune checkpoint inhibitors and tumor vaccines, to form a multi-level and multi-dimensional immunotherapy strategy, thus further enhancing the effect of immunotherapy. Multidisciplinary cooperation and integrated treatment can optimize the treatment plan and maximize the survival rate and quality of life of patients. Future research and clinical practice will further advance this field, promising more effective treatment options for patients with osteosarcoma. In this review, we reviewed metabolic and senescence characteristics in the immune microenvironment of osteosarcoma and related immunotherapies, and provide a reference for development of more personalized and effective therapeutic strategies.

Advances in Osteosarcoma

PURPOSE OF REVIEW

This article gives a brief overview of the most recent developments in osteosarcoma treatment, including targeting of signaling pathways, immune checkpoint inhibitors, drug delivery strategies as single or combined approaches, and the identification of new therapeutic targets to face this highly heterogeneous disease.

RECENT FINDINGS

Osteosarcoma is one of the most common primary malignant bone tumors in children and young adults, with a high risk of bone and lung metastases and a 5-year survival rate around 70% in the absence of metastases and 30% if metastases are detected at the time of diagnosis. Despite the novel advances in neoadjuvant chemotherapy, the effective treatment for osteosarcoma has not improved in the last 4 decades. The emergence of immunotherapy has transformed the paradigm of treatment, focusing therapeutic strategies on the potential of immune checkpoint inhibitors. However, the most recent clinical trials show a slight improvement over the conventional polychemotherapy scheme. The tumor microenvironment plays a crucial role in the pathogenesis of osteosarcoma by controlling the tumor growth, the metastatic process and the drug resistance and paved the way of new therapeutic options that must be validated by accurate pre-clinical studies and clinical trials.

Nasopharyngeal carcinoma cells promote regulatory T cell development and suppressive activity via CD70-CD27 interaction

Despite the intense CD8+ T-cell infiltration in the tumor microenvironment of nasopharyngeal carcinoma, anti-PD-1 immunotherapy shows an unsatisfactory response rate in clinical trials, hindered by immunosuppressive signals. To understand how microenvironmental characteristics alter immune homeostasis and limit immunotherapy efficacy in nasopharyngeal carcinoma, here we establish a multi-center single-cell cohort based on public data, containing 357,206 cells from 50 patient samples. We reveal that nasopharyngeal carcinoma cells enhance development and suppressive activity of regulatory T cells via CD70-CD27 interaction. CD70 blocking reverts Treg-mediated suppression and thus reinvigorate CD8+ T-cell immunity. Anti-CD70+ anti-PD-1 therapy is evaluated in xenograft-derived organoids and humanized mice, exhibiting an improved tumor-killing efficacy. Mechanistically, CD70 knockout inhibits a collective lipid signaling network in CD4+ naïve and regulatory T cells involving mitochondrial integrity, cholesterol homeostasis, and fatty acid metabolism. Furthermore, ATAC-Seq delineates that CD70 is transcriptionally upregulated by NFKB2 via an Epstein-Barr virus-dependent epigenetic modification. Our findings identify CD70+ nasopharyngeal carcinoma cells as a metabolic switch that enforces the lipid-driven development, functional specialization and homeostasis of Tregs, leading to immune evasion. This study also demonstrates that CD70 blockade can act synergistically with anti-PD-1 treatment to reinvigorate T-cell immunity against nasopharyngeal carcinoma.

Managing the immune microenvironment of osteosarcoma: the outlook for osteosarcoma treatment

Osteosarcoma, with poor survival after metastasis, is considered the most common primary bone cancer in adolescents. Notwithstanding the efforts of researchers, its five-year survival rate has only shown limited improvement, suggesting that existing therapeutic strategies are insufficient to meet clinical needs. Notably, immunotherapy has shown certain advantages over traditional tumor treatments in inhibiting metastasis. Therefore, managing the immune microenvironment in osteosarcoma can provide novel and valuable insight into the multifaceted mechanisms underlying the heterogeneity and progression of the disease. Additionally, given the advances in nanomedicine, there exist many advanced nanoplatforms for enhanced osteosarcoma immunotherapy with satisfactory physiochemical characteristics. Here, we review the classification, characteristics, and functions of the key components of the immune microenvironment in osteosarcoma. This review also emphasizes the application, progress, and prospects of osteosarcoma immunotherapy and discusses several nanomedicine-based options to enhance the efficiency of osteosarcoma treatment. Furthermore, we examine the disadvantages of standard treatments and present future perspectives for osteosarcoma immunotherapy.

Strategies to Overcome Resistance to Immune-Based Therapies in Osteosarcoma

Improving the prognosis and cure rate of HGOSs (high-grade osteosarcomas) is an absolute need. Immune-based treatment approaches have been increasingly taken into consideration, in particular for metastatic, relapsed and refractory HGOS patients, to ameliorate the clinical results currently achieved. This review is intended to give an overview on the immunotherapeutic treatments targeting, counteracting or exploiting the different immune cell compartments that are present in the HGOS tumor microenvironment. The principle at the basis of these strategies and the possible mechanisms that HGOS cells may use to escape these treatments are presented and discussed. Finally, a list of the currently ongoing immune-based trials in HGOS is provided, together with the results that have been obtained in recently completed clinical studies. The different strategies that are presently under investigation, which are generally aimed at abrogating the immune evasion of HGOS cells, will hopefully help to indicate new treatment protocols, leading to an improvement in the prognosis of patients with this tumor.

Immunotherapy for hepatocellular carcinoma recurrence after liver transplantation, can we harness the power of immune checkpoint inhibitors?

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death globally and liver transplantation (LT) can serve as the best curative treatment option. However, HCC recurrence after LT remains the major obstacle to the long-term survival of recipients. Recently, immune checkpoint inhibitors (ICIs) have revolutionized the treatment of many cancers and provided a new treatment strategy for post-LT HCC recurrence. Evidence has been accumulated with the real-world application of ICIs in patients with post-LT HCC recurrence. Notably, the use of these agents as immunity boosters in recipients treated with immunosuppressors is still controversial. In this review, we summarized the immunotherapy for post-LT HCC recurrence and conducted an efficacy and safety evaluation based on the current experience of ICIs for post-LT HCC recurrence. In addition, we further discussed the potential mechanism of ICIs and immunosuppressive agents in regulating the balance between immune immunosuppression and lasting anti-tumor immunity.

Synergistic potential of immune checkpoint inhibitors and therapeutic cancer vaccines

Cancer vaccines and immune checkpoint inhibitors (ICIs) function at different stages of the cancer immune cycle due to their distinct mechanisms of action. Therapeutic cancer vaccines enhance the activation and infiltration of cytotoxic immune cells into the tumor microenvironment (TME), while ICIs, prevent and/or reverse the dysfunction of these immune cells. The efficacy of both classes of immunotherapy has been evaluated in monotherapy, but they have been met with several challenges. Although therapeutic cancer vaccines can activate anti-tumor immune responses, these responses are susceptible to attenuation by immunoregulatory molecules. Similarly, ICIs are ineffective in the absence of tumor-infiltrating lymphocytes (TILs). Further, ICIs are often associated with immune-related adverse effects that may limit quality of life and compliance. However, the combination of the improved immunogenicity afforded by cancer vaccines and restrained immunosuppression provided by immune checkpoint inhibitors may provide a suitable platform for therapeutic synergism. In this review, we revisit the history and various classifications of therapeutic cancer vaccines. We also provide a summary of the currently approved ICIs. Finally, we provide mechanistic insights into the synergism between ICIs and cancer vaccines.

Immunotherapeutic Strategies in the Management of Osteosarcoma

Osteosarcoma (OS) is the most common primary malignant bone cancer with a high tendency for metastasis. Although treatment strategies involving surgery and chemotherapy have improved outcomes for patients with OS, the prognosis of recurrent OS is quite unsatisfactory. Primary reasons leading to mortality in OS patients are resistance to currently used therapies and the subsequent lung metastasis. Immunotherapy, however, has been shown to be a promising therapeutic strategy against OS. As research progresses, immunotherapy is gradually becoming irreplaceable. This article provides a critical evaluation of several therapeutic strategies for OS including immunomodulation, vaccine therapy, and immunologic checkpoint blockade.

Deletion of PD-1 destabilizes the lineage identity and metabolic fitness of tumor-infiltrating regulatory T cells

Regulatory T (T_reg) cells have an immunosuppressive function and highly express the immune checkpoint receptor PD-1 in the tumor microenvironment; however, the function of PD-1 in tumor-infiltrating (TI) T_reg cells remains controversial. Here, we showed that conditional deletion of PD-1 in T_reg cells delayed tumor progression. In Pdcd1^fl/flFoxp3^{eGFP-Cre-ERT2(+/-)} mice, in which both PD-1-expressing and PD-1-deficient T_reg cells coexisted in the same tissue environment, conditional deletion of PD-1 in T_reg cells resulted in impairment of the proliferative and suppressive capacity of TI T_reg cells. PD-1 antibody therapy reduced the TI T_reg cell numbers, but did not directly restore the cytokine production of TI CD8⁺ T cells in TC-1 lung cancer. Single-cell analysis indicated that PD-1 signaling promoted lipid metabolism, proliferation and suppressive pathways in TI T_reg cells. These results suggest that PD-1 ablation or inhibition can enhance antitumor immunity by weakening T_reg cell lineage stability and metabolic fitness in the tumor microenvironment.

Up-regulation of Core 1 Beta 1, 3-Galactosyltransferase Suppresses Osteosarcoma Growth with Induction of IFN-γ Secretion and Proliferation of CD8+ T Cells

AIM

Abnormal glycosylation often occurs in tumor cells. T-synthase (core 1 beta 1,3- galactosyltransferase, C1GALT1, or T-synthase) is a key enzyme involved in O-glycosylation. Although T-synthase is known to be important in human tumors, the effects of T-synthase and T-antigen on human tumor responses remain poorly defined.

METHODS

In this study, a T-synthase-specific short hairpin RNA (shRNA) or T-synthase-specific eukaryotic expression vector(pcDNA3.1(+)) was transfected into murine Osteosarcoma LM8 cells to assess the effects of T-synthase on T cells and cytokines.

RESULTS

The up-regulation of T-synthase promoted the proliferation of osteosarcoma cells in vitro, but it promoted the proliferation of tumor initially up to 2-3 weeks but showed significant growth inhibitory effect after 3 weeks post-implantation in vivo. Osteosarcoma cells with high T-synthase expression in vitro promoted the proliferation and inhibited the apoptosis of CD8+ T cells. Further, T-synthase upregulation promoted CD8+ T-cell proliferation and the increased production of CD4+ T cell-derived IFN-γ cytokines to induce the increased tumor lethality of CTLs.

CONCLUSION

Our data suggest that high T-synthase expression inhibits tumor growth by improving the body's anti-tumor immunity. Therefore, using this characteristic to prepare tumor cell vaccines with high immunogenicity provides a new idea for clinical immunotherapy of osteosarcoma.

Advanced 3D Magnetic Scaffolds for Tumor-Related Bone Defects

The need for bone substitutes is a major challenge as the incidence of serious bone disorders is massively increasing, mainly attributed to modern world problems, such as obesity, aging of the global population, and cancer incidence. Bone cancer represents one of the most significant causes of bone defects, with reserved prognosis regarding the effectiveness of treatments and survival rate. Modern therapies, such as hyperthermia, immunotherapy, targeted therapy, and magnetic therapy, seem to bring hope for cancer treatment in general, and bone cancer in particular. Mimicking the composition of bone to create advanced scaffolds, such as bone substitutes, proved to be insufficient for successful bone regeneration, and a special attention should be given to control the changes in the bone tissue micro-environment. The magnetic manipulation by an external field can be a promising technique to control this micro-environment, and to sustain the proliferation and differentiation of osteoblasts, promoting the expression of some growth factors, and, finally, accelerating new bone formation. By incorporating stimuli responsive nanocarriers in the scaffold's architecture, such as magnetic nanoparticles functionalized with bioactive molecules, their behavior can be rigorously controlled under external magnetic driving, and stimulates the bone tissue formation.

Identification of necroptosis-related subtypes, development of a novel signature, and characterization of immune infiltration in colorectal cancer

Introduction

Necroptosis, a type of programmed cell death, has recently been extensively studied as an important pathway regulating tumor development, metastasis, and immunity. However, the expression patterns of necroptosis-related genes (NRGs) in colorectal cancer (CRC) and their potential roles in the tumor microenvironment (TME) have not been elucidated.

Methods

We explored the expression patterns of NRGs in 1247 colorectal cancer samples from genetics and transcriptional perspective. Based on a consensus clustering algorithm, we identified NRG molecular subtypes and gene subtypes, respectively. Furthermore, we constructed a necroptosis-related signature for predicting overall survival time and verified the predictive ability of the model. Using the ESTIMATE, CIBERSORT, and ssGSEA algorithms, we assessed the association between the above subtypes, scores and immune infiltration.

Results

Most NRGs were differentially expressed between CRC tissues and normal tissues. We found that distinct subtypes exhibited different NRGs expression, patients' prognosis, immune checkpoint gene expression, and immune infiltration characteristics. The scores calculated from the necroptosis-related signature can be used to classify patients into high-risk and low-risk groups, with the high-risk group corresponding to reduced immune cell infiltration and immune function, and a greater risk of immune dysfunction and immune escape.

Discussion

Our comprehensive analysis of NRGs in CRC demonstrated their potential role in clinicopathological features, prognosis, and immune infiltration in the TME. These findings help us deepen our understanding of NRGs and the tumor microenvironment landscape, and lay a foundation for effectively assessing patient outcomes and promoting more effective immunotherapy.

Current Status and Prospects of Targeted Therapy for Osteosarcoma

Osteosarcoma (OS) is a highly malignant tumor occurring in bone tissue with a high propensity to metastasize, and its underlying mechanisms remain largely elusive. The OS prognosis is poor, and improving the survival of OS patients remains a challenge. Current treatment methods such as surgical approaches, chemotherapeutic drugs, and immunotherapeutic drugs remain ineffective. As research progresses, targeted therapy is gradually becoming irreplaceable. In this review, several treatment modalities for osteosarcoma, such as surgery, chemotherapy, and immunotherapy, are briefly described, followed by a discussion of targeted therapy, the important targets, and new technologies for osteosarcoma treatment.

The depths of PD-1 function within the tumor microenvironment beyond CD8+ T cells

Programmed cell death-1 (PD-1; CD279) is a cell surface receptor that is expressed in both innate and adaptive immune cells. The role of PD-1 in adaptive immune cells, specifically in CD8+ T cells, has been thoroughly investigated but its significance in other immune cells is yet to be well established. This review will address the role of PD-1 based therapies in enhancing non-CD8+ T cell immune responses within cancer. Specifically, the expression and function of PD-1 in non-CD8+ immune cell compartments such as CD4+ T helper cell subsets, myeloid cells and innate lymphoid cells (ILCs) will be discussed. By understanding the immune cell specific function of PD-1 within tissue resident innate and adaptive immune cells, it will be possible to stratify patients for PD-1 based therapies for both immunogeneic and non-immunogeneic neoplastic disorders. With this knowledge from fundamental and translational studies, PD-1 based therapies can be utilized to enhance T cell independent immune responses in cancers.

CD146 is closely associated with the prognosis and molecular features of osteosarcoma: Guidance for personalized clinical treatment

Background: Osteosarcoma (OSA), a focus for orthopedic surgeons, always results in severe death due to metastasis. CD146 is severely expressed in several tumors, indicating its potential as a biomarker for OSA.

Method: Two OSA cohorts were enrolled in this study. A Therapeutically Applicable Research to Generate Effective Treatments-Osteosarcoma (TARGET-OS) cohort was used as a training cohort, and GSE21257 was used as the external validation cohort. The R package “limma” was used to discriminate the differentially expressed genes among CD146-high and CD146-low patients and was further annotated by the enriched signaling pathways. The R package MOVICS was used to evaluate immune infiltration and the response to chemotherapy and immunotherapy. All statistical analyses were performed by R version 4.0.2, and p < 0.05 was considered statistically significant.

Result: CD146 plays an important role in promoting the progression, invasion, and metastasis of several tumors. In the current study, we first revealed an integrative unfavorable prognosis in patients with tumors (p < 0.01, HR: 1.10, 95% CI: 1.07-1.14). CD146 is tightly correlated with m5C RNA methylation modification genes in OSA. Furthermore, we revealed that CD146 acts as an oncogene in OSA patients and is linked to poor prognosis in both the TARGET-OS cohort (p = 0.019, HR: 2.61, 95% CI: 1.171-5.834) and the GSE21257 cohort (p = 0.005, HR: 3.61, 95% CI: 1.474-8.855), with a total of 137 patients, regardless of whether they were adjusted for clinical pathological features. Highly-expressed CD146 impacts the signaling pathways of cytokine‒cytokine receptor interactions and is associated with the high infiltration of immunocytes. Moreover, patients with high CD146 expression were more likely to be sensitive to anti-PD-1 immunotherapy, while patients with low expression of CD146 were more likely to be sensitive to cisplatin and doxorubicin chemotherapy.

Conclusion: Overall, CD146 is an independent prognostic factor for OSA patients and can help doctors select clinical treatment strategies.

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.

A single-beam of light priming the immune responses and boosting cancer photoimmunotherapy

Mirroring the rapid clinical performance, immune checkpoint blockade (ICB) leads a remarkable clinical advance in combating cancer, but suffers poor response in most cancers. The low presence of tumor-infiltration lymphocytes and the poor immunogenicity in tumor microenvironment (TME) are the main factors hindering the effectiveness of ICB in the treatment of immunological "cold" tumors. Aiming at boosting immune response via TME modulation, we report a near-infrared laser-guided photoimmuno-strategy in which synergistic phototherapy, immune adjuvant, and ICB are integrated into one versatile nanoporphyrin platform. The prepared nanoporphyrins are self-assembled from purpurin18-lipids and have photodynamic/photothermal and immunomodulatory effects that can be tuned under a single laser irradiation, concomitant with fluorescence or MSOT imaging. In this work, the contributions of each component in the nanoporphyrin platform were specified. In particular, phototherapy-driven in situ tumor cell death provided abundant tumor-associated antigens to initiate immune responses. With the assist of spatiotemporally delivered immune adjuvant, phototherapy potentiated tumor immunogenicity, reprogrammed "cold" tumors into "hot" ones, and sensitized tumors to ICB therapy. Further combined with PD-L1 blockade, the photoimmune-strategy substantially stimulated tumor-specific immune-responses and long-term immunological memory against primary tumor, abscopal tumor as well as metastatic foci. Such single light-primed photoimmunotherapy offers a promising solution to overcome common hurdles in ICB treatment and can potentially be integrated into existing clinical practice.

Lipid nanoparticle-mediated lymph node-targeting delivery of mRNA cancer vaccine elicits robust CD8+ T cell response

The targeted delivery of messenger RNA (mRNA) to desired organs remains a great challenge for in vivo applications of mRNA technology. For mRNA vaccines, the targeted delivery to the lymph node (LN) is predicted to reduce side effects and increase the immune response. In this study, we explored an endogenously LN-targeting lipid nanoparticle (LNP) without the modification of any active targeting ligands for developing an mRNA cancer vaccine. The LNP named 113-O12B showed increased and specific expression in the LN compared with LNP formulated with ALC-0315, a synthetic lipid used in the COVID-19 vaccine Comirnaty. The targeted delivery of mRNA to the LN increased the CD8+ T cell response to the encoded full-length ovalbumin (OVA) model antigen. As a result, the protective and therapeutic effect of the OVA-encoding mRNA vaccine on the OVA-antigen-bearing B16F10 melanoma model was also improved. Moreover, 113-O12B encapsulated with TRP-2 peptide (TRP2180-188)-encoding mRNA also exhibited excellent tumor inhibition, with the complete response of 40% in the regular B16F10 tumor model when combined with anti-programmed death-1 (PD-1) therapy, revealing broad application of 113-O12B from protein to peptide antigens. All the treated mice showed long-term immune memory, hindering the occurrence of tumor metastatic nodules in the lung in the rechallenging experiments that followed. The enhanced antitumor efficacy of the LN-targeting LNP system shows great potential as a universal platform for the next generation of mRNA vaccines.

Immune checkpoints in osteosarcoma: Recent advances and therapeutic potential

Osteosarcoma is the most common primary malignant bone tumor and is associated with a high risk of recurrence and distant metastasis. Effective treatment for osteosarcoma, especially advanced osteosarcoma, has stagnated over the past four decades. The advent of immune checkpoint inhibitor (ICI) has transformed the treatment paradigm for multiple malignant tumor types and indicated a potential therapeutic strategy for osteosarcoma. In this review, we discuss recent advances in immune checkpoints, including programmed cell death protein-1 (PD-1), programmed cell death protein ligand-1 (PD-L1), and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), and their related ICIs for osteosarcoma treatment. We present the main existing mechanisms of resistance to ICIs therapy in osteosarcoma. Moreover, we summarize the current strategies for improving the efficacy of ICIs in osteosarcoma and address the potential predictive biomarkers of ICIs treatment in osteosarcoma.

Dual Blockade of PD-1 and LAG3 Immune Checkpoints Increases Dendritic Cell Vaccine Mediated T Cell Responses in Breast Cancer Model

PURPOSE

Increasing the efficiency of unsuccessful immunotherapy methods is one of the most important research fields. Therefore, the use of combination therapy is considered as one of the ways to increase the effectiveness of the dendritic cell (DC) vaccine. In this study, the inhibition of immune checkpoint receptors such as LAG3 and PD-1 on T cells was investigated to increase the efficiency of T cells in response to the DC vaccine.

METHODS

We used trimethyl chitosan-dextran sulfate-lactate (TMC-DS-L) nanoparticles (NPs) loaded with siRNA molecules to quench the PD-1 and LAG3 checkpoints' expression.

RESULTS

Appropriate physicochemical characteristics of the generated NPs led to efficient inhibition of LAG3 and PD-1 on T cells, which was associated with increased survival and activity of T cells, ex vivo. Also, treating mice with established breast tumors (4T1) using NPs loaded with siRNA molecules in combination with DC vaccine pulsed with tumor lysate significantly inhibited tumor growth and increased survival in mice. These ameliorative effects were associated with increased anti-tumor T cell responses and downregulation of immunosuppressive cells in the tumor microenvironment and spleen.

CONCLUSION

These findings strongly suggest that TMC-DS-L NPs loaded with siRNA could act as a novel tool in inhibiting the expression of immune checkpoints in the tumor microenvironment. Also, combination therapy based on inhibition of PD-1 and LAG3 in combination with DC vaccine is an effective method in treating cancer that needs to be further studied.

A novel signature to guide osteosarcoma prognosis and immune microenvironment: Cuproptosis-related lncRNA

Objective

Osteosarcoma (OS) is a common bone malignancy with poor prognosis. We aimed to investigate the relationship between cuproptosis-related lncRNAs (CRLncs) and the survival outcomes of patients with OS.

Methods

Transcriptome and clinical data of 86 patients with OS were downloaded from The Cancer Genome Atlas (TCGA). The GSE16088 dataset was downloaded from the Gene Expression Omnibus (GEO) database. The 10 cuproptosis-related genes (CRGs) were obtained from a recently published article on cuproptosis in Science. Combined analysis of OS transcriptome data and the GSE16088 dataset identified differentially expressed CRGs related to OS. Next, pathway enrichment analysis was performed. Co-expression analysis obtained CRLncs related to OS. Univariate COX regression analysis and least absolute shrinkage and selection operator (LASSO) regression analysis were used to construct the risk prognostic model of CRLncs. The samples were divided evenly into training and test groups to verify the accuracy of the model. Risk curve, survival, receiver operating characteristic (ROC) curve, and independent prognostic analyses were performed. Next, principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE) analysis were performed. Single-sample gene set enrichment analysis (ssGSEA) was used to explore the correlation between the risk prognostic models and OS immune microenvironment. Drug sensitivity analysis identified drugs with potential efficacy in OS. Real-time quantitative PCR, Western blotting, and immunohistochemistry analyses verified the expression of CRGs in OS. Real-time quantitative PCR was used to verify the expression of CRLncs in OS.

Results

Six CRLncs that can guide OS prognosis and immune microenvironment were obtained, including three high-risk CRLncs (AL645608.6, AL591767.1, and UNC5B-AS1) and three low-risk CRLncs (CARD8-AS1, AC098487.1, and AC005041.3). Immune cells such as B cells, macrophages, T-helper type 2 (Th2) cells, regulatory T cells (Treg), and immune functions such as APC co-inhibition, checkpoint, and T-cell co-inhibition were significantly downregulated in high-risk groups. In addition, we obtained four drugs with potential efficacy for OS: AUY922, bortezomib, lenalidomide, and Z.LLNle.CHO. The expression of LIPT1, DLAT, and FDX1 at both mRNA and protein levels was significantly elevated in OS cell lines compared with normal osteoblast hFOB1.19. The mRNA expression level of AL591767.1 was decreased in OS, and that of AL645608.6, CARD8-AS1, AC005041.3, AC098487.1, and UNC5B-AS1 was upregulated in OS.

Conclusion

CRLncs that can guide OS prognosis and the immune microenvironment and drugs that may have a potential curative effect on OS obtained in this study provide a theoretical basis for OS survival research and clinical decision-making.

Increased expression of ST2 on regulatory T cells is associated with cancer associated fibroblast-derived IL-33 in laryngeal cancer

Interleukin (IL)- 33 plays an essential role in regulatory T cell (Treg)-mediated immunosuppression in cancers and underlies the crosstalk between Tregs and the tumor microenvironment. However, the phenotypic characteristics of subset Tregs modulated by IL-33 and its association with the tumor microenvironment are not fully understood. This study aimed to examine the expression of ST2, the receptor of IL-33, on Tregs in tumors and to evaluate their association with cancer associated fibroblasts (CAFs) and reciprocal influences on the prognosis of laryngeal cancer. Our results showed that increased numbers of Tregs were found in laryngeal tumor tissues. Tregs in stromal IL-33-positive tumor tissues demonstrated significantly higher expression of ST2 than those in IL-33^- or adjacent nontumor tissues. ST2-expressing Tregs exhibited upregulation of Ki67 and CTLA4 compared with their ST2^- negative counterparts. Furthermore, IL-33 in the tumor microenvironment was mainly derived from fibroblasts. ST2 expression on Tregs was correlated with the number of IL-33-positive CAFs. High ST2 expression on Tregs, combined high ST2 on Tregs and the presence of IL-33 expressing CAFs was associated with worse survival outcomes in laryngeal cancer. This study indicated that increased expression of ST2 on Tregs is associated with microenvironmental IL-33 signaling derived from CAFs in laryngeal cancer, unraveling the special role of Tregs and fibroblasts in modulating IL-33/ST2 involved immune-evasive tumor microenvironment.

Immune Microenvironment in Osteosarcoma: Components, Therapeutic Strategies and Clinical Applications

Osteosarcoma is a primary malignant tumor that tends to threaten children and adolescents, and the 5-year event-free survival rate has not improved significantly in the past three decades, bringing grief and economic burden to patients and society. To date, the genetic background and oncogenesis mechanisms of osteosarcoma remain unclear, impeding further research. The tumor immune microenvironment has become a recent research hot spot, providing novel but valuable insight into tumor heterogeneity and multifaceted mechanisms of tumor progression and metastasis. However, the immune microenvironment in osteosarcoma has been vigorously discussed, and the landscape of immune and non-immune component infiltration has been intensively investigated. Here, we summarize the current knowledge of the classification, features, and functions of the main infiltrating cells, complement system, and exosomes in the osteosarcoma immune microenvironment. In each section, we also highlight the complex crosstalk network among them and the corresponding potential therapeutic strategies and clinical applications to deepen our understanding of osteosarcoma and provide a reference for imminent effective therapies with reduced adverse effects.

The prospect of targeting T cell immunoglobulin and mucin-domain containing-3 in renal cell carcinoma immunotherapy

Despite the advances in the diagnosis and treatment of renal cell carcinoma (RCC), it remains one of the most deadly urological cancers. At present, using immune checkpoint inhibition and their combination with antiangiogenic therapy is the standard of care in patients with advanced RCC. Unfortunately, a considerable part of tumour-bearing hosts does not benefit from this type of treatment. However, our knowledge about the detailed role of mucin-domain containing-3 (TIM-3) in the RCC cells is little, and further studies are required in this field, but its significant expression in the RCC microenvironment makes this receptor a promising target for designing new monoclonal antibodies alone or in combination with other checkpoint inhibitors for RCC immunotherapy.

Excessive immunosuppression by regulatory T cells antagonizes T cell response to schistosome infection in PD-1-deficient mice

Schistosomiasis is caused by parasitic flatworms known as schistosomes and affects over 200 million people worldwide. Prevention of T cell exhaustion by blockade of PD-1 results in clinical benefits to cancer patients and clearance of viral infections, however it remains largely unknown whether loss of PD-1 could prevent or cure schistosomiasis in susceptible mice. In this study, we found that S. japonicum infection dramatically induced PD-1 expression in T cells of the liver where the parasites chronically inhabit and elicit deadly inflammation. Even in mice infected by non-egg-producing unisex parasites, we still observed potent induction of PD-1 in liver T cells of C57BL/6 mice following S. japonicum infection. To determine the function of PD-1 in schistosomiasis, we generated PD-1-deficient mice by CRISPR/Cas9 and found that loss of PD-1 markedly increased T cell count in the liver and spleen of infected mice. IL-4 secreting Th2 cells were significantly decreased in the infected PD-1-deficient mice whereas IFN-γ secreting CD4⁺ and CD8⁺ T cells were markedly increased. Surprisingly, such beneficial changes of T cell response did not result in eradication of parasites or in lowering the pathogen burden. In further experiments, we found that loss of PD-1 resulted in both beneficial T cell responses and amplification of regulatory T cells that prevented PD-1-deficient T cells from unleashing anti-parasite activity. Moreover, such PD-1-deficient Tregs exert excessive immunosuppression and express larger amounts of adenosine receptors CD39 and CD73 that are crucial for Treg-mediated immunosuppression. Our experimental results have elucidated the function of PD-1 in schistosomiasis and provide novel insights into prevention and treatment of schistosomiasis on the basis of modulating host adaptive immunity.

Chronic schistosome infection leads to exaggerated upregulation of PD-1 in the liver, and loss of PD-1 markedly increased T cell presence in the liver of schistosome infected mice, which was accompanied by suppressed Th2 cytokines but markedly increased IFN-γ secretion in CD4⁺ and CD8⁺ T cells. The beneficial T cell response did not result in eradication of parasites or lowering the pathogen burden. Loss of PD-1 also resulted in amplification of Tregs and excessive Treg-mediated immunosuppression may prevent T cells from unleashing anti-parasitic immunity.

Enhanced antitumor immune response in melanoma tumor model by anti-PD-1 small interference RNA encapsulated in nanoliposomes

Programmed cell death protein-1 (PD-1), as an immune checkpoint molecule, attenuates T-cell activity and induces T-cell exhaustion. Although siRNA has a great potential in cancer immunotherapy, its delivery to target cells is the main limitation of using siRNA. This study aimed to prepare a liposomal formulation as a siRNA carrier to silence PD-1 expression in T cells and investigate it's in vivo antitumor efficacy. The liposomal siRNA was prepared and characterized by size, zeta potential, and biodistribution. Following that, the uptake assay and mRNA silencing were evaluated in vitro at mRNA and protein levels. siRNA-PD-1 (siPD-1)-loaded liposome nanoparticles were injected into B16F0 tumor-bearing mice to evaluate tumor growth, tumor-infiltrating lymphocytes, and survival rate. Liposomal siPD-1 efficiently silenced PD-1 mRNA expression in T cells (P < 0.0001), and siPD-1-loaded liposomal nanoparticles enhanced the infiltration of T-helper 1 (Th 1) and cytotoxic T lymphocytes into the tumor tissue (P < 0.0001). Liposome-PD-1 siRNA monotherapy and PD-1 siRNA-Doxil (liposomal doxorubicin) combination therapy improved the survival significantly, compared to the control treatment (P < 0.001). Overall, these findings suggest that immunotherapy with siPD-1-loaded liposomes by enhancing T-cell-mediated antitumor immune responses could be considered as a promising strategy for the treatment of melanoma cancer.

PD-L1 signaling selectively regulates T cell lymphatic transendothelial migration

Programmed death-1 (PD-1) and its ligand PD-L1 are checkpoint molecules which regulate immune responses. Little is known about their functions in T cell migration and there are contradictory data about their roles in regulatory T cell (Treg) function. Here we show activated Tregs and CD4 effector T cells (Teffs) use PD-1/PD-L1 and CD80/PD-L1, respectively, to regulate transendothelial migration across lymphatic endothelial cells (LECs). Antibody blockade of Treg PD-1, Teff CD80 (the alternative ligand for PD-L1), or LEC PD-L1 impairs Treg or Teff migration in vitro and in vivo. PD-1/PD-L1 signals through PI3K/Akt and ERK to regulate zipper junctional VE-cadherin, and through NFκB-p65 to up-regulate VCAM-1 expression on LECs. CD80/PD-L1 signaling up-regulates VCAM-1 through ERK and NFκB-p65. PD-1 and CD80 blockade reduces tumor egress of PD-1high fragile Tregs and Teffs into draining lymph nodes, respectively, and promotes tumor regression. These data provide roles for PD-L1 in cell migration and immune regulation.

Oral Immune-Related Adverse Events Caused by Immune Checkpoint Inhibitors: Salivary Gland Dysfunction and Mucosal Diseases

Conventional chemotherapy and targeted therapies have limited efficacy against advanced head and neck squamous cell carcinoma (HNSCC). The immune checkpoint inhibitors (ICIs) such as antibodies against CTLA-4, PD-1, and PD-L1 interrupt the co-inhibitory pathway of T cells and enhance the ability of CD8+ T cells to destroy tumors. Even in advanced HNSCC patients with recurrent diseases and distant metastasis, ICI therapy shows efficiency and become an effective alternative to conventional chemotherapy. However, as this therapy releases the immune tolerance state, cytotoxic CD8+ T cells can also attack organs and tissues expressing self-antigens that cross-react with tumor antigens and induce immune-related adverse events (irAEs). When patients with HNSCC are treated with ICIs, autoimmune diseases occur in multiple organs including the skin, digestive tract, endocrine system, liver, and respiratory tract. Treatment of various malignancies, including HNSCC, with ICIs may result in the appearance of oral irAEs. In the oral cavity, an oral lichenoid reaction (OLR) and pemphigoid develop. Sicca syndrome also occurs in association with ICIs, affecting the salivary glands to induce xerostomia. It is necessary to elucidate the pathogenic mechanisms of these intractable diseases that are not seen with conventional therapy. Early diagnosis and appropriate approaches to irAEs are needed for efficient treatment of advanced HNSCC by ICIs.

Immune Reconstitution following High-Dose Chemotherapy and Autologous Stem Cell Transplantation with or without Pembrolizumab Maintenance Therapy in Patients with Lymphoma

Autologous stem cell transplantation (ASCT) is a standard of care for patients with chemosensitive, relapsed/refractory (R/R) classical Hodgkin lymphoma (cHL) and diffuse large B cell lymphoma (DLBCL). Whereas the clinical benefit of ASCT has traditionally been attributed solely to cytoreduction from intensive chemotherapy, ASCT has important immunogenic effects that may contribute to its antitumor efficacy and could provide a favorable immune environment for post-ASCT immune-based maintenance treatments. We previously reported clinical results of a phase II trial (ClinicalTrials.gov identifier NCT02362997) testing 8 doses of pembrolizumab maintenance therapy after ASCT for patients with R/R cHL or DLBCL. To clarify the impact of pembrolizumab on immune reconstitution, we compared the kinetics of peripheral blood immune cell recovery after ASCT for trial patients receiving pembrolizumab maintenance to those of a contemporaneous control cohort of similar patients undergoing ASCT without pembrolizumab maintenance. This study was conducted to characterize the impact of post-ASCT pembrolizumab maintenance therapy on immune reconstitution for patients with R/R DLBCL and cHL and to identify candidate biomarkers of efficacy and immune-related adverse events (irAEs). Peripheral blood (PB) mononuclear cell samples were prospectively collected at 1 to 18 months after ASCT and analyzed by flow cytometry using a panel of fluorophore-conjugated monoclonal antibodies to identify B cells, natural killer (NK) cells, and various dendritic cell (DC) and T cell subsets. A median of 5 (range, 1 to 8) post-ASCT PB samples were collected from 144 patients (59 in the pembrolizumab group and 85 in the control group). Clinical characteristics of the 2 cohorts were similar. Compared with cHL patients, DLBCL patients (all of whom received anti-CD20 monoclonal antibody therapy before ASCT) had delayed CD19⁺ cell reconstitution that persisted for at least 18 months after ASCT. No other differences in immune reconstitution based on lymphoma subtype were observed. Post-ASCT pembrolizumab maintenance therapy was associated with an elevation in circulating DCs (driven by higher levels of plasmacytoid and immature DCs) that persisted for the duration of pembrolizumab treatment, along with a significant reduction in PD-1⁺ T cells that persisted for 6 to 12 months after completion of pembrolizumab therapy. Despite the key role of T cells in mediating the effects of PD-1 blockade, pembrolizumab maintenance did not affect recovery of any T cell subsets. In an exploratory analysis, a higher baseline CD4⁺ terminal effector memory cell count (defined as CD3⁺CD4⁺CD45RA⁺CD62L^-) was associated with inferior progression-free survival (PFS), but only among patients who received pembrolizumab maintenance (P = .003). As continuous variables, lower absolute levels of NK cells (P = .009), PD-1⁺ CD4⁺ T cells (P = .005), and PD-1⁺ CD8⁺ T cells (P = .005) before pembrolizumab initiation were each associated with a higher risk of grade 2+ irAEs. Our findings indicate that post-ACST pembrolizumab maintenance therapy is associated with a persistent elevation of circulating DCs, but its impact on the reconstitution of other immune cells in peripheral blood appears limited. Our study suggests that early features of post-ASCT immune reconstitution could be associated with PFS and the risk of irAE and warrant additional investigation. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Simultaneous silencing of the A2aR and PD-1 immune checkpoints by siRNA-loaded nanoparticles enhances the immunotherapeutic potential of dendritic cell vaccine in tumor experimental models

Following various immunotherapies, lack of proper anti-tumor immune responses is considered a significant problem in novel cancer therapeutic approaches. The expression of inhibitory checkpoint molecules on tumor-infiltrating T cells is one of the main reasons for the ineffectiveness of various immunotherapies. Therefore, we decided to inhibit two of the most important immune checkpoints expressed on tumor-associated T cells, PD-1 and A2aR. Ligation of PD-1 with PD-L1 and A2aR with adenosine significantly suppress T cell responses against tumor cells. Whitin tumors, specific inhibition of these molecules on T cells is of particular importance for successful immunotherapy as well as the elimination of treatment-associated side-effects. Thus, in this study, superparamagnetic iron oxide (SPION) nanoparticles (NPs) were covered by chitosan lactate (CL), functionalized with TAT peptide, and loaded with siRNA molecules against PD-1 and A2aR. Appropriate physicochemical properties of the prepared NPs resulted in efficient delivery of siRNA to tumor-derived T cells and suppressed the expression of A2aR and PD-1, ex vivo. T cell functions such as cytokine secretion and proliferation were considerably enhanced by the downregulation of these molecules which led to an increase in their survival time. Interestingly, treatment of CT26 and 4T1 mouse tumors with siRNA-loaded NPs not only inhibited tumor growth but also markedly increased anti-tumor immune responses and survival time. The results strongly support the efficacy of SPION-CL-TAT NPs loaded with anti-PD-1/A2aR siRNAs in cancer therapy and their further development for cancer patients in the near future.

Immune Checkpoint Inhibitors in 10 Years: Contribution of Basic Research and Clinical Application in Cancer Immunotherapy

Targeting immune evasion via immune checkpoint pathways has changed the treatment paradigm in cancer. Since CTLA-4 antibody was first approved in 2011 for treatment of metastatic melanoma, eight immune checkpoint inhibitors (ICIs) centered on PD-1 pathway blockade are approved and currently administered to treat 18 different types of cancers. The first part of the review focuses on the history of CTLA-4 and PD-1 discovery and the preclinical experiments that demonstrated the possibility of anti-CTLA-4 and anti-PD-1 as anti-cancer therapeutics. The approval process of clinical trials and clinical utility of ICIs are described, specifically focusing on non-small cell lung cancer (NSCLC), in which immunotherapies are most actively applied. Additionally, this review covers the combination therapy and novel ICIs currently under investigation in NSCLC. Although ICIs are now key pivotal cancer therapy option in clinical settings, they show inconsistent therapeutic efficacy and limited responsiveness. Thus, newly proposed action mechanism to overcome the limitations of ICIs in a near future are also discussed.

The foundations of immune checkpoint blockade and the ipilimumab approval decennial

Cancer immunity, and the potential for cancer immunotherapy, have been topics of scientific discussion and experimentation for over a hundred years. Several successful cancer immunotherapies - such as IL-2 and interferon-α (IFNα) - have appeared over the past 30 years. However, it is only in the past decade that immunotherapy has made a broad impact on patient survival in multiple high-incidence cancer indications. The emergence of immunotherapy as a new pillar of cancer treatment (adding to surgery, radiation, chemotherapy and targeted therapies) is due to the success of immune checkpoint blockade (ICB) drugs, the first of which - ipilimumab - was approved in 2011. ICB drugs block receptors and ligands involved in pathways that attenuate T cell activation - such as cytotoxic T lymphocyte antigen 4 (CTLA4), programmed cell death 1 (PD1) and its ligand, PDL1 - and prevent, or reverse, acquired peripheral tolerance to tumour antigens. In this Review we mark the tenth anniversary of the approval of ipilimumab and discuss the foundational scientific history of ICB, together with the history of the discovery, development and elucidation of the mechanism of action of the first generation of drugs targeting the CTLA4 and PD1 pathways.