Osteosarcoma Pulmonary Metastases Research Articles

Combined Auranofin and Celecoxib Suppresses the Local Progression and Pulmonary Metastases of Osteosarcoma In Vivo.

Osteosarcoma (OS) is a rare malignant tumor with a poor survival rate. Our previous study reported that auranofin (AUR), a thioredoxin reductase inhibitor, suppresses OS pulmonary metastases; however, the local progression of OS is not affected, in vivo. Nonetheless, the development of augmentation therapy with AUR to inhibit OS local progression remains challenging. Celecoxib (CE), an anti-inflammatory drug, potently enhances the therapeutic activity of AUR against colon cancer. Consequently, this study investigated the combined effects of AUR and CE on OS local progression and pulmonary metastases, in vivo. C3H/HeSlc mice were implanted with the murine OS cell line, LM8. The mice were treated either with a vehicle control, AUR, or combination of AUR and CE (AUR-CE). The primary tumor size and weight were evaluated for the study duration and at resection, respectively. Hematoxylin and eosin and Ki-67 staining were performed to evaluate OS local progression and pulmonary metastases. Mice in the AUR-CE group showed statistically significantly suppressed tumor sizes and weights at the time of excision compared with those in the vehicle. The mice in the AUR group did not show a statistically significant effect. Histopathological analysis of the primary tumor revealed a statistically significant decrease of the Ki-67-positive cells in the AUR-CE group compared with the vehicle group. Histopathological and quantitative analyses demonstrated that the AUR and AUR-CE groups had statistically significant reductions in the development of OS pulmonary metastases compared with the vehicle group. The combination of AUR and CE significantly inhibited OS local progression and pulmonary metastases.

Beauvericin suppresses the proliferation and pulmonary metastasis of osteosarcoma by selectively inhibiting TGFBR2 pathway.

Osteosarcoma (OS) patients, particularly those with distant metastasis, experience rapid progression and derive poor survival benefits from traditional therapies. Currently, effective drugs for treating patients with metastatic OS remain scarce. Here, we found that the cyclic hexadepsipeptide beauvericin (BEA) functioned as a new selective TGFBR2 inhibitor with potent antiproliferative and antimetastatic activities against OS cells. Functionally, BEA inhibited TGF-β signaling-mediated proliferation, invasiveness, mesenchymal phenotype, and extracellular matrix remodeling of OS cells, and suppressed tumor growth and reduced pulmonary metastasis in vivo. Mechanistic investigation revealed that BEA selectively and directly bound to Asn 332 of TGFBR2 and inhibited its kinase activity, thereby suppressing the aggressive progression of OS cells. Together, our study identifies an innovative and natural selective TGFBR2 inhibitor with effective antineoplastic activity against metastatic OS and demonstrates that targeting TGFBR2 could be a potential therapeutic strategy for metastatic OS.

Computed tomography aspects of thoracic metastases from osteosarcoma: pictorial essay.

Osteosarcoma is the most common primary bone tumor, with a higher incidence in the second decade of life, and it often leads to pulmonary metastases. The most common pattern seen on computed tomography is one of multiple well-defined nodules in the lung parenchyma, often with calcifications. Because of the variety of presentations of pulmonary metastases in osteosarcoma, including atypical forms, knowledge of the computed tomography aspects of these lesions is important for characterizing and evaluating the extent of the disease, as well as for distinguishing metastatic disease from other benign or malignant lung diseases. This essay discusses the main tomographic findings of pulmonary metastases from osteosarcoma.

Spontaneous pneumothorax in metastatic osteosarcoma: a case series

BackgroundMalignancy-associated secondary spontaneous pneumothorax (MSSP) has an incidence of 1% with a risk for recurrence of 9.4% reported in association with sarcomas, histiocytoma, malignant thymoma, and cancers of the breast and thyroid.Case presentationWe report a series of four patients who presented to us with MSSP associated with pulmonary metastasis of osteosarcoma, all four being young males with metastasis to the lungs. All four patients were non-smokers and had no family history of malignancy. Less than 2% of all spontaneous pneumothoraxes present with bilateral pneumothorax, and our series reports the same in three patients. The occurrence of pneumothorax in two of the patients was in the week following chemotherapy. As there was evidence of pulmonary metastasis in these patients along with the clinical presentation of pneumothorax following chemotherapy, tumor necrosis was considered the likely etiology of spontaneous pneumothorax in these patients. All four patients required intercostal chest drain insertion, and the ICD tubes had to be retained for a prolonged duration due to either persistent air leak or secondary infection. ICD tube insertion further compromised the poor mobility of patients with lower limb lesions due to increased pain and was detrimental to the emotional morale of the patient and caregivers. The 2-year survival in such patients with pneumothorax is less than 10%.ConclusionsOur series highlights the need for respiratory evaluation and follow-up both clinically and radiologically in cases of osteosarcoma, especially in the immediate post-chemotherapy period.

SAR1A regulates the RhoA/YAP and autophagy signaling pathways to influence osteosarcoma invasion and metastasis.

Osteosarcoma is the most prevalent form of primary bone malignancy affecting adolescents. Secretion-associated Ras-related GTPase 1A (SAR1A) is a key regulator of endoplasmic reticulum (ER) homeostasis, but its role as a regulator of osteosarcoma metastasis has yet to be clarified. Bioinformatics analyses revealed SAR1A and RHOA to be upregulated in osteosarcoma patients, with the upregulation of these genes being associated with poor 5-year metastasis-free survival rates. In addition, the upregulation of SAR1A and RHOA in osteosarcoma was highly positively correlated. Immunohistochemical analyses additionally revealed that SAR1A levels were increased in osteosarcoma pulmonary metastases. In vitro wound healing and Transwell assays indicated that knocking down SAR1A or RHOA impaired the invasive and migratory activity of osteosarcoma cells, whereas RHOA overexpression had the opposite effect. Western blotting and immunofluorescent staining revealed the inhibition of osteosarcoma cell epithelial-mesenchymal transition following SAR1A or RHOA knockdown; RHOA overexpression had the opposite effect. Following SAR1A knockdown, phalloidin staining indicated that osteosarcoma cells showed reduced lamellipodia formation. Endoplasmic reticulum stress levels and reactive oxygen species production were enhanced following the knockdown of SAR1A, as was autophagic activity, with lung metastases being reduced in vivo after such knockdown. Knocking down SAR1A suppresses osteosarcoma cell metastasis through the RhoA/YAP, ER stress, and autophagic pathways, offering new insights into the regulation of autophagic activity in the context of osteosarcoma cell metastasis and suggesting that these pathways could be amenable to therapeutic intervention.

An exploratory clinical study of the efficacy and safety of tumor-infiltrating lymphocytes in the treatment of metastatic osteosarcoma

Objective: To explore the safety and efficacy of tumor-infiltrating lymphocytes (TILs) extracted from tumor tissue in patients with pulmonary metastasis of osteosarcoma, the TILs were amplified in vitro to reach clinical dosage and reinfused to the patients combined with high-dose interleukin 2 (IL-2). Methods: Twelve subjects with pathologically diagnosed osteosarcoma were enrolled from December 2019 to June 20, 2021 in Shanghai General Hospital. All subjects progressed with metastasis after standard chemotherapy and failed multiple lines of treatments. Fresh tumor tissue was obtained from the metastatic site and extracted and amplified by Good Manufacturing Practice (GMP) workshop to produce TILs to clinical treatment dosage (109-1011). High-dose IL-2 (100 000-200 000 U/kg) was administered immediately after autogenous TILs infusion to promote the activation, proliferation and antitumor cytolytic activity in vivo. Adverse events (AE) were graded according to Common Terminology Criteria for Adverse Events (CTCAE) standard and tumor response was assessed according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Results: One patient did not receive treatment due to failure in isolating TILs, total of 11 patients received a single re-infusion of autologous TILs. There were 10 males and 1 female with a median age of 19.9 years (12-33 years). Six of these patients received higher dose levels of 1.0×1010 TILs. The 11 patients were followed-up for 1 to 13 months and tolerated well. The most common adverse events reported were fever (10/11), constipation (3/11) and elevated gamma-glutamyl transferase (GGT) (3/11). The high incidence of fever was due to the IL-2 infusion. All patients experienced a transient drop in lymphocyte count and leukopenia leading to non-myeloid ablative lymphocyte clearance. The AE included grade 4 hematologic toxicity, including 8 cases of lymphocytopenia, 2 cases of neutropenia and 1 case of thrombocytopenia. No AE of neurotoxicity occurred. Of all the 11 patients, 9 patients got stable disease (SD) and 2 patients had progressive disease (PD). The disease control rate was 9/11. The median duration of SD was more than 4 months, and the maximum tumor volume decreased by close to 20%. Patient number 9 had sustained SD status for more than 6 months. Conclusions: TILs with in vitro expansion ability could be isolated from tumor tissues of advanced osteosarcoma patients. TILs amplified and reinfused in vitro have anti-osteosarcoma activity.

Siglec-15-induced autophagy promotes invasion and metastasis of human osteosarcoma cells by activating the epithelial–mesenchymal transition and Beclin-1/ATG14 pathway

BackgroundPulmonary metastasis is the main cause of poor prognosis in osteosarcoma. Sialic acid-bound immunoglobulin lectin 15 (Siglec-15) has been demonstrated to be obviously correlated with pulmonary metastasis in osteosarcoma patients. However, the effect of Siglec-15 on autophagy in osteosarcoma remains unclear, while the role and mechanism of Siglec-15-related autophagy in lung metastasis also remain unknown.MethodsThe expression levels of Siglec-15 and Beclin-1 were detected in osteosarcoma tissues using immunohistochemistry (IHC). The effect of Siglec-15 on metastasis was investigated using Transwell, wound healing and animal experiments with osteosarcoma cells. Corresponding proteins were confirmed using Western blotting when Siglec-15 or Beclin-1 was silenced or overexpressed. Changes in autophagy and the cytoskeleton were detected using immunofluorescence and transmission electron microscopy.ResultsSiglec-15 and Beclin-1 expression was evaluated both in lung metastases and in patients who presented with pulmonary metastasis of osteosarcoma. Immunoprecipitation experiments revealed that Siglec-15 interacts directly with Beclin-1, an important autophagic protein. Moreover, loss of Siglec-15 distinctly inhibited autophagy and reduced Beclin-1/ATG14 expression. The decreased invasion and migration caused by Siglec-15 silencing could be reversed by Beclin-1 overexpression. Additionally, autophagy can promote the epithelial–mesenchymal transition (EMT) and affect cytoskeletal rearrangement, which was confirmed by overexpression or silencing of Beclin-1.ConclusionsThese findings confirmed the role of Siglec-15 in the regulation of autophagy and elaborated the relationship and mechanisms between autophagy and the metastasis of osteosarcoma cells.

Abstract 6092: The dual roles of C-X-C MOTIF chemokine LIGAND 10 in pediatric osteosarcoma

Abstract Osteosarcoma is the most common malignant bone tumor in children and young adults. Despite the use of multi-agents chemotherapy and aggressive surgery, the survival of patients with osteosarcoma remains at 60% over the past three decades. In addition, the survival of patients who develop metastasis is dismal and often less than 25%. We have previously reported that serum C-X-C motif chemokine ligand 10 (CXCL10) is associated with survival in a large cohort of osteosarcoma patients. CXCL10 is an interferon-induced chemokine that binds to its cognate receptor CXCR3 to elicit its cellular effects via both autocrine and paracrine signaling. CXCL10 can promote tumor cell migration and metastasis via autocrine signaling, while it recruits CXCR3+ immune cells to exert a tumoricidal effect via paracrine signaling. However, little is known about the effect of circulating CXCL10 in cancer. To understand the role of CXCL10 in the pediatric bone tumor, we showed that a number of osteosarcoma cell lines expressed the CXCR3 protein. The addition of exogenous CXCL10 promoted tumor cell migration of three osteosarcoma cell lines but did not affect cell proliferation. However, the migratory effect of osteosarcoma cells is not specific to CXCL10, as other CXCR3-associated chemokines (CXCL4, CXCL9, and CXCL10) exerted similar effects. Using an orthotopic xenograft mouse model, we demonstrated intravenous injection of CXCL10 increased the development of pulmonary metastases of osteosarcoma. In contrast, expression profiling of osteosarcoma primary tumors showed that elevated expression of CXCL10 and CXCR3 was associated with a better prognosis, suggesting that a paracrine effect of CXCL10 by recruiting CXCR3+ immune cells to the tumor site. This notion is supported by our immune cell population deconvolution results, indicating that the predominant infiltrating immune cell types are macrophages and CD8+ T cells. Taken together, our results suggest a model in which CXCL10 may play both pro-tumor and anti-tumor roles in osteosarcoma. While a high level of exogenous or circulating CXCL10 may promote tumor cell migration and metastasis, the chemokine can also recruit CXCR3+ immune cells to exert a favorable prognostic effect. Further characterization of the sources of CXCL10 in the tumor site and circulation may lead to the development of a therapeutic approach that promotes CXCL10’s anti-tumor effects and minimizes its pro-tumor effects to improve the survival of osteosarcoma patients. Citation Format: Xiang Chen, Margaret Clement, John Hicks, Tsz Kwong Man. The dual roles of C-X-C MOTIF chemokine LIGAND 10 in pediatric osteosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6092.

Identification of hub genes specific to pulmonary metastasis in osteosarcoma through integrated bioinformatics analysis.

Pulmonary metastasis is the most frequent cause of death in osteosarcoma (OS) patients. Recently, several bioinformatics studies specific to pulmonary metastatic osteosarcoma (PMOS) have been applied to identify genetic alterations. However, the interpretation and reliability of the results obtained were limited for the independent database analysis. The expression profiles and key pathways specific to PMOS remain to be comprehensively explored. Therefore, in our study, three original datasets of GEO database were selected. Initially, three microarray datasets (GSE14359, GSE14827, and GSE85537) were downloaded from the GEO database. Differentially expressed genes (DEGs) between PMOS and nonmetastatic osteosarcoma (NMOS) were identified and mined using DAVID. Subsequently, GO and KEGG pathway analyses were carried out for DEGs. Corresponding PPI network of DEGs was constructed based on the data collected from STRING datasets. The network was visualized with Cytoscape software, and ten hub genes were selected from the network. Finally, survival analysis of these hub genes also used the TARGET database. In total, 569 upregulated and 1238 downregulated genes were filtered as DEGs between PMOS and NMOS. Based on the GO analysis result, these DEGs were significantly enriched in the anatomical structure development, extracellular matrix, biological adhesion, and cell adhesion terms. Based on the KEGG pathway analysis result, these DEGs were mainly enriched in the pathways in cancer, PI3K-Akt signaling, MAPK signaling, focal adhesion, cytokine-cytokine receptor interaction, and IL-17 signaling. Hub genes (ANXA1 and CXCL12) were significantly associated with overall survival time in OS patient. Our results may provide new insight into pulmonary metastasis of OS. However, experimental studies remain necessary to elucidate the biological function and mechanism underlying PMOS.

Surgical Treatment for Pneumothorax and Tumor-bronchial Fistula Secondary to Pulmonary Metastasis of Osteosarcoma in Pediatric and Adolescent Patients.

Pneumothorax and tumor-bronchial fistula are rare complications of pulmonary metastasis of osteosarcoma. We herein report the cases of 3 pediatric and adolescent patients who developed pneumothorax or tumor-bronchial fistula during treatment of pulmonary metastasis of osteosarcoma with chemotherapeutics or antiangiogenic agents. Two patients developed pneumothorax, and the other patient developed tumor-bronchial fistula. All of the patients finally underwent the surgery to treat their complications. Although it is not a curative surgery, surgery for pneumothorax and tumor-bronchial fistula is acceptable. The operative procedure should be considered on the basis of the predicted prognosis of the patient.

Poly (ADP-ribose) polymerase 1 (PARP1) inhibition promotes pulmonary metastasis of osteosarcoma by boosting ezrin phosphorylation.

Due to the large proportion of BRCA deficiency and chromosomal instability in OS patients, poly (ADP-ribose) polymerase inhibitors (PARPi) could be an effective strategy for anti-OS therapy. In two orthotopic OS mouse models, we discovered that although PARPi had inhibitory effect on the growth of the orthotopic OS tumors regardless of BRCA deficiency, the treatment of PARPi essentially aggravated the pulmonary metastasis of OS in both models. A protein playing a crucial role in OS metastasis, ezrin, was identified as an interactive protein for PARP1. The phosphorylation of ezrin was significantly promoted during PARP inhibition. Besides the traditional function of phosphorylated ezrin at plasma membrane, we newly identified its nuclear speckle localization and its function with mRNA export. Ezrin knockdown or phosphorylation inhibition could partially rescue PARPi induced metastasis. Collectively, we unveiled a new mechanism for PARP-involved OS metastasis, which proposed a novel combinational therapy strategy using PARP and ezrin inhibitors for future OS treatment.

Cinnamaldehyde decreases the invasion and u-PA expression of osteosarcoma by down-regulating the FAK signalling pathway.

Cancer metastasis is the major cause of the high mortality risk of patients with osteosarcoma. Cinnamaldehyde has been shown to exhibit multiple tumour-suppressing activities, but its role in human osteosarcoma is not yet completely defined. In this study, the antimetastatic effect of cinnamaldehyde on highly metastatic human osteosarcoma cells was observed in vitro and in vivo using Saos-2 and 143B cells. Cinnamaldehyde reduced the activity and protein level of urokinase-type plasminogen activator (u-PA) and suppressed the invasion ability of osteosarcoma cells by inhibiting the phosphorylation of focal adhesion kinase. In addition, cinnamaldehyde reduced cell movement, cell-matrix adhesion, and the expression of the mesenchymal markers of epithelial-to-mesenchymal transition, namely, fibronectin and N-cadherin. Importantly, the oral administration of cinnamaldehyde remarkably suppressed the pulmonary metastasis of osteosarcoma in mice. Results indicated that cinnamaldehyde has therapeutic potential for inhibiting osteosarcoma metastasis.

The Thioredoxin Reductase Inhibitor Auranofin Suppresses Pulmonary Metastasis of Osteosarcoma, But Not Local Progression.

Auranofin (AUR), a thioredoxin reductase (TXNRD) inhibitor, shows anticancer activity against several cancers. This study investigated the effects of AUR on the local progression and pulmonary metastasis of osteosarcoma (OS). Publicly available expression cohorts were analysed to study the relationship between TXNRD-2 expression and the survival of patients with OS. The murine OS cell line LM8 was stimulated with AUR. Cell viability, apoptosis-related protein levels, caspase activity, and wound healing were analysed. Tumor progression and pulmonary metastasis were investigated in C3H mice implanted with LM8 cells. High-level expression of TXNRD-2 represented a negative prognostic factor for metastasis and overall survival in patients with OS. AUR induced apoptosis of OS cells via the oxidative stress-MAPK-Caspase 3 pathway, and suppressed the migration of OS cells. AUR inhibited the pulmonary metastasis of OS, but not local progression. AUR represents a potential therapeutic drug for suppressing pulmonary metastasis of OS.

Platelet-derived lysophosphatidic acid mediated LPAR1 activation as a therapeutic target for osteosarcoma metastasis

Osteosarcoma is the most common primary malignant bone cancer, with high rates of pulmonary metastasis. Osteosarcoma patients with pulmonary metastasis have worse prognosis than those with localized disease, leading to dramatically reduced survival rates. Therefore, understanding the biological characteristics of metastatic osteosarcoma and the molecular mechanisms of invasion and metastasis of osteosarcoma cells will lead to the development of innovative therapeutic intervention for advanced osteosarcoma. Here, we identified that osteosarcoma cells commonly exhibit high platelet activation-inducing characteristics, and molecules released from activated platelets promote the invasiveness of osteosarcoma cells. Given that heat-denatured platelet releasate maintained the ability to promote osteosarcoma invasion, we focused on heat-tolerant molecules, such as lipid mediators in the platelet releasate. Osteosarcoma-induced platelet activation leads to abundant lysophosphatidic acid (LPA) release. Exposure to LPA or platelet releasate induced morphological changes and increased invasiveness of osteosarcoma cells. By analyzing publicly available transcriptome datasets and our in-house osteosarcoma patient-derived xenograft tumors, we found that LPA receptor 1 (LPAR1) is notably upregulated in osteosarcoma. LPAR1 gene KO in osteosarcoma cells abolished the platelet-mediated osteosarcoma invasion in vitro and the formation of early pulmonary metastatic foci in experimental pulmonary metastasis models. Of note, the pharmacological inhibition of LPAR1 by the orally available LPAR1 antagonist, ONO-7300243, prevented pulmonary metastasis of osteosarcoma in the mouse models. These results indicate that the LPA–LPAR1 axis is essential for the osteosarcoma invasion and metastasis, and targeting LPAR1 would be a promising therapeutic intervention for advanced osteosarcoma.

Machine learning-based CT radiomics features for the prediction of pulmonary metastasis in osteosarcoma.

This study aims to build machine learning-based CT radiomic features to predict patients developing metastasis after osteosarcoma diagnosis. This retrospective study has included 81 patients with a histopathological diagnosis of osteosarcoma. The entire dataset was divided randomly into training (60%) and test sets (40%). A data augmentation technique for the minority class was performed in the training set, along with feature's selection and model's training. The radiomic features were extracted from CT's image of the local osteosarcoma. Three frequently used machine learning models tried to predict patients with lung metastases (MT) and those without lung metastases (non-MT). According to the higher area under the curve (AUC), the best classifier was chosen and applied in the testing set with unseen data to provide an unbiased evaluation of the final model. The best classifier for predicting MT and non-MT groups used a Random Forest algorithm. The AUC and accuracy results of the test set were bulky (accuracy of 73% [ 95% coefficient interval (CI): 54%; 87%] and AUC of 0.79 [95% CI: 0.62; 0.96]). Features that fitted the model (radiomics signature) derived from Laplacian of Gaussian and wavelet filters. Machine learning-based CT radiomics approach can provide a non-invasive method with a fair predictive accuracy of the risk of developing pulmonary metastasis in osteosarcoma patients. Models based on CT radiomic analysis help assess the risk of developing pulmonary metastases in patients with osteosarcoma, allowing further studies for those with a worse prognosis.

Overall survival after perioperative chemotherapy in the management of pulmonary metastasis in osteosarcoma.

e23508 Background: Pulmonary metastasectomy is performed on a select cohort of patients with advanced osteosarcoma with the potential for long term survival. However, evidence on peri-operative chemotherapy at time of metastasectomy is not completely understood and difficult to summarize without a systematic examination of existing literature. The purpose of this project is to perform a meta-analysis of existing studies to determine overall survival (OS) and prognostic factors in adults and children with advanced and recurrent osteosarcoma receiving chemotherapy around time of metastasectomy. Methods: We reviewed survival studies conducted in children and adults with advanced and recurrent osteosarcoma who undergo pulmonary metastasectomy published in English with more than 5 patients. The primary outcome was overall survival. Literature searches were performed in multiple electronic databases including Ovid MEDLINE (1946 to present), Ovid EMBASE (1974 to present), Web of Science, and Cochrane Library. Two investigators independently screened all citations, abstracts, and full-text articles. Results: 24 out of 80 observational studies between 1977 to 2018 were included. 2146 patients were studied of which 987 underwent pulmonary metastasectomy for osteosarcoma. 822 patients received perioperative chemotherapy in this setting. No randomized controlled trials were identified. Studies included patients from Asia, Africa, Europe, and North America. The median OS ranged between 20 to 90 months. 5-year OS ranged between 15 to 63%. Factors associated with survival included: age, number of lesions, disease free interval, time of development of metastases, number of lesions and laterality of pulmonary disease. Conclusions: Overall survival in study has a significant range. Factors influencing survival included intrinsic factors such as patient age and disease characteristics, as well as extrinsic factors such as evolution of chemotherapy regimen over the past four decades. The main limitations are related to the inherently low-quality evidence as a result of lack of randomized controlled trials. More comprehensive data is needed to guide shared decision making in this area.

Pathways of immune exclusion in metastatic osteosarcoma are associated with inferior patient outcomes

BackgroundCurrent therapy for osteosarcoma pulmonary metastases (PMs) is ineffective. The mechanisms that prevent successful immunotherapy in osteosarcoma are incompletely understood. We investigated the tumor microenvironment of metastatic osteosarcoma with the...

MiR-135a Reduces Osteosarcoma Pulmonary Metastasis by Targeting Both BMI1 and KLF4

Because of the modest response rate after surgery and chemotherapy, treatment of osteosarcoma (OS) remains challenging due to tumor recurrence and metastasis. miR-135a has been reported to act as an anticarcinogenic regulator of several cancers. However, its expression and function in osteosarcoma remain largely unknown. Here, we reported that abridged miR-135a expression in OS cells and tissues, and its expression is inversely correlated with the expression of BMI1 and KLF4, which are described as oncogenes in several cancers. Ectopic expression of miR-135a inhibited cell invasion and expression of BMI1 and KLF4 in OS cells. In vivo investigation confirmed that miR-135a acts as a tumor suppressor in OS to inhibit tumor growth and lung metastasis in xenograft nude mice. BMI1 and KLF4 were revealed to be direct targets of miR-135a, and miR-135a had a similar effect as the combination of si-BMI1 and si-KLF4 on inhibiting tumor progression and the expression of BMI1 and KLF4 in vivo. Altogether, our results demonstrate that the targeting of BMI1/KLF4 with miR-135a may provide an applicable strategy for exploring novel therapeutic approaches for OS.

Long-term survival with multiple metastasectomies for pulmonary osteosarcoma: a case report

BackgroundRepeat pulmonary metastasectomy (PM) considerably improves the prognosis of patients with pulmonary metastases of osteosarcoma. Reports have demonstrated a significantly improved prognosis in patients who have undergone repeat metastasectomy for osteosarcoma; however, there have been no reports with more than six metastasectomies. Herein, we describe the long-term survival of a patient following resection of multiple tumors and other treatments for metastatic osteosarcoma.Case presentationA 28-year-old woman underwent extensive resection and postoperative adjuvant chemotherapy for right tibial sarcoma. Over the years, she developed repeated pulmonary metastases. First, 116 metastases were removed from the bilateral lungs. After that, multiple PMs of approximately 250 tumors and other treatments for deep metastatic lesions were performed. The patient died of the underlying disease 24 years after the primary surgery.ConclusionsThis case report demonstrates the long-term survival benefit of a multidisciplinary treatment centered on multiple metastasectomies.

Bempegaldesleukin (BEMPEG; NKTR-214) efficacy as a single agent and in combination with checkpoint-inhibitor therapy in mouse models of osteosarcoma.

Survival of patients with relapsed/refractory osteosarcoma has not improved in the last 30 years. Several immunotherapeutic approaches have shown benefit in murine osteosarcoma models, including the anti‐programmed death‐1 (anti‐PD‐1) and anti‐cytotoxic T‐lymphocyte antigen‐4 (anti‐CTLA‐4) immune checkpoint inhibitors. Treatment with the T‐cell growth factor interleukin‐2 (IL‐2) has shown some clinical benefit but has limitations due to poor tolerability. Therefore, we evaluated the efficacy of bempegaldesleukin (BEMPEG; NKTR‐214), a first‐in‐class CD122‐preferential IL‐2 pathway agonist, alone and in combination with anti‐PD‐1 or anti‐CTLA‐4 immune checkpoint inhibitors in metastatic and orthotopic murine models of osteosarcoma. Treatment with BEMPEG delayed tumor growth and increased overall survival of mice with K7M2‐WT osteosarcoma pulmonary metastases. BEMPEG also inhibited primary tumor growth and metastatic relapse in lungs and bone in the K7M3 orthotopic osteosarcoma mouse model. In addition, it enhanced therapeutic activity of anti‐CTLA‐4 and anti‐PD‐1 checkpoint blockade in the DLM8 subcutaneous murine osteosarcoma model. Finally, BEMPEG strongly increased accumulation of intratumoral effector T cells and natural killer cells, but not T‐regulatory cells, resulting in improved effector:inhibitory cell ratios. Collectively, these data in multiple murine models of osteosarcoma provide a path toward clinical evaluation of BEMPEG‐based regimens in human osteosarcoma.