Trabectedin (ET-743) promotes differentiation in myxoid liposarcoma tumors

Lurbinectedin Inactivates the Ewing Sarcoma Oncoprotein EWS-FLI1 by Redistributing It within the Nucleus

There is a great need to develop novel approaches to target oncogenic transcription factors with small molecules. Ewing sarcoma is emblematic of this need, as it depends on the continued activity of the EWS-FLI1 transcription factor to maintain the malignant phenotype. We have previously shown that the small molecule trabectedin interferes with EWS-FLI1. Here, we report important mechanistic advances and a second-generation inhibitor to provide insight into the therapeutic targeting of EWS-FLI1. We discovered that trabectedin functionally inactivated EWS-FLI1 by redistributing the protein within the nucleus to the nucleolus. This effect was rooted in the wild-type functions of the EWSR1, compromising the N-terminal half of the chimeric oncoprotein, which is known to be similarly redistributed within the nucleus in the presence of UV light damage. A second-generation trabectedin analogue lurbinectedin (PM01183) caused the same nuclear redistribution of EWS-FLI1, leading to a loss of activity at the promoter, mRNA, and protein levels of expression. Tumor xenograft studies confirmed this effect, and it was increased in combination with irinotecan, leading to tumor regression and replacement of Ewing sarcoma cells with benign fat cells. The net result of combined lurbinectedin and irinotecan treatment was a complete reversal of EWS-FLI1 activity and elimination of established tumors in 30% to 70% of mice after only 11 days of therapy. Our results illustrate the preclinical safety and efficacy of a disease-specific therapy targeting the central oncogenic driver in Ewing sarcoma. Cancer Res; 76(22); 6657-68. ©2016 AACR.

Non-coding RNA/microRNA-modulatory dietary factors and natural products for improved cancer therapy and prevention: Alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins

Non-coding small RNA molecules, the microRNAs (miRNAs), contribute decisively to the epigenetic regulation processes in cancer cells. Problematic pathogenic properties of cancer cells and the response of cancers towards anticancer drugs are highly influenced by miRNAs. Both increased drug activity and formation of tumor resistance are regulated by miRNAs. Further to this, the survival and proliferation of cancer cells and the formation of metastases is based on the modulated expression of certain miRNAs. In particular, drug-resistant cancer stem-like cells (CSCs) depend on the presence and absence of specific miRNAs. Fortunately, several small molecule natural compounds were discovered that target miRNAs involved in the modulation of tumor aggressiveness and drug resistance. This review gives an overview of the effects of a selection of naturally occurring small molecules (alkaloids, organosulfur compounds, aliphatic carboxylic acids and water-soluble vitamins) on miRNAs that are closely tangled with cancer diseases.

Efficacy of trabectedin for the treatment of liposarcoma

INTRODUCTION

Trabectedin (ET-743) is a synthetic marine derived alkylating agent, extracted originally from a Caribbean Sea sponge. It is approved for the treatment of Soft Tissue sarcomas (STS) in Europe and recently by the FDA for liposarcomas and leiomyosarcomas.

AREAS COVERED

Trabectedin has multiple mechanisms of action, including one targeting the FUS-CHOP oncogene in Myxoid/Round cell Liposarcomas. Numerous Phase I, II and III clinical trials have been conducted with Trabectedin. It has been studied as monotherapy or in combination with other chemotherapeutic agents. The recommended dose based on clinical trials is 1.5 milligrams/m(2) continuous infusion over 24 hours once every 3 weeks for STS with evidence of disease control in multiple clinical trials at this dose. The most common Grade 3/4 toxicities include neutropenia and transient noncumulative elevations of ALT and AST. Steroid pretreatment has shown efficacy in reducing liver and bone marrow toxicity. In phase III testing comparing trabectedin to dacarbazine, trabectedin was associated with a significantly improved progression free survival rate in patients with advanced lipo- and leiomyosarcomas.

EXPERT OPINION

Trabectedin is an important new addition to the limited treatment options currently available for STS, especially for patients with liposarcoma that have progressed on standard chemotherapeutic regimens.

Recent advances in targeted therapy for Ewing sarcoma

Ewing sarcoma is an aggressive, poorly differentiated neoplasm of solid bone that disproportionally afflicts the young. Despite intensive multi-modal therapy and valiant efforts, 70% of patients with relapsed and metastatic Ewing sarcoma will succumb to their disease. The persistent failure to improve overall survival for this subset of patients highlights the urgent need for rapid translation of novel therapeutic strategies. As Ewing sarcoma is associated with a paucity of mutations in readily targetable signal transduction pathways, targeting the key genetic aberration and master regulator of Ewing sarcoma, the EWS/ETS fusion, remains an important goal.

Results of sub-analysis of a phase 2 study on trabectedin treatment for extraskeletal myxoid chondrosarcoma and mesenchymal chondrosarcoma

Background

Trabectedin is reported to be particularly effective against translocation-related sarcoma. Recently, a randomized phase 2 study in patients with translocation-related sarcomas unresponsive or intolerable to standard chemotherapy was conducted, which showed clinical benefit of trabectedin compared with best supportive care (BSC). Extraskeletal myxoid chondrosarcoma (EMCS) and Mesenchymal chondrosarcoma (MCS) are very rare malignant soft tissue sarcomas, and are associated with translocations resulting in fusion genes. In addition, the previous in vivo data showed that trabectedin affect tumor necrosis and reduction in vascularization in a xenograft model of a human high-grade chondrosarcoma. The aim of the present analysis was to clarify the efficacy of trabectedin for EMCS and MCS subjects in the randomized phase 2 study.

Methods

Five subjects with EMCS and MCS received trabectedin treatment in the randomized phase 2 study. Three MCS subjects were allocated to the BSC group. Objective response and progression-free survival (PFS) were assessed according to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 by central radiology imaging review.

Results

The median follow-up time of the randomized phase 2 study was 22.7 months, and one subject with MCS was still receiving trabectedin treatment at the final data cutoff. The median PFS was 12.5 months (95 % CI: 7.4–not reached) in the trabectedin group, while 1.0 months (95 % CI: 0.3–1.0 months) in MCS subjects of the BSC group. The six-month progression-free rate was 100 % in the trabectedin group. One subject with MCS showed partial response, and the others in the trabectedin group showed stable disease. Overall survival of EMCS and MCS subjects was 26.4 months (range, 10.4–26.4 months) in the trabectedin group. At the final data cutoff, two of five subjects were still alive.

Conclusions

This sub-analysis shows that trabectedin is effective for patients with EMCS and MCS compared with BSC. The efficacy results were better than previously reported data of TRS. These facts suggest that trabectedin become an important choice of treatment for patients with advanced EMCS or MCS who failed or were intolerable to standard chemotherapy.

Trial registration

The randomized phase 2 study is registered with the Japan Pharmaceutical Information Center, number JapicCTI-121850 (May 31, 2012).

Clinical relevance of peroxisome proliferator-activated receptor-gamma expression in myxoid liposarcoma

Background

Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcription factor that belongs to the nuclear hormone receptor superfamily. PPARγ is essential in adipocyte differentiation from precursor cells. Its antitumorigenic effects are reported in certain malignancies; however, its effects in liposarcoma are unclear.

Methods

We analyzed PPARγ expression using immunohistochemistry (IHC) in 46 patients with myxoid liposarcoma [MLS; median age, 47 years (range, 14–90 years) and mean follow-up period, 91 months (range, 13–358 months)]. PPARγ mRNA expression levels were measured by quantitative reverse transcription polymerase chain reaction. Further, we evaluated the correlation of PPARγ expression with clinical outcomes.

Results

We found that the metastasis-free survival rate was significantly higher in lower PPARγ expressers [34 patients with labeling index (LI) <50 %] than in higher expressers (12 patients with LI ≥50 %; p = 0.01). Cox multivariate analysis revealed that a higher PPARγ level was an independent predictor of metastasis (relative risk = 6.945, p = 0.026). Furthermore, using 28 fresh MLS specimens, we confirmed an increased PPARγ mRNA expression level in the higher LI group (p = 0.001).

Conclusions

In this study, higher PPARγ expression in MLS was a risk factor associated with distant metastasis; therefore, it would be a novel prognostic marker for MLS. Further analyses will help to understand the correlation between PPARγ expression and tumor malignancy in liposarcoma.

Trabectedin for the treatment of soft tissue sarcomas

INTRODUCTION

Trabectedin, a marine-derived DNA-binding antineoplastic agent, has been registered by the EMA and recently also by the FDA for the treatment of patients with advanced soft-tissue sarcoma (STS), a rare and heterogeneous disease.

AREAS COVERED

The antitumor activity of trabectedin is related both to direct effects on cancer cells, such as growth inhibition, cell death and differentiation, and indirect effects related to its anti-inflammatory and anti-angiogenic properties. Furthermore, trabectedin is the first compound that targets an oncogenic transcription factor with high selectivity in mixoid liposarcomas. This peculiar mechanism of action is the basis of its clinical development. The clinical pharmacology of trabectedin, the subsequent phase I, II and III trials are summarized and put into perspectives in this review.

EXPERT OPINION

Trabectedin is a relevant pleiotropic antitumoral agent within the complex scenario of the management of STS. It can be used in advanced STS, either after failure of anthracyclines and ifosfamide or in patients unfit for these drugs, especially when reaching a high-tumor control and a long-term benefit is a priority. Toxicity profile is acceptable and manageable with no reported cumulative toxicities. Therefore, trabectedin has become one relevant therapeutic option in metastatic STS, especially in selected histologies.

Drug-induced hepatotoxicity in cancer patients - implication for treatment

INTRODUCTION

All anticancer drugs can cause idiosyncratic liver injury. Therefore, hepatoprotective agents assume particular importance to preserve liver function. Hepatic injury represents 10% of cases of acute hepatitis in adults; drug-related damage is still misjudged because of relative clinical underestimation and difficult differential diagnosis. Chemotherapeutic agents can produce liver toxicity through different pathways, resulting in different categories of liver injuries, but these drugs are not homogeneously hepatotoxic. Frequently, anticancer-induced hepatotoxicity is idiosyncratic and influenced by multiple factors.

AREAS COVERED

The aim of this paper is to perform a review of the literature regarding anticancer-induced liver toxicity. We described hepatotoxicity mechanisms of principal anticancer agents and respective dose reductions. Furthermore, we reviewed studies on hepatoprotectors and their optimal use. Tiopronin, magnesium isoglycyrrhizinate and S-Adenosylmethionine (AdoMet) demonstrated, in some small studies, a potential hepatoprotective activity.

EXPERT OPINION

Actually, in the literature only small experiences are reported. Even though hepatoprotective agents seem to be useful in the oncologic setting, the lack of well-designed prospective Phase III randomized controlled trials is a major limit in the introduction of hepatoprotectors in cancer patients and these kind of studies are warranted to support their use and to give further recommendations for the clinical practice.

Regulation of Cellular Identity in Cancer

Neoplastic transformation requires changes in cellular identity. Emerging evidence increasingly points to cellular reprogramming, a process during which fully differentiated and functional cells lose aspects of their identity while gaining progenitor characteristics, as a critical early step during cancer initiation. This cell identity crisis persists even at the malignant stage in certain cancers, suggesting that reactivation of progenitor functions supports tumorigenicity. Here, we review recent findings that establish the essential role of cellular reprogramming during neoplastic transformation and the major players involved in it with a special emphasis on pancreatic cancer.

Regulation of Cellular Identity in Cancer

Neoplastic transformation requires changes in cellular identity. Emerging evidence increasingly points to cellular reprogramming, a process during which fully differentiated and functional cells lose aspects of their identity while gaining progenitor characteristics, as a critical early step during cancer initiation. This cell identity crisis persists even at the malignant stage in certain cancers, suggesting that reactivation of progenitor functions supports tumorigenicity. Here, we review recent findings that establish the essential role of cellular reprogramming during neoplastic transformation and the major players involved in it with a special emphasis on pancreatic cancer.

Diagnostic use of fluorescence in situ hybridization in expert review in a phase 2 study of trabectedin monotherapy in patients with advanced, translocation-related sarcoma

Background

Fluorescence in situ hybridization (FISH) is one of the most powerful genetic analysis tools for pathological diagnoses. FISH can detect various genetic abnormalities including gene translocation that was specifically found in translocation-related sarcomas (TRSs). Here, we report the use of FISH in expert review in a phase 2 study of trabectedin monotherapy for patients with advanced TRS.

Methods

TRS patients (n = 76) were enrolled in the trial at 12 study sites after pathological diagnoses were made, including morphological examination with or without evidence of translocation by genetic testing. Following histological reviews of the representative specimens at the study sites, we performed immunohistochemistry using the appropriate antibodies and FISH for genetic confirmation of the tumor types in the expert review.

Results

Among the 76 TRS cases, no split signal for SS18 probe was detected by FISH in three synovial sarcoma cases that were diagnosed at the study sites. Malignant peripheral nerve sheath tumor (MPNST) was diagnosed in two cases and sarcomatoid carcinoma in one. One of the cases was a small round cell variant of MPNST. After excluding these three cases, we assessed the other 73. There were no split signals detected in 7 of the 73 cases by FISH analysis, due to decalcification and hyperfixation procedures. Excluding these seven cases, FISH detected translocations in 95 % (63/66) of the study cases with a high sensitivity.

Conclusions

The diagnosis of TRS by FISH was highly sensitive and enabled genetic confirmation of the pathological diagnoses. We strongly recommend FISH as a confirmatory diagnostic test for TRS, which would enable the selection of patients with TRS in whom trabectedin is expected to be effective.

This study was done in part that registered with Japan Pharmaceutical Information Center, number JapicCTI-121850.

Trabectedin for inoperable or recurrent soft tissue sarcoma in adult patients: a retrospective cohort study

Background

Trabectedin is an antineoplastic agent used for patients with soft tissue sarcoma (STS) who fail standard-of-care treatment. Real-world data of its performance is scarce. This study evaluates the safety and effectiveness of trabectedin for patients with advanced STS who were treated at a high-volume sarcoma center.

Methods

A retrospective chart review was performed on 77 patients treated with trabectedin (24 h infusion q3w) between 01/2005 and 05/2014. Data regarding safety, objective radiological response, progression-free and overall survival were analyzed.

Results

Median age at treatment onset was 52y [interquartile range (IQR): 45-61y]. Tumors included leiomyosarcoma (41.6 %), liposarcoma (18.2 %), and synovial sarcoma (13 %). Trabectedin was provided as ≥ third-line chemotherapy in 71.4 %. Median number of cycles was 2 (range: 1–17). Dose reduction and treatment delays occurred in 19.5 and 40.3 %, respectively. Toxicities occurred in 78 %, primarily for neutropenia or elevated liver enzymes. Two patients died secondary to trabectedin-induced rhabdomyolysis. Treatment was discontinued because of disease progression (84.7 %), toxicity (10 %), and patient preference (5 %). Partial response or stable disease occurred in 14.1 and 33.8 %, respectively, while 52.1 % developed progressive disease. Median progression-free survival was 1.3 m (IQR: 0.7–3.5 m) and was significantly higher in patients lacking severe toxicities or progressive disease. Median overall survival was 6.7 m (IQR: 2.3–12.7 m) and was significantly higher in patients with leiomyosarcoma or liposarcoma relative to other histologies.

Conclusions

Trabectedin has an acceptable safety profile as an anti-tumor agent. Our data further suggest there may be some benefit in using trabectedin particularly in patients with leiomyo- or liposarcoma who failed standard-of-care agents.

The value of trabectedin in the treatment of soft tissue sarcoma

Soft tissue sarcomas (STSs) are a group of rare tumors accounting for less than 1% of all adult malignant tumors, a heterogeneous group of more than 50 histological subtypes. Five percent to 30% of STS patients experience local recurrence and 10%–38% present with clinically detectable metastases. Doxorubicin either alone or in combination with ifosfamide has been used as first-line chemotherapy for advanced disease. After failure of first-line chemotherapy, high-dose ifosfamide, gemcitabine + docetaxel, and dacarbazine may be applicable, although high-level evidence is lacking. Trabectedin is a synthetic, marine-derived alkylating agent derived from the Caribbean tunicate, Ecteinascidia turbinata. Several clinical trials have shown that trabectedin has a favorable toxicity profile and is an alternative therapeutic option in adult patients with advanced STS who have not responded to treatment with doxorubicin and ifosfamide. Several clinical trials also recommend the 24-hour intravenous infusion every 3 weeks regimen. The most frequently reported grade 3/4 adverse events were neutropenia and elevated serum levels of AST/ALT. Steroid pretreatment is an effective way of reducing the extent of hepatotoxicity, and steroids are now given routinely before trabectedin administration. Further studies are ongoing to evaluate the efficacy and safety of combination therapy of trabectedin with other agents.

Trabectedin for the treatment of breast cancer

INTRODUCTION

Trabectedin is an anti-tumor compound registered in Europe and in several other countries, for the second-line treatment of soft tissue sarcoma (STS) and for ovarian cancer in combination with liposomal doxorubicin. Trabectedin inhibits cancer cell proliferation mainly affecting the transcription regulation. Trabectedin also acts as a modulator of tumor microenvironment by reducing the number of tumor associated macrophages (TAM). Because of its unique mechanism of action, trabectedin has the potential to act as antineoplastic agent also in several solid malignancies, including breast cancer (BC).

AREAS COVERED

This article reviews the preclinical and clinical data of trabectedin focusing on development in metastatic BC (mBC). Comments regarding the nature and the results of these trials are included.

EXPERT OPINION

Trabectedin is thought to have a crucial activity with defective DNA-repair machinery and also in modulating the tumor micro-environment and the immune-system of cancer patients. From the current available data, we recognize a potential activity of trabectedin in mBC and support the renewed efforts to better elucidate the value of trabectedin in this indication.

Increased sensitivity to platinum drugs of cancer cells with acquired resistance to trabectedin

BACKGROUND

In order to investigate the mechanisms of acquired resistance to trabectedin, trabectedin-resistant human myxoid liposarcoma (402-91/T) and ovarian carcinoma (A2780/T) cell lines were derived and characterised in vitro and in vivo.

METHODS

Resistant cell lines were obtained by repeated exposures to trabectedin. Characterisation was performed by evaluating drug sensitivity, cell cycle perturbations, DNA damage and DNA repair protein expression. In vivo experiments were performed on A2780 and A2780/T xenografts.

RESULTS

402-91/T and A2780/T cells were six-fold resistant to trabectedin compared with parental cells. Resistant cells were found to be hypersensitive to UV light and did not express specific proteins involved in the nucleotide excision repair (NER) pathway: XPF and ERCC1 in 402-91/T and XPG in A2780/T. NER deficiency in trabectedin-resistant cells was associated with the absence of a G2/M arrest induced by trabectedin and with enhanced sensitivity (two-fold) to platinum drugs. In A2780/T, this collateral sensitivity, confirmed in vivo, was associated with an increased formation of DNA interstrand crosslinks.

CONCLUSIONS

Our finding that resistance to trabectedin is associated with the loss of NER function, with a consequent increased sensitivity to platinum drugs, provides the rational for sequential use of these drugs in patients who have acquired resistance to trabectedin.

Efficacy of trabectedin in malignant solitary fibrous tumors: a retrospective analysis from the French Sarcoma Group

Background

Advanced malignant solitary fibrous tumors (SFTs) are rare soft-tissue sarcomas with a poor prognosis. Several treatment options have been reported, but with uncertain rates of efficacy. Our aim is to describe the activity of trabectedin in a retrospective, multi-center French series of patients with SFTs.

Methods

Patients were mainly identified through the French RetrospectYon database and were treated between January 2008 and May 2013. Trabectedin was administered at an initial dose of 1.5 mg/m², q3 weeks. The best tumor response was assessed according to the Response Evaluation Criteria In Solid Tumors 1.1. The Kaplan–Meier method was used to estimate median progression-free survival (PFS) and overall survival (OS). The growth-modulation index (GMI) was defined as the ratio between the time to progression with trabectedin (TTP_n) and the TTP with the immediately prior line of treatment (TTP_n-1).

Results

Eleven patients treated with trabectedin for advanced SFT were identified. Trabectedin had been used as second-line treatment in 8 patients (72.7 %) and as at least third-line therapy in a further 3 (27.3 %). The best RECIST response was a partial response (PR) in one patient (9.1 %) and stable disease (SD) in eight patients (72.7 %). Disease-control rate (DCR = PR + SD) was 81.8 %. After a median follow-up of 29.2 months, the median PFS was 11.6 months (95 % CI = 2.0; 15.2 months) and the median OS was 22.3 months (95 % CI = 9.1 months; not reached). The median GMI was 1.49 (range: 0.11–4.12).

Conclusion

Trabectedin is a very promising treatment for advanced SFTs. Further investigations are needed.

Efficacy and Safety of Trabectedin or Dacarbazine for Metastatic Liposarcoma or Leiomyosarcoma After Failure of Conventional Chemotherapy: Results of a Phase III Randomized Multicenter Clinical Trial

PURPOSE

This multicenter study, to our knowledge, is the first phase III trial to compare trabectedin versus dacarbazine in patients with advanced liposarcoma or leiomyosarcoma after prior therapy with an anthracycline and at least one additional systemic regimen.

PATIENTS AND METHODS

Patients were randomly assigned in a 2:1 ratio to receive trabectedin or dacarbazine intravenously every 3 weeks. The primary end point was overall survival (OS), secondary end points were disease control-progression-free survival (PFS), time to progression, objective response rate, and duration of response-as well as safety and patient-reported symptom scoring.

RESULTS

A total of 518 patients were enrolled and randomly assigned to either trabectedin (n = 345) or dacarbazine (n = 173). In the final analysis of PFS, trabectedin administration resulted in a 45% reduction in the risk of disease progression or death compared with dacarbazine (median PFS for trabectedin v dacarbazine, 4.2 v 1.5 months; hazard ratio, 0.55; P < .001); benefits were observed across all preplanned subgroup analyses. The interim analysis of OS (64% censored) demonstrated a 13% reduction in risk of death in the trabectedin arm compared with dacarbazine (median OS for trabectedin v dacarbazine, 12.4 v 12.9 months; hazard ratio, 0.87; P = .37). The safety profiles were consistent with the well-characterized toxicities of both agents, and the most common grade 3 to 4 adverse effects were myelosuppression and transient elevation of transaminases in the trabectedin arm.

CONCLUSION

Trabectedin demonstrates superior disease control versus conventional dacarbazine in patients who have advanced liposarcoma and leiomyosarcoma after they experience failure of prior chemotherapy. Because disease control in advanced sarcomas is a clinically relevant end point, this study supports the activity of trabectedin for patients with these malignancies.

The PARP inhibitor olaparib enhances the sensitivity of Ewing sarcoma to trabectedin

Recent preclinical evidence has suggested that Ewing Sarcoma (ES) bearing EWSR1-ETS fusions could be particularly sensitive to PARP inhibitors (PARPinh) in combination with DNA damage repair (DDR) agents. Trabectedin is an antitumoral agent that modulates EWSR1-FLI1 transcriptional functions, causing DNA damage. Interestingly, PARP1 is also a transcriptional regulator of EWSR1-FLI1, and PARPinh disrupts the DDR machinery. Thus, given the impact and apparent specificity of both agents with regard to the DNA damage/DDR system and EWSR1-FLI1 activity in ES, we decided to explore the activity of combining PARPinh and Trabectedin in in vitro and in vivo experiments. The combination of Olaparib and Trabectedin was found to be highly synergistic, inhibiting cell proliferation, inducing apoptosis, and the accumulation of G2/M. The drug combination also enhanced γH2AX intranuclear accumulation as a result of DNA damage induction, DNA fragmentation and global DDR deregulation, while EWSR1-FLI1 target expression remained unaffected. The effect of the drug combination was corroborated in a mouse xenograft model of ES and, more importantly, in two ES patient-derived xenograft (PDX) models in which the tumors showed complete regression. In conclusion, the combination of the two agents leads to a biologically significant deregulation of the DDR machinery that elicits relevant antitumor activity in preclinical models and might represent a promising therapeutic tool that should be further explored for translation to the clinical setting.

(18)F-FDG PET/MRI for therapy response assessment in sarcoma: comparison of PET and MR imaging results

BACKGROUND

(18)F-Fluorodeoxyglucose (FDG) positron emission tomography (PET) has proven to be of substantial benefit in imaging of sarcoma patients. We therefore investigated the feasibility and benefit of combined PET/magnetic resonance imaging (MRI).

METHODS

Twelve patients with sarcoma who underwent FDG PET/MRI for staging and response assessment after chemotherapy were included.

RESULTS

Based on contrast-enhanced MRI and application of Choi criteria, therapy response was classified as stable disease in 6/12 patients (50%) and as partial remission in 6/12 patients (50%).

CONCLUSION

In sarcoma patients, response assessment using Choi criteria based on contrast-enhanced MRI in comparison to FDG PET imaging only demonstrates slight correlation.

Liposarcoma miRNA signatures identified from genome-wide miRNA expression profiling

AIMS

To identify the miRNA expression profile of liposarcoma (LPS) that could facilitate detection of LPS, and provide the basis for further investigation of molecular-targeted therapeutic drugs.

MATERIALS & METHODS

A real-time quantitative PCR assay was performed to analyze the expression of 1888 miRNAs from 25 LPS tumor tissue samples, 16 samples of adipose tissue adjacent to the tumors and 18 normal adipose tissue samples from patients with LPS.

RESULTS

Ten dysregulated miRNAs were identified that effectively distinguished LPS tissue from adipose tissue and benign lipoma tissue, and LPS tumor tissues from normal adipose tissues in LPS patients. Furthermore, the expression profiles of miRNAs could also classify the subtype of LPS.

CONCLUSION

The identified miRNAs appear to be novel biomarkers for the detection of LPS, and may contribute to an understanding of the mechanisms of LPS tumorigenesis and its development, and further elucidate the characteristics of LPS subtypes.

Targeting the EWS-FLI1 transcription factor in Ewing sarcoma

PURPOSE

Preclinical data indicate there is strong synergism of action against Ewing sarcoma in sequential treatment with trabectedin followed by irinotecan and it appears to be related to a selective blockade of the transcription factor EWS-FLI1. This combination was evaluated in Ewing sarcoma patient who was progressing with standard therapies.

METHODS

Trabectedin was given as a 24-h iv infusion on day 1 at the dose of 1 mg/sqm, and irinotecan 75 mg/sqm on day 2 and then on days 2 and 4, every 3 weeks from the seventh course.

RESULTS

The therapy was well tolerated with transient hematological toxicity and transaminitis and induced stabilization of the disease lasting for 11 courses, with clinical improvement and marked reduction of the need for opioids. However, shortly before the 12th course, sudden death occurred, possibly due to cerebral stroke, presumably not related to the drug treatment.

CONCLUSIONS

The encouraging clinical benefit observed with the combination and its good tolerability deserves further investigation in Ewing sarcoma.

Trabectedin monotherapy after standard chemotherapy versus best supportive care in patients with advanced, translocation-related sarcoma: a randomised, open-label, phase 2 study

BACKGROUND

Trabectedin binds to the minor groove of DNA and blocks DNA repair machinery. Preclinical data have shown that trabectedin also modulates the transcription of the oncogenic fusion proteins of translocation-related sarcomas. We aimed to assess the efficacy and safety of trabectedin as second-line therapy or later for patients with advanced translocation-related sarcoma.

METHODS

We did a multicentre randomised open-label study in Japan. Eligible patients had pathological diagnosis of translocation-related sarcoma, were aged 19 years or older, were unresponsive or intolerant to standard chemotherapy regimens, no more than four previous chemotherapy regimens, Eastern Cooperative Oncology Group performance status 0 or 1, adequate bone marrow reserve, renal and liver functions, and had measurable lesions. Patients were randomly assigned (1:1) by the minimisation method to receive either trabectedin (1·2 mg/m(2) given via a central venous line over 24 h on day 1 of a 21 day treatment cycle) or best supportive care, which was adjusted centrally by pathological subtype. Investigators, patients, and the sponsor were unmasked to the treatment assignment. Progression-free survival and objective responses were assessed by a masked central radiology imaging review. Efficacy was assessed by masked central radiology imaging review. The primary endpoint was progression-free survival for the full analysis set population. Follow-up is ongoing for the patients under study treatment. The study is registered with Japan Pharmaceutical Information Center, number JapicCTI-121850.

FINDINGS

Between July 11, 2012, and Jan 20, 2014, 76 patients were enrolled and allocated to receive either trabectedin (n=39) or best supportive care (n=37). After central review to confirm pathological subtypes, 73 patients (37 in the trabectedin group and 36 in the best supportive care group) were included in the primary efficacy analysis. Median progression-free survival of the trabectedin group was 5·6 months (95% CI 4·1-7·5) and the best supportive care group was 0·9 months (0·7-1·0). The hazard ratio (HR) for progression-free survival of trabectedin versus best supportive care was 0·07 (90% CI 0·03-0·14 and 95% CI 0·03-0·16) by a Cox proportional hazards model (p<0·0001). The most common drug-related adverse events for patients treated with trabectedin were nausea (32 [89%] of 36), decreased appetite (21 [58%]), decreased neutrophil count (30 [83%]), increased alanine aminotransferase (24 [67%]), and decreased white blood cell count (20 [56%]).

INTERPRETATION

Trabectedin significantly reduced the risk of disease progression and death in patients with advanced translocation-related sarcoma after standard chemotherapy such as doxorubicin, and should be considered as a new therapeutic treatment option for this patient population.

FUNDING

Taiho Pharmaceutical Co., Ltd.

Trabectedin in soft tissue sarcomas

Soft tissue sarcomas are a group of rare tumors derived from mesenchymal tissue, accounting for about 1% of adult cancers. There are over 60 different histological subtypes, each with their own unique biological behavior and response to systemic therapy. The outcome for patients with metastatic soft tissue sarcoma is poor with few available systemic treatment options. For decades, the mainstay of management has consisted of doxorubicin with or without ifosfamide. Trabectedin is a synthetic agent derived from the Caribbean tunicate, Ecteinascidia turbinata. This drug has a number of potential mechanisms of action, including binding the DNA minor groove, interfering with DNA repair pathways and the cell cycle, as well as interacting with transcription factors. Several phase II trials have shown that trabectedin has activity in anthracycline and alkylating agent-resistant soft tissue sarcoma and suggest use in the second- and third-line setting. More recently, trabectedin has shown similar progression-free survival to doxorubicin in the first-line setting and significant activity in liposarcoma and leiomyosarcoma subtypes. Trabectedin has shown a favorable toxicity profile and has been approved in over 70 countries for the treatment of metastatic soft tissue sarcoma. This manuscript will review the development of trabectedin in soft tissue sarcomas.

Advances in the targeted therapy of liposarcoma

Liposarcoma (LPS) is the most common type of soft-tissue sarcoma. Complete surgical resection is the only curative means for localized disease; however, both radiation and conventional cytotoxic chemotherapy remain controversial for metastatic or unresectable disease. An increasing number of trials with novel targeted therapy of LPS have provided encouraging data during recent years. This review will provide an overview of the advances in our understanding of LPS and summarize the results of recent trials with novel therapies targeting different genetic and molecular aberrations for different subtypes of LPS.

Trabectedin for advanced soft tissue sarcomas: optimizing use

Patients with locally advanced or metastatic soft tissue sarcoma have a poor outlook with median survival in the order of 1 year. There is therefore an urgent need for novel agents to impact this disease. Trabectedin is one such novel agent that has demonstrated activity for patients with advanced soft tissue sarcoma and it was licensed in Europe in 2007 for patients in the second-line setting or first-line in those patients deemed unsuitable to receive cytotoxics. In order to best serve patients with novel agents, it is imperative to understand the mechanism or mechanisms of action and the best ways of assessing response in order to optimize antitumor activity. Frequently, the mechanism of action and the optimal means of assessing response will be different from those of traditional cytotoxics. Trial design should reflect these factors to ensure that active drugs are not wrongly marked as futile. This review discusses a number of factors that may influence the optimization of trabectedin use. These factors include the administration schedule, the optimal timing of trabectedin administration in the disease process, the histopathological and molecular subtypes that may be most sensitive to trabectedin, the challenge of assessing response, particularly using radiology, and, finally, the safety considerations with this agent.

Comparison of response evaluation criteria in solid tumours and Choi criteria for response evaluation in patients with advanced soft tissue sarcoma treated with trabectedin: a retrospective analysis

BACKGROUND

To assess the additional value of density measurement using contrast-enhancement sequences (Choi assessment) in a real-life cohort of adult soft tissue sarcoma patients treated with trabectedin.

METHODS

Eligibility criteria included adults (age ⩾18) treated between 01/2007 and 12/2011, with at least two trabectedin cycles after failure or intolerance to doxorubicin/ifosfamide. Baseline and first computed tomography (CT)-scans were centrally reviewed by an experienced radiologist.

RESULTS

The retrospective cohort consists of 134 (73 female) patients treated with trabectedin 1.5 mg/m(2) given as a 24-h infusion every 3 weeks. Patients received a median of five trabectedin cycles (range: 2-33) and the main cause of discontinuation was progressive disease (PD) (n = 105, 78.4%). Response Evaluation Criteria in Solid Tumours (RECIST) assessment was feasible in 128 (95.5%) patients, with Choi assessment performed in 92 (68.7%) patients, generally due to inadequate sequences or exclusive lung metastases. Concordance between both methods was fair (Kappa = 0.290). We identified five patients with false PD (i.e. PD according to RECIST but stable disease/partial response as per Choi). Univariate analysis did not identify any predictive factors for false PD. Median overall survival (OS) of patients with PD as per RECIST but stable disease/partial response (SD/PR) according to Choi was better than for patients with PD according to both RECIST and Choi (14 months versus 8 months; p = 0.052).

CONCLUSIONS

Choi assessment may identify patients with false PD who achieved improved efficacy outcomes, suggesting that trabectedin may delay tumour progression even in the case of non-dimensional response. Dual size and tumour density assessment may be more suitable to evaluate responses to trabectedin in sarcoma patients as well as to improve the decision-making strategies for the continuation of trabectedin therapy.

Normal and functional TP53 in genetically stable myxoid/round cell liposarcoma

Myxoid/round-cell liposarcoma (MLS/RCLS) is characterized by either the fusion gene FUS-DDIT3 or the less commonly occurring EWSR1-DDIT3 and most cases carry few or no additional cytogenetic changes. There are conflicting reports concerning the status and role of TP53 in MLS/RCLS. Here we analysed four MLS/RCLS derived cell lines for TP53 mutations, expression and function. Three SV40 transformed cell lines expressed normal TP53 proteins. Irradiation caused normal posttranslational modifications of TP53 and induced P21 expression in two of these cell lines. Transfection experiments showed that the FUS-DDIT3 fusion protein had no effects on irradiation induced TP53 responses. Ion Torrent AmpliSeq screening, using the Cancer Hotspot panel, showed no dysfunctional or disease associated alleles/mutations. In conclusion, our results suggest that most MLS/RCLS cases carry functional TP53 genes and this is consistent with the low numbers of secondary mutations observed in this tumor entity.

Antiangiogenic activity of trabectedin in myxoid liposarcoma: involvement of host TIMP-1 and TIMP-2 and tumor thrombospondin-1

Trabectedin is a marine natural product, approved in Europe for the treatment of soft tissue sarcoma and relapsed ovarian cancer. Clinical and experimental evidence indicates that trabectedin is particularly effective against myxoid liposarcomas where response is associated to regression of capillary networks. Here, we investigated the mechanism of the antiangiogenic activity of trabectedin in myxoid liposarcomas. Trabectedin directly targeted endothelial cells, impairing functions relying on extracellular matrix remodeling (invasion and branching morphogenesis) through the upregulation of the inhibitors of matrix metalloproteinases TIMP-1 and TIMP-2. Increased TIMPs synthesis by the tumor microenvironment following trabectedin treatment was confirmed in xenograft models of myxoid liposarcoma. In addition, trabectedin upregulated tumor cell expression of the endogenous inhibitor thrombospondin-1 (TSP-1, a key regulator of angiogenesis-dependent dormancy in sarcoma), in in vivo models of myxoid liposarcomas, in vitro cell lines and primary cell cultures from patients' myxoid liposarcomas. Chromatin Immunoprecipitation analysis showed that trabectedin displaced the master regulator of adipogenesis C/EBPβ from the TSP-1 promoter, indicating an association between the up-regulation of TSP-1 and induction of adipocytic differentiation program by trabectedin. We conclude that trabectedin inhibits angiogenesis through multiple mechanisms, including directly affecting endothelial cells in the tumor microenvironment--with a potentially widespread activity--and targeting tumor cells' angiogenic activity, linked to a tumor-specific molecular alteration.

Trabectedin for desmoplastic small round cell tumours: a possible treatment option?

BACKGROUND

Desmoplastic small round cell tumour (DSRCT) is a rare sarcoma typically affecting young males and usually widely metastatic at presentation. Despite multimodal treatment approaches, the prognosis for DSRCT is extremely poor. Alkylator- and anthracyclines- based regimens are widely used as therapy and an initial response is common. Durable responses are exceptionally rare so further systemic treatment options for these patients represent an unmet medical need. We report two cases of metastatic, pretreated DSRCT patients achieving disease stabilisation with Trabectedin.

METHODS

Retrospective review of 2 patients with progressive DSRCT, treated with Trabectedin.

RESULTS

Two males aged 19 and 23 years treated with Trabectedin, 1.5 mg/m(2) over 24 hours 3 weekly for 6 and 5 cycles respectively. Best responses were stable disease in patient 1 and partial response (RECIST 1.1) in patient 2. Progression free survival was 4 months in both cases. Persistent neutropenia required 4 weekly administration in one patient but no other grade 3-4 toxicities occurred.

CONCLUSIONS

This report supports Trabectedin to be active and safe in pre-treated DSRCT patients. Further prospective and collaborative efforts are desirable to better define its role in the management of this disease.

Trabectedin, a drug acting on both cancer cells and the tumour microenvironment

Trabectedin is the first marine-derived anti-neoplastic drug approved for the treatment of advanced soft tissue sarcoma and, in combination with pegylated liposomal doxorubicin, for the treatment of patients with relapsed platinum-sensitive ovarian cancer. From the beginning of its development, trabectedin showed some peculiar properties that clearly distinguished it from other anti-cancer drugs. In this mini-review, we will outline the current state of knowledge regarding the mode of action of trabectedin, which appears to represent a new class of anti-neoplastic drugs acting both on cancer cells and on the tumour microenvironment.

Randomised phase III trial of trabectedin versus doxorubicin-based chemotherapy as first-line therapy in translocation-related sarcomas

AIM

This randomised phase III trial evaluated first-line trabectedin versus doxorubicin-based chemotherapy (DXCT) in patients with advanced/metastatic translocation-related sarcomas (TRS).

METHODS

Patients were randomly assigned (1:1) to receive trabectedin 1.5mg/m2 24-h intravenous (i.v.) infusion every 3 weeks (q3wk) (Arm A), or doxorubicin 75 mg/m2 i.v., q3wk, or doxorubicin 60 mg/m2 i.v. plus ifosfamide (range, 6-9 g/m2) i.v. q3wk (Arm B). Progression-free survival (PFS) by independent review was the primary efficacy end-point.

RESULTS

One hundred and twenty-one patients were randomised; 88 of them had TRS confirmed by central pathology review (efficacy population). Twenty-nine PFS events were assessed by independent review (16 with trabectedin; 13 with DXCT). PFS showed non-significant difference between arms (stratified log rank test, p=0.9573; hazard ratio=0.86, p=0.6992). At the time of this analysis, 63.9% and 58.3% of patients were alive in trabectedin and DXCT arms, respectively. There was no statistically significant difference in survival curves. Response rate according to Response Evaluation Criteria in Solid Tumours (RECIST) v.1.0 was significantly higher in DXCT arm (27.0% versus 5.9%), but response according to Choi criteria showed fewer differences between treatment arms (45.9% versus 37.3%). Safety profile was as expected for both arms, with higher incidence of severe neutropenia, alopecia and mucositis in the DXCT arm.

CONCLUSION

Neither trabectedin nor doxorubicin-based chemotherapy showed significant superiority in the first-line treatment of patients with advanced translocation-related sarcoma.

Tumor calcification: a new response pattern of myxoid liposarcoma to trabectedin

Introduction

Myxoid/round-cell liposarcoma (MRCL) is a specific histological subtype that accounts for 30–35% of liposarcomas and whose virulence depends on the quantity of round-cells within the tumor. MRCL is associated with specific chromosomal translocations resulting in the formation of CHOP/FUS and CHOP/EWS fusion proteins. A high sensitivity of MRCL to trabectedin was reported.

Case Report

We report the case of a 63-year-old woman with a bulky and metastatic MRCL, treated with trabectedin 1.5 mg/m² as a first-line treatment. She experienced a long-lasting clinical benefit. The patients received 14 cycles of trabectedin and achieved a durable partial response to the metastases and a stable disease of the primary tumor, which is a very favorable safety profile. Also noteworthy is that we have observed a calcification of the primary tumor and the metastasis. The response, which lasted 30 months, led to a symptomatic improvement, associated with an excellent general condition and an absence of pain.

Conclusion

To the best of our knowledge, this is the first report of a MRCL treated with trabectedin that resulted in a calcification of the primary tumor and the metastases, associated with an outstandingly long response. This case suggests that trabectedin may represent a feasible first-line therapeutic option for patients with MRCL, with meaningful clinical benefits and an acceptable safety profile.

Systemic treatment of soft-tissue sarcoma-gold standard and novel therapies

Soft-tissue sarcoma (STS) is a rare and heterogeneous group of tumours that comprise approximately 1% of all adult cancers, and encompass over 50 different subtypes. These tumours exhibit a wide range of differing behaviours and underlying molecular pathologies, and can arise anywhere in the body. Surgical resection is critical to the management of locoregional disease. In the locally advanced or metastatic disease settings, systemic therapy has an important role in the multidisciplinary management of sarcoma. Cytotoxic therapy that usually consists of doxorubicin and ifosfamide has been the mainstay of treatment for many years. However recent advances in molecular pathogenesis, the development of novel targeted therapies, changes in clinical trial design and increased international collaboration have led to the development of histology-driven therapy. Furthermore, genomic profiling has highlighted that some STS are driven by translocation, mutation or amplification and others have more complex and chaotic karyotypes. In this Review, we aim to describe the current gold standard treatment for specific STS subtypes as well as outline future promising therapies in the pipeline.

Resistance to minor groove binders

In this paper multiple resistance mechanisms to minor groove binders (MGBs) are overviewed. MGBs with antitumor properties are natural products or their derivatives and, as expected, they are all substrates of P-glycoprotein (P-gp). However, a moderate expression of P-gp does not appear to reduce the sensitivity to trabectedin, the only MGB so far approved for clinical use. Resistance to this drug is often related to transcriptional mechanisms and to DNA repair pathways, particularly defects in transcription-coupled nucleotide excision repair (TC-NER). Therefore tumors resistant to trabectedin may become hypersensitive to UV rays and other DNA damaging agents acting in the major groove, such as Platinum (Pt) complexes. If this is confirmed in clinic, that will provide the rationale to combine trabectedin sequentially with Pt derivates.

Trabectedin for advanced soft tissue sarcomas: a single institution experience

BACKGROUND

We retrospectively analyzed data from patients who had been treated with trabectedin at our institution between April 2009 and August 2011.

PATIENTS & METHODS

Data from 25 patients with recurrent soft tissue sarcoma (leiomyosarcoma: n = 8; liposarcoma: n = 5) were used to assess the efficacy and safety of trabectedin 1.5 mg/m(2) given every 3 weeks.

RESULTS

Most patients (n = 14) had been heavily pretreated with ≥ 2 previous chemotherapy lines. Eight (32%) patients achieved a partial response according to dimensional and tumor density changes, and seven (28%) patients had stable disease for ≥ 3 months (clinical benefit rate = 60%; n = 15). Median progression-free survival was 6.4 months and overall survival 19.3 months. Common adverse events were fatigue, nausea, anemia and transient transaminase increases.

CONCLUSION

Treatment with trabectedin is effective and well tolerated in heavily pretreated soft tissue sarcoma patients. Tapering dexamethasone courses and switching trabectedin administration to an every 4 weeks schedule effectively dealt with persistent fatigue without compromising effectiveness.

The intriguing patterns of tumor response to trabectedin

Among soft tissue sarcomas, myxoid liposarcomas are exceedingly sensitive to trabectedin. Obvious tumor shrinkage is seen in some patients, whereas nondimensional changes in tumor tissue are seen in others especially after the first cycles of therapy. These patterns of tumor response are reminiscent of the way in which solid tumors respond to targeted therapies. The finding of trabectedin's ability to target the FUS-CHOP-mediated transcriptional block, restoring adipogenic differentiation within the tumor in myxoid liposarcomas, confirmed a 'targeted' activity that differs from its well-known atypical alkylating mechanism of action. Uterine leiomyosarcoma may show similar patterns of dimensional and nondimensional responses to trabectedin. Unusual cases of delayed response are occasionally seen and suggest other mechanisms of action, including activity on the tumor microenvironment which has recently been reported. An intriguing question is whether the different patterns of response have clinically or therapeutically meaningful correlations.

A current perspective on the role for molecular studies in soft tissue tumor pathology

Soft tissue sarcomas represent an heterogenous group of malignancies. They represent a diagnostic challenge, and their accurate classification impact over treatment options. Sarcomas, similarly to hematologic neoplasm, often harbor relatively specific genetic aberrations, the recognition of which can be used to improved diagnostic accuracy. This review will focus on the clinical relevance of molecular analysis in soft tissue sarcomas, trying to elucidate its role as a diagnostic tool as well as a potential prognostic/predictive marker.

Mode of action of trabectedin in myxoid liposarcomas

To elucidate the mechanisms behind the high sensitivity of myxoid/round cell liposarcoma (MRCL) to trabectedin and the suggested selectivity for specific subtypes, we have developed and characterized three MRCL xenografts, namely ML017, ML015 and ML004 differing for the break point of the fusion gene FUS-CHOP, respectively of type I, II and III. FUS-CHOP binding to the promoters of some target genes such as Pentraxin 3 or Fibronectin 1, assessed by chromatin immunoprecipitation, was strongly reduced in the tumor 24 h after the first or the third weekly dose of trabectedin, indicating that the drug at therapeutic doses causes a detachment of the FUS-CHOP chimera from its target promoters as previously shown in vitro. Moreover, the higher sensitivity of MRCL types I and II appears to be related to a more prolonged block of the transactivating activity of the fusion protein. Doxorubicin did not affect the binding of FUS-CHOP to target promoters. Histologically, the response to trabectedin in ML017 and ML015 was associated with a marked depletion of non-lipogenic tumoral cells and vascular component, as well as lipidic maturation as confirmed by PPARγ2 expression in western Blot. By contrast, in ML004 no major changes either in the cellularity or in the amount of mature were found, and consistently PPARγ2 was null. In conclusion, the data support the view that the selective mechanism of action of trabectedin in MRCL is specific and related to its ability to cause a functional inactivation of the oncogenic chimera with consequent derepression of the adypocytic differentiation.

Hyperexpression of HOXC13, located in the 12q13 chromosomal region, in well‑differentiated and dedifferentiated human liposarcomas

Liposarcoma (LPS) is the most common soft tissue neoplasm in adults and is characterized by neoplastic adipocyte proliferation. Some subtypes of LPSs show aberrations involving the chromosome 12. The most frequent are t(12;16) (q13;p11) present in more than 90% of myxoid LPSs and 12q13-15 amplification in well-differentiated and dedifferentiated LPSs. In this region, there are important oncogenes such as CHOP (DDIT3), GLI, MDM2, CDK4, SAS, HMGA2, but also the HOXC locus, involved in development and tumor progression. In this study, we evaluated the expression of HOXC13, included in this chromosomal region, in a series of adipocytic tumors. We included 18 well-differentiated, 4 dedifferentiated, 11 myxoid and 6 pleomorphic LPSs as well as 13 lipomas in a tissue microarray. We evaluated the HOXC13 protein and gene expression by immunohistochemistry and quantitative PCR. Amplification/translocation of the 12q13-15 region was verified by FISH. Immunohistochemical HOXC13 overexpression was observed in all well-differentiated and dedifferentiated LPSs, all characterized by the chromosome 12q13-15 amplification, and confirmed by quantitative PCR analysis. In conclusion, our data show a deregulation of the HOXC13 marker in well-differentiated and dedifferentiated LPSs, possibly related to 12q13-15 chromosomal amplification.

Emerging therapies for sarcoma

STS are uncommon tumors of the connective tissues. The OS of patients with advanced sarcomas has improved in the last 20 years, but remains under 2 years. Drug discovery for this disease has been complicated by the fact that there are many different subtypes that comprise STS. In fact, emerging data suggest that each of these subtypes may represent a different entity, with a unique molecular profile and responsiveness to therapy. Testing of new agents and determining predictors for response in this heterogeneous disease is therefore of utmost importance.

Novel systemic therapies in advanced liposarcoma: a review of recent clinical trial results

Liposarcoma is one of the most common adult soft tissue sarcomas an consists of three histologic subtypes (well and dedifferentiated, myxoid/round cell, and pleomorphic). Surgery is the mainstay of treatment for localized disease; however for unresectable or metastatic disease, effective treatment options are currently limited. In the past decade, a better understanding of the distinct genetic and molecular aberrations for each of the three histologic subtypes has led to the development of several novel systemic therapies. Data from phase I and early phase II clinical trials have been reported. Despite challenges with conducting clinical trials in liposarcoma, preliminary results for several of these novel, biology-driven therapies are encouraging.

Molecular targeted therapies in non-GIST soft tissue sarcomas: what the radiologist needs to know

Non-gastrointestinal stromal soft tissue sarcomas are uncommon neoplasms that have a dismal prognosis due to a high incidence of metastases and a poor response to conventional chemotherapy. The identification of characteristic genetic alterations in several of these tumors has opened the window for molecular targeted therapies in patients who have failed conventional chemotherapy. Imaging plays a critical role in assessing the response to these novel therapeutic agents. Just like the response of gastrointestinal stromal tumors to imatinib, the response of non-gastrointestinal stromal soft tissue sarcomas to molecular targeted drugs is better evaluated on imaging by alternate tumor response criteria such as the Choi criteria. In addition, these drugs are associated with distinct class-specific drug toxicities that can come to attention for the first time on imaging. The purpose of this article is to provide a primer for the radiologist on the various molecular targeted therapies in advanced/metastatic non-gastrointestinal stromal soft tissue sarcomas with emphasis on the role of imaging in assessing treatment response and complications.