Targeted therapies in sarcomas: challenging the challenge

Patient Perceptions of the Impact of Treatment (Surgery and Radiotherapy) for Soft Tissue Sarcoma

BACKGROUND AND OBJECTIVES

Treatment for soft tissue sarcoma (STS) is challenging for patients. This study aimed to gain an in-depth understanding of patients' experiences of STS treatment, including whether the sequence of treatment (preoperative or postoperative radiotherapy) influences patient perceptions.

METHODS

Face-to-face semi-structured interviews were conducted with nineteen patients who had been treated for STS with surgery and radiotherapy between 2011 and 2016. Topics discussed included perceptions of treatment, social support, and coping mechanisms. Qualitative, inductive, thematic analysis was conducted and structured using the Framework approach.

RESULTS

Treatment sequence itself did not appear to cause concern, but uncertainty regarding treatment and side effects could negatively impact participants. Social relationships and individual coping strategies influenced participants' experiences of treatment.

CONCLUSIONS

Participants' perceptions of the treatment process varied; the experience was highly individual. It is important to ensure individual psychosocial and information needs are met. In particular, the removal of uncertainty regarding treatment is important in supporting patients undergoing treatment for soft tissue sarcoma.

Oncolytic reovirus inhibits angiogenesis through induction of CXCL10/IP-10 and abrogation of HIF activity in soft tissue sarcomas

The tumor-selective viral replication capacity and pro-apoptotic effects of oncolytic reovirus have been reported to be dependent on the presence of an activated RAS pathway in several solid tumor types. However, the mechanisms of selective anticancer efficacy of the reovirus-based formulation for cancer therapy (Reolysin, pelareorep) have not been rigorously studied in soft tissue sarcomas (STS). Here we report that Reolysin triggered a striking induction of the anti-angiogenic chemokine interferon-γ-inducible protein 10 (IP-10)/CXCL10 (CXC chemokine ligand 10) in both wild type and RAS mutant STS cells. Further analysis determined that Reolysin treatment possessed significant anti-angiogenic activity irrespective of RAS status. In addition to CXCL10 induction, Reolysin dramatically downregulated the expression of hypoxia inducible factor (HIF)-1α, HIF-2α and inhibited vascular endothelial growth factor (VEGF) secretion. CXCL10 antagonism significantly diminished the anti-angiogenic effects of Reolysin indicating that it is a key driver of this phenomenon. Xenograft studies demonstrated that Reolysin significantly improved the anticancer activity of the anti-angiogenic agents sunitinib, temsirolimus, and bevacizumab in a manner that was associated with increased CXCL10 levels. This effect was most pronounced following treatment with Reolysin in combination with temsirolimus. Further analysis in additional sarcoma xenograft models confirmed the significant increase in CXCL10 and increased anticancer activity of this combination. Our collective results demonstrate that Reolysin possesses CXCL10-driven anti-angiogenic activity in sarcoma models, which can be harnessed to enhance the anticancer activity of temsirolimus and other agents that target the tumor vasculature.

Targeting pediatric sarcoma with a bispecific ligand immunotoxin targeting urokinase and epidermal growth factor receptors

Children with high risk sarcoma have a poor prognosis despite surgical resection, irradiation and chemotherapy. Alternative therapies are urgently needed. Urokinase-type plasminogen activator receptor (uPAR) and epidermal growth factor receptor (EGFR) are surface proteins expressed by some pediatric sarcomas. We show for the first time that a de-immunized bispecific ligand toxin, EGFATFKDEL, directed against EGFR and uPAR, successfully targets pediatric sarcoma. Using flow cytometry, we identified a rhabdomyosarcoma (RMS) cell line, RH30, that expresses both uPAR and EGFR, and a Ewing sarcoma (EWS) cell line, TC-71, that expresses only uPAR. We tested the differential sensitivity of these two sarcoma cell lines to toxin-induced killing, using both in vitro assays and an in vivo murine model. We show that pediatric sarcomas are highly sensitive to EGFATFKDEL (at subnanomolar concentrations) in vitro. In vivo, tumor growth was significantly attenuated after treatment with EGFTFKDEL, compared to untreated controls, in both RH30 and TC-71 tumor bearing mice. In addition, we found that simultaneously targeting both receptors in a dual positive cell line was more effective than targeting a single receptor or antigen, resulting in a greater tumor response, including complete tumor regression in an animal model of bulky disease. Our findings provide support for further exploration of bispecific targeting of pediatric sarcomas with bispecific ligand toxins, such as EGFATFKDEL.

Outcomes of Primary Colorectal Sarcoma: A National Cancer Data Base (NCDB) Review

INTRODUCTION

Primary colorectal sarcomas are a rare entity with anecdotally poor outcomes. We sought to inform surgeons, oncologists, and researchers of the characteristics and outcomes of these understudied and difficult-to-manage tumors.

METHODS

The National Cancer Data Base (NCDB) was queried for patients with pathologically confirmed primary sarcoma of the colon or rectum (1998-2012). Gastrointestinal stromal tumors were excluded. Unadjusted overall survival was reported using the Kaplan-Meier method. Patients with colorectal adenocarcinoma were used as a comparison cohort.

RESULTS

Four hundred thirty-three patients with primary colorectal sarcoma were identified (57.5% leiomyosarcoma subtype). Median age was 63 [inter-quartile range 52, 75] years with 23.1% between the ages of 18 and 50 and 48.7% female. Majority of sarcomas were located in the colon (70.7%). When compared to 696,902 patients with adenocarcinoma, sarcoma patients were younger, had larger tumors, were more likely node negative and rectal in location, and higher grade (all p < 0.001), while sex, race, and comorbidity score were similar (all p > 0.05). Overall survival was lower at 5 years in patients with sarcoma (43.8%) than adenocarcinoma (52.3%, p < 0.001).

CONCLUSION

Primary colorectal sarcomas are rare and present at a younger age and higher grade than adenocarcinoma of the colon and rectum. Survival is significantly worse compared to adenocarcinoma patients.

Significant blockade of multiple receptor tyrosine kinases by MGCD516 (Sitravatinib), a novel small molecule inhibitor, shows potent anti-tumor activity in preclinical models of sarcoma

Sarcomas are rare but highly aggressive mesenchymal tumors with a median survival of 10–18 months for metastatic disease. Mutation and/or overexpression of many receptor tyrosine kinases (RTKs) including c-Met, PDGFR, c-Kit and IGF1-R drive defective signaling pathways in sarcomas. MGCD516 (Sitravatinib) is a novel small molecule inhibitor targeting multiple RTKs involved in driving sarcoma cell growth. In the present study, we evaluated the efficacy of MGCD516 both in vitro and in mouse xenograft models in vivo. MGCD516 treatment resulted in significant blockade of phosphorylation of potential driver RTKs and induced potent anti-proliferative effects in vitro. Furthermore, MGCD516 treatment of tumor xenografts in vivo resulted in significant suppression of tumor growth. Efficacy of MGCD516 was superior to imatinib and crizotinib, two other well-studied multi-kinase inhibitors with overlapping target specificities, both in vitro and in vivo. This is the first report describing MGCD516 as a potent multi-kinase inhibitor in different models of sarcoma, superior to imatinib and crizotinib. Results from this study showing blockade of multiple driver signaling pathways provides a rationale for further clinical development of MGCD516 for the treatment of patients with soft-tissue sarcoma.

Molecular targeted therapy in gynaecologic malignancies: primer for radiologists

The identification of characteristic genetic alteration in gynaecological malignancies has opened the door for molecular targeted therapy. The purpose of this review is to provide a primer for the radiologist on these agents with emphasis on the role of imaging in treatment response assessment and drug toxicities. The use of targeted therapy in gynaecological malignancies will likely increase in the future and make the role of the radiologist critical in response assessment and detection of toxicities.

Bone Sarcomas in Pediatrics: Progress in Our Understanding of Tumor Biology and Implications for Therapy

The pediatric bone sarcomas osteosarcoma and Ewing sarcoma represent a tremendous challenge for the clinician. Though less common than acute lymphoblastic leukemia or brain tumors, these aggressive cancers account for a disproportionate amount of the cancer morbidity and mortality in children, and have seen few advances in survival in the past decade, despite many large, complicated, and expensive trials of various chemotherapy combinations. To improve the outcomes of children with bone sarcomas, a better understanding of the biology of these cancers is needed, together with informed use of targeted therapies that exploit the unique biology of each disease. Here we summarize the current state of knowledge regarding the contribution of receptor tyrosine kinases, intracellular signaling pathways, bone biology and physiology, the immune system, and the tumor microenvironment in promoting and maintaining the malignant phenotype. These observations are coupled with a review of the therapies that target each of these mechanisms, focusing on recent or ongoing clinical trials if such information is available. It is our hope that, by better understanding the biology of osteosarcoma and Ewing sarcoma, rational combination therapies can be designed and systematically tested, leading to improved outcomes for a group of children who desperately need them.

The importance of being dead: cell death mechanisms assessment in anti-sarcoma therapy

Cell death can occur through different mechanisms, defined by their nature and physiological implications. Correct assessment of cell death is crucial for cancer therapy success. Sarcomas are a large and diverse group of neoplasias from mesenchymal origin. Among cell death types, apoptosis is by far the most studied in sarcomas. Albeit very promising in other fields, regulated necrosis and other cell death circumstances (as so-called "autophagic cell death" or "mitotic catastrophe") have not been yet properly addressed in sarcomas. Cell death is usually quantified in sarcomas by unspecific assays and in most cases the precise sequence of events remains poorly characterized. In this review, our main objective is to put into context the most recent sarcoma cell death findings in the more general landscape of different cell death modalities.

The angiogenic asset of soft tissue sarcomas: a new tool to discover new therapeutic targets

STS (soft tissue sarcomas) are rare malignant tumours deriving from cells of mesenchymal origin and represent only 1% of all malignant neoplasms. It has been extensively demonstrated that angiogenesis has an important role in cancer malignancy. Particularly, a lot of studies demonstrate the importance of angiogenesis in the development of carcinomas, whereas little is known about the role of angiogenesis in sarcomas and especially in STS. This review aims at summarizing the new discoveries about the nature and the importance of angiogenesis in STS and the new possible therapeutic strategies involved. Only a few studies concerning STS focus on tumour neovascularization and proangiogenic factors and look for a correlation with the patients prognosis/survival. These studies demonstrate that intratumoural MVD (microvessels density) may not accurately represent the angiogenic capacity of STS. Nevertheless, this does not exclude the possibility that angiogenesis could be important in STS. The importance of neoangiogenesis in soft tissue tumours is confirmed by the arising number of publications comparing angiogenesis mediators with clinical features of patients with STS. The efficacy of anti-angiogenic therapies in other types of cancer is well documented. The understanding of the involvement of the angiogenic process in STS, together with the necessity to improve the therapy for this often mortal condition, prompted the exploration of anti-tumour compounds targeting this pathway. In conclusion, this review emphasizes the importance to better understand the mechanisms of angiogenesis in STS in order to subsequently design-specific target therapies for this group of poorly responding tumours.

Sustained inhibition of receptor tyrosine kinases and macrophage depletion by PLX3397 and rapamycin as a potential new approach for the treatment of MPNSTs

PURPOSE

Malignant peripheral nerve sheath tumor (MPNST) is a highly aggressive tumor type that is resistant to chemotherapy and there are no effective therapies. MPNSTs have been shown to have gene amplification for receptor tyrosine kinases (RTK), PDGFR and c-Kit. We tested the c-Kit inhibitor, imatinib, and PLX3397, a selective c-Fms and c-Kit inhibitor, to evaluate their efficacy against MPNST cells in vitro and in vivo.

EXPERIMENTAL DESIGN

We tested the efficacy of imatinib or PLX3397 either alone or in combination with TORC1 inhibitor rapamycin in a cell proliferation assay in vitro and by immunoblotting to determine target inhibition. Immunoblotting and immunohistochemical analysis was further carried out using xenograft samples in vivo.

RESULTS

Our in vitro studies show that imatinib and PLX3397 similarly inhibit cell growth and this can be enhanced with rapamycin with comparable target specificity. However, in vivo studies clearly demonstrate that compared with imatinib, PLX3397 results in sustained blockade of c-Kit, c-Fms, and PDGFRβ, resulting in significant suppression of tumor growth. Moreover, staining for Iba-1, a marker for macrophages, indicates that PLX3397 results in significant depletion of macrophages in the growing tumors. The combination of PLX3397 and rapamycin results in even greater macrophage depletion with continued growth suppression, even when the drug treatment is discontinued.

CONCLUSIONS

Taken together, our data strongly suggest that PLX3397 is superior to imatinib in the treatment of MPNSTs, and the combination of PLX3397 with a TORC1 inhibitor could provide a new therapeutic approach for the treatment of this disease.

Inflammatory stress and sarcomagenesis: a vicious interplay

Chronic inflammation represents one of the hallmarks of cancer, but its role in sarcomagenesis has long been overlooked. Sarcomas are a rare and heterogeneous group of tumors of mesenchymal origin accounting for less than 1 % of cancers in adults but 21 % of cancers in the pediatric population. Sarcomas are associated with bad prognosis, and their management requires a multidisciplinary team approach. Several lines of evidence indicate that inflammation has been implicated in sarcomagenesis leading to the activation of the key transcription factors HIF-1, NF- κB, and STAT-3 involved in a complex inflammatory network. In the past years, an increasing number of new targets have been identified in the treatment of sarcomas leading to the development of new drugs that aim to interrupt the vicious connection between inflammation and sarcomagenesis. This article makes a brief overview of preclinical and clinical evidence of the molecular pathways involved in the inflammatory stress response in sarcomagenesis and the most targeted therapies.

The role of inflammation in sarcoma

Sarcomas encompass a heterogenous group of tumors with diverse pathologically and clinically overlapping features. It is a rarely curable disease, and their management requires a multidisciplinary team approach. Chronic inflammation has emerged as one of the hallmarks of tumors including sarcomas. Classical inflammation-associated sarcomas comprise the inflammatory malignant fibrous histiocytoma and Kaposi sarcoma. The identification of specific chromosomal translocations and important intracellular signaling pathways such as Ras/Raf/MAPK, insulin-like growth factor, PI3K/AKT/mTOR, sonic hedgehog and Notch together with the increasing knowledge of angiogenesis has led to development of targeted therapies that aim to interrupt these pathways. Innovative agents like oncolytic viruses opened the way to design new therapeutic options with encouraging findings. Preclinical evidence also highlights the therapeutic potential of anti-inflammatory nutraceuticals as they can inhibit multiple pathways while being less toxic. This chapter gives an overview of actual therapeutic standards, newest evidence-based studies and exciting options for targeted therapies in sarcomas.

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.