RANK ligand blockade with denosumab in combination with sorafenib in chemorefractory osteosarcoma: a possible step forward?

From biology to personalized medicine: Recent knowledge in osteosarcoma

High-grade osteosarcoma is the most common paediatric bone cancer. More than one third of patients relapse and die of osteosarcoma using current chemotherapeutic and surgical strategies. To improve outcomes in osteosarcoma, two crucial challenges need to be tackled: 1-the identification of hard-to-treat disease, ideally from diagnosis; 2- choosing the best combined or novel therapies to eradicate tumor cells which are resistant to current therapies leading to disease dissemination and metastasize as well as their favorable microenvironment. Genetic chaos, tumor complexity and heterogeneity render this task difficult. The development of new technologies like next generation sequencing has led to an improvement in osteosarcoma oncogenesis knownledge. This review summarizes recent biological and therapeutical advances in osteosarcoma, as well as the challenges that must be overcome in order to develop personalized medicine and new therapeutic strategies and ultimately improve patient survival.

Comprehensive conservative treatment for multiple metastases of skull osteosarcoma: A case report

Background

Skull osteosarcoma is relatively rare, and it is difficult to be diagnosed according to medical history and imaging examination due to the complex structure and diverse components of the brain. Consequently, there is only a limited number of patients who can undergo neoadjuvant chemotherapy before the operation. Although neoadjuvant chemotherapy plays an important role in the treatment of osteosarcoma, there is still a "bottleneck" in the current treatment method which when pulmonary metastasis occurs, or surgical treatment is not Enneking appropriate. Under such circumstances, the choice of treatment can be an issue.

Case

A 16-year-old male patient with multiple metastases of skull osteosarcoma was reported. The patient suffered not only tinnitus and hearing loss in the right ear but also right facial paralysis and headache. The preoperative brain MRI showed a tumor in the right cerebellopontine angle (CPA) area. He underwent skull tumor resection at another hospital in November 2018, during which process the biopsy revealed epithelioid osteoblastoma-like osteosarcoma. The patient had supplemental radiotherapy 1 month after surgery because of tumor recurrence. 32 months afterward, pulmonary metastases and multiple bone metastases were found. Then the patient underwent multiple conservative treatments which include Denosumab, Anlotinib, and DIA (cisplatin + ifosfamide + doxorubicin) chemotherapy at our hospital. After a series of 6 cycles of treatment, the patient can walk without aid. Lactate dehydrogenase (LDH) and Alkaline phosphatase (AKP) returned to a normal level. Fluorodeoxyglucose (FDG) metabolism in all bone metastases decreased to normal except for the ones in the proximal left femur, and the FDG metabolism in the left femur is significantly lower than that before treatment. Multiple bone metastases showed different extents of high-density calcification, and the volume of the local bone metastases has been reduced significantly. The patient's condition stayed stable at latest follow-up.

Conclusion

We found that multiple conservative treatments, which include Denosumab, Anlotinib and DIA chemotherapy, can improve patients' life quality, and help avoid further osteolytic destruction for patients with skull osteosarcoma and multiple metastases. Its specific mechanism and scope of the application still need to be further studied.

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.

Sorafenib and Doxorubicin Show Synergistic Effects in Human and Canine Osteosarcoma Cell Lines

Osteosarcoma (OSA) is the most common bone tumor in both humans and dogs and has a nearly ten-fold higher incidence in dogs than humans. Despite advances in the treatment of other cancers, the overall survival rates for OSA have stagnated for the past four decades. Therefore, there is a great need to identify novel and effective treatments. We screened a series of tyrosine kinase inhibitors and selected sorafenib, a multi-kinase inhibitor, for further evaluation alone and in combination with cisplatin, carboplatin, and doxorubicin on canine and human OSA cell lines. Our data point to synergistic effects when sorafenib is combined with doxorubicin, but not when combined with cisplatin or carboplatin, in both human and canine OSA. Based on current findings, clinical trials using a combination of doxorubicin and sorafenib in proof-of-concept studies in dogs are warranted. These studies can be carried out relatively quickly in dogs where case load is high and, in turn, provide useful data for the initiation of clinical trials in humans.

Current research progress in targeted anti-angiogenesis therapy for osteosarcoma

Osteosarcoma (OS) is the most common primary malignant bone tumour with a peak in incidence during adolescence. Delayed patient presentation and diagnosis is common with approximately 15% of OS patients presenting with metastatic disease at initial diagnosis. With the introduction of neoadjuvant chemotherapy in the 1970s, disease prognosis improved from 17% to 60%-70% 5-year survival, but outcomes have not significantly improved since then. Novel and innovative therapeutic strategies are urgently needed as an adjunct to conventional treatment modalities to improve outcomes for OS patients. Angiogenesis is crucial for tumour growth, metastasis and invasion, and its prevention will ultimately inhibit tumour growth and metastasis. Dysregulation of angiogenesis in bone microenvironment involving osteoblasts and osteoclasts might contribute to OS development. This review summarizes existing knowledge regarding pre-clinical and developmental research of targeted anti-angiogenic therapy for OS with the aim of highlighting the limitations associated with this application. Targeted anti-angiogenic therapies include monoclonal antibody to VEGF (bevacizumab), tyrosine kinase inhibitors (Sorafenib, Apatinib, Pazopanib and Regorafenib) and human recombinant endostatin (Endostar). However, considering the safety and efficacy of these targeted anti-angiogenesis therapies in clinical trials cannot be guaranteed at this point, further research is needed to completely understand and characterize targeted anti-angiogenesis therapy in OS.

Reduced Serum sRANKL and sTREM2 Levels in High-Grade Gliomas: Association with Prognosis

INTRODUCTION

High-grade gliomas (HGG), including Glioblastoma multiforme (GBM), account for the majority of primary brain tumors. Nevertheless, prognostic and diagnostic biomarkers are quite limited for HGG. The objective of this study was to investigate the prognostic value of sRANKL and sTREM2 levels in HGG patients.

METHODS

Twelve consecutive patients with HGG, 14 patients with non-glial tumors (non-GT) and 20 age and gender-matched healthy controls were recruited. Overall survival duration of the patients was recorded. Pre-operative serum levels of sRANKL and sTREM2 were measured by ELISA. Tumors of HGG patients were analyzed by immunohistochemical staining for p53 and Ki67 and percentage scores were calculated.

RESULTS

Patients with HGG and non-GT showed lower serum sRANKL and sTREM2 levels than healthy individuals. Levels of sRANKL were inversely correlated with the overall survival of patients (p=0.002, R=0.787), while sTREM2 levels were inversely correlated with p53 score (p=0.018, R=-0.666) but not survival.

CONCLUSION

Brain tumor patients show suppressed levels of glial activity biomarkers in the peripheral circulation. Serum sRANKL levels may serve as a potential prognostic biomarker for HGG.

Pathogenesis and Current Treatment of Osteosarcoma: Perspectives for Future Therapies

Osteosarcoma is the most common primary malignant bone tumor in children and young adults. The standard-of-care curative treatment for osteosarcoma utilizes doxorubicin, cisplatin, and high-dose methotrexate, a standard that has not changed in more than 40 years. The development of patient-specific therapies requires an in-depth understanding of the unique genetics and biology of the tumor. Here, we discuss the role of normal bone biology in osteosarcomagenesis, highlighting the factors that drive normal osteoblast production, as well as abnormal osteosarcoma development. We then describe the pathology and current standard of care of osteosarcoma. Given the complex heterogeneity of osteosarcoma tumors, we explore the development of novel therapeutics for osteosarcoma that encompass a series of molecular targets. This analysis of pathogenic mechanisms will shed light on promising avenues for future therapeutic research in osteosarcoma.

Evaluation of the Receptor Activator of Nuclear Factor Kappa B Ligand (RANKL) Expression in Osteosarcoma and Its Association with the Clinicopathological Data

BACKGROUND

The receptor activator of nuclear factor kappa B ligand (RANKL) is one of the key regulators of bone remodelling in bone oncology, including osteosarcoma. We assessed RANKL immunohistochemical expression in osteosarcoma, its association, and disease-free survival with the patients' clinicopathological characteristics.

METHODS

  One hundred osteosarcoma cases from 2003 to 2018 in Hospital Universiti Sains Malaysia were retrieved. The tissue samples were stained for RANKL, and the association with the clinicopathological characteristics was evaluated. Staining was interpreted in a semiquantitative scoring system and classified into negative and positive expressions.  Results: Eighty-two cases had a positive expression of RANKL in which 56 and 26 patients were classified as low expression and high expression, respectively. The positive expression of RANKL did not show a significant association with clinicopathological characteristics. However, Kaplan Meier survival analysis showed a significant improvement in the disease-free survival patients who underwent limb salvage surgery (LSS) than amputated patients (p-value 0.002), whereas poorer survival was observed among conventional osteosarcomas compared to non-conventional osteosarcoma (p-value 0.01).

CONCLUSION

Limb salvage surgery had proven to improve osteosarcoma patients' survival compared to amputation, which could improve overall quality of life in osteosarcoma patients. However, our data did not show a significant association between positive RANKL immunohistochemistry with any of the clinicopathological characteristics and patients' final survival. Further studies may be acquired to understand the suitability of using RANKL immunohistochemistry as prognostication in the management of osteosarcoma patients.

Translational cell biology of highly malignant osteosarcoma

Highly malignant osteosarcoma (HMO) is the most frequent malignant bone tumor preferentially occurring in adolescents and children with a second more flat peak in patients over the age of 60. The younger patients benefit from combined neoadjuvant chemotherapy with 65-70% 5-year survival rate. In patients with metastatic HMO the 5-year survival rate is consistently poor with approximately 30%. In the last several years strategies for target therapies have been developed by using next generation sequencing (NGS) for defining targetable molecular factors. However, it has so far been challenging to establish an effective target therapy for so-called 'orphan tumors' without recognizable driver mutations, including HMO. The molecular genetic studies using NGS have shown that HMOs are genomically unstable tumors with highly complex chaotic karyotypes. Before the background of this genetic complexity more investigations should be performed in the future for defining targetable biological factors. As the prognosis could not be improved for 40 years one may expect improvements for patients only by gaining a deeper understanding of the cell and molecular biology of HMO. The cell of origin of HMO is being clarified now. The majority of studies indicate that an osteoblastic progenitor cell is probably the cell of origin of HMO and not an undifferentiated mesenchymal stem cell. This means that the established histopathological definition of HMO through verification of osteoid production by the osteoblastic cells is well justified and will probably be the cornerstone for a precise differential diagnosis of HMO also in the years to come.

Precision Medicine in Osteosarcoma: MATCH Trial and Beyond

Osteosarcoma (OS) is a rare bone malignant tumour with a poor prognosis in the case of recurrence. So far, there is no agreement on the best systemic therapy for relapsed OS. The availability of next generation sequencing techniques has recently revolutionized clinical research. The sequencing of the tumour and its matched normal counterpart has the potential to reveal a wide landscape of genetic alterations with significant implications for clinical practice. The knowledge that the genomic profile of a patient’s tumour can be precisely mapped and matched to a targeted therapy in real time has improved the development of precision medicine trials (PMTs). PMTs aiming at determining the effectiveness of targeted therapies could be advantageous for patients with a tumour refractory to standard therapies. Development of PMTs for relapsed OS is largely encouraging and is in its initial phase. Assessing OS features, such as its rarity, its age distribution, the technical issues related to the bone tissue origin, and its complex genomic landscape, represents a real challenge for PMTs development. In this light, a multidisciplinary approach is required to fully exploit the potential of precision medicine for OS patients.

Can Denosumab be used in combination with Doxorubicin in Osteosarcoma?

Osteosarcoma is an aggressive bone tumor of the pediatric age. It is therefore important to improve conventional therapies (chemotherapy and surgery). Anticancer drugs often cause osteoporosis due to a misbalance of RANK/RANK-L/OPG pathway.

Denosumab is a monoclonal antibody with high affinity and specificity to RANK-L, the ligand released by osteoblasts that enhances osteoclasts differentiation and bone resorption. It is used in osteoporosis and in other conditions characterized by bone mass loss. Doxorubicin is a chemotherapic drug used in several kinds of tumors, and also patients treated with it often develop osteoporosis.

We investigated the effects of Denosumab alone and in combination with Doxorubicin, in two human osteosarcoma cell lines (MG63 and U-2 OS). We evaluated the effect of these treatments on apoptosis, cell cycle progression, invasion capacity and bone metabolism.

We observed for the first time an anti-invasive effect of Denosumab in OS cells and confirmed its anti-osteoporotic activity also in Osteosarcoma. On the other hand, we demonstrate that Denosumab not only does not affect apoptosis and cell cycle progression, but when used in combination with Doxorubicin, it causes an unexpected reduction of its activity. These results indicate that the presence of Denosumab might inhibit the efficacy of the chemotherapic drug.

In conclusion, while our results certainly support and confirm the efficacy of Denosumab in Osteoporosis, we discourage the use of Denosumab in addition to conventional chemotherapy in Osteosarcoma, even though, certainly further investigations are necessary to better clarify the clinical role of this monoclonal antibody in cancer.

The Osteosarcoma Microenvironment: A Complex But Targetable Ecosystem

Osteosarcomas are the most frequent primary bone sarcomas, affecting mainly children, adolescents, and young adults, and with a second peak of incidence in elderly individuals. The current therapeutic management, a combined regimen of poly-chemotherapy and surgery, still remains largely insufficient, as patient survival has not improved in recent decades. Osteosarcomas are very heterogeneous tumors, both at the intra- and inter-tumor level, with no identified driver mutation. Consequently, efforts to improve treatments using targeted therapies have faced this lack of specific osteosarcoma targets. Nevertheless, these tumors are inextricably linked to their local microenvironment, composed of bone, stromal, vascular and immune cells and the osteosarcoma microenvironment is now considered to be essential and supportive for growth and dissemination. This review describes the different actors of the osteosarcoma microenvironment and gives an overview of the past, current, and future strategies of therapy targeting this complex ecosystem, with a focus on the role of extracellular vesicles and on the emergence of multi-kinase inhibitors.

[Osteoid-forming bone tumors : Morphology and current translational cell biology]

Osteoid osteoma and osteoblastoma are the most important benign osteoid-forming tumors. They grow slowly and are well differentiated. Histologically, the tumor cells show no atypia and no increased mitoses. In typical cases, they can be clearly diagnosed. However, the rare cases on the dividing line between osteoblastoma and osteosarcoma are extremely problematic. In these cases, molecular genetic investigations should contribute to finding the correct diagnosis in the future.Juvenile highly malignant osteosarcoma is the most important malignant osteoid-forming tumor. About 40 years ago, neoadjuvant chemotherapy was introduced for the mostly young patients. This therapy highly significantly improved prognosis. However, a plateau phase was quickly reached and the last several decades have seen no further progress in conventional therapeutic approaches. There is no doubt that further progress can only be achieved on the basis of new molecular genetic and cell biological findings. The target-therapeutic strategies derived from these findings will be discussed in this review.The rare parosteal osteosarcoma and the even rarer periosteal osteosarcoma are mostly not highly malignant tumors that are located on the surface of bone. The parosteal osteosarcoma is usually G1 and the periosteal osteosarcoma G2. Occasionally, the differential diagnosis between a parosteal osteosarcoma and a fibrous dysplasia is difficult. In such rare cases, the detection of GNAS mutations in fibrous dysplasia can prove useful. In contrast to chondromas and chondrosarcomas, periosteal osteosarcomas do not contain IDH1 and IDH2 mutations.

Receptor Tyrosine Kinases in Osteosarcoma: 2019 Update

The primary conclusions of our 2014 contribution to this series were as follows: Multiple receptor tyrosine kinases (RTKs) likely contribute to aggressive phenotypes in osteosarcoma and, therefore, inhibition of multiple RTKs is likely necessary for successful clinical outcomes. Inhibition of multiple RTKs may also be useful to overcome resistance to inhibitors of individual RTKs as well as resistance to conventional chemotherapies. Different combinations of RTKs are likely important in individual patients. AXL, EPHB2, FGFR2, IGF1R, and RET were identified as promising therapeutic targets by our in vitro phosphoproteomic/siRNA screen of 42 RTKs in the highly metastatic LM7 and 143B human osteosarcoma cell lines. This chapter is intended to provide an update on these topics as well as the large number of osteosarcoma clinical studies of inhibitors of multiple tyrosine kinases (multi-TKIs) that were recently published.

Radiopharmaceuticals for Treatment of Osteosarcoma

Although trace amounts of radioactivity are routinely used to detect osteosarcoma, the use of larger therapeutic amounts of radiation is often an unrecognized opportunity to treat metastatic osteosarcoma. This chapter will review a number of approaches to use ionizing radiation in the form of injectable radiopharmaceuticals. Since bone metastases are a common pattern of metastatic spread of cancer in general, a number of bone-seeking radiopharmaceuticals have been developed and FDA approved for treatment of bone metastases. Although osteosarcoma, a bone-forming cancer, would seem ideally suited to be treated with bone seekers, patterns of relapse involving non-ossifying metastases remain a major problem to be overcome. Thus, this review will not only describe experience using a number of bone-seeking radiopharmaceuticals such as 153-samarium-EDTMP, 153-samarium-DOTMP, and 223-radium against osteosarcoma, but also approaches to identify patients who may benefit as well as some means to the improve overall efficacy including combination therapy with routine agents and using nuclear imaging to develop best strategy for use. These include imaging with not only ^99mTc-MDP standard bone scans, but also ^99mTc-MDP bone scans with SPECT CT, bone-specific sodium fluoride PET-CT (Na¹⁸F), and ¹⁸FDG-PET-CT. Accurate knowledge of oligometastatic active disease can facilitate more effective use of combination therapy, including radiosensitizers and local control measures, for example, stereotactic body radiotherapy (SBRT) and/or cryoablation to reduce disease burden as well as manage and prevent micrometastatic disease from growing and metastasizing. Finally, a new tumor-specific radiopharmaceutical, CLR 131, may also provide another radiopharmaceutical to treat both osteoblastic and non-ossifying areas of osteosarcoma.

FGF-induced LHX9 regulates the progression and metastasis of osteosarcoma via FRS2/TGF-β/β-catenin pathway

Background

Fibroblast growth factor (FGF) and tumor growth factor-β (TGFβ) have emerged as pivotal regulators during the progression of osteosarcoma (OS). LHX9 is one crucial transcription factor controlled by FGF, however, its function in OS has not been investigated yet.

Methods

The expression of LHX9, FRS2, BMP4, TGF-beta R1, SMAD2, beta-catenin and metastasis-related proteins was measured by real-time quantitative PCR (RT-qPCR) and Western blot. CCK-8 assay and colony formation assay were employed to determine the proliferation of OS cells, while scratch wound healing assay and transwell assay were used to evaluate their migration and invasion, respectively. In vivo tumor growth and metastasis were determined by subcutaneous or intravenous injection of OS cells into nude mice.

Results

LHX9 expression was evidently up-regulated in OS tumor tissues and cell lines. Knockdown of LHX9 impaired the proliferation, migration, invasion and metastasis of OS cells. Mechanistically, LHX9 silencing led to the down-regulation of BMP-4, β-catenin and metastasis-related proteins, which was also observed in beta-catenin knockdown OS cells. By contrast, FRS2 knockdown conduced to the up-regulation of LHX9, BMP4, β-catenin and TGF-βR1, while TGF-beta inhibition repressed the expression of LHX9 and metastasis-related proteins. Additionally, let-7c modulates LHX9 and metastasis-related proteins by suppressing TGF-beta R1 expression on transcriptional level.

Conclusions

This study revealed LHX9 was essential for the proliferation, migration, invasion, and metastasis of OS cells via FGF and TGF-β/β-catenin signaling pathways.

Efficacy and safety of apatinib in advance osteosarcoma with pulmonary metastases: A single-center observational study

This study was designed to evaluate the efficacy and safety of apatinib in patients with advanced osteosarcoma and pulmonary metastases following failed first-line chemotherapy.There were 10 patients with osteosarcoma pulmonary metastases, whose first-line chemotherapy had failed, had received apatinib treatment as a single agent. All patients had at least 1 measurable lung tumor. Progression free survival (PFS), overall survival (OS), objective response rate (ORR), disease control rate (DCR), and treatment-related adverse effects (AEs) were reviewed and evaluated. Tumor response was assessed by response evaluation criteria in solid tumor criteria (RECIST). The 10 patients in this study received apatinib treatment for 2 to 16 months with a median of 7.5 months. The median PFS was 7.5 months. The 6-month, 8-month, and 10-month PFS rates were 60%, 40% and 26.6%, respectively. The median OS was 14 months. After 6-month apatinib treatment, 2 patients achieved partial response and 5 patients achieved stable disease, while 3 patients were evaluated as progression of the disease. At the 6-month follow-up, the ORR was 20.0% and the DCR was 70.0%. Hand-foot syndrome with grade 1/2 was the most common treatment-related AE. No drug-related severe AEs occurred.After failed first-line chemotherapy, apatinib as a single agent exhibited efficacy and acceptable safety in patients with advanced osteosarcoma and pulmonary metastases.

Dysregulation of macrophage polarization is associated with the metastatic process in osteosarcoma

Osteosarcoma (OS) is the most common bone sarcoma in adolescents, and has poor prognosis. A vicious cycle is established between OS cells and their microenvironment in order to facilitate the tumor growth and cell spreading. The present work aims to better characterize the tumor microenvironment in OS in order to identify new therapeutic targets relating to metastatic process. Tissue microarrays of pre-chemotherapy OS biopsies were used for characterizing the tumor niche by immunohistochemistry. Parameters studies included: immune cells (M1, M2-subtypes of tumor-associated macrophages (TAM); T, B lymphocytes; mast cells), vascularization (endothelial, perivascular cells), OPG, RANKL, and mitotic index. Two groups of patients were defined, 22 localized OS (OS Meta-) and 28 metastatic OS (OS Meta+). The OS Meta- group was characterized by a higher infiltration of INOS+ M1-polarizedmacrophages and upregulated OPG immunostaining. OS Meta+ tumors showed a significant increase in CD146+ cells. INOS+ M1-macrophages were correlated with OPG staining, and negatively with the presence of metastases. CD163+ M2-macrophages were positively correlated with CD146+ cells. In multivariate analysis, INOS and OPG were predictive factors for metastasis. An older age, non-metastatic tumor, good response to chemotherapy, and higher macrophage infiltration were significantly associated with better overall survival. TAMs are associated with better overall survival and a dysregulation of M1/M2 polarized-macrophages in favor of M1 subtype was observed in non-metastatic OS.

A review of the mechanism of action and clinical applications of sorafenib in advanced osteosarcoma

OBJECTIVE

To summarise the contemporary literature regarding sorafenib and its effectiveness as a novel treatment in advanced osteosarcoma.

BACKGROUND

Modern treatment has seen the cure rate of osteosarcoma increase to 65%. However, in patients who do not achieve remission, prognosis is poor, as there are no effective, consensual second line therapies. Sorafenib has emerged as a potentially viable drug to be used in this context.

METHOD

A literature review was conducted evaluating articles pertaining to osteosarcoma and sorafenib.

DISCUSSION

Clinical studies were prioritised, but preclinical data was also evaluated to elaborate on mechanisms and potential targets for the future. Limitations of the review and data were explored.

CONCLUSION

In isolation, sorafenib was shown to only provide brief clinical benefit due to various described mechanisms. However, when combined with other drugs that addressed its weaknesses or other aspects of the pathogenesis of osteosarcoma, it proved to be effective in reducing disease progression in a variety of advanced cases. Further investigation into the use of sorafenib in combination therapy is needed. Specifically, the combination of sorafenib with denosumab has displayed potential to be an effective future treatment for osteosarcoma.

Denosumab: Current Use in the Treatment of Primary Bone Tumors

Denosumab, a human monoclonal antibody that inhibits bone resorption by binding on the receptor activator of the nuclear factor kappa-β ligand, has recently emerged as an additional option in the treatment of musculoskeletal osteolytic tumors. This article focuses on the recent literature regarding the effectiveness of denosumab in the management of giant cell tumor, multiple myeloma, aneurysmal bone cyst, and osteosarcoma. The mechanism of action of denosumab in the management of these tumors and the associated side effects are discussed in detail. [ Orthopedics. 2017; 40(4):204-210.].

Prognostic Value of Osteoprotegerin and sRANKL in Bronchoalveolar Lavage Fluid of Patients with Advanced Non-small Cell Lung Cancer

Osteoprotegerin (OPG) is a soluble decoy receptor for receptor activator of nuclear factor-kappa B ligand (sRANKL). OPG promotes endothelial cell survival and neoangiogenesis. Dysregulation of the OPG/RANKL system has been detected in several tumors. In the present study, we evaluated the clinical usefulness of OPG and sRANKL assessment in bronchoalveolar lavage fluid (BALF) of patients with advanced non-small cell lung cancer (NSCLC). We measured the concentration of OPG and sRANKL in BALF of 44 NSCLC patients and 15 healthy volunteers taken as control subjects. The OPG content was higher in the NSCLC group than that in controls [0.48 (0.12-1.45) vs. 0.23 (0.14-0.75) pmol/l; p = 0.0001]. There were no significant differences in sRANKL content between the NSCLC and control groups [1.22 (0.74-23.00) vs. 1.12 (0.79-4.39) pmol/l; p = 0.67]. However, we found that the greater the level of sRANKL in NSCLC patients, the shorter the overall survival. We found a correlation between the content of sRANKL and the percentage of lymphocytes in BALF of NSCLC patients (r = 0.52; p = 0.041). We conclude that NSCLC patients have a higher content of OPG in BALF than healthy people. A high level of sRANKL in BALF of NSCLC patients may predict worse survival.

Novel insights and therapeutic interventions for pediatric osteosarcoma

High-grade osteosarcomas are the most common primary malignant tumors of bone. With complete surgical resection and multi-agent chemotherapy up to 70% of patients with high-grade osteosarcomas and localized extremity tumors can become long-term survivors. The prognosis, however, is poor for patients with nonresectable, primary metastatic or relapsed disease. Outcome is essentially unchanged for three decades. Herein, we describe selected novel insights into the genomics, biology and immunology of the disease and discuss selected strategies, which hold promise to overcome the current stagnation in the therapeutic success in childhood osteosarcoma.

RANKL blockade prevents and treats aggressive osteosarcomas

Osteosarcoma (OS) is the most common primary bone cancer, which occurs primarily in children and adolescents, severely affecting survivors' quality of life. Despite its chemosensitivity and treatment advances, long-term survival rates for OS patients have stagnated over the last 20 years. Thus, it is necessary to develop new molecularly targeted therapies for this metastatic bone cancer. Mutations in TP53 and RB are linked to OS predisposition and to the evolution of spontaneous OS. We established receptor activator of nuclear factor κB ligand (RANKL) as a therapeutic target for suppression and prevention of OS. Combined conditional osteoblast-specific deletions of Rb, p53, and the protein kinase A (PKA) regulatory subunit Prkar1α genes in genetically engineered mouse models (GEMMs) generate aggressive osteosarcomas, characterized by PKA, RANKL, and osteoclast hyperactivity. Whole-body Rankl deletion completely abrogates tumorigenesis. Although osteoblastic Rank deletion has little effect, osteoclastic Rank deletion delays tumorigenesis and prolongs life span. The latter is associated with inactivation of osteoclastogenesis and up-regulation of the tumor suppressor phosphatase and tensin homolog (PTEN). Further, we use these GEMMs as preclinical platforms to show that RANKL blockade with RANK-Fc arrests tumor progression and improves survival and also inhibits lung metastasis. Moreover, preemptive administration of RANK-Fc completely prevents tumorigenesis in mice highly predisposed to this aggressive cancer. Denosumab, a fully human monoclonal antibody against RANKL, is currently used to treat patients with osteoporosis or bone metastases. Our studies provide a strong rationale to consider RANKL blockade for the treatment and prevention of aggressive RANKL-overexpressing OS in humans.

RANK-RANKL signalling in cancer

Oncogenic events combined with a favourable environment are the two main factors in the oncological process. The tumour microenvironment is composed of a complex, interconnected network of protagonists, including soluble factors such as cytokines, extracellular matrix components, interacting with fibroblasts, endothelial cells, immune cells and various specific cell types depending on the location of the cancer cells (e.g. pulmonary epithelium, osteoblasts). This diversity defines specific "niches" (e.g. vascular, immune, bone niches) involved in tumour growth and the metastatic process. These actors communicate together by direct intercellular communications and/or in an autocrine/paracrine/endocrine manner involving cytokines and growth factors. Among these glycoproteins, RANKL (receptor activator nuclear factor-κB ligand) and its receptor RANK (receptor activator nuclear factor), members of the TNF and TNFR superfamilies, have stimulated the interest of the scientific community. RANK is frequently expressed by cancer cells in contrast with RANKL which is frequently detected in the tumour microenvironment and together they participate in every step in cancer development. Their activities are markedly regulated by osteoprotegerin (OPG, a soluble decoy receptor) and its ligands, and by LGR4, a membrane receptor able to bind RANKL. The aim of the present review is to provide an overview of the functional implication of the RANK/RANKL system in cancer development, and to underline the most recent clinical studies.

Osteosarcoma: Cells-of-Origin, Cancer Stem Cells, and Targeted Therapies

Osteosarcoma (OS) is the most common type of primary solid tumor that develops in bone. Although standard chemotherapy has significantly improved long-term survival over the past few decades, the outcome for those patients with metastatic or recurrent OS remains dismally poor and, therefore, novel agents and treatment regimens are urgently required. A hypothesis to explain the resistance of OS to chemotherapy is the existence of drug resistant CSCs with progenitor properties that are responsible of tumor relapses and metastasis. These subpopulations of CSCs commonly emerge during tumor evolution from the cell-of-origin, which are the normal cells that acquire the first cancer-promoting mutations to initiate tumor formation. In OS, several cell types along the osteogenic lineage have been proposed as cell-of-origin. Both the cell-of-origin and their derived CSC subpopulations are highly influenced by environmental and epigenetic factors and, therefore, targeting the OS-CSC environment and niche is the rationale for many recently postulated therapies. Likewise, some strategies for targeting CSC-associated signaling pathways have already been tested in both preclinical and clinical settings. This review recapitulates current OS cell-of-origin models, the properties of the OS-CSC and its niche, and potential new therapies able to target OS-CSCs.

Deciphering signaling networks in osteosarcoma pathobiology

Osteosarcoma is the most frequent type of primary bone tumors among children and adolescents. During the past years, little progress has been made regarding prognosis of osteosarcoma patients, especially for those with metastatic disease. Genomic instability and gene alterations are common, but current data do not reveal a consistent and repeatable pattern of osteosarcoma development, thus paralleling the tumor's high heterogeneity. Critical signal transduction pathways have been implicated in osteosarcoma pathobiology and are being evaluated as therapeutic targets, including receptor activator for nuclear factor-κB (RANK), Wnt, Notch, phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin, and mechanotransduction pathways. Herein, we recapitulate and discuss recent advances in the context of molecular mechanisms and signaling networks that contribute to osteosarcoma progression and metastasis, towards patient-tailored and novel-targeted treatments.

Rank ligand as a target in musculoskeletal neoplasms

Receptor activator of nuclear factor-κB ligand (RANKL) is a tumor necrosis factor (TNF) family member, which signals through the osteoclast surface RANK. As such, RANKL is required for osteoclast differentiation and function, namely bone resorption. There is now growing evidence that RANKL is a therapeutic target for musculoskeletal neoplasms, namely giant cell tumor of bone (GCTB) and osteosarcoma.

Bone microenvironment signals in osteosarcoma development

The bone is a complex connective tissue composed of many different cell types such as osteoblasts, osteoclasts, chondrocytes, mesenchymal stem/progenitor cells, hematopoietic cells and endothelial cells, among others. The interaction between them is finely balanced through the processes of bone formation and bone remodeling, which regulates the production and biological activity of many soluble factors and extracellular matrix components needed to maintain the bone homeostasis in terms of cell proliferation, differentiation and apoptosis. Osteosarcoma (OS) emerges in this complex environment as a result of poorly defined oncogenic events arising in osteogenic lineage precursors. Increasing evidence supports that similar to normal development, the bone microenvironment (BME) underlies OS initiation and progression. Here, we recapitulate the physiological processes that regulate bone homeostasis and review the current knowledge about how OS cells and BME communicate and interact, describing how these interactions affect OS cell growth, metastasis, cancer stem cell fate and therapy outcome.

Uterine leiomyosarcoma with osteoclast-like giant cells associated with high expression of receptor activator of nuclear factor κB ligand

The occurrence of osteoclast-like giant cells (OLGCs) in uterine leiomyosarcomas (LMSs) is a rare phenomenon. The nature of OLGCs and the significance of their accumulation in these tumors are poorly understood. Recent studies revealed that the formation of osteoclasts requires a specific cytokine, receptor activator of nuclear factor κB ligand (RANKL), in bone. In this study, we investigated the expression of RANKL in 2 cases of uterine LMS with OLGCs by means of immunohistochemistry and compared the extent of RANKL expression with that in conventional uterine LMSs and leiomyomas by using real-time reverse-transcription quantitative polymerase chain reaction. Our cases of uterine LMS with OLGCs showed markedly high expression of RANKL messenger RNA with clear RANKL immunoreactivity compared with messenger RNA expression and immunoreactivity of conventional uterine LMSs and leiomyomas. These findings suggest that the tumors producing RANKL may account for accumulation of OLGCs in tumor tissue because of RANKL-related osteoclastogenesis.