Prognostic and therapeutic relevance of the IGF pathway in Ewing's sarcoma patients

RNA-binding proteins in bone pathophysiology

Bone remodelling is a highly regulated process that maintains mineral homeostasis and preserves bone integrity. During this process, intricate communication among all bone cells is required. Indeed, adapt to changing functional situations in the bone, the resorption activity of osteoclasts is tightly balanced with the bone formation activity of osteoblasts. Recent studies have reported that RNA Binding Proteins (RBPs) are involved in bone cell activity regulation. RBPs are critical effectors of gene expression and essential regulators of cell fate decision, due to their ability to bind and regulate the activity of cellular RNAs. Thus, a better understanding of these regulation mechanisms at molecular and cellular levels could generate new knowledge on the pathophysiologic conditions of bone. In this Review, we provide an overview of the basic properties and functions of selected RBPs, focusing on their physiological and pathological roles in the bone.

Insulin Receptor Isoforms and Insulin Growth Factor-like Receptors: Implications in Cell Signaling, Carcinogenesis, and Chemoresistance

This comprehensive review thoroughly explores the intricate involvement of insulin receptor (IR) isoforms and insulin-like growth factor receptors (IGFRs) in the context of the insulin and insulin-like growth factor (IGF) signaling (IIS) pathway. This elaborate system encompasses ligands, receptors, and binding proteins, giving rise to a wide array of functions, including aspects such as carcinogenesis and chemoresistance. Detailed genetic analysis of IR and IGFR structures highlights their distinct isoforms, which arise from alternative splicing and exhibit diverse affinities for ligands. Notably, the overexpression of the IR-A isoform is linked to cancer stemness, tumor development, and resistance to targeted therapies. Similarly, elevated IGFR expression accelerates tumor progression and fosters chemoresistance. The review underscores the intricate interplay between IRs and IGFRs, contributing to resistance against anti-IGFR drugs. Consequently, the dual targeting of both receptors could present a more effective strategy for surmounting chemoresistance. To conclude, this review brings to light the pivotal roles played by IRs and IGFRs in cellular signaling, carcinogenesis, and therapy resistance. By precisely modulating these receptors and their complex signaling pathways, the potential emerges for developing enhanced anti-cancer interventions, ultimately leading to improved patient outcomes.

Molecularly Defined Subsets of Ewing Sarcoma Tumors Differ in Their Responses to IGF1R and WEE1 Inhibition

PURPOSE

Targeted cancer therapeutics have not significantly benefited patients with Ewing sarcoma with metastatic or relapsed disease. Understanding the molecular underpinnings of drug resistance can lead to biomarker-driven treatment selection.

EXPERIMENTAL DESIGN

Receptor tyrosine kinase (RTK) pathway activation was analyzed in tumor cells derived from a panel of Ewing sarcoma tumors, including primary and metastatic tumors from the same patient. Phospho-RTK arrays, Western blots, and IHC were used. Protein localization and the levels of key markers were determined using immunofluorescence. DNA damage tolerance was measured through PCNA ubiquitination levels and the DNA fiber assay. Effects of pharmacologic inhibition were assessed in vitro and key results validated in vivo using patient-derived xenografts.

RESULTS

Ewing sarcoma tumors fell into two groups. In one, IGF1R was predominantly nuclear (nIGF1R), DNA damage tolerance pathway was upregulated, and cells had low replication stress and RRM2B levels and high levels of WEE1 and RAD21. These tumors were relatively insensitive to IGF1R inhibition. The second group had high replication stress and RRM2B, low levels of WEE1 and RAD21, membrane-associated IGF1R (mIGF1R) signaling, and sensitivity to IGF1R or WEE1-targeted inhibitors. Moreover, the matched primary and metastatic tumors differed in IGF1R localization, levels of replication stress, and inhibitor sensitivity. In all instances, combined IGF1R and WEE1 inhibition led to tumor regression.

CONCLUSIONS

IGF1R signaling mechanisms and replication stress levels can vary among Ewing sarcoma tumors (including in the same patient), influencing the effects of IGF1R and WEE1 treatment. These findings make the case for using biopsy-derived predictive biomarkers at multiple stages of Ewing sarcoma disease management.

Dysregulated heparan sulfate proteoglycan metabolism promotes Ewing sarcoma tumor growth

The Ewing sarcoma family of tumors is a group of malignant small round blue cell tumors (SRBCTs) that affects children, adolescents, and young adults. The tumors are characterized by reciprocal chromosomal translocations that generate chimeric fusion oncogenes, the most common of which is EWSR1-FLI1. Survival is extremely poor for patients with metastatic or relapsed disease, and no molecularly-targeted therapy for this disease currently exists. The absence of a reliable genetic animal model of Ewing sarcoma has impaired investigation of tumor cell/microenvironmental interactions in vivo. We have developed a new genetic model of Ewing sarcoma based on Cre-inducible expression of human EWSR1-FLI1 in wild type zebrafish, which causes rapid onset of SRBCTs at high penetrance. The tumors express canonical EWSR1-FLI1 target genes and stain for known Ewing sarcoma markers including CD99. Growth of tumors is associated with activation of the MAPK/ERK pathway, which we link to dysregulated extracellular matrix metabolism in general and heparan sulfate catabolism in particular. Targeting heparan sulfate proteoglycans with the specific heparan sulfate antagonist Surfen reduces ERK1/2 signaling and decreases tumorigenicity of Ewing sarcoma cells in vitro and in vivo. These results highlight the important role of the extracellular matrix in Ewing sarcoma tumor growth and the potential of agents targeting proteoglycan metabolism as novel therapies for this disease.

The Role of Tyrosine Kinases as a Critical Prognostic Parameter and Its Targeted Therapies in Ewing Sarcoma

Ewing sarcoma (ES) is a rare, highly aggressive, bone, or soft tissue-associated tumor. Although this sarcoma often responds well to initial chemotherapy, 40% of the patients develop a lethal recurrence of the disease, with death recorded in 75-80% of patients with metastatic ES within 5 years, despite receiving high-dose chemotherapy. ES is genetically well-characterized, as indicated by the EWS-FLI1 fusion protein encoded as a result of chromosomal translocation in 80-90% of patients with ES, as well as in ES-related cancer cell lines. Recently, tyrosine kinases have been identified in the pathogenesis of ES. These tyrosine kinases, acting as oncoproteins, are associated with the clinical pathogenesis, metastasis, acquisition of self-renewal traits, and chemoresistance of ES, through the activation of various intracellular signaling pathways. This review describes the recent progress related to cellular and molecular functional roles of tyrosine kinases in the progression of ES.

Transcriptome profiling of Ewing sarcomas - treatment resistance pathways and IGF-dependency

Ewing sarcomas (ESs) are aggressive sarcomas driven by EWS fusion genes. We sought to investigate whether whole-transcriptome sequencing (RNA-seq) could be used to detect patterns associated with chemotherapy response or tumor progression after first-line treatment. Transcriptome sequencing (RNA-seq) of 13 ES cases was performed. Among the differentially expressed pathways, we identified IGF2 expression as a potential driver of chemotherapy response and progression. We investigated the effect of IGF2 on proliferation, radioresistance, apoptosis, and the transcriptome pattern in four ES cell lines and the effect of IGF2 expression in a validation series of 14 patients. Transcriptome analysis identified differentially expressed genes (adj. P < 0.005) and pathways associated with chemotherapy response (285 genes), short overall survival (662 genes), and progression after treatment (447 genes). Imprinting independent promoter P3-mediated IGF2 expression was identified in a subset of cases with aggressive clinical course. In ES cell lines, IGF2 induced proliferation, but promoted radioresistance only in CADO cells. High IGF2 expression was also significantly associated with shorter overall survival in patients with ES. Transcriptome analysis of the clinical samples and the cell lines revealed an IGF-dependent signature, potentially related to a stem cell-like phenotype. Transcriptome analysis is a potentially powerful complementary tool to predict the clinical behavior of ES and may be utilized for clinical trial stratification strategies and personalized oncology. Certain gene signatures, for example, IGF-related pathways, are coupled to biological functions that could be of clinical importance. Finally, our results indicate that IGF inhibition may be successful as a first-line therapy in conjunction with conventional radiochemotherapy for a subset of patients.

Introducing fluorescence guided surgery into orthopedic oncology: A systematic review of candidate protein targets for Ewing sarcoma

Ewing sarcoma (ES), an aggressive bone and soft‐tissue tumor, is treated with chemotherapy, radiotherapy, and surgery. Intra‐operative distinction between healthy and tumorous tissue is of paramount importance but challenging, especially after chemotherapy and at complex anatomical locations. Near infrared (NIR) fluorescence‐guided surgery (FGS) is able to facilitate the determination of tumor boundaries intra‐operatively, improving complete resection and therefore survival. This review evaluates potential ES‐specific proteins from the literature as targets for NIR FGS.

Caveolin-1 promotes Ewing sarcoma metastasis regulating MMP-9 expression through MAPK/ERK pathway

Ewing sarcoma (ES) is a bone and soft tissue sarcoma affecting mostly children and young adults. Caveolin-1 (CAV1) is a well-known target of EWS/FLI1, the main driver of ES, with an oncogenic role in ES. We have previously described how CAV1 is able to induce metastasis in ES via matrix metalloproteinase-9 (MMP-9). In the present study we showed how CAV1 silencing in ES reduced MEK1/2 and ERK1/2 phosphorylation. Accordingly, chemical inhibition of MEK1/2 resulted in reduction in MMP-9 expression and activity that correlated with reduced migration and invasion. IQ Motif Containing GTPase Activating Protein 1 (IQGAP1) silencing reduced MEK1/2 and ERK1/2 phosphorylation and MMP-9 expression. Furthermore, IQGAP1 silenced cells showed a marked decrease in their migratory and invasive capacity. We demonstrated that CAV1 and IQGAP1 localize in close proximity at the cellular edge, thus IQGAP1 could be the connecting node between CAV1 and MEK/ERK in ES metastatic phenotype. Analysis of the phosphorylation profile of CAV1-silenced cells showed a decrease of p-ribosomal protein S6 (RPS6). RPS6 can be phosphorylated by p90 ribosomal S6 kinases (RSK) proteins. CAV1-silenced cells showed reduced levels of p-RSK1 and treatment with U0126 provoked the same effect. Despite not affecting ERK1/2 and RPS6 phosphorylation status neither MMP-9 expression nor activity, RSK1 silencing resulted in a reduced migratory and invasive capacity in vitro and reduced incidence of metastases in vivo in a novel orthotopic model. The present work provides new insights into CAV1-driven metastatic process in ES unveiling novel key nodes.

Insulin-Like Growth Factor (IGF) Pathway Targeting in Cancer: Role of the IGF Axis and Opportunities for Future Combination Studies

Despite a strong preclinical rationale for targeting the insulin-like growth factor (IGF) axis in cancer, clinical studies of IGF-1 receptor (IGF-1R)-targeted monotherapies have been largely disappointing, and any potential success has been limited by the lack of validated predictive biomarkers for patient enrichment. A large body of preclinical evidence suggests that the key role of the IGF axis in cancer is in driving treatment resistance, via general proliferative/survival mechanisms, interactions with other mitogenic signaling networks, and class-specific mechanisms such as DNA damage repair. Consequently, combining IGF-targeted agents with standard cytotoxic agents, other targeted agents, endocrine therapies, or immunotherapies represents an attractive therapeutic approach. Anti-IGF-1R monoclonal antibodies (mAbs) do not inhibit IGF ligand 2 (IGF-2) activation of the insulin receptor isoform-A (INSR-A), which may limit their anti-proliferative activity. In addition, due to their lack of specificity, IGF-1R tyrosine kinase inhibitors are associated with hyperglycemia as a result of interference with signaling through the classical metabolic INSR-B isoform; this may preclude their use at clinically effective doses. Conversely, IGF-1/IGF-2 ligand-neutralizing mAbs inhibit proliferative/anti-apoptotic signaling via IGF-1R and INSR-A, without compromising the metabolic function of INSR-B. Therefore, combination regimens that include these agents may be more efficacious and tolerable versus IGF-1R-targeted combinations. Herein, we review the preclinical and clinical experience with IGF-targeted therapies to-date, and discuss the rationale for future combination approaches as a means to overcome treatment resistance.

The role of AXL and the in vitro activity of the receptor tyrosine kinase inhibitor BGB324 in Ewing sarcoma

New targets for Ewing sarcoma (ES) patients are urgently needed. Therefore, we investigated the expression and genetic aberrations of the oncogenic receptor tyrosine kinase (RTK) AXL in ES and determined the efficacy of AXL targeting on cell viability and migration. First, AXL and Gas6 (ligand) mRNA expression was determined by RT-PCR on 29 ES samples. Low, medium and high AXL mRNA expression was observed in 31% (n = 9), 48% (n = 14) and 21% (n = 6) of samples. Gas6 was abundantly present in all specimens. We next tested AXL protein expression immunohistochemically in 36 tumors (primary, post-chemotherapy, metastasized and relapsed samples) from 25 ES patients. Low, medium and high AXL protein expression was observed in 17% (n = 6), 19% (n = 7) and 36% (n = 13) of samples. In primary tumors (n = 15), high AXL expression correlated significantly with a worse overall survival compared to patients with lower expression (61 vs. 194 months, p = 0.026). No genetic aberrations were detected in the AXL RTK domain (n = 29). The AXL-inhibitor BGB324 affected viability (IC50 0.79-2.13 μmol/L) and migratory potential of all tested ES cell lines in vitro (n = 5-6). BGB324 chemosensitized chemotherapy-resistant ES-4 cells to vincristine and doxorubicin. These data suggest that AXL is a potential novel, druggable therapeutic target in ES.

Targeted Chemotherapy in Bone and Soft-Tissue Sarcoma

Historically surgical intervention has been the mainstay of therapy for bone and soft-tissue sarcomas, augmented with adjuvant radiation for local control. Although cytotoxic chemotherapy revolutionized the treatment of many sarcomas, classic treatment regimens are fraught with side effects while outcomes have plateaued. However, since the approval of imatinib in 2002, research into targeted chemotherapy has increased exponentially. With targeted therapies comes the potential for decreased side effects and more potent, personalized treatment options. This article reviews the evolution of medical knowledge regarding sarcoma, the basic science of sarcomatogenesis, and the major targets and pathways now being studied.

Akt and Hippo Pathways in Ewing's Sarcoma Tumors and Their Prognostic Significance

Background: Ewing's sarcoma tumor is an aggressive malignancy of bone and soft tissue in children and young adults. Despite advances in modern therapy, metastasis occurs and results in high mortality. Intracellular molecules Yap, Akt, mTOR, and Erk are signaling pathway members that regulate the proliferation of tumor cells.

Objective and Methods: We studied the immunohistochemical expression of these proteins in 36 tumor samples from adult and pediatric patients with Ewing's sarcoma tumors. Patients' age, sex, tumor site, tumor size, clinical stage and survival (overall and disease-free survival) were collected. Tissue microarrays slides were stained with antibodies against Yap, Akt, mTOR, and Erk proteins.

Results: Tumors exhibited variable expression of Yap, Akt, mTOR, and Erk (from negative, low to high), with high levels of expression present in 31%, 53%, 77% and 0% respectively. Immunohistochemical expression of Akt was associated with worse overall and disease-free survival (p<0.05). The other biomarkers did not demonstrate any difference in survival between low versus high expression.

Conclusion: Although Yap, Akt, mTOR, and Erk protein are all expressed in Ewing's sarcoma by immunohistochemistry, only Akt expression is associated with worse prognosis. Larger studies are needed to verify these results and plan targeted therapy, particularly against Akt.

Prognostic value of IGF-1R expression in bone and soft tissue sarcomas: a meta-analysis

Accumulated evidence has indicated a correlation between IGF-1R and bone and soft tissue sarcoma (BSTS) progression. However, research on the prognostic role of IGF-1R in sarcomas has revealed very different or even totally opposite results. This meta-analysis aimed to unveil the controversial role IGF-1R plays in predicting the outcome of BSTS patients. We systematically reviewed the evidence for the effect of IGF-1R expression in multiple types of BSTSs, including osteosarcoma, Ewing’s sarcoma, synovial sarcoma, liposarcoma, and rhabdomyosarcoma, to elucidate this issue. The prognostic value of IGF-1R expression in BSTS patients was evaluated regarding overall survival, measured by pooled hazard ratios (HRs) with 95% confidence intervals (CIs). Seven studies including 627 patients were enrolled in this meta-analysis. Our results demonstrated that IGF-1R expression was associated with poor outcome in terms of overall survival in BSTS patients (pooled HR =2.15, 95% CI: 1.06–4.38; P=0.03). In subtypes of BSTSs, elevated IGF-1R expression was revealed to be significantly correlated with worse prognosis in osteosarcoma (pooled HR =2.20, 95% CI: 1.59–0.03; P<0.001), while no statistical significance was discovered in Ewing’s sarcoma (pooled HR =1.01, 95% CI: 0.45–2.27; P=0.99). Expression of IGF-1R could be a negative prognostic biomarker for patients suffering from BSTSs.

Theranostic applications of antibodies in oncology

Targeted therapies, including antibodies, are becoming increasingly important in cancer therapy. Important limitations, however, are that not every patient benefits from a specific antibody therapy and that responses could be short-lived due to acquired resistance. In addition, targeted therapies are quite expensive and are not completely devoid of side-effects. This urges the need for accurate patient selection and response monitoring. An important step towards personalizing antibody treatment could be the implementation of theranostics. Antibody theranostics combine the diagnostic and therapeutic potential of an antibody, thereby selecting those patients who are most likely to benefit from antibody treatment. This review focuses on the clinical application of theranostic antibodies in oncology. It provides detailed information concerning the suitability of antibodies for theranostics, the different types of theranostic tests available and summarizes the efficacy of theranostic antibodies used in current clinical practice. Advanced theranostic applications, including radiolabeled antibodies for non-invasive functional imagining, are also addressed. Finally, we discuss the importance of theranostics in the emerging field of personalized medicine and critically evaluate recent data to determine the best way to apply antibody theranostics in the future.

Targeting receptor tyrosine kinases in osteosarcoma and Ewing sarcoma: current hurdles and future perspectives

Osteosarcoma (OS) and Ewing sarcoma (ES) are the two most common types of primary bone cancer, which mainly affect children and young adults. Despite intensive multi-modal treatment, the survival of both OS and ES has not improved much during the last decades and new therapeutic options are awaited. One promising approach is the specific targeting of transmembrane receptor tyrosine kinases (RTKs) implicated in these types of bone cancer. However, despite encouraging in vitro and in vivo results, apart from intriguing results of Insulin-like Growth Factor-1 Receptor (IGF-1R) antibodies in ES, clinical studies are limited or disappointing. Primary resistance to RTK inhibitors is frequently observed in OS and ES patients, and even patients that initially respond well eventually develop acquired resistance. There are, however, a few remarks to make concerning the current set-up of clinical trials and about strategies to improve RTK-based treatments in OS and ES. This review provides an overview concerning current RTK-mediated therapies in OS and ES and discusses the problems observed in the clinic. More importantly, we describe several strategies to overcome resistance to RTK inhibitors which may significantly improve outcome of OS and ES patients.

Dural metastasis of Ewing's sarcoma

BACKGROUND

Metastatic Ewing's sarcoma to the central nervous system is an uncommon condition and debate concerning the true origin of its metastases is still up to date. To the best of our knowledge, only two cases of dural metastatic Ewing's sarcoma have been published in the English medical literature. We present an additional case in a 24-year-old female and discuss the pathogenesis of these unusual tumors with review of the relevant literature concerning their treatment and outcome.

CASE DESCRIPTION

A 24-year-old female with previous history of pelvis Ewing's sarcoma and recently discovered lung metastases, presented with moderate headache for the past 2 weeks and weakness in her left leg for the past 2 days. Computed tomography scan and magnetic resonance imaging revealed an extra-axial right frontoparietal mass invading the superior sagittal sinus but with clear delineation with brain parenchyma. Imaging features were suggestive of a meningioma as no abnormalities in the skull abutting to the tumor were noted. The patient underwent surgical removal of her tumor. Near total resection was achieved and histological examination showed evidence of metastatic Ewing's sarcoma. Postoperative adjuvant radiation and chemotherapy were administered. The patient improved well postoperatively with full recovery of her motor weakness. She is symptom free with no signs of progression, at most recent follow-up, 8 months after surgery.

CONCLUSION

Despite its rarity, metastatic Ewing's sarcoma must be considered in the differential diagnosis of extra-axial dural masses particularly meningiomas.

Simultaneous targeting of insulin-like growth factor-1 receptor and anaplastic lymphoma kinase in embryonal and alveolar rhabdomyosarcoma: a rational choice

BACKGROUND

Rhabdomyosarcoma (RMS) is an aggressive soft tissue tumour mainly affecting children and adolescents. Since survival of high-risk patients remains poor, new treatment options are awaited. The aim of this study is to investigate anaplastic lymphoma kinase (ALK) and insulin-like growth factor-1 receptor (IGF-1R) as potential therapeutic targets in RMS.

PATIENTS AND METHODS

One-hundred-and-twelve primary tumours (embryonal RMS (eRMS)86; alveolar RMS (aRMS)26) were collected. Expression of IGF-1R, ALK and downstream pathway proteins was evaluated by immunohistochemistry. The effect of ALK inhibitor NVP-TAE684 (Novartis), IGF-1R antibody R1507 (Roche) and combined treatment was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays in cell lines (aRMS Rh30, Rh41; eRMS Rh18, RD).

RESULTS

IGF-1R and ALK expression was observed in 72% and 92% of aRMS and 61% and 39% of eRMS, respectively. Co-expression was observed in 68% of aRMS and 32% of eRMS. Nuclear IGF-1R expression was an adverse prognostic factor in eRMS (5-year survival 46.9 ± 18.7% versus 84.4 ± 5.9%, p=0.006). In vitro, R1507 showed diminished viability predominantly in Rh41. NVP-TAE684 showed diminished viability in Rh41 and Rh30, and to a lesser extent in Rh18 and RD. Simultaneous treatment revealed synergistic activity against Rh41 and Rh30.

CONCLUSION

Co-expression of IGF-1R and ALK is detected in eRMS and particularly in aRMS. As combined inhibition reveals synergistic cytotoxic effects, this combination seems promising and needs further investigation.

The strength of small: improved targeting of insulin-like growth factor-1 receptor (IGF-1R) with F(ab')₂-R1507 fragments in Ewing sarcomas

PURPOSE

To investigate whether F(ab')₂-fragments of the monoclonal Insulin-like Growth Factor-1 Receptor (IGF-1R) antibody R1507 (F(ab')₂-R1507) can successfully target IGF-1R in Ewing sarcomas (ES).

MATERIALS AND METHODS

BALB/c nude mice were subcutaneously implanted with IGF-1R-expressing human ES xenografts (EW-5 and EW-8) which previously showed heterogeneous or no uptake of indium-111-labelled R1507 IgG ((111)In-R1507), respectively. Mice were injected with (111)In-F(ab')₂-R1507 or (111)In-R1507 as a reference. Biodistribution and immuno-SPECT/computed tomography (CT) imaging studies were carried out 2, 4, 8 and 24 h post-injection (p.i.) for (111)In-F(ab')₂-R1507 and 24 h p.i. for (111)In-R1507.

RESULTS

Biodistribution studies showed specific accumulation of (111)In-F(ab')₂-R1507 in EW-5 xenografts from t=2 h p.i. onwards (3.6 ± 0.2%ID/g at t = 24 h p.i.) and (111)In-F(ab')₂-R1507 immuno-SPECT showed almost homogeneous intratumoural distribution at t=24h p.i. Tumour-to-blood ratios of (111)In-F(ab')₂-R1507 were significantly higher than those of (111)In-R1507 at t=24 h p.i. (2.4 ± 0.4 versus 0.5 ± 0.1, respectively; p<0.05). More importantly, (111)In-F(ab')₂-R1507 also specifically accumulated in EW-8 tumours (3.7 ± 0.7%ID/g at t = 24 h p.i). In both EW-5 and EW-8 tumours, there was a good spatial correlation between IGF-1R expression and (111)In-F(ab')₂-R1507 tumour distribution.

CONCLUSION

(111)In-F(ab')₂-R1507 fragments can successfully target IGF-1R in ES models and have superior tumour penetrating and IGF-1R-targeting properties as compared to (111)In-R1507. This suggests that anti-IGF-1R therapies in ES and other tumours may be improved by using smaller therapeutic compounds, although further in vivo studies addressing this topic are warranted.