Neoadjuvant Chemotherapy in High-Grade Myxoid Liposarcoma: Results of the Expanded Cohort of a Randomized Trial From Italian (ISG), Spanish (GEIS), French (FSG), and Polish Sarcoma Groups (PSG).

PURPOSE: A randomized trial was conducted to compare neoadjuvant standard (S) anthracycline + ifosfamide (AI) regimen with histology-tailored (HT) regimen in selected localized high-risk soft tissue sarcoma (STS). The results of the trial demonstrated the superiority of S in all STS histologies except for high-grade myxoid liposarcoma (HG-MLPS) where S and HT appeared to be equivalent. To further evaluate the noninferiority of HT compared with S, the HG-MLPS cohort was expanded. PATIENTS AND METHODS: Patients had localized high-grade (cellular component >5%; size ≥5 cm; deeply seated) MLPS of extremities or trunk wall. The primary end point was disease-free survival (DFS). The secondary end point was overall survival (OS). The trial used a noninferiority Bayesian design, wherein HT would be considered not inferior to S if the posterior probability of the true hazard ratio (HR) being >1.25 was <5%. RESULTS: From May 2011 to June 2020, 101 patients with HG-MLPS were randomly assigned, 45 to the HT arm and 56 to the S arm. The median follow-up was 66 months (IQR, 37-89). Median size was 107 mm (IQR, 84-143), 106 mm (IQR, 75-135) in the HT arm and 108 mm (IQR, 86-150) in the S arm. At 60 months, the DFS and OS probabilities were 0.86 and 0.73 (HR, 0.60 [95% CI, 0.24 to 1.46]; log-rank P = .26 for DFS) and 0.88 and 0.90 (HR, 1.20 [95% CI, 0.37 to 3.93]; log-rank P = .77 for OS) in the HT and S arms, respectively. The posterior probability of HR being >1.25 for DFS met the Bayesian monitoring cutoff of <5% (4.93%). This result confirmed the noninferiority of trabectedin to AI suggested in the original study cohort. CONCLUSION: Trabectedin may be an alternative to standard AI in HG-MLPS of the extremities or trunk when neoadjuvant treatment is a consideration.

Is perioperative chemotherapy effective in patients with localized myxoid liposarcoma?

BACKGROUND: This study aimed to compare the local recurrence, distant metastasis and disease-specific survival rates of patients with localized myxoid liposarcoma in the surgery and adjuvant chemotherapy group versus the surgery alone group. METHODS: A total of 456 patients in the Japanese National Bone and Soft Tissue Tumour Registry database who had localized myxoid liposarcoma and underwent surgery and adjuvant chemotherapy or surgery alone between 2001 and 2019 were included in this retrospective study. The study adjusted for background differences between patients who underwent surgery and adjuvant chemotherapy (n = 228) or surgery alone (n = 228) using propensity score matching. RESULTS: Univariate analysis showed no significant difference in local recurrence rate between the two groups (5-year local recurrence-free survival: 98.6% [95% confidence interval: 95.9-99.6] vs. 94.0% [95% confidence interval: 89.7-96.6], P = 0.052). Univariate analysis showed no difference in the incidence of distant metastases between the two groups (5-year distant metastasis-free survival: 80.5% [95% confidence interval: 73.9-85.8] vs. 75.1% [95% confidence interval: 67.7-81.2], P = 0.508). Univariate analysis showed no difference in disease-specific survival between the two groups (5-year disease-specific survival: 92.6% [95% confidence interval: 86.1-96.2] vs. 93.2% [95% confidence interval: 87.6-96.4], P = 0.804). In the high-risk group (n = 203) with high-grade tumours and tumour size ≥10 cm, there were no significant differences in the local recurrence, distant metastasis and disease-specific survival rates between the surgery and adjuvant chemotherapy group and the surgery alone group. CONCLUSION: The effect of adjuvant chemotherapy on localized myxoid liposarcoma appears to be limited.

Effectiveness and Safety of Trabectedin and Radiotherapy for Patients With Myxoid Liposarcoma: A Nonrandomized Clinical Trial.

Importance: Preclinical data about the synergistic activity of radiotherapy (RT) and trabectedin have been reported. The combination of trabectedin and RT in treating myxoid liposarcomas appears worth exploring. Objective: To explore the effectiveness and safety of trabectedin combined with RT. Design, Setting, and Participants: This international, open-label, phase 2 nonrandomized clinical trial including 46 patients with myxoid liposarcoma was conducted in 4 centers in Spain, 1 in Italy, and 2 in France from July 1, 2016, to September 30, 2019. Eligible patients had to have a histologic, centrally reviewed diagnosis of localized resectable myxoid liposarcoma arising from an extremity or the trunk wall. Interventions: Trabectedin was administered at the recommended dose stemming from the phase 1 trial (1.5 mg/m2), with intravenous infusion during 24 hours every 21 days for a total of 3 cycles. Radiotherapy was started after completion of the first trabectedin infusion (cycle 1, day 2). Patients received 25 fractions of radiation for a total of 45 Gy. Surgery was planned 3 to 4 weeks after the administration of the last preoperative cycle and not until 4 weeks after the end of preoperative RT. Pathologic specimens were mapped in tumor sections to estimate the histologic changes and the percentage of viable tumor after neoadjuvant treatment. Main Outcomes and Measures: The primary objective of the phase 2 part of the study was overall response. Secondary objectives were effectiveness measured by relapse-free survival and activity measured by functional imaging and pathologic response. Results: A total of 46 patients were enrolled. Four patients were not evaluable. The median age was 43 years (range, 18-77 years), and 31 patients were male (67%). Overall, 9 of 41 patients (22%) achieved a partial response with neoadjuvant treatment with trabectedin and RT, with 5 of 39 patients (13%) achieving a complete pathologic response and 20 of 39 patients (51%) having 10% or less of a viable remaining tumor. Partial responses according to Choi criteria were observed in 24 of 29 evaluable patients (83%), and no patient had disease progression. Treatment was well tolerated. Conclusions and Relevance: Although the primary end point of this phase 2 nonrandomized clinical trial was not met (Response Evaluation Criteria in Solid Tumors response in ≥70% of patients), results suggest this combination was well tolerated and effective in terms of pathologic response. Thus, trabectedin plus RT might be a treatment option regarding tolerability; further evidence should be generated in this setting.

Myxoid Liposarcomas: Systemic Treatment Options.

OPINION STATEMENT: Myxoid/round-cell liposarcoma (MRCL) account for 30% of liposarcomas and are the most chemo-sensitive subtype of liposarcoma. The 5-year local relapse and distant metastasis rates are 10% and 20%, respectively. In the advanced setting, the first-line median progression-free survival and overall survival is 9 and 30 months, respectively. The overall response rate (ORR) by RECIST with anthracycline-based chemotherapy is around 40% and with trabectedin is 20%, although response is higher when captured by CHOI criteria. Anthracycline-based combination chemotherapy regimens remain the standard of care first-line treatment option. However, trabectedin is also effective and may be considered in the first-line setting when anthracyclines cannot be prescribed. Beyond chemotherapy, new therapeutic classes are being developed, including autologous adoptive modified T cell receptor cellular therapies which have shown promising results thus far. These new therapies utilize the immunogenic potential of cancer testis antigens, NY-ESO-1 and MAGE-A4, which are expressed in the vast majority of MRCL. Early phase trials have shown encouraging results with up to 40% ORR and a median progression-free survival up to 8.7 months. Other innovative strategies are being developed, tailored to the molecular biology of MRCL. This review summarizes current evidence for the use of standard chemotherapy and the new biomarker-selected treatments under development.

Trabectedin use in soft-tissue sarcoma patients in a real-world setting: Data from an Italian national drug-access registry.

Trabectedin is a marine-derived anticancer drug approved for the treatment of patients with advanced soft-tissue sarcomas (STS). Here, we aimed to analyze its use in a large cohort of STS patients treated in Italy in a real-world setting. Data on STS patients treated with trabectedin in Italy were prospectively collected from January 2013 to December 2019 by the national drug regulator, the Italian Medicines Agency (AIFA). Time-to-off-treatment (TToT) was defined as the time between the initial prescription of trabectedin and the date of treatment discontinuation for any cause. The impact of the different baseline covariates, including the initial prescribed dose of trabectedin, on TToT was evaluated using an accelerated failure time (AFT) models with log-logistic distribution. In total, we analyzed data from 2633 sarcoma patients and 14 950 individual cycles of trabectedin. The median number of cycles of trabectedin received per patient was 3 (interquartile range 2-7). The labeled 1.5 mg/sqm dose was used in 27.3% of all first prescriptions. Overall, the median TToT was 93 days. In the final AFT model, the variables significantly associated to longer TToT were female gender (+13% increase in TToT); ECOG performance status 0 (+50%); histological diagnosis of leiomyosarcoma (+22%), well-differentiated/dedifferentiated liposarcoma (+72%) or myxoid liposarcoma (+61%); receiving treatment in a high-volume center (+23%). In this large real-world cohort of STS patients treated with trabectedin, our findings support the use of trabectedin in STS patients, in particular in leiomyosarcoma and liposarcoma patients, and highlight the role of treatment center volume in their management.

Real-World Experience of Efficacy and Safety of Trabectedin in Patients with Soft Tissue Sarcoma: A Bicentric Retrospective Analysis.

INTRODUCTION: Soft tissue sarcomas (STSs) are a rare and heterogenous group of tumors, with poor prognostic, judging from their frequency to relapse. Few drugs are available after the conventional first-line regimen. Since 2007, trabectedin got approval after failure of anthracyclines and ifosfamide, for advanced or metastatic STS. This led to a FDA approval in 2015, but real-world evidence is still required, complementary to the pivotal phase II and III trials. METHODS: One hundred twenty-six patients with STS, treated by trabectedin between 2002 and 2019, were analyzed in this retrospective study, in two French centers. The effects of trabectedin on survival, response, and toxicity were described. All patients were tested for toxicities, and efficacy was assessed in patients exposed to at least 2 cycles of trabectedin. RESULTS: Three median cycles were administered per patient (1-79). Among the 113 patients analyzed for efficacy, the median progression-free survival was 3.0 months (95% CI: 2.3-4.8), with an overall survival of 12.3 months (95% CI: 10.2-16.9). The rate of disease control was 46% at the end of treatment. Myxoid liposarcoma (n = 11) was the histology subtype that benefited most from this chemotherapy with median progression-free survival and overall survival of 13.3 months (95% CI: 2.3-18.7) and 27.8 months (95% CI: 3.2-64.7), respectively. Adverse events were manageable. DISCUSSION AND CONCLUSION: Efficacy of trabectedin is confirmed in terms of clinical benefit and low toxicity, especially for myxoid liposarcoma. Combinatory regimens are under clinical trials to optimize the place of this chemotherapy.

[Neoadjuvant Use of Isolated Limb Perfusion in Large Myxoid Liposarcoma of the Thigh: a Case Report]. / Neoadjuvantní uzití izolované perfuze koncetiny u objemného myxoidního liposarkomu stehna: kazuistika.

Large unresectable STS presents a therapeutic challenge. Several options are being explored to avoid amputation without compromising the oncological outcome. Neoadjuvant chemotherapy delivers inconsistent and rather unsatisfactory results, preoperative radiotherapy compromises healing, hence it can impede adjuvant systemic treatment. We present a case report of neoadjuvant use of isolated limb perfusion with TNF-alfa and Alkeran (Melphalan) in a patient with initially unresectable large myxoid liposarcoma of the thigh. We achieved 55% reduction in size of the tumor that allowed for wide resection with a safe margin. Pathology confirmed 99% tumor necrosis. The patient has a full function of his extremity and is disease-free at one year follow-up. ILP should be considered as a treatment option which, in selected cases, can contribute to limb sparing surgery. Key words: sarcoma, soft tissue, regional perfusion, chemotherapy, surgery, orthopedic, limb salvage.

Mechanisms of responsiveness to and resistance against trabectedin in murine models of human myxoid liposarcoma.

Myxoid liposarcoma (MLPS) is a rare soft-tissue sarcoma characterised by the expression of FUS-DDIT3 chimera. Trabectedin has shown significant clinical anti-tumour activity against MLPS. To characterise the molecular mechanism of trabectedin sensitivity and of resistance against it, we integrated genomic and transcriptomic data from treated mice bearing ML017 or ML017/ET, two patient-derived MLPS xenograft models, sensitive to and resistant against trabectedin, respectively. Longitudinal RNA-Seq analysis of ML017 showed that trabectedin acts mainly as a transcriptional regulator: 15 days after the third dose trabectedin modulates the transcription of 4883 genes involved in processes that sustain adipocyte differentiation. No such differences were observed in ML017/ET. Genomic analysis showed that prolonged treatment causes losses in 4p15.2, 4p16.3 and 17q21.3 cytobands leading to acquired-resistance against the drug. The results dissect the complex mechanism of action of trabectedin and provide the basis for novel combinatorial approaches for the treatment of MLPS that could overcome drug-resistance.

Clinical outcomes of patients with advanced synovial sarcoma or myxoid/round cell liposarcoma treated at major cancer centers in the United States.

BACKGROUND: Outcomes data regarding advanced synovial sarcoma (SS) and myxoid/round cell liposarcoma (MRCL) are limited, consisting primarily of retrospective series and post hoc analyses of clinical trials. METHODS: In this multi-center retrospective study, data were abstracted from the medical records of 350 patients from nine sarcoma centers throughout the United States and combined into a registry. Patients with advanced/unresectable or metastatic SS (n = 249) or MRCL (n = 101) who received first-line systemic anticancer therapy and had records of tumor imaging were included. Overall survival (OS), time to next treatment, time to distant metastasis, and progression-free survival (PFS) were evaluated using the Kaplan-Meier method and Cox regression. RESULTS: At start of first-line systemic anticancer therapy, 92.4% of patients with SS and 91.1% of patients with MRCL had metastatic lesions. However, 74.7% of patients with SS and 72.3% of patients with MRCL had ≥2 lines of systemic therapy. Median OS and median PFS from first-line therapy for SS was 24.7 months (95% CI, 20.9-29.4) and 7.5 months, respectively (95% CI, 6.4-8.4). Median OS and median PFS from start of first-line therapy for MRCL was 29.9 months (95% CI, 27-44.6) and 8.9 months (95% CI 4.5-12.0). CONCLUSIONS: To the best of our knowledge, this is the largest retrospective study of patients with SS and MRCL. It provides an analysis of real-world clinical outcomes among patients treated at major sarcoma cancer centers and could inform treatment decisions and design of clinical trials. In general, the survival outcomes for this selected population appear more favorable than in published literature.

Magnetic resonance imaging assessment of chemotherapy-related adipocytic maturation in myxoid/round cell liposarcomas: specificity and prognostic value.

OBJECTIVE: To investigate the specificity, clinical implication and prognostic value of MRI adipocytic maturation (MAM) in myxoid/round cells liposarcomas (MRC-LPS) treated with neoadjuvant chemotherapy (NAC). METHODS: Of the 89 patients diagnosed with MRC-LPS at our sarcoma reference center between 2008 and 2018, 28 were included as they were treated with NAC, surgery and radiotherapy. All patients underwent contrast-enhanced MRIs at baseline and late evaluation. A control cohort of 13 high-grade pleomorphic and dedifferentiated LPS with same inclusion criteria was used to evaluate the specificity of MAM in MRC-LPS. Two radiologists analyzed the occurrence of MAM, changes in the tumor architecture, shape and surrounding tissues during NAC. Pathological features of tumor samples were reviewed and correlated with MRI. Metastatic relapse-free survival was estimated with Kaplan-Meier curves and Cox models. Associations between prognostic T1-based delta-radiomics features and MAM were investigated with Student t-test. RESULTS: MAM was more frequent in MRC-LPS (p = 0.045) and not specific of any type of chemotherapy (p = 0.7). Regarding MRC-LPS, 14 out of 28 patients (50%) demonstrated MAM. Eight patients showed metastatic relapses. MAM was not associated with metastatic relapse-free survival (p = 0.9). MAM correlated strongly with the percentage of histological adipocytic differentiation on surgical specimen (p < 0.001), which still expressed the tumor marker NY-ESO-1. None of the prognostic T1-based delta-radiomics features was associated with MAM. CONCLUSION: MAM seems a neutral event during NAC. ADVANCES IN KNOWLEDGE: MAM predominated in MRC-LPS and was not specific of a type of chemotherapy. Occurrence of MAM was not associated with better patients' metastasis free survival.

Combination of PPARγ Agonist Pioglitazone and Trabectedin Induce Adipocyte Differentiation to Overcome Trabectedin Resistance in Myxoid Liposarcomas.

PURPOSE: This study was aimed at investigating whether the PPARγ agonist pioglitazone-given in combination with trabectedin-is able to reactivate adipocytic differentiation in myxoid liposarcoma (MLS) patient-derived xenografts, overcoming resistance to trabectedin. EXPERIMENTAL DESIGN: The antitumor and biological effects of trabectedin, pioglitazone, and the combination of the two drugs were investigated in nude mice bearing well-characterized MLS xenografts representative of innate or acquired resistance against trabectedin. Pioglitazone and trabectedin were given by daily oral and weekly i.v. administrations, respectively. Molecular studies were performed by using microarrays approach, real-time PCR, and Western blotting. RESULTS: We found that the resistance of MLS against trabectedin is associated with the lack of activation of adipogenesis. The PPARγ agonist pioglitazone reactivated adipogenesis, assessed by histologic and gene pathway analyses. Pioglitazone was well tolerated and did not increase the toxicity of trabectedin. The ability of pioglitazone to reactivate adipocytic differentiation was observed by morphologic examination, and it is consistent with the increased expression of genes such as ADIPOQ implicated in the adipogenesis process. The determination of adiponectin by Western blotting constitutes a good and reliable biomarker related to MLS adipocytic differentiation. CONCLUSIONS: The finding that the combination of pioglitazone and trabectedin induces terminal adipocytic differentiation of some MLSs with the complete pathologic response and cure of tumor-bearing mice provides a strong rationale to test the combination of trabectedin and pioglitazone in patients with MLS.

Establishment and characterisation of a new patient-derived model of myxoid liposarcoma with acquired resistance to trabectedin.

BACKGROUND: Myxoid liposarcoma is a histological subtype of liposarcoma particularly sensitive to trabectedin. In clinical use this drug does not cause cumulative toxicity, allowing prolonged treatment, generally until disease progression. No other effective therapies are available for trabectedin-resistant patients. METHODS: Through repeated in vivo treatment in athymic nude mice, we have obtained a patient-derived xenograft with acquired resistance to trabectedin. RESULTS: At basal level, the morphology of the resistant and sensitive models did not differ, in keeping with the finding that the transcriptional profiles of the resistant and sensitive tumours were very similar. After trabectedin treatment adipogenesis was induced in the parental xenograft but not in the resistant one, as assessed by pathological and molecular analysis. A defective transcription-coupled-nucleotide excision repair in the resistant tumour due to mutation of the UVSSA gene may be implicated in the mechanism of resistance. CONCLUSIONS: This is the first in vivo model of myxoid liposarcoma with acquired resistance to trabectedin. Although further studies are necessary to characterise the resistance mechanisms, this is a useful tool for studying new therapeutic strategies to overcome trabectedin resistance in patients.

JAK-STAT signalling controls cancer stem cell properties including chemotherapy resistance in myxoid liposarcoma.

Myxoid liposarcoma (MLS) shows extensive intratumoural heterogeneity with distinct subpopulations of tumour cells. Despite improved survival of MLS patients, existing therapies have shortcomings as they fail to target all tumour cells. The nature of chemotherapy-resistant cells in MLS remains unknown. Here, we show that MLS cell lines contained subpopulations of cells that can form spheres, efflux Hoechst dye and resist doxorubicin, all properties attributed to cancer stem cells (CSCs). By single-cell gene expression, western blot, phospho-kinase array, immunoprecipitation, immunohistochemistry, flow cytometry and microarray analysis we showed that a subset of MLS cells expressed JAK-STAT genes with active signalling. JAK1/2 inhibition via ruxolitinib decreased, while stimulation with LIF increased, phosphorylation of STAT3 and the number of cells with CSC properties indicating that JAK-STAT signalling controlled the number of cells with CSC features. We also show that phosphorylated STAT3 interacted with the SWI/SNF complex. We conclude that MLS contains JAK-STAT-regulated subpopulations of cells with CSC features. Combined doxorubicin and ruxolitinib treatment targeted both proliferating cells as well as cells with CSC features, providing new means to circumvent chemotherapy resistance in treatment of MLS patients.

A comprehensive review of the current evidence for trabectedin in advanced myxoid liposarcoma.

Myxoid liposarcoma (MLS) is a rare mesenchymal tumor that constitutes 10-20% of all liposarcomas. MLS is a translocation-related sarcoma (TRS) related to the chromosomal translocation t(12:16) (q13:p11), producing the FUS-CHOP oncoprotein that constitutes one of the main targets of trabectedin in MLS patients. It is known to be chemosensitive namely to trabectedin in contrast to other soft tissue sarcomas. The efficacy of this agent in MLS have been demonstrated in different settings including treatment-naïve and pre-treated patients with both locally advanced and metastatic disease. However, the benefits of trabectedin in MLS are shadowed by the limited activity of this drug in other subtypes of sarcomas that are enrolled within the same trials. This prompted us to screen the medical literature for clinical data that evaluates the efficacy and safety of trabectedin in MLS. In this review, we will summarize the available evidence for the applicability of trabectedin in MLS.

Preserving quality of life as a key treatment goal in advanced soft tissue sarcomas.

INTRODUCTION: Health-related quality of life (HRQoL) is a patient-reported outcome that addresses patients' perceptions of symptoms across physical, emotional, cognitive and social domains. As HRQoL is currently rarely measured outside clinical trials in oncology, it must be inferred from patients' everyday performance during treatment. To gain insight into the HRQoL of advanced STS patients receiving palliative treatment in clinical practice, three case studies of patients treated with trabectedin are examined. Areas covered: The patient in Case 1 has maintained complete remission for more than 8 years after receiving nine cycles of second-line trabectedin followed by secondary surgery for recurrent myxoid liposarcoma, and was able to resume normal activities during trabectedin treatment. Case 2 describes 10 years' follow-up of a patient with myxoid liposarcoma who remains well after many lines of chemotherapy including extended use of trabectedin in the second line. The third case illustrates the feasibility of extending survival time in an elderly patient with metastatic leiomyosarcoma who was able to maintain a busy and active lifestyle while receiving second-line trabectedin. Expert commentary: Owing to its relatively benign safety profile, trabectedin frequently permits prolonged therapy and is generally well tolerated, often allowing patients to carry on with normal daily activities.

Retroperitoneal or mesenteric primary liposarcoma: clinical and prognostic evaluations on five cases.

BACKGROUND: Retroperitoneal or mesenteric primary liposarcoma is a malignant neoplasia whose prognosis depends on the biological variants, the radical resection surgery and the histological subtypes, as well as on local and remote recurrences. Liposarcoma is the most common variant of this tumour among tumours of soft retroperitoneal tissue. The purpose of this study is to evaluate whether the treatment of this disease, carried out at the Ivrea Hospital for urgent reasons, may be considered in line with the experience of high-volume Centres. PATIENTS AND METHODS: Between 1982 and 2016 five patients were hospitalized with a diagnosis of acute abdomen due to retroperitoneal or mesenteric primary liposarcoma: one myxoid of the mesentery, one well-differentiated of lesser epiploon, one well-differentiated of mesentery, and two dedifferentiates of the retroperitoneum. RESULTS: The five patients, all males, had a average age of 59 years (range 48-86) and were all subjected to general anaesthesia and open technique for total tumour removal. Only the patient with the myxoid liposarcoma had two recurrences. All are alive and healthy after a follow-up of 177 months (range 9-420). CONCLUSION: These tumours should be removed radically, if necessary in conjunction with contiguous organs. Rarity and therapeutic complexity require a treatment, sometimes even multimodal, in highvolume centres. Patients admitted in General Surgery Unit for unpostponable urgency should be operated by surgeons experienced in the treatment of abdominal disease to achieve survival results in line to those achievable in Hub Centres.

12 years of fighting liposarcoma: a case report.

The proportion of liposarcoma in the structure of cancer incidence is from 10 to 35% of all mesenchymal tumors. This clinical observation describes an 12-year struggle with myxoid liposarcoma of the left upper arm, during which 17 surgeries were performed due to local recurrences, 17 radiation therapy courses and 5 chemotherapy courses were conducted. Clinical observation shows the whole complexity of myxoid liposarcoma treatment. The effectiveness of therapeutic management is determined by persistent surgery, and also by the lack of expression of Pgp, glutathione-S-transferase, metallothionein and mutant p53 in tumor structure.

FUS-DDIT3 Fusion Protein-Driven IGF-IR Signaling is a Therapeutic Target in Myxoid Liposarcoma.

Purpose: Myxoid liposarcoma is an aggressive disease with particular propensity to develop hematogenic metastases. Over 90% of myxoid liposarcoma are characterized by a reciprocal t(12;16)(q13;p11) translocation. The resulting chimeric FUS-DDIT3 fusion protein plays a crucial role in myxoid liposarcoma pathogenesis; however, its specific impact on oncogenic signaling pathways remains to be substantiated. We here investigate the functional role of FUS-DDIT3 in IGF-IR/PI3K/Akt signaling driving myxoid liposarcoma pathogenesis.Experimental Design: Immunohistochemical evaluation of key effectors of the IGF-IR/PI3K/Akt signaling axis was performed in a comprehensive cohort of myxoid liposarcoma specimens. FUS-DDIT3 dependency and biological function of the IGF-IR/PI3K/Akt signaling cascade were analyzed using a HT1080 fibrosarcoma-based myxoid liposarcoma tumor model and multiple tumor-derived myxoid liposarcoma cell lines. An established myxoid liposarcoma avian chorioallantoic membrane model was used for in vivo confirmation of the preclinical in vitro results.Results: A comprehensive subset of myxoid liposarcoma specimens showed elevated expression and phosphorylation levels of various IGF-IR/PI3K/Akt signaling effectors. In HT1080 fibrosarcoma cells, overexpression of FUS-DDIT3 induced aberrant IGF-IR/PI3K/Akt pathway activity, which was dependent on transcriptional induction of the IGF2 gene. Conversely, RNAi-mediated FUS-DDIT3 knockdown in myxoid liposarcoma cells led to an inactivation of IGF-IR/PI3K/Akt signaling associated with diminished IGF2 mRNA expression. Treatment of myxoid liposarcoma cell lines with several IGF-IR inhibitors resulted in significant growth inhibition in vitro and in vivoConclusions: Our preclinical study substantiates the fundamental role of the IGF-IR/PI3K/Akt signaling pathway in myxoid liposarcoma pathogenesis and provides a mechanism-based rationale for molecular- targeted approaches in myxoid liposarcoma cancer therapy. Clin Cancer Res; 23(20); 6227-38. ©2017 AACR.

Efficacy of Trabectedin in Patients with Advanced Translocation-Related Sarcomas: Pooled Analysis of Two Phase II Studies.

BACKGROUND: Trabectedin is reported as effective, especially against translocation-related sarcomas (TRSs) after failure of or intolerance to standard chemotherapy. We conducted two phase II studies of TRS, confirming high efficacy of 1.2 mg/m2 trabectedin. The updated data of 66 patients in these studies was integrated to evaluate the efficacy of trabectedin against each histological subtype, and analyze final overall survival (OS). METHODS: Trabectedin was administered on day one of a 21-day cycle. Efficacy was assessed using progression-free survival (PFS), OS, and best overall response. An analysis of OS and PFS was performed for subgroups divided by baseline lymphocyte count (<1,000/µL, ≥1,000/µL) or number of previous chemotherapy regimens (0, 1, 2, ≥3 regimens), and a Weibull parametric model was used to estimate the numerical relationship between lymphocyte count and PFS and OS. RESULTS: Median PFS and OS in overall patients were 5.6 (95% confidence interval [CI]: 4.1-7.3) and 17.5 months (95% CI: 12.6-23.6), respectively. PFS in the myxoid and round-cell liposarcoma (MRCL) group (7.4 months [95% CI: 5.6-11.1]) was longer than in the other subtypes. The response rate was also highest in the MRCL group. Median OS was longer in patients with baseline lymphocyte counts ≥1,000/µL than in those with counts of <1,000/µL, but median PFS was not different between the two subgroups. CONCLUSION: Our updated and pooled data showed that trabectedin exerted prolonged disease control and antitumor effects in patients with advanced TRS, especially in MRCL. We consider that the subgroup analyses also provide important information for trabectedin treatment in patients with TRS. IMPLICATIONS FOR PRACTICE: The progression-free survival (PFS) for the integrated data of 66 patients with translocation-related sarcomas (TRSs) in two phase II studies of trabectedin 1.2 mg/m2 was 5.6 months (95% confidence interval: 4.1-7.3). PFS and response rate in myxoid/round-cell liposarcoma was longer than that of other subtypes. The overall survival (OS) in all TRS subtypes was similar to previous data of TRS patients. In subgroup analysis, the patients with baseline lymphocyte count ≥1,000/µL exhibited better OS, although PFS was not different by baseline lymphocyte count. Our data are considered important information for trabectedin treatment in TRS patients.

Trabectedin and Campthotecin Synergistically Eliminate Cancer Stem Cells in Cell-of-Origin Sarcoma Models.

Trabectedin has been approved for second-line treatment of soft tissue sarcomas. However, its efficacy to target sarcoma initiating cells has not been addressed yet. Here, we used pioneer models of myxoid/round cell liposarcoma (MRCLS) and undifferentiated pleomorphic sarcoma (UPS) developed from transformed human mesenchymal stromal/stem cells (MSCs) to evaluate the effect of trabectedin in the cell type responsible for initiating sarcomagenesis and their derived cancer stem cells (CSC) subpopulations. We found that low nanomolar concentrations of trabectedin efficiently inhibited the growth of sarcoma-initiating cells, induced cell cycle arrest, DNA damage and apoptosis. Interestingly, trabectedin treatment repressed the expression of multiple genes responsible for the development of the CSC phenotype, including pluripotency factors, CSC markers and related signaling pathways. Accordingly, trabectedin induced apoptosis and reduced the survival of CSC-enriched tumorsphere cultures with the same efficiency that inhibits the growth of bulk tumor population. In vivo, trabectedin significantly reduced the mitotic index of MRCLS xenografts and inhibited tumor growth at a similar extent to that observed in doxorubicin-treated tumors. Combination of trabectedin with campthotecin (CPT), a chemotherapeutic drug that shows a robust anti-tumor activity when combined with alkylating agents, resulted in a very strong synergistic inhibition of tumor cell growth and highly increased DNA damage and apoptosis induction. Importantly, the enhanced anti-tumor activity of this combination was also observed in CSC subpopulations. These data suggest that trabectedin and CPT combination may constitute a novel strategy to effectively target both the cell-of-origin and CSC subpopulations in sarcoma.