Coefficient of variation of T2-weighted MRI may predict the prognosis of malignant peripheral nerve sheath tumor

BACKGROUND

We investigated whether non-enhancement MRI features, including measurement of the heterogeneity of the tumor with MR T2 imaging by calculating coefficient of variation (CV) values, were associated with the prognosis of non-metastatic malignant peripheral nerve sheath tumors (MPNST).

METHODS

This retrospective study included 42 patients with MPNST who had undergone surgical resection (mean age, 50 years ± 21; 20 male participants). Non-enhancement MR images were evaluated for signal intensity heterogeneity on T1- and T2-weighted imaging, tumor margin definition on T1- and T2-weighted imaging, peritumoral edema on T2-weight imaging, and CV. We measured the signal intensities of MR T2-weighted images and calculated the corresponding CV values. CV is defined as the ratio of the standard deviation to the mean. The associations between factors and overall survival (OS) were investigated via the Kaplan-Meier method with log-rank tests and the Cox proportional hazards model.

RESULTS

The mean CV value of MR T2 images was 0.2299 ± 0.1339 (standard deviation) (range, 0.0381-0.8053). Applying receiver operating characteristics analysis, the optimal cut-off level for CV value was 0.137. This cut-off CV value was used for its stratification into high and low CV values. At multivariate survival analysis, a high CV value (hazard ratio = 3.63; 95% confidence interval = 1.16-16.0; p = 0.047) was identified as an independent predictor of OS.

CONCLUSION

The CV value of the signal intensity of heterogenous MPNSTs MR T2-weighted images is an independent predictor of patients' OS.

The Combined Use of Inflammation Markers, Modified Glasgow Prognostic Score, and Sarculator Nomogram in Extremity Soft Tissue Sarcoma: A Multicenter Observational Study

BACKGROUND

Sarculator is a validated nomogram designed to predict overall survival (OS) in extremity soft tissue sarcoma (STS). Inflammation plays a critical role in cancer development and progression. There were no reports which investigated the relationship between Sarculator and inflammation.

METHODS

A total of 217 patients with extremity STS were included. The Sarculator-predicted 10-year probability of OS (pr-OS) was stratified into two subgroups: lower risk (10-year pr-OS ≥ 60%) and higher risk (10-year pr-OS < 60%). The modified Glasgow prognostic score (mGPS) varied from 0 to 2.

RESULTS

Out of the 217 patients, 67 were classified as higher risk, while 150 were lower risk. A total of 181 patients had an mGPS of 0, and 36 had a score of 1 or 2. The 5-year OS was 83.3%. When patients were divided into two groups according to the 10-year pr-OS, those with a higher risk had poorer OS than those with a lower risk. Among the patients with a higher risk, those with an mGPS of 1 or 2 had poorer OS compared to those with a score of 0.

CONCLUSIONS

The mGPS could potentially play an important role in identifying patients who are at high risk of death and metastasis in the higher-risk group on the Sarculator.

Genetic characterization of a novel organoid from human malignant giant-cell tumor

Malignant giant-cell tumors are extremely rare bone sarcomas that transform from conventional giant-cell tumors during long periods of treatment. Owing to their rarity, no further analysis of their molecular pathogenesis exists, and thus, no standard treatment has been established. Recently, organoid culture methods have been highlighted for recapturing the tumor microenvironment, and we have applied the culture methods and succeeded in establishing patient-derived organoids (PDO) of rare sarcomas. This study aimed to investigate the genomic characteristics of our established novel organoids from human malignant giant-cell tumors. At our institute, we treated a patient with malignant giant-cell tumor. The remaining sarcoma specimens after surgical resection were cultured according to the air-liquid interface organoid-culture method. Organoids were xenografted into NOD-scid IL2Rgnull mice. The developed tumors were histologically and genomically analyzed to compare their characteristics with those of the original tumors. Genetic changes over time throughout treatment were analyzed, and the genomic status of the established organoid was confirmed. Organoids from malignant giant-cell tumors could be serially maintained using air-liquid interface organoid-culture methods. The tumors developed in xenografted NOD-scid IL2Rgnull mice. After several repetitions of the process, a patient-derived organoid line from the malignant giant-cell tumor was established. Immunohistochemical analyses and next-generation sequencing revealed that the established organoids lacked the H3-3A G34W mutation. The xenografted organoids of the malignant giant-cell tumor had phenotypes histologically and genetically similar to those of the original tumor. The established organoids were confirmed to be derived from human malignant giant-cell tumors. In summary, the present study demonstrated a novel organoid model of a malignant giant-cell tumor that was genetically confirmed to be a malignant transformed tumor. Our organoid model could be used to elucidate the molecular pathogenesis of a malignant giant-cell tumor and develop novel treatment modalities.

Targeting the Clear Cell Sarcoma Oncogenic Driver Fusion Gene EWSR1::ATF1 by HDAC Inhibition

Clear cell sarcoma (CCS), a rare but extremely aggressive malignancy with no effective therapy, is characterized by the expression of the oncogenic driver fusion gene EWSR1::ATF1. In this study, we performed a high-throughput drug screening, finding that the histone deacetylase inhibitor vorinostat exerted an antiproliferation effect with the reduced expression of EWSR1::ATF1. We expected the reduced expression of EWSR1::ATF1 to be due to the alteration of chromatin accessibility; however, assay for transposase-accessible chromatin using sequencing and a cleavage under targets and release using nuclease assay revealed that chromatin structure was only slightly altered, despite histone deacetylation at the EWSR1::ATF1 promoter region. Alternatively, we found that vorinostat treatment reduced the level of BRD4, a member of the bromodomain and extraterminal motif protein family, at the EWSR1::ATF1 promoter region. Furthermore, the BRD4 inhibitor JQ1 downregulated EWSR1::ATF1 according to Western blotting and qPCR analyses. In addition, motif analysis revealed that vorinostat treatment suppressed the transcriptional factor SOX10, which directly regulates EWSR1::ATF1 expression and is involved in CCS proliferation. Importantly, we demonstrate that a combination therapy of vorinostat and JQ1 synergistically enhances antiproliferation effect and EWSR1::ATF1 suppression. These results highlight a novel fusion gene suppression mechanism achieved using epigenetic modification agents and provide a potential therapeutic target for fusion gene-related tumors.

Significance

This study reveals the epigenetic and transcriptional suppression mechanism of the fusion oncogene EWSR1::ATF1 in clear cell sarcoma by histone deacetylase inhibitor treatment as well as identifying SOX10 as a transcription factor that regulates EWSR1::ATF1 expression.

Clinical Outcome of Low-Grade Myofibroblastic Sarcoma in Japan: A Multicenter Study from the Japanese Musculoskeletal Oncology Group

This retrospective multicenter study aimed to analyze the clinical features and prognosis of 24 patients diagnosed with LGMS between 2002 and 2019 in the Japanese sarcoma network. Twenty-two cases were surgically treated and two cases were treated with radical radiotherapy (RT). The pathological margin was R0 in 14 cases, R1 in 7 cases, and R2 in 1 case. The best overall response in the two patients who underwent radical RT was one complete response and one partial response. Local relapse occurred in 20.8% of patients. Local relapse-free survival (LRFS) was 91.3% at 2 years and 75.4% at 5 years. In univariate analysis, tumors of 5 cm or more were significantly more likely to cause local relapse (p < 0.01). In terms of the treatment of relapsed tumors, surgery was performed in two cases and radical RT was performed in three cases. None of the patients experienced a second local relapse. Disease-specific survival was 100% at 5 years. A wide excision aimed at the microscopically R0 margin is considered the standard treatment for LGMS. However, RT may be a viable option in unresectable cases or in cases where surgery is expected to cause significant functional impairment.

Local surgery feasibility and safety after carbon ion radiotherapy for primary bone sarcomas

BACKGROUND

It is known that several complications are caused by local surgery after radiotherapy. Clinical reports that describe the postoperative complications associated with surgery after carbon ion radiotherapy are sparse. This study aimed to elucidate local surgery feasibility after carbon ion radiotherapy specifically for primary bone sarcomas.

METHODS

The medical, surgical, and irradiation records of patients who had local surgery at the area irradiated with carbon ion beams between 2004 and 2018 were reviewed retrospectively to evaluate the feasibility and indication of local surgery after CIRT.

RESULTS

There were eight patients who had 10 local surgeries at the irradiated sites among the 42 carbon ion radiotherapy patients. There were seven males and one female with a median age of 50 years (range 26-73 years). The reasons for surgery were three for skin toxicity and associated infection, five for bone collapse, and associated implant failure, and two for tumor regrowth. All surgical fields included the area of more than 60 Gy (RBE) irradiated dose. All three surgical cases caused by skin toxicity and associated infection had Grade I wound complication after surgery according to the Clavien-Dindo Classification.

CONCLUSION

Local surgery after CIRT appeared feasible in selected patients with primary bone sarcoma, especially for the patients with bone collapse and associated implant failure. However, infection and prescribed irradiation dose at the incision site must be carefully evaluated.

Establishment of Organoids From Human Epithelioid Sarcoma With the Air-Liquid Interface Organoid Cultures

Background

Although biological resources are essential for basic and preclinical research in the oncological field, those of sarcoma are not sufficient for rapid development of the treatment. So far, some sarcoma cell lines have been established, however, the success rate was low and the established sarcoma types were frequently biased. Therefore, an efficient culture method is needed to determine the various types of sarcomas. Organoid culture is a 3-dimentional culture method that enables the recapitulation of the tumor microenvironment and the success rate reported is higher than the 2-dimentional culture. The purpose of this study was to report our newly established organoids from human epithelioid sarcoma using the air-liquid interface organoid culture method.

Methods

We treated 2 patients with epithelioid sarcoma in our institute. The remaining sarcoma specimens after surgical resection were embedded in collagen type 1 gels according to the air-liquid interface organoid culture method. After serial passages, we xenografted the organoids to NOD-scid IL2Rgnull (NSG) mice. Using the developed tumors, we performed histological and genomic analyses to compare the similarities and differences with the original epithelioid sarcoma from the patient.

Results

Organoids from the epithelioid sarcoma could be serially cultured and maintained in collagen type 1 gels for more than 3 passages. Developed orthotopic tumor xenografts were detected in the NSG mice. After the process was repeated severally, the patient derived organoid lines from the epithelioid sarcoma were established. The established organoids showed loss of integrase interactor 1 expression with polymerase chain reaction and immunohistochemical analyses. The xenografted organoids of the epithelioid sarcoma had histologically similar phenotypes with the original tumor and genetically resembled it to some degree.

Conclusions

The present study demonstrated 2 novel established organoid models of epithelioid sarcoma, and our organoid models could be used to investigate the molecular pathogenesis and develop a novel treatment.

Impact of Surgical Resection and Reasons for Poor Prognosis of Pelvic Osteosarcoma Based on the Bone Tumor Registry in Japan

Simple Summary

Pelvic osteosarcoma has a poor prognosis compared to osteosarcomas in other locations, and the reasons for this remains unknown. Surgical resection of pelvic osteosarcoma is technically demanding and often results in dysfunction and complications. In this study, we investigated the reasons underlying the poor prognosis of pelvic osteosarcoma by comparing it to femoral osteosarcoma using data from the Bone Tumor Registry in Japan. We used propensity score analysis to determine whether surgical resection of pelvic osteosarcoma improved its prognosis. We demonstrated that pelvic osteosarcoma had a poor prognosis because it occurred more often in the elderly, often had a larger tumor size, and had metastasis at presentation more often in comparison to femoral osteosarcoma. These three factors were also associated with the non-surgical treatment of pelvic osteosarcoma, which also led to a poor outcome. The overall survival rate was only comparable in pelvic osteosarcoma and femoral osteosarcoma in cases treated with surgical resection. Propensity score analysis revealed that surgical treatment improved the prognosis of pelvic osteosarcoma. As such, we propose that surgical resection should be considered based on tumor stage and patient age in order to improve the prognosis of pelvic osteosarcoma.

Abstract

Pelvic osteosarcoma has a poor prognosis compared to osteosarcomas in other locations, and the reasons for this remain unknown. Surgical resection of pelvic osteosarcoma is technically demanding and often results in dysfunction and complications. In this study, we investigated the reasons underlying the poor prognosis of pelvic osteosarcoma by comparing it to femoral osteosarcoma using data from the Bone Tumor Registry in Japan. We used propensity score analysis to determine whether surgical resection of pelvic osteosarcoma improved its prognosis. We demonstrated that pelvic osteosarcoma had a poor prognosis because it occurred more often in the elderly, often had larger tumor size, and had metastasis at presentation more often in comparison to femoral osteosarcoma. These three factors were also associated with the non-surgical treatment of pelvic osteosarcoma, which also led to a poor outcome. The overall survival rate was only comparable in pelvic osteosarcoma and femoral osteosarcoma in cases treated with surgical resection. Propensity score analysis revealed that surgical treatment improved the prognosis of pelvic osteosarcoma. As such, we propose that surgical resection should be considered based on tumor stage and patient age in order to improve the prognosis of pelvic osteosarcoma.

Efficacy and safety of TAS-115, a novel oral multi-kinase inhibitor, in osteosarcoma: an expansion cohort of a phase I study

Background osteosarcoma is a rare, primary malignant bone tumour with limited available treatments for advanced or recurrent disease, resulting in a poor prognosis for patients. TAS-115 is a novel tyrosine kinase inhibitor under investigation in a phase I study in patients with solid tumours. We report data of osteosarcoma patients in the expansion cohort of this ongoing study. Patients and methods an analysis of this multicentre, open-label study was performed 6 months after the final patient was enrolled, and included patients aged ≥15 years, with unresectable or recurrent osteosarcoma, and who had refractory to standard therapy or for whom no standard therapy was available. TAS-115 650 mg/day was orally administered in a 5 days on/2 days off schedule. Results a total of 20 patients with osteosarcoma were enrolled. The most common adverse drug reactions (ADRs) were neutrophil count decreased (75%), aspartate aminotransferase increased (50%), and platelet count decreased (50%); 85% of patients had grade ≥ 3 ADRs. Long-term disease control (>1 year) with TAS-115 was achieved in three patients. The best overall response was stable disease (50%); no patient achieved a complete or partial response. Median progression-free survival was 3 months; 4-month and 12-month progression-free rates were 42% and 31%, respectively. Conclusion the safety and tolerability of TAS-115 and long-term disease stability for patients with unresectable or recurrent osteosarcoma were confirmed in this study, suggesting that TAS-115 is a promising novel therapy for advanced osteosarcoma patients. Trial registration number: JapicCTI-132333 (registered on November 8, 2013).

Primary breast angiosarcoma with disseminated intravascular coagulation is successfully treated with self-subcutaneous unfractionated heparin calcium injection: A case report

Angiosarcoma is a rare sarcoma with a poor prognosis and is prone to disseminated intravascular coagulation (DIC), where DIC often interferes with chemotherapy. Primary angiosarcoma of the breast (PASB) is a type of angiosarcoma that is located in mammary parenchyma and is not associated with radiation exposure. The current study reported a 47-year-old female with DIC associated with PASB. The DIC of the patient relapsed during mono-chemotherapy with paclitaxel (PTX) after first-line anticoagulant therapy using thrombomodulin-α. The second-line danaparoid sodium therapy, followed by self-subcutaneous injection of unfractionated heparin calcium (UFH), resulted in long-term stabilization of DIC. Under this second-line anticoagulant therapy, the patient continued chemotherapy and chemoradiotherapy for >13 months in the outpatient setting without impairment of quality of life. The present case suggested that self-subcutaneous injections of UFH may be a useful therapeutic option for long-term control of DIC associated with PASB. However, further prospective clinical trails are needed to verify the efficacy of self-subcutaneous injection of UFH in similar settings.

Malignant gastrointestinal neuroectodermal tumor with BRAF mutation and a history of malignant melanoma: A case report

Malignant gastrointestinal neuroectodermal tumors (GNETs), also called clear-cell sarcoma-like tumors of the gastrointestinal tract, are rare and highly aggressive tumors originating in the gastrointestinal tract. These tumors are generally immunohistochemically positive for S-100 protein (S-100) and SRY-related HMG-box 10 (SOX10), and often contain EWSR1-ATF1 or EWSR1-CREB1. The histological features of GNETs overlap with those of clear-cell sarcoma of the tendons and aponeuroses. However, GNETs immunohistochemically lack melanocyte-specific markers and often demonstrate positivity for CD56, synaptophysin and neuron-specific enolase. The present case reports a woman with a history of desmoplastic malignant melanoma exhibiting a BRAF mutation, which later transformed into a GNET of the small intestine with both a BRAF mutation and two subtypes of EWSR1-ATF1 fusion genes. Tumor cells were revealed to be weakly immunoreactive or negative for S-100 and SOX10, lacked markers of melanocytic differentiation and were focally positive for CD56. Combination therapy with dabrafenib mesylate and trametinib dimethyl sulfoxide proved to be temporarily effective against this tumor. The present case is relatively unique as, to the best of our knowledge, there is no case of GNET with a history of melanoma. Furthermore, there is no report of GNET exhibiting both a BRAF mutation and an EWSR1-ATF1 fusion gene. Further accumulation of similar cases is necessary to elucidate the pathological significance of this GNET having a BRAF mutation.

A case of Stewart-Treves syndrome occurring in the abdominal wall successfully treated with eribulin: A case report

Angiosarcoma (AS) is a rare and aggressive tumor with high rates of local recurrence and distant metastasis. Stewart-Treves syndrome (STS) is defined as AS arising in the setting of chronic lymphedema, and is extremely uncommon in the lower abdominal wall. Eribulin mesylate (eribulin) is a non-taxane microtubule inhibitor that has been approved in Japan for treating soft tissue sarcoma. The current study reports the case of a 76 year-old woman with STS in the lower abdominal wall who exhibited an excellent response to eribulin. Having undergone surgery and postoperative radiation therapy (RT) for cervical cancer 12 years earlier, the patient presented with a mass in her left lower abdominal wall, where chronic lymphedema had developed. Contrast-enhanced computed tomography revealed multiple enhancing nodules in the left lower abdominal wall and edema of the subcutaneous tissues in the whole lower abdomen. A histologic analysis of the specimens revealed AS, and she was diagnosed as STS. A total of 3 cycles of combination chemotherapy with gemcitabine and docetaxel were administered, but the patient discontinued treatment owing to severe adverse events. RT was performed for the tumor, but multiple reddish nodules appeared in the whole lower abdominal wall 3 months later. At this point, eribulin administration was offered. After 4 cycles of treatment, there was a clear reduction in the size of the nodules. All lesions were stable, no new lesions had developed, and the side effects of treatment were minor over the course of 1 year. The results reveal that eribulin may serve as a potential therapeutic option for the treatment of STS.

Prognostic factors and skeletal-related events in patients with bone metastasis from gastric cancer

The number of studies on bone metastasis (BM) from gastric cancer (GC) is currently limited. Therefore, the aim of the present study was to investigate the characteristics, skeletal-related events (SREs) and prognosis of GC in patients with BMs. Data from 60 patients with BMs from GC were retrospectively retrieved and patient-, tumor- and BM-related characteristics were analyzed. Kaplan-Meier survival curves were analyzed using the univariate log-rank test. Multivariate analyses were conducted using the Cox proportional hazards model. The median patient age was 63.5 years (range, 26-83 years). Visceral or brain metastases were observed at BM diagnosis in 61.7% of the patients. Multiple BMs were detected in 83.3% and SREs occurred in 76.7% of the patients. The median overall survival (OS) after BM diagnosis and SRE occurrence was 9 months (range, 0-43 months) and 5 months (range, 0-36 months), respectively. On multivariate analysis, poor Eastern Cooperative Oncology Group performance status (P=0.030), the administration of chemotherapy prior to BM diagnosis (P<0.001) and no chemotherapy after BM diagnosis (P=0.002) were significant prognostic factors for unfavorable OS, whereas the non-use of bone-modifying agents (BMAs) was the only independent prognostic factor for poor SRE-free survival (SRS; P=0.022). Among patients without SREs at BM diagnosis, the median SRS duration was 7 months (range, 0-43 months). In conclusion, chemotherapy may confer a survival benefit in GC patients with BMs. In addition, the prognosis for GC patients with BMs presenting with SREs is poor, but treatment with BMAs may prevent or delay the development of SREs.

A long-term follow-up study of extracorporeal irradiated autografts in limb salvage surgery for malignant bone and soft tissue tumors: A minimum follow-up of 10 years after surgery

BACKGROUND AND OBJECTIVES

The aim of this study is to assess the survival, function, radiographic appearance, and modes of failure of extracorporeal irradiated (ECI) autografts in a long-term setting.

METHODS

We retrospectively reviewed 87 patients who were treated for bone and soft tissue tumors using ECI autografts between 1988 and 2009.

RESULTS

The 56 patients had a minimum follow-up of 10 years, and the median follow-up period was 16.5 years. The reimplantation procedures included 24 osteoarticular grafts, 16 intercalary grafts, 10 autograft-prosthetic composite grafts, and 6 hemicortical grafts. The 15-year graft and event-free survival rates were 76.8% and 47.9%, respectively. Infection and structural failure were the most common reasons for additional surgery. The time for additional surgery was significantly longer in patients with composite grafts (P < .01). The median Musculoskeletal Tumor Society score and the International Society of Limb Salvage score were 80% and 84%, respectively.

CONCLUSIONS

ECI autografts are a durable option for reconstruction after resection of musculoskeletal tumors and provide good function over more than 15 years. Most graft failures occurred within 5 years of the index surgery. However, composite grafts showed a tendency to fail more than 10 years after the surgery.

TAS-115 inhibits PDGFRα/AXL/FLT-3 signaling and suppresses lung metastasis of osteosarcoma

Osteosarcoma is the most common malignant bone tumor in adolescence and childhood. Metastatic osteosarcoma has a poor prognosis with an overall 5‐year survival rate of approximately 20%. TAS‐115 is a novel multiple receptor tyrosine kinase inhibitor that is currently undergoing clinical trials. Using the mouse highly lung‐metastatic osteosarcoma cell line, LM8, we showed that TAS‐115 suppressed the growth of subcutaneous grafted tumor and lung metastasis of osteosarcoma at least partially through the inhibition of platelet‐derived growth factor receptor alpha, AXL, and Fms‐like tyrosine kinase 3 phosphorylation. We also show that these signaling pathways are activated in various human osteosarcoma cell lines and are involved in proliferation. Our results suggest that TAS‐115 may have potential for development into a novel treatment for metastatic osteosarcoma.

Clinical outcomes of chondroblastoma treated using synthetic bone substitute: risk factors for developing radiographic joint degeneration

Background

Chondroblastoma (CB) is a rare locally aggressive bone tumor that commonly occurs in the epiphysis or apophysis of long bones. Although surgical treatment of CB carries potential risk for physeal or articular cartilage damage, risk factors for joint degeneration have not been well described. In addition, we have mainly used synthetic bone substitute (SBS) to fill the bone defect after intralesional curettage as treatment for CB. This study thus aimed to evaluate the incidence of and risk factors for adjacent-joint radiographic degeneration after SBS treatment for CB.

Methods

We retrospectively reviewed 48 patients treated for CB at our institutions between 1996 and 2017. Clinical data, radiographic images, treatments, and local recurrence were analyzed.

Results

We identified 40 patients [29 males and 11 females with a mean age of 19 years (range, 8–35 years)] who received SBS to fill the defect after curettage with a minimum follow-up of 1 year. The mean follow-up period was 71 months (range, 13–239 months). A total of 8 patients (20%) developed local recurrence. Radiographic analysis showed that 5 patients (16.7%) developed radiographic joint degeneration. Joint degeneration was significantly associated with the affected joint (p = 0.004).

Conclusions

Curettage and SBS filling had been found to be a reasonable treatment method for CB, which commonly occurs in the epiphysis or apophysis. Radiographic joint degeneration was not uncommon after CB treatment, especially in the talus and proximal humerus.

Malignant peripheral nerve-sheath tumors in an adolescent patient with mosaic localized NF1: A case report

Malignant peripheral nerve-sheath tumors (MPNSTs) are rare malignancies that are often observed in patients with neurofibromatosis type 1 (NF1). However, the occurrence of MPNST associated with mosaic localized NF1 is extremely rare. Previous reports have revealed that MPNST was associated with mosaic localized NF1 in only three patients who were >40 years of age. The present report details a 16-year-old man who presented with pain and a 3 cm mass on the medial side of the right knee. Magnetic resonance imaging revealed a circumscribed soft tissue tumor located in the subcutaneous tissue. His previous doctor believed that it was benign and conducted a marginal resection. However, postoperative histology results demonstrated spindle cell sarcoma, following which the patient was referred to The Osaka International Cancer Institute. Localized café-au-lait spots were identified in the affected leg, which inferred that the patient had NF1-related MPNST. A wide resection was performed to completely resect the residual tumor; however, a definitive histological diagnosis was challenging due to the small residual tumor. Hence, the genomic mutations of NF1 in the regional café-au-lait spots were analyzed. The result revealed an NF1 microdeletion and a consistently limited expression of NF1 in the tumor sample. Finally, the patient was diagnosed with MPNST with mosaic localized NF1. Local recurrence and distant metastasis were not observed 1.5 years after surgery. In conclusion, the present report presented MPNST in an adolescent patient with mosaic localized NF1. The occurrence of MPNSTs correlated with mosaic localized NF1 is extremely rare. However, it is of high-grade malignancy and therefore, its clinical features should be considered by orthopedists and pathologists.

Eribulin Suppresses Clear Cell Sarcoma Growth by Inhibiting Cell Proliferation and Inducing Melanocytic Differentiation Both Directly and Via Vascular Remodeling

Clear cell sarcoma (CCS) is a rare but chemotherapy-resistant and often fatal high-grade soft-tissue sarcoma (STS) characterized by melanocytic differentiation under control of microphthalmia-associated transcription factor (MITF). Eribulin mesilate (eribulin) is a mechanistically unique microtubule inhibitor commonly used for STS treatment, particularly liposarcoma and leiomyosarcoma. In this study, we examined the antitumor efficacy of eribulin on four human CCS cell lines and two mouse xenograft models. Eribulin inhibited CCS cell proliferation by inducing cell-cycle arrest and apoptosis, shrunk CCS xenograft tumors, and increased tumor vessel density. Eribulin induced MITF protein upregulation and stimulated tumor cell melanocytic differentiation through ERK1/2 inactivation (a MITF negative regulator) in vitro and in vivo Moreover, tumor reoxygenation, probably caused by eribulin-induced vascular remodeling, attenuated cell growth and inhibited ERK1/2 activity, thereby upregulating MITF expression and promoting melanocytic differentiation. Finally, downregulation of MITF protein levels modestly debilitated the antiproliferative effect of eribulin on CCS cells. Taken together, eribulin suppresses CCS through inhibition of cell proliferation and promotion of tumor differentiation by acting both directly on tumor cells and indirectly through tumor reoxygenation.

Clinical features and prognostic factors in patients with esophageal cancer with bone metastasis

There have been few reports on bone metastases (BMs) from esophageal cancer (EC). The aim of the present study was to investigate the clinicopathological features and prognostic factors in patients with EC with BMs. The present study retrospectively collected data from 58 patients with BMs from EC who were treated at our institution between 2007 and 2016. Patient, tumor and BM-associated characteristics were analyzed. Kaplan-Meier survival curves were constructed and analyzed using the univariate log-rank test. Multivariate analyses were conducted using the Cox proportional hazards model. The median patient age was 67 years (range, 39–84 years). Multiple BMs were detected in 38 patients (65.5%) and 52 patients (89.7%) exhibited osteolytic BMs. Skeletal-related events (SREs) occurred in 53 patients (91.4%). The one-year overall survival (OS) was 25.3%, and the median OS was 5 months (range, 0–54). Univariate analyses revealed that performance status, visceral or brain metastasis, serum carcinoembryonic antigen (CEA), C-reactive protein, albumin level, and receipt of chemotherapy following BM diagnosis were significantly associated with OS. Multivariate analyses of these factors demonstrated that higher serum CEA levels and no chemotherapy were significant risk factors for poor OS. Multiple osteolytic BMs are frequently observed in patients with EC with BMs, and SREs commonly occur. The prognoses of patients with EC with BMs are poor, but chemotherapy administration following the BM diagnosis should confer a survival benefit.

Prognostic implication of adjuvant/neoadjuvant chemotherapy consisting of doxorubicin and ifosfamide in patients with extraskeletal osteosarcoma

BACKGROUND

Extraskeletal osteosarcoma (ESOS) is an extremely rare soft tissue sarcoma. Their prognosis remains poor. Our purposes were to identify the effective chemotherapeutic regimen for ESOS.

METHODS

We retrospectively reviewed 16 patients with ESOS treated at the Osaka University Orthopaedic Oncology Group between 1992 and 2012. We extracted the clinical data on patients. Kaplan-Meier method and the log-rank test were used for survival analyses.

RESULTS

Median age of the patients was 61.5 years (range 25-79 years). Wide local excision was performed for 11 patients and 9 patients were treated combined with chemotherapy. The 5-year disease-specific survival (DSS) rate was 53.9%. The 5-year DSS rates for patients treated with adjuvant/neoadjuvant chemotherapy or not were 66.7% or 25%, respectively (p = 0.0215). Furthermore, the 5-year DSS rates for patients treated with adjuvant/neoadjuvant chemotherapy consisting of doxorubicin and ifosfamide and those treated with other regimens were 100% or 40%, respectively (p = 0.0327).

CONCLUSION

The present study demonstrated that adjuvant/neoadjuvant chemotherapy, especially consisting of doxorubicin and ifosfamide, was potentially efficacious for ESOS. Further prospective study using this multimodality treatment approach to patients with ESOS should be strongly warranted.

Favorable outcomes of localized synovial sarcoma patients with a high utilization rate of neoadjuvant and/or adjuvant chemotherapy

Synovial sarcoma (SS) is considered to be a chemosensitive, soft tissue sarcoma. Therefore, neoadjuvant and/or adjuvant chemotherapy (N/AC) is used for the treatment of high-risk SS patients. However, the role of N/AC remains controversial. The present study aimed to review the clinical outcomes of surgically treated localized SS and investigate the effects of N/AC with long-term observation. The clinical outcomes of 54 patients with surgically treated localized SS were retrospectively analyzed. The median patient age was 42 years (range, 8-81 years), and the median follow-up period was 94 months for survivors (range, 7-220 months). A total of 38 patients (70%) received chemotherapy. Of these, 32 (59%) patients received neoadjuvant chemotherapy, 33 (61%) received adjuvant chemotherapy, and 27 (50%) received neoadjuvant and adjuvant chemotherapy. Fourteen patients (26%) received adjuvant radiotherapy. Three patients (6%) had local recurrence and 13 patients (24%) developed distant metastasis. The overall survival (OS) rates at 5 and 10 years were 87 and 84%, respectively. N/AC did not improve survival. In conclusion, we found satisfactory long-term OS among patients with a high utilization rate of N/AC. Further study should be necessary to evaluate which population of SS would benefit from N/AC.

Survival analysis of elderly patients with osteosarcoma

BACKGROUND

Few studies have described the characteristics and prognostic factors of elderly patients with osteosarcoma. We retrospectively investigated clinico-pathological features and prognostic factors in osteosarcoma patients > 40 years old.

METHODS

Patients with high-grade osteosarcoma > 40 years old who were treated at our institutions from 2000 to 2016 were recruited for this study. Information on patient, tumour, and treatment-related factors was collected and statistically analyzed. The median follow-up was 26.5 months (range, 5-139 months) for all patients.

RESULTS

Fifty patients (30 males and 20 females) were included. The median age at diagnosis was 59.5 years (range, 41-81 years). The primary lesions were found in the limbs in 32 patients, trunk in 12, and craniofacial bones in six. Primary and secondary osteosarcoma occurred in 41 and 9 patients, respectively. Eight patients exhibited initial distant metastasis. Definitive surgery and chemotherapy were performed in 39 patients each. The rate of good responders after neoadjuvant chemotherapy was 38%. The five year overall survival (OS) rates for all patients and those without distant metastasis at diagnosis were 44.5% and 51.1%, respectively. Multivariate analysis showed that definitive surgery was the only significant prognostic factor in non-metastatic patients. The five year OS and disease-free survival (DFS) rates for non-metastatic patients who received definitive surgery were 64.3% and 60%, respectively. Among these patients, neoadjuvant and/or adjuvant chemotherapy significantly improved both OS and DFS.

CONCLUSIONS

Complete surgical resection and intensive chemotherapy should be performed for osteosarcoma patients > 40 years old despite distinct clinicopathological characteristics from those of younger patients.

Clinical outcomes and significant factors in the survival rate after decompression surgery for patients who were non-ambulatory due to spinal metastases

BACKGROUND

The development of effective chemotherapy regimens and molecular targeting agents are improving the overall survival rates in patients with cancer. However, patients who are non-ambulatory due to metastatic epidural spinal cord compression (MESCC) may be assessed as unable to tolerate chemotherapy secondary to poor performance status. This means that the ambulatory status of patients with cancer might be significant for survival time.

METHODS

We investigated the functional outcomes and factors influencing overall survival in 31 patients who were non-ambulatory due to MESCC and underwent decompression surgery. The functional outcome was determined by the Frankel grading system.

RESULT

Twenty-one patients (68%) improved by at least 1 Frankel grade; 17 patients (55%) became ambulatory postoperatively. Most of postoperatively ambulatory patients could undergo postoperative chemotherapy (14/17, 82%). On the other hand, only a few postoperatively non-ambulatory patients could undergo postoperative chemotherapy (2/15, 13%). We observed a complication rate of 35.5% with specific complications including wound infection, pneumonia, and deep vein thrombosis/pulmonary embolus. The median survival duration was 7.0 months. Factors that significantly affected the overall survival in univariate analyses were revised Tokuhashi score (RTS) ≥ 4, postoperative chemotherapy, ambulatory status, and complications (RTS ≥ 4, P < 0.05; postoperative chemotherapy, P < 0.001; ambulatory status, P < 0.001; complications, P < 0.01).

CONCLUSIONS

Decompression surgery for patients who are non-ambulatory due to MESCC directly contributes to functional outcomes and may indirectly contribute to overall survival. If non-ambulatory patients who are assessed as unable to tolerate chemotherapy due to poor performance status regain the ability to walk by decompression surgery, they will have a chance to receive postoperative chemotherapy, thereby increasing their chances of prolonging survival. However, postoperative complications may shorten their survival; therefore, we should carefully consider the surgical indications. RTS is useful for judging the surgical indication.

Calcific myonecrosis mimicking soft tissue sarcoma: A case report

Calcific myonecrosis is a rare soft tissue condition. The first case was reported in 1960, however, the precise pathophysiology of calcific myonecrosis remains unclear. The disease was thought to arise from compartment syndrome within a confined space resulting in necrosis and fibrosis, subsequent repeated intralesional hemorrhage, mass enlargement and calcification. Several previous reports have described calcific myonecrosis, which include the formation of calcific myonecrosis after a prolonged period of post trauma. Notably, calcific myonecrosis has typically been described in the lower legs and characteristic imaging findings have been indicated. Furthermore, surgical intervention carries a high risk of complications. In the present case report 2 cases of calcific myonecrosis that occurred after a prolonged period of time following a traumatic event that impacted the lower leg were reported. CT images revealed disruption of calcified fascia and disease expansion into the outside of the fascia. Previous reports have implied that there is late focal enlargement of calcific myonecrosis following earlier enlargement, which may be caused by herniation through muscle fascia. However, no previous publications have focused on images for evidence of late local enlargement. To the best of our knowledge, this is the first report focusing on fascial herniation of calcific myonecrosis using images. Analysis of this feature using images may aid clinicians to differentiate calcific myonecrosis from malignancies.

Atypical femoral fracture associated with bone-modifying agent for bone metastasis of breast cancer: A report of two cases

Atypical femoral fractures (AFFs) are recently observed as a complication of long-term bone-modifying agent (BMA; bisphosphonate or denosumab) therapy for bone metastases. We describe the cases of two women diagnosed with breast cancer who developed incomplete AFF associated with BMAs prescribed for bone metastases. Radiographs of their femurs revealed thickening of the lateral subtrochanteric cortex, and tomosynthesis revealed a visible fracture line in the thickened cortex. They were initially treated with conservative management; however, the incomplete fracture resulted in a complete fracture. These cases highlight two major implications. First, symptomatic incomplete AFF associated with BMAs prescribed for bone metastases should be treated with surgical prophylaxis, given the fact that fracture healing is expected to require a longer duration and an incomplete fracture might potentially progress to a complete fracture during long-term conservative management. Second, tomosynthesis is useful in identifying radiolucent fracture lines that are reliable predictors of fracture propagation.

Trabectedin is a promising antitumor agent potentially inducing melanocytic differentiation for clear cell sarcoma

Clear cell sarcoma is an aggressive soft tissue sarcoma and highly resistant to conventional chemotherapy and radiation therapy. This devastating disease is defined by EWSR1‐ATF1 fusion gene resulting from chromosomal translocation t(12;22)(q13;q12) and characterized by melanocytic differentiation. A marine‐derived antineoplastic agent, trabectedin, inhibits the growth of myxoid liposarcoma and Ewing sarcoma by causing adipogenic differentiation and neural differentiation, respectively. In this study, we examined the antitumor effects and mechanism of action of trabectedin on human clear cell sarcoma cell lines. We showed that trabectedin decreased the cell proliferation of five clear cell sarcoma cell lines in a dose‐dependent manner in vitro and reduced tumor growth of two mouse xenograft models. Flow cytometry and immunoblot analyses in vitro and immunohistochemical analysis in vivo revealed that trabectedin‐induced G2/M cell cycle arrest and apoptosis. Furthermore, trabectedin increased the expression of melanocytic differentiation markers along with downregulation of ERK activity in vitro and the rate of melanin‐positive cells in vivo. These results suggest that trabectedin has potent antitumor activity against clear cell sarcoma cells by inducing cell cycle arrest, apoptosis, and, in part, by promoting melanocytic differentiation through inactivation of ERK signaling. Our present study indicates that trabectedin is a promising differentiation‐inducing agent for clear cell sarcoma.

Therapeutic potential of TAS-115 via c-MET and PDGFRα signal inhibition for synovial sarcoma

Background

The prognosis of synovial sarcoma (SS), an aggressive soft tissue sarcoma, remains poor. We previously reported that c-MET or platelet-derived growth factor receptor α (PDGFRα) signalling pathway is related to SS progression based upon the findings of phospho-receptor tyrosine kinase (RTK) arrays. TAS-115 is a novel c-MET/ vascular endothelial growth factor receptor-targeting tyrosine kinase inhibitor that has been shown to inhibit multiple RTKs. Here we aimed to investigate the therapeutic potential of TAS-115 against SS.

Methods

We first evaluated which signalling pathway was relevant to the viability of three human SS cell lines: Yamato-SS, SYO-1 and HS-SY-II. Next, we assessed the anticancer activity and mechanism of action of TAS-115 in these SS cell lines. Finally, we compared the ability of TAS-115 to inhibit c-MET and PDGFRα phosphorylation with that of pazopanib.

Results

We classified the SS cell lines as c-MET-dependent or PDGFRα-dependent based upon the differences in the signalling pathway relevant for growth and/or survival. We also found that c-MET and PDGFRα were the primary activators of both phosphatidylinositol 3-kinase/AKT and mitogen-activated protein kinase pathways in c-MET-dependent and PDGFRα-dependent SS cells, respectively. TAS-115 treatment blocked the phosphorylation of PDGFRα as well as that of c-MET and their downstream effectors, leading to marked growth inhibition in both types of SS cell lines in in vitro and in vivo studies. Furthermore, PDGFRα phosphorylation, on at least four representative autophosphorylation sites, was impeded by TAS-115 equivalently to pazopanib.

Conclusions

These experimental results have demonstrated the significance of c-MET and PDGFRα signalling for growth and/or survival of SS tumours. TAS-115 monotherapy may benefit SS patients whose tumours are dependent upon either c-MET or PDGFRα signalling by functioning as a multiple tyrosine kinase inhibitor to suppress c-MET as well as PDGFRα pathways.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3324-3) contains supplementary material, which is available to authorized users.

Functional and therapeutic relevance of hepatocyte growth factor/c-MET signaling in synovial sarcoma

Synovial sarcoma (SS) is an aggressive soft tissue sarcoma with a poor prognosis and, thus, novel therapeutic strategies for SS are urgently required. In the present study, we investigated the functional and therapeutic relevance of hepatocyte growth factor (HGF)/c‐MET signaling in SS. Both HGF and c‐MET were highly expressed in Yamato‐SS cells, resulting in activation of c‐MET and its downstream AKT and extracellular signal‐regulated kinase signaling pathways, whereas c‐MET was expressed but not activated in SYO‐1 or HS‐SY‐II cells. c‐MET‐activated Yamato‐SS cells showed higher anchorage‐independent growth ability and less sensitivity to chemotherapeutic agents than did c‐MET‐inactivated SYO‐1 or HS‐SY‐II cells. INC280, a selective c‐MET inhibitor, inhibited growth of Yamato‐SS cells both in vitro and in vivo but not that of SYO‐1 or HS‐SY‐II cells. INC280 induced cell cycle arrest and apoptosis, and blocked phosphorylation of c‐MET and its downstream effectors in Yamato‐SS cells. Co‐expression of HGF and c‐MET in SS clinical samples correlated with a poor prognosis in patients with SS. Taken together, activation of HGF/c‐MET signaling in an autocrine fashion leads to an aggressive phenotype in SS and targeting of this signaling exerts superior antitumor effects on c‐MET‐activated SS. HGF/c‐MET expression status is a potential biomarker for identification of SS patients with a worse prognosis who can benefit from c‐MET inhibitors.

A case report of pancreatic metastasis from synovial sarcoma successfully treated by metastasectomy with adjuvant chemotherapy

INTRODUCTION

Synovial sarcoma is a malignant soft tissue sarcoma which arises near joints. The most frequent metastasis sites of synovial sarcoma are the lungs, lymph nodes, and bone. Pancreatic metastasis is quite rare; only 3 cases have been reported worldwide to date. We herein present the 4th case of pancreatic metastasis from synovial sarcoma.

METHODS AND RESULTS

A 32-year-old man underwent extended excision of synovial sarcoma in the left pelvis and femur in 2009. In 2013, follow-up contrast-enhanced computed tomography revealed a 35-mm heterogeneously enhanced mass in the pancreas body. Endoscopic ultrasound-guided fine needle aspiration of the mass revealed a diffuse proliferation of atypical spindle cells in a fascicular arrangement. Because the histology was quite similar to the resected specimen of synovial sarcoma in 2009, the mass was suspected to be a metastasis from synovial sarcoma. Laparoscopic distal pancreatectomy with adjuvant adriamycin/ifosfamide chemotherapy was subsequently performed. Synovial sarcoma-specific SS18-SSX1 (synovial sarcoma translocation, chromosome 18-synovial sarcoma X1) or SS18-SSX2 chimera mRNA was detected in the resected specimen, confirming the diagnosis of metastasis from synovial sarcoma. The patient did well for 30 months without recurrence.

CONCLUSION

This case suggests that pancreatic metastasis from synovial sarcoma can be successfully treated by metastasectomy with adjuvant chemotherapy.

Radiofrequency ablation of osteoid osteoma using a three-dimensional navigation system

OBJECTIVE

This study aimed to report the clinical outcomes for patients with osteoid osteoma (OO) treated by radiofrequency ablation (RFA) using a three-dimensional (3D) navigation system.

METHODS

We performed RFA using a 3D navigation system on 32 patients with clinically and radiologically diagnosed OO. This study included 25 males and 7 females with a median age of 20 years (range, 10-39 years). The median duration of follow-up was 18 months (range, 1-65 months). We investigated technical specifications, tumor localization, technical success, clinical success, biopsy success, complications, incomplete treatment, and recurrences.

RESULTS

Eighteen tumors were located in the femur, seven in the tibia, two in the humerus, and one each in the fibula, scapula, patella, lumbar vertebra, and acetabula. All procedures were technically successful, and pain relief was achieved in all patients. However, local recurrence developed in one patient, needing additional RFA. The clinical success rate was 96.8%. Biopsy showed OO in 12 patients (37%). Complications occurred in three patients (9%), two cases of fractures and one of osteomyelitis.

CONCLUSIONS

A 3D navigation provides real-time imaging and enables us to set the RFA needle in the correct position, particularly in case of OO-aroused complex anatomical structures. Our initial results indicated that radiofrequency ablation using a 3D navigation system is feasible and safe for patients with OO.

Treatment outcomes of Japanese patients with Ewing sarcoma: differences between skeletal and extraskeletal Ewing sarcoma

OBJECTIVE

The incidence of Ewing sarcoma is lower in non-Caucasian populations, compared with Caucasian populations, for unknown reasons. Most studies from western countries have reported improvement in outcomes following multi-agent chemotherapy, with no difference in outcome between skeletal and extraskeletal Ewing sarcoma. However, there are few studies of Ewing sarcoma in non-Caucasian populations, with especially few comparing outcomes between skeletal and extraskeletal Ewing sarcoma. Thus, the purpose of this study is to determine whether the outcomes and prognostic factors of Ewing sarcoma in the Japanese population are similar to those in Caucasian populations and to determine whether skeletal and extraskeletal Ewing sarcoma have similar outcomes in Japanese patients.

METHODS

We retrospectively evaluated the outcomes of 74 Japanese patients with Ewing sarcoma treated between 1981 and 2011 from the Osaka University Orthopaedic Oncology Group.

RESULTS

Extraskeletal Ewing sarcoma, tumors in the extremities, localized disease at presentation and diagnosis after 2000 were significantly associated with a favorable outcome. Among patients with localized disease at presentation, a significantly better outcome was observed for those with extraskeletal Ewing sarcoma, those who underwent a VDC/IE based or VAIA chemotherapy protocol, and those who were diagnosed after 2000. In the multivariable analyses, extraskeletal Ewing sarcoma was an independent predictor of increased overall survival among all patients and the subset of patients with localized disease.

CONCLUSIONS

The outcome of patients with Ewing sarcoma in Japan has improved in the last decade. The outcomes and prognostic factors are similar for Japanese and Caucasian patients, though in this series of Japanese patients, a better prognosis was observed for patients with extraskeletal rather than skeletal Ewing sarcoma.

Trabectedin is a promising antitumour agent for synovial sarcoma

Synovial sarcoma (SS) is an aggressive soft tissue tumour with poor prognosis. Using five human SS cell lines, we examined the cytotoxic effects of trabectedin (ET-743; Yondelis(®)), a novel marine natural product, which was approved in Europe for the treatment of soft tissue sarcomas (STS). The significant growth inhibitory effects were observed in all SS cell lines below nanomolar concentration of trabectedin. Furthermore, trabectedin significantly suppressed the tumour growth in xenograft models. Flow cytometer analysis in vitro and immunohistochemical analysis in vivo revealed its effect of cell cycle inhibition and apoptosis induction. We also examined the expression of ERCC1, 5 and BRCA1 in SS cell lines and clinical samples, and majority of them showed highly trabectedin-sensitive pattern as previously reported in other cancers. Our preclinical data indicated that trabectedin could be a promising therapeutic option for patients with SS.

Comparison of clinical and functional outcome between surgical treatment and carbon ion radiotherapy for pelvic chondrosarcoma

BACKGROUND

As there are no reports of studies in patients with pelvic chondrosarcoma treated with carbon ion radiotherapy (CIRT), the aim of this study was to evaluate the applicability of CIRT for patients with chondrosarcoma of the pelvis.

METHODS

The medical records of 31 patients with chondrosarcoma of the pelvis treated either by surgical resection or by CIRT between 1983 and 2014 were reviewed. There were 22 males and 9 females with a median age of 43 years (range 16-77 years). The median duration of follow-up was 66 months (range 5-289 months). Twenty-four patients underwent surgery, and 7 patients received CIRT (70.4 GyE in 16 fractions over 4 weeks).

RESULTS

The overall local recurrence rate was 32 %, and the estimated overall 5- and 10-year survival rates were 72 and 57 %, respectively. The mean Musculoskeletal Tumor Society functional score was 59 %. The treatment procedures (surgery or CIRT) did not affect overall survival (P = 0.347). However, the patients who underwent surgery had impaired function compared with those who received CIRT (P = 0.03).

CONCLUSION

Although more patients need to be monitored to assess the clinical and functional outcomes of CIRT for patients with chondrosarcoma of the pelvis, this treatment might offer an acceptable alternative.

A giant periosteal chondroma of the distal femur successfully reconstructed with synthetic bone grafts and a bioresorbable plate: a case report

Periosteal chondromas are rare benign cartilaginous tumors that arise adjacent to the cortex beneath the periosteum. These lesions are usually slow-growing and rarely exceed 3 cm in the greatest dimension. Here, we describe a 17-year-old boy who had a giant periosteal chondroma of the right distal femur, which was treated with intralesional resection and intensive curettage. In addition, we report a novel application of a bioresorbable plate in the management of the large bone defect after resection of a benign bone tumor.

Combined targeting of mTOR and c-MET signaling pathways for effective management of epithelioid sarcoma

Background

Epithelioid sarcoma (EpS) is a high-grade malignant soft-tissue sarcoma characterized by local recurrences and distant metastases. Effective treatments for EpS have not been established and thus novel therapeutic approaches against EpS are urgently required. mTOR inhibitors exert antitumor effects on several malignancies but AKT reactivation by mTOR inhibition attenuates the antitumor effects of mTOR inhibitors. This reactivation is receptor tyrosine kinase (RTK)-dependent due to a release of negative feedback inhibition. We found that c-MET was the most highly activated RTK in two human EpS cell lines, Asra-EPS and VAESBJ. Here we investigated the functional and therapeutic relevance of mTOR and/or c-MET signaling pathways in EpS both in vitro and in vivo.

Methods

We first examined the effects of an mTOR inhibitor, RAD001 (everolimus), on cell proliferation, cell cycle, AKT/mTOR signaling, and xenograft tumor growth in EpS cell lines. Next, we determined whether RAD001-induced AKT reactivation was blocked by silencing of c-MET or treatment with a selective c-MET inhibitor, INC280. Finally, we evaluated the antitumor effects of RAD001 combined with INC280 on EpS cell lines compared with either single agent or control in vitro and in vivo.

Results

Constitutive AKT phosphorylation was observed in Asra-EPS and VAESBJ cells. RAD001 suppressed EpS cell growth by inducing cell cycle arrest but enhanced AKT phosphorylation, which resulted in intrinsic resistance to mTOR inhibitors. In both EpS cell lines, RAD001-induced AKT phosphorylation was dependent on c-MET signaling. INC280 inhibited phosphorylation of c-MET and its downstream molecules, and decreased RAD001-induced phosphorylation of both AKT and ERK in EpS. Compared with a single agent or control, the combination of RAD001 and INC280 exerted superior antitumor effects on the growth of EpS cell lines in vitro and in vivo.

Conclusions

Targeting of mTOR and c-MET signaling pathways significantly abrogates the growth of EpS in preclinical models and may be a promising therapeutic approach for patients with EpS.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-4598-13-185) contains supplementary material, which is available to authorized users.

Establishment of a novel clear cell sarcoma cell line (Hewga-CCS), and investigation of the antitumor effects of pazopanib on Hewga-CCS

Background

Clear cell sarcoma (CCS) is a therapeutically unresolved, aggressive, soft tissue sarcoma (STS) that predominantly affects young adults. This sarcoma is defined by t(12;22)(q13;q12) translocation, which leads to the fusion of Ewing sarcoma gene (EWS) to activating transcription factor 1 (ATF1) gene, producing a chimeric EWS-ATF1 fusion gene. We established a novel CCS cell line called Hewga-CCS and developed an orthotopic tumor xenograft model to enable comprehensive bench-side investigation for intensive basic and preclinical research in CCS with a paucity of experimental cell lines.

Methods

Hewga-CCS was derived from skin metastatic lesions of a CCS developed in a 34-year-old female. The karyotype and chimeric transcript were analyzed. Xenografts were established and characterized by morphology and immunohistochemical reactivity. Subsequently, the antitumor effects of pazopanib, a recently approved, novel, multitargeted, tyrosine kinase inhibitor (TKI) used for the treatment of advanced soft tissue sarcoma, on Hewga-CCS were assessed in vitro and in vivo.

Results

Hewga-CCS harbored the type 2 EWS-ATF1 transcript. Xenografts morphologically mimicked the primary tumor and expressed S-100 protein and antigens associated with melanin synthesis (Melan-A, HMB45). Pazopanib suppressed the growth of Hewga-CCS both in vivo and in vitro. A phospho-receptor tyrosine kinase array revealed phosphorylation of c-MET, but not of VEGFR, in Hewga-CCS. Subsequent experiments showed that pazopanib exerted antitumor effects through the inhibition of HGF/c-MET signaling.

Conclusions

CCS is a rare, devastating disease, and our established CCS cell line and xenograft model may be a useful tool for further in-depth investigation and understanding of the drug-sensitivity mechanism.