Expression of receptor tyrosine kinases epidermal growth factor receptor and HER-2/neu in synovial sarcoma

When destiny doesn't pan out: Implications for the treatment of sarcomas after the agnostic approval of trastuzumab deruxtecan

In April 2024, the Food and Drug Administration provided accelerated approval for Trastuzumab Deruxtecan for adult patients with advanced solid tumors which have positive immunochemical staining (IHC3+) for HER2 expression, including sarcomas. There should be ample consideration prior to utilization of trastuzumab deruxtecan for patients with sarcomas, as HER2 targeted therapy has been ineffective in certain subtypes.

Synovial Sarcoma: A Complex Disease with Multifaceted Signaling and Epigenetic Landscapes

PURPOSE OF REVIEW

Aside from a characteristic SS18-SSX translocation identified in almost all cases, no genetic anomalies have been reliably isolated yet to drive the pathogenesis of synovial sarcoma. In the following review, we explore the structural units of wild-type SS18 and SSX, particularly as they relate to the transcriptional alterations and cellular pathway changes imposed by SS18-SSX.

RECENT FINDINGS

Native SS18 and SSX contribute recognizable domains to the SS18-SSX chimeric proteins, which inflict transcriptional and epigenetic changes through selective protein interactions involving the SWI/SNF and Polycomb chromatin remodeling complexes. Multiple oncogenic and developmental pathways become altered, collectively reprogramming the cellular origin of synovial sarcoma and promoting its malignant transformation. Synovial sarcoma is characterized by complex epigenetic and signaling landscapes. Identifying the operational pathways and concomitant genetic changes induced by SS18-SSX fusions could help develop tailored therapeutic strategies to ultimately improve disease control and patient survivorship.

Standard treatment and emerging drugs for managing synovial sarcoma: adult's and pediatric oncologist perspective

INTRODUCTION

in this review we discuss the standard of care for both pediatric and adult synovial sarcoma (SS), the prognostic differences between them, and the treatments available for localized and advanced diseases. We also overview the biology and the recent drugs under consideration in clinical trials on SS. Areas covered: we focus on new targeted therapies being investigated for advanced SS, especially anti-angiogenic drugs, and immunotherapy. We review all the published data and ongoing trials dedicated to SS or to soft tissue sarcoma in general, paying particular attention to the results obtained in SS patients. Expert opinion: we expect new treatment strategies to become available for SS in the near future. The ongoing and published trials on targeted therapies and immunotherapy mainly concern adult patients, but the somatic biology of pediatric SS has some similarities as in adult disease. A stronger cooperation between adult and pediatric oncologists in recent years has led to a more shared effort to find new treatment strategies for advanced SS patients, regardless of their age.

Primary monophasic synovial sarcoma of the pleura: Neoadjuvant chemotherapy followed by complete resection

We describe a rare case of primary pleural synovial sarcoma in a 27-year-old man with a 4-month history of dry cough and left-sided chest pain. A CT scan showed a large cystic mass in the left pleural cavity. The patient underwent two video-assisted thoracoscopic biopsies and the diagnosis of synovial sarcoma of the pleura was established. After neoadjuvant chemotherapy, which resulted in a partial response, the tumor was completely resected with extrapleural pneumonectomy. Pathological findings showed less than 5% of viable cancer and free surgical margins. The patient is clinically well 24 months after surgery, with no evidence of recurrent disease.

EGFR is involved in dermatofibrosarcoma protuberans progression to high grade sarcoma

Dermatofibrosarcoma protuberans (DFSP), amounting to 6% of all soft tissue sarcomas, has a slow growth rate, contrasting with a likelihood for local recurrence and a 10-20% evolution to higher-grade sarcoma, or "transformed DFSP" (DFSP-T). At molecular level, the characteristic COL1A1-PDGFB rearrangement, leading to sustained PDGFR signaling, is not linked to the evolutive potential. Here, we studied EGFR, another tyrosine kinase receptor, using laser-microdissection to select the different histologic components of DFSP (DFSP center, DFSP infiltrative periphery, DFSP-T higher-grade sarcoma), in 22 patients followed over 3 to 156 months. EGFR protein and mRNA were expressed in 13/22 patients with DFSP or DFSP-T, and increased with tumor progression, both in microdissected areas of higher-grade sarcomas and in microdissected areas of local extension. No cancer-associated EGFR gene mutation or copy-number variation, nor any KRAS, BRAF, NRAS hotspot mutations were found in any microdissected area. Among epithelial-mesenchymal transition factors tested, SNAIL 1/2 had the same expression pattern as EGFR while ZEB1/2 or TWIST1/2 did not. Using a proteome profiler phospho-kinase array on 3 DFSP and 3 DFSP-T cryopreserved tissue samples, EGFR phosphorylation was detected in each case. Among EGFR downstream pathways, we found positive correlations between phosphorylation levels of EGFR and STAT5a/b (r = 0.87, p < 0.05) and TOR (r = 0.95, p < 0.01), but not ERK in the MAPK pathway (r = -0.18, p > 0.70). We thus demonstrated that in DFSP evolution to high grade sarcoma, EGFR and SNAIL were involved, with EGFR activation and signaling through TOR and STAT5a/b downstream effectors, which could lead on to new therapies for advanced DFSP.

Survival changes in Patients with Synovial Sarcoma, 1983-2012

Background: Synovial sarcoma (SyS) is a rare malignancy that typically invades the extremities and occurs predominantly in adolescents. Studies on incidence and survival in SyS that were based on a large population had not been reported yet.

Methods: To evaluate changes in incidence and survival in SyS over three decades, we accessed data on SyS cases in each decade between 1983 and 2012 (1983-1992, 1993-2002, and 2003-2012) from the Surveillance, Epidemiology, and End Results (SEER) database. The survival difference between decades, age groups, sexes, race, pathologic types, sites, stages and socioeconomic status (SES) over three decades were accessed by comparing Kaplan-Meier curves.

Results: We located 2,070 SyS cases in 18 SEER registry regions between 1983 and 2012. Our study demonstrated that the incidence of SyS per 1,000,000 continued to increase from 0.906 to 1.348 to 1.548 in the total population and in most age groups and that the age of incidence peak was 15-29 years in three decades. But, the survival of patients with SyS did not significantly improve throughout the three decades, with 5-year survival rates of 69.4%, 61.1% and 60.5% respectively (p > 0.05). Interestingly, the widening survival gaps among races, sexes, pathological types and various SES over time were observed, with narrowing p values.

Conclusions: This study demonstrated the increasing incidence and unimproved survival rates across three decades in a large sample, indicating the urgency for further development of diagnosis, improving health care providers' awareness of SyS and lead to the development of novel treatments.

Synovial Sarcoma: Advances in Diagnosis and Treatment Identification of New Biologic Targets to Improve Multimodal Therapy

Synovial sarcoma is a translocation-associated soft-tissue malignancy that frequently affects adolescents and young adults. It is driven by one of the fusion oncoproteins SS18-SSX1, SS18-SSX2, or rarely, SS18-SSX4. Prognosis of patients with recurrent or metastatic disease is generally poor, and newer therapeutic strategies are needed. In this review, we present recent discoveries in the pathogenesis, diagnosis, and treatment of synovial sarcoma. We discuss potential therapeutic strategies to improve clinical outcomes in this disease.

Exploiting receptor tyrosine kinase co-activation for cancer therapy

Studies over the past decade have shown that many cancers have evolved receptor tyrosine kinase (RTK) co-activation as a mechanism to drive tumour progression and limit the lethal effects of therapy. This review summarises the general principles of RTK co-activation and discusses approaches to exploit this phenomenon in cancer therapy and drug discovery. Computational strategies to predict kinase co-dependencies by integrating drug screening data and kinase inhibitor selectivity profiles will also be described. We offer a perspective on the implications of RTK co-activation on tumour heterogeneity and cancer evolution and conclude by surveying emerging computational and experimental approaches that will provide insights into RTK co-activation biology and deliver new developments in effective cancer therapies.

Modeling synovial sarcoma metastasis in the mouse: PI3'-lipid signaling and inflammation

Solid tumor metastasis is a complex biology, impinged upon by a variety of dysregulated signaling pathways. PI3'-lipid signaling has been associated with metastasis and inflammation in many cancers, but the relationship between tumor cell-intrinsic PI3'-lipid signaling and inflammatory cell recruitment has remained enigmatic. Elevated PI3'-lipid signaling associates with progression of synovial sarcoma, a deadly soft tissue malignancy initiated by a t(X;18) chromosomal translocation that generates an SS18-SSX fusion oncoprotein. Here, we show in genetically engineered mouse models of locally induced expression of SS18-SSX1 or SS18-SSX2 that Pten silencing dramatically accelerated and enhanced sarcomagenesis without compromising synovial sarcoma characteristics. PTEN deficiency increased tumor angiogenesis, promoted inflammatory gene expression, and enabled highly penetrant spontaneous pulmonary metastasis. PTEN-deficient sarcomas revealed infiltrating myeloid-derived hematopoietic cells, particularly macrophages and neutrophils, recruited via PI3'-lipid-induced CSF1 expression in tumor cells. Moreover, in a large panel of human synovial sarcomas, enhanced PI3'-lipid signaling also correlated with increased inflammatory cell recruitment and CSF1R signal transduction in both macrophages and endothelial cells. Thus, both in the mouse model and in human synovial sarcomas, PI3'-lipid signaling drives CSF1 expression and associates with increased infiltration of the monocyte/macrophage lineage as well as neutrophils.

Translational research in diagnosis and management of soft tissue tumours

Finding a soft tissue mass in the superficial regions is a common event in daily clinical practice. Correct management of the diagnostic process is crucial to avoid blunders. Diagnosis is posed by pathology, although both imaging and a better understanding of the cellular and molecular mechanisms play an important a role in the characterization, staging and follow-up of soft tissue masses. Cellular and molecular mechanisms can explain either the development of chemo-resistance and the underlying pre- and post-surgery metastasis formation. These are mandatory to improve prognosis and unveil novel parameters predicting therapeutic response. Imaging mainly involves ultrasound and MR and is fundamental not only in diagnosis but also in the first step of therapy: the biopsy. Novel imaging techniques like Ultrasound Elastosonography, Dynamic Contrast-Enhanced MR imaging (DCE), Diffusion Weighted MR imaging (DWI) and MR Spectroscopy (MRS) are discussed. This paper aims at reviewing and discussing pathological methods and imaging in the diagnosis of soft tissue masses underscoring that the most appropriate treatment depends on advanced molecular and radiological studies.

Multi-platform profiling of over 2000 sarcomas: identification of biomarkers and novel therapeutic targets

Background: Drug development in sarcoma has been hampered by the rarity and heterogeneity of the disease and lack of predictive biomarkers to therapies. We assessed protein expression and gene alterations in a large number of bone and soft tissue sarcomas in order to categorize the molecular alterations, identify predictive biomarkers and discover new therapeutic targets. Methods: Data from sarcoma specimens profiled for protein expression, gene amplification/translocation and DNA sequencing was reviewed. Results: 2539 sarcoma specimens of 22 subtypes were included. TOPO2A was the most overexpressed protein at 52.8%. There was overexpression or loss of other sarcoma relevant proteins such as SPARC, PTEN and MGMT. Approximately 50% of the sarcomas expressed PD-L1 by IHC and presented with PD-1+ TILs, notably the LMS, chondrosarcomas, liposarcomas and UPS. Gene amplification/rearrangement of ALK, cMYC, HER2, PIK3CA, TOPO2A and cMET was relatively uncommon. EGFR gene amplification occurred at a rate of 16.9%. DNA sequencing of 47 genes identified mutations in 47% of the samples. The most commonly mutated genes were TP53 (26.3%) and BRCA2 (17.6%). Overexpression of TOPO2A was associated with TP53 mutation (P = 0.0001). Conclusion: This data provides the landscape of alterations in sarcoma. Future clinical trials are needed to validate these targets.

ErbB receptors as prognostic and therapeutic drug targets in bone and soft tissue sarcomas

ErbB receptors have been intensely studied to understand their importance in cancer biology and as therapeutic targets, and many ErbB inhibitors are now used in the clinical setting. A large number of studies have been conducted to examine the expression of ErbB family members in bone and soft tissue sarcomas, including osteosarcomas, synovial sarcomas, Ewing sarcomas, rhabdomyosarcomas, and so on. Nevertheless, the clinical implications of ErbB receptors remain elusive. To illustrate the potential of ErbB family members as prognostic and therapeutic drug targets in bone and soft tissue sarcomas, we summarized the molecular evidence and observations from clinical and basic trials.

Inverse prognostic impact of ErbB2 mRNA and protein expression level in tumors of soft tissue sarcoma patients

BACKGROUND

Human epidermal growth factor receptor 2 (ErbB2) is overexpressed in a variety of human malignancies. Moreover, ErbB2 has been reported to influence cancer patient survival and progression of different tumor entities. However, information regarding the prognostic impact of ErbB2 in soft tissue sarcoma (STS) patients is limited and conflicting.

MATERIAL AND METHODS

ErbB2 mRNA and protein levels were defined by quantitative real-time PCR and enzyme-linked immunosorbent assay (ELISA), and the prognostic impact of ErbB2 mRNA and protein levels in tumor tissue of 124 soft tissue sarcoma patients were investigated.

RESULTS

The median ErbB2 mRNA expression level in tumor tissue was decreased 3.9-fold compared to non-neoplastic surrounding tissue (p = 0.001). Furthermore, an increased ErbB2 mRNA expression level was associated with an improved tumor-specific survival (p = 0.01, log rank test). Multivariate Cox's proportional hazard regression analyses revealed an increased ErbB2 mRNA expression level as an independent favorable prognostic factor for tumor-specific survival of STS patients (n = 124; RR = 3.0; 95 % CI = 1.6-5.7; p < 0.001). In addition, multivariate Cox's proportional hazard regression analyses showed that an increased ErbB2 protein expression level correlated with poorer recurrence-free survival of STS patients (n = 47; RR = 9.9; 95 % CI = 1.7-59.7; p = 0.012), in particular for STS patients who received postoperative radiotherapy (n = 27; RR = 17.9; 95 % CI = 1.3-247.7; p = 0.031).

CONCLUSION

This study suggests an inverse prognostic value of ErbB2 mRNA and protein expression level.

SRC signaling is crucial in the growth of synovial sarcoma cells

Synovial sarcoma is a soft-tissue malignancy characterized by a reciprocal t(X;18) translocation encoding a chimeric transcriptional modifier. Several receptor tyrosine kinases have been found activated in synovial sarcoma; however, no convincing therapeutic concept has emerged from these findings. On the basis of the results of phosphokinase screening arrays, we here investigate the functional and therapeutic relevance of the SRC kinase in synovial sarcoma. Immunohistochemistry of phosphorylated SRC and its regulators CSK and PTP1B (PTPN1) was conducted in 30 synovial sarcomas. Functional aspects of SRC, including dependence of SRC activation on the SS18/SSX fusion proteins, were analyzed in vitro. Eventually, synovial sarcoma xenografts were treated with the SRC inhibitor dasatinib in vivo. Activated phospho (p)-(Tyr416)-SRC was detected in the majority of tumors; dysregulation of CSK or PTP1B was excluded as the reason for the activation of the kinase. Expression of the SS18/SSX fusion proteins in T-REx-293 cells was associated with increased p-(Tyr416)-SRC levels, linked with an induction of the insulin-like growth factor pathway. Treatment of synovial sarcoma cells with dasatinib led to apoptosis and inhibition of cellular proliferation, associated with reduced phosphorylation of FAK (PTK2), STAT3, IGF-IR, and AKT. Concurrent exposure of cells to dasatinib and chemotherapeutic agents resulted in additive effects. Cellular migration and invasion were dependent on signals transmitted by SRC involving regulation of the Rho GTPases Rac and RhoA. Treatment of nude mice with SYO-1 xenografts with dasatinib significantly inhibited tumor growth in vivo. In summary, SRC is of crucial biologic importance and represents a promising therapeutic target in synovial sarcoma.

A novel multi-kinase inhibitor pazopanib suppresses growth of synovial sarcoma cells through inhibition of the PI3K-AKT pathway

Synovial sarcoma is an aggressive soft tissue sarcoma with only a modest response to conventional cytotoxic agents. In the present study, we evaluated the potential antitumor effects of a novel anti-angiogenesis agent, pazopanib, against synovial sarcoma cells. We found that pazopanib directly inhibited the growth of synovial sarcoma cells by inducing G1 arrest. Multiplex analyses revealed that the PI3K-AKT pathway was highly suppressed in pazopanib-sensitive synovial sarcoma cells. Furthermore, administration of pazopanib highly suppressed the tumor growth in a xenograft model. Taken together, these results suggest pazopanib as a possible agent against synovial sarcoma and may warrant further clinical studies.

Pediatric sarcomas: translating molecular pathogenesis of disease to novel therapeutic possibilities

Pediatric sarcomas represent a diverse group of rare bone and soft tissue malignancies. Although the molecular mechanisms that propel the development of these cancers are not well understood, identification of tumor-specific translocations in many sarcomas has provided significant insight into their tumorigenesis. Each fusion protein resulting from these chromosomal translocations is thought to act as a driving force in the tumor, either as an aberrant transcription factor (TF), constitutively active growth factor, or ligand-independent receptor tyrosine kinase. Identification of transcriptional targets or signaling pathways modulated by these oncogenic fusions has led to the discovery of potential therapeutic targets. Some of these targets have shown considerable promise in preclinical models and are currently being tested in clinical trials. This review summarizes the molecular pathology of a subset of pediatric sarcomas with tumor-associated translocations and how increased understanding at the molecular level is being translated to novel therapeutic advances.

Downstream and intermediate interactions of synovial sarcoma-associated fusion oncoproteins and their implication for targeted therapy

Synovial sarcoma (SS), an aggressive type of soft tissue tumor, occurs mostly in adolescents and young adults. The origin and molecular mechanism of the development of SS remain only partially known. Over 90% of SS cases are characterized by the t(X;18)(p11.2;q11.2) translocation, which results mainly in the formation of SS18-SSX1 or SS18-SSX2 fusion genes. In recent years, several reports describing direct and indirect interactions of SS18-SSX1/SSX2 oncoproteins have been published. These reports suggest that the fusion proteins particularly affect the cell growth, cell proliferation, TP53 pathway, and chromatin remodeling mechanisms, contributing to SS oncogenesis. Additional research efforts are required to fully explore the protein-protein interactions of SS18-SSX oncoproteins and the pathways that are regulated by these partnerships for the development of effective targeted therapy.

Targeted agents for sarcoma: is individualized therapy possible in such a diverse tumor type?

A wide variety of cytogenetic abnormalities and molecular pathways have been implicated in the pathogenesis of sarcoma, and significant progress has been made in the past decade toward identifying potential therapeutic targets. However, apart from gastrointestinal stromal tumors (GISTs) and dermatofibrosarcoma protuberans (DFSP), little progress has been made toward translating that knowledge into effective therapeutic strategies. The identification of activating KIT mutations in the majority of GISTs was a defining moment that led to the first effective targeted therapy for sarcoma, and the subsequent use of imatinib mesylate has revolutionized the treatment of GISTs. Beyond imatinib, the most promising agents to date--and the agents most extensively studied--are the multitargeted tyrosine kinase inhibitors. Several other classes of agents have also shown some activity in soft tissue sarcomas, including mammalian target of rapamycin inhibitors, inhibitors of growth factor receptors, histone deacetylase inhibitors, agents that modulate the p53 pathway, inhibitors of molecular chaperone proteins (eg, heat shock protein 90 [Hsp90]), and other signal transduction inhibitors. Despite a large number of completed and ongoing phase II studies, few agents have moved to phase III testing, and much work remains to be done to fully validate the identified targets and determine the optimal treatment strategy. Ongoing studies are exploring a wide range of combination strategies. This review will highlight some of the emerging targeted therapies that appear to hold promise and may eventually contribute to improved systemic therapy for sarcoma.

Molecular characterization of synovial sarcoma in children and adolescents: evidence of akt activation

Synovial sarcoma (SS) is the most frequent nonrhabdomyosarcomatous soft tissue sarcoma encountered in adolescents and young adults, and despite advances in the treatment of local disease, metastases remain the main cause of death. The aim of this study was to characterize a single-center series of pediatric SS molecularly to seek any biomarkers or pathways that might make suitable targets for new agents. Seventeen cases of pediatric SS showing the SYT-SSX fusion transcript were screened immunohistochemically, biochemically, molecularly, and cytogenetically (depending on the available material) to investigate any expression/activation of epidermal growth factor receptor, platelet-derived growth factor receptor alpha (PDGFRalpha), PDGFRbeta, Akt, and deregulated Wnt pathway. The most relevant outcome was the finding of activated epidermal growth factor receptor, PDGFRalpha, and PDGFRbeta, which activated Akt in both the monophasic and biphasic histologic subtypes. Consistently, Akt activation was completely abolished in an SS cell line assay when stimulated by PDGF-AA and treated with the phosphatidylinositol 3-kinase inhibitor LY294002. Our results also showed the nuclear localization of beta-catenin and cyclin D1 gene products in monophasic SS and the movement of beta-catenin into the cytoplasm in the glandular component of the biphasic subtype. Although they need to be confirmed in larger series, these preliminary data suggest that therapeutic strategies including specific inhibitors of the phosphatidylinositol 3-kinase/Akt pathway might be exploited in SS.

Novel targeted therapies in the treatment of soft-tissue sarcomas

Systemic therapy options for sarcomas historically have been limited once these tumors become resistant to traditional cytotoxic chemotherapy. Ongoing preclinical research into their biology and clinical trials based on rational biologic targeting have identified novel therapies. For example, the success of imatinib in gastrointestinal stromal tumor has led to the use of other tyrosine kinase inhibitors in other sarcoma subtypes. Other novel therapies include targeting of the mTOR pathway, and IGF-1 receptor. The heterogeneity of these tumors demands intelligently designed protocols in recognizing efficacy that may be restricted to certain histologic subtypes. This article will cover recent trials of new biologic agents in sarcomas that have exhibited promising activity.

Adaptor protein Crk induces Src-dependent activation of p38 MAPK in regulation of synovial sarcoma cell proliferation

The adaptor protein Crk mediates intracellular signaling related to cell motility and proliferation and is implicated in human tumorigenesis. The role of Crk in the growth of human sarcoma has remained unclear, however. The present study shows that Crk-induced activation of Src and subsequent signaling by p38 mitogen-activated protein kinase (MAPK) contribute to the enhanced proliferation of human synovial sarcoma cells. Depletion of Crk by RNA interference markedly inhibited proliferation of the synovial sarcoma cell lines HS-SYII, SYO-1, and Fuji as well as prevented anchorage-independent growth. Conversely, reconstitution with CrkII by authentic small interfering RNA-resistant Crk gene restored proliferation in Crk-silenced SYO-1 cells. Crk-depleted synovial sarcoma cells manifested enhanced transcriptional activity and expression of the p16(INK4A) gene, resulting in their accumulation in G(1) phase of the cell cycle. In response to hepatocyte growth factor stimulation, Crk prominently induced the tyrosine phosphorylation of Grb2-associated binder 1 through activation of Src and focal adhesion kinase, and the Src family kinase inhibitor PP2 almost completely inhibited the proliferation of SYO-1 cells. Crk also induced the phosphorylation of p38 MAPK, and SB203580, a p38 MAPK-specific inhibitor, increased expression of p16(INK4A) gene in SYO-1 cells. Furthermore, SB203580 or depletion of p38 MAPK by small interfering RNA suppressed both the phosphorylation of Akt triggered by hepatocyte growth factor and the proliferation of SYO-1 cells. These results suggest that Crk promotes proliferation of human synovial sarcoma cells through activation of Src and its downstream signaling by a novel p38 MAPK-Akt pathway, with these signaling molecules providing potent new targets for molecular therapeutics.

Recent advances in the molecular pathology of soft tissue sarcoma: implications for diagnosis, patient prognosis, and molecular target therapy in the future

In the present paper, recent advances in the molecular pathology of soft tissue sarcomas (STS) and the implications for their prognostic value are reviewed, and the potential targets of molecular therapy are discussed. According to the molecular genetic aspect, STS are divided into two groups: chromosome translocation-associated sarcomas and sarcomas without specific translocation. In the former group,specific fusion transcripts, such as SS18–SSX, EWS–FLI1, and PAX3–FKHR, could be detected in synovial sarcoma, Ewing's sarcoma and primitive neuroectodermal tumor, and alveolar rhabdomyosarcoma,respectively. The direct or indirect interactions between these fusion transcripts and cell cycle regulators have been elucidated by several investigators. Therefore, these fusion transcripts are promising candidates as molecular targets. As evaluated in carcinomas,alterations of several tumor-suppressor genes and adhesion molecules and overexpression of growth factors and their receptors have been extensively assessed in STS. In mixed-type STS, epidermal growth factor receptor overexpression was associated with decreased overall survival, suggesting the beneficial role of epidermal growth factor receptor inhibitors in STS. In malignant rhabdoid tumor and epithelioid sarcoma, frequent alteration of the SMARCB1/INI1 tumor-suppressor gene and the loss of its protein have been demonstrated, indicating that this molecule could be an effective target of these sarcomas. In sarcomas with epithelioid differentiation,such as synovial sarcoma and epithelioid sarcoma, overexpression of dysadherin, which downregulates E-cadherin expression, was a poor prognostic factor. In conclusion, further studies are necessary to search for effective and specific molecules for the inhibition of tumor growth in each type of STS, especially in sarcomas without specific translocation.

Combined vascular endothelial growth factor receptor/epidermal growth factor receptor blockade with chemotherapy for treatment of local, uterine, and metastatic soft tissue sarcoma

PURPOSE

Soft tissue sarcoma (STS) is a rare heterogeneous malignancy. Overall survival has been stagnant for decades, primarily because systemic therapies are ineffective versus metastases, the leading cause of STS lethality. Consequently, we examined whether tyrosine kinase receptors active in STS growth signaling might be blockable and whether multireceptor blockade might synergize with low-dose STS chemotherapy by therapeutically affecting STS cells and their associated microenvironment.

EXPERIMENTAL DESIGN

Vandetanib (AstraZenca), a tyrosine kinase inhibitor of vascular endothelial growth factor receptor 2 and epidermal growth factor receptor, was evaluated alone and with chemotherapy in vitro and in vivo in three human STS nude mouse xenograft models of different STS locations (muscle, uterus, lung), stages (primary, metastatic), and subtypes (leiomyosarcoma, fibrosarcoma, uterine sarcoma: luciferase-expressing MES-SA human uterine sarcoma cells surgically implanted into uterine muscularis with bioluminescence tumor growth assessment; developed by us).

RESULTS

In vitro, human STS cells were sensitive to vandetanib. Vandetanib alone and with chemotherapy statistically significantly inhibited leiomyosarcoma local growth and fibrosarcoma lung metastasis. Direct injection of MES-SA into nude mice uterine muscularis resulted in high tumor take (88%), whereas s.c. injection resulted in no growth, suggesting microenvironmental tumor growth modulation. Vandetanib alone and with chemotherapy statistically significantly inhibited uterine sarcoma growth. In all models, vandetanib induced increased apoptosis, decreased tumor cell proliferation, and decreased angiogenesis.

CONCLUSIONS

Vandetanib has antitumor effects against human STS subtypes in vitro and in vivo, where it also affects the tumor-associated microenvironment. Given the urgent need for better systemic approaches to STS, clinical trials evaluating vandetanib, perhaps with low-dose chemotherapy, seem warranted.

High expression of neuropeptide Y1 receptors in ewing sarcoma tumors

PURPOSE

Peptide receptors are frequently overexpressed in human tumors, allowing receptor-targeted scintigraphic imaging and therapy with radiolabeled peptide analogues. Neuropeptide Y (NPY) receptors are new candidates for these applications, based on their high expression in specific cancers. Because NPY receptors are expressed in selected sarcoma cell lines and because novel treatment options are needed for sarcomas, this study assessed the NPY receptor in primary human sarcomas.

EXPERIMENTAL DESIGN

Tumor tissues of 88 cases, including Ewing sarcoma family of tumors (ESFT), synovial sarcomas, osteosarcomas, chondrosarcomas, liposarcomas, angiosarcomas, rhabdomyosarcomas, leiomyosarcomas, and desmoid tumors, were investigated for NPY receptor protein with in vitro receptor autoradiography using (125)I-labeled NPY receptor ligands and for NPY receptor mRNA expression with in situ hybridization.

RESULTS

ESFT expressed the NPY receptor subtype Y1 on tumor cells in remarkably high incidence (84%) and density (mean, 5,314 dpm/mg tissue). Likewise, synovial sarcomas expressed Y1 on tumor cells in high density (mean, 7,497 dpm/mg; incidence, 40%). The remaining tumors expressed NPY receptor subtypes Y1 or Y2 at lower levels. Moreover, many of the sarcomas showed Y1 expression on intratumoral blood vessels. In situ hybridization for Y1 mRNA confirmed the autoradiography results.

CONCLUSIONS

NPY receptors are novel molecular markers for human sarcomas. Y1 may inhibit growth of specific sarcomas, as previously shown in an in vivo mouse model of human ESFT. The high Y1 expression on tumor cells of ESFT and synovial sarcomas and on blood vessels in many other sarcomas represents an attractive basis for an in vivo tumor targeting.

Epidermal growth factor receptor blockade in combination with conventional chemotherapy inhibits soft tissue sarcoma cell growth in vitro and in vivo

PURPOSE

The epidermal growth factor receptor (EGFR) is highly expressed in many human soft tissue sarcomas (STS). However, EGFR blockade has not apparently been used for human STS therapy; therefore, we examined the in vitro and in vivo effects and the underlying mechanisms before considering EGFR blockade as a therapy for STS patients.

EXPERIMENTAL DESIGN

Human STS tissues and cell lines were used to study EGFR expression and activation. Western blot analysis was used to evaluate effects of EGFR activation on downstream signaling. Cell culture assays were used to assess the effect of EGF stimulation as well as EGFR blockade (using an EGFR tyrosine kinase inhibitor, Iressa; AstraZeneca) on STS cell growth, apoptosis, and chemosensitivity. An in vivo study (HT1080 human fibrosarcoma cell line in nude/nude mice: Iressa, doxorubicin, Iressa + doxorubicin, vehicle) was used to examine tumor growth; pEGFR, proliferating cell nuclear antigen, and terminal deoxyribonucleotide transferase-mediated nick-end labeling staining helped assess the effect of therapy in vivo on STS EGFR activation, proliferation, and apoptosis.

RESULTS

EGFR was expressed and activated in STS cell lines and tumors, probably due to ligand binding rather than EGFR mutation. Stimulation caused activation of AKT and mitogen-activated protein kinase pathways. EGFR blockade inhibited these effects and also caused increased apoptosis, a p53-independent G(0)-G(1) cell cycle arrest, and decreased cyclin D1 expression. In vivo, Iressa + doxorubicin had markedly synergistic anti-STS effects.

CONCLUSION

EGFR blockade combined with conventional chemotherapy results in anti-human STS activity in vitro and in vivo, suggesting the possibility that combining these synergistic treatments will improve anti-STS therapy.

Therapeutic Potential of Directed Tyrosine Kinase Inhibitor Therapy in Sarcomas

Background

Sarcomas are rare mesenchymally derived tumors for which there are limited treatment options. This paper discusses the current therapeutic potential of directed tyrosine kinase inhibitors (TKIs) in sarcoma.

Methods

The authors review antibody-based strategies and small molecular inhibitors of TKIs, with specific emphasis placed on the potential use of these targeted agents as therapeutic options for the treatment of sarcomas that are not gastrointestinal stromal tumors.

Results

Many TKs have been shown to be mutated or overexpressed in human sarcoma tumors and cell lines and may serve as potential targets for promising new sarcoma therapies. Furthermore, the novel mechanism of targeting TKs may complement the antitumor activity of existing sarcoma treatment options.

Conclusions

TKIs such as imatinib, sunitinib, and sorefanib are promising new therapeutic options for the management of patients with soft tissue sarcoma.

EGFR and gastrointestinal stromal tumor: an immunohistochemical and FISH study of 82 cases

Gastrointestinal stromal tumor is the most common mesenchymal neoplasm of the gastrointestinal tract. Mutually exclusive KIT or platelet-derived growth factor receptor-alpha mutations are key events in gastrointestinal stromal tumor pathogenesis, and specific treatment targeting KIT/platelet-derived growth factor receptor-alpha activation is available. Epidermal growth factor receptor plays an important role in cancer biology and also constitutes a promising molecular target of therapy. Very few reports have been published in the literature about the relationship between gastrointestinal stromal tumor and epidermal growth factor receptor. The aim of this study was to investigate epidermal growth factor receptor immunohistochemical expression and epidermal growth factor receptor gene amplification in 82 consecutive gastrointestinal stromal tumor cases using tissue microarray technique. Hematoxylin- and eosin-stained sections and clinical information were reviewed, and expression of CD117 (KIT), CD34 and epidermal growth factor receptor was investigated by immunohistochemistry. Epidermal growth factor receptor gene copy number was determined using fluorescence in situ hybridization. Immunohistochemistry revealed that CD117 and CD34 were expressed in 96 and 57% of tumors, respectively. Variable epidermal growth factor receptor protein immunohistochemical overexpression was detected in 96% of gastrointestinal stromal tumor cases, but none of the 75 cases with represented tumor tissue cores and countable fluorescence signals exhibited epidermal growth factor receptor gene amplification by fluorescence in situ hybridization. These results show that there is no correlation between epidermal growth factor receptor protein overexpression by immunohistochemistry and epidermal growth factor receptor gene amplification by fluorescence in situ hybridization. Considering that the mechanisms of epidermal growth factor receptor protein overexpression are not well understood and the possibility that anti-epidermal growth factor receptor therapy may be beneficial for patients with gastrointestinal stromal tumor that overexpresses epidermal growth factor receptor, additional studies are encouraged.

Molecular detection of SS18-SSX fusion gene transcripts by cRNA in situ hybridization in synovial sarcoma using formalin-fixed, paraffin-embedded tumor tissue specimens

SS18-SSX fusion genes resulting from a chromosomal translocation t(X;18)(p11.2;q11.2) are a genetic hallmark of synovial sarcoma. Although such cytogenetic or molecular aberrations have mostly been detected by fluorescence in situ hybridization or reverse transcription-polymerase chain reaction, the expression of SS18-SSX has been poorly investigated at a cellular or tissue level. In this study, biotinylated tyramide (BT)-based in situ hybridization (ISH) was performed to detect SS18-SSX transcripts using formalin-fixed, paraffin-embedded tissues from 15 synovial sarcomas. Digoxigenin-labeled cRNA probes flanking the fusion points of SS18-SSX1 and SS18-SSX2 were generated by in vitro transcription, and hybridized signals were detected by a streptavidin-biotin complex method after chemical enhancement with BT. The localizations of signals were compared with the immunohistochemical expressions of epithelial or neuroectodermal markers and those of cell adhesion including cytokeratins (CAM5.2, AE1/AE3, CK7), epithelial membrane antigen, E-cadherin, beta-catenin, c-erbB-2 (HER2/neu), CD56, and claudin-1. The ISH signals of the SS18-SSX transcripts were identified in 13 synovial sarcomas, and their fusion types correlated with those determined by reverse transcription-polymerase chain reaction. In biphasic tumors, the ISH signals tended to localize to epithelial areas, whereas spindle-cell areas or monophasic fibrous tumors showed a less intense or focal expression pattern. Notably, the expression patterns of AE1/AE3, CK7, and c-erbB-2 often colocalized with the ISH signals (7 of 11 cases positive for each marker). Our results suggest that BT-based ISH can be used as a molecular technique for the detection of SS18-SSX using formalin-fixed, paraffin-embedded tissues.

Oncogene coexpression in mesenchymal neoplasia correlates with EGF transcription

Epidermal growth factor (EGF) is a potent mitogenic factor for cells of mesodermal and ectodermal origin, and its over-expression is associated with a variety of cancers. We asked whether oncogene coexpression occurs in mesenchymal neoplasms, if coexpression correlates with EGF transcription, and whether coexpression can be attributed to the EGF-induced overexpression of oncogenes. We quantified the mRNA concentrations of EGF and 14 oncogenes in 42 primary sarcomas, 31 benign tumors, and 10 skeletal muscle controls, and compared mRNA concentrations and gene pair correlations in EGF positive (EGF+) tumors to transcript concentrations and correlations in EGF negative (EGF-) tumors. Transcripts were detected by real time reverse transcription-polymerase chain reaction. Pearson's correlation coefficients identified gene associations, and gene synchrony associated with EGF expression was evaluated using chi square. Transcript concentrations in tumors were compared graphically and with t tests. Gene correlations predominated in EGF+ benign tumors and in EGF- primary sarcomas. The dichotomy in oncogene coexpression evident in benign and malignant tumors could not be attributed to statistical differences in mRNA content between EGF+ and EGF- tumors. EGF may enhance, or may indicate the presence of, oncogene coexpression in benign mesenchymal lesions, but counters gene synchronization in sarcomas.

Clinical relevance of molecular genetics to paediatric sarcomas

The application of cytogenetic and molecular genetic analyses to paediatric sarcomas has identified a number of characteristic changes associated with types and subtypes of sarcomas. This has led to increased understanding of the underlying molecular biology of some sarcomas and provided an important adjunct to standard morphological and immunohistochemical diagnoses. Characteristic genetic abnormalities, particularly specific chromosome translocations and associated fusion genes, have diagnostic and in some cases prognostic value. There is also the potential to detect micrometastastic disease. Fusion genes are most readily detected by fluorescence in situ hybridisation and reverse transcription-PCR technologies. The expression profiles of tumours with specific fusion genes are characteristically similar and the molecular signatures of sarcomas are also proving to be of diagnostic and prognostic value. Furthermore, fusion genes and other emerging molecular events associated with sarcomas represent potential targets for novel therapeutic approaches which are desperately required to improve the outcome of children with certain categories of sarcoma, including rhabdomyosarcomas and the Ewing's family of tumours. Increased understanding of the molecular biology of sarcomas is leading towards more effective treatments which may complement or be less toxic than conventional radiotherapy and cytotoxic chemotherapy. Here we review paediatric sarcomas that have associated molecular genetic changes which can increase diagnostic and prognostic accuracy and impact on clinical management.