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Solitary fibrous tumor (SFT) is a rare soft-tissue sarcoma. This nonhereditary cancer is the result of an environmental intrachromosomal gene fusion between NAB2 and STAT6 on chromosome 12, which fuses the activation domain of STAT6 with the repression domain of NAB2. Currently there is not an approved chemotherapy regimen for SFTs. The best response on available pharmaceuticals is a partial response or stable disease for several months. The purpose of this study is to investigate the potential of RNA-based therapies for the treatment of SFTs. Specifically, in vitro SFT cell models were engineered to harbor the characteristic NAB2–STAT6 fusion using the CRISPR/SpCas9 system. Cell migration as well as multiple cancer-related signaling pathways were increased in the engineered cells as compared to the fusion-absent parent cells. The SFT cell models were then used for evaluating the targeting efficacies of NAB2–STAT6 fusion-specific antisense oligonucleotides (ASOs) and CRISPR/CasRx systems. Our results showed that fusion specific ASO treatments caused a 58% reduction in expression of fusion transcripts and a 22% reduction in cell proliferation after 72 h in vitro. Similarly, the AAV2-mediated CRISPR/CasRx system led to a 59% reduction in fusion transcript expressions in vitro, and a 55% reduction in xenograft growth after 29 days ex vivo.

Supplementary Figures (From S1 to S10)

Supplementary Table S4 - Affinity energies of nilotinib and avapritinib for the different structures of MRP-1.

MRP-1 is implicated in multidrug resistance and was described as prognostic in high-risk patients with soft-tissue sarcoma (STS) in a previous study. The current research aimed to validate MRP-1 prognostic/predictive value in localized sarcomas treated with anthracyclines plus ifosfamide within the ISG-1001 phase III study. In addition, the inhibitory activity on MRP-1 was investigated in preclinical studies to identify new combinations able to increase the efficacy of standard chemotherapy in STS. MRP-1 expression was assessed by IHC in tissue microarrays from patients with STS and tested for correlation with disease-free survival (DFS) and overall survival (OS). In vitro studies tested the efficacy of MRP-1 inhibitors (nilotinib, ripretinib, selumetinib, and avapritinib) in sarcoma cell lines. The effect of combinations of the most active MRP-1 inhibitors and chemotherapy was measured on the basis of apoptosis. MRP-1 was evaluable in 231 of 264 cases who entered the study. MRP-1 expression (strong intensity) was independently associated with worse DFS [HR, 1.78; 95% confidence interval (CI), 1.11–2.83; P = 0.016], in the multivariate analysis, with a trend for a worse OS (HR, 1.78; 95% CI, 0.97–3.25; P = 0.062). In vitro studies showed that the addition of MRP-1 inhibitors (nilotinib or avapritinib) to doxorubicin plus palifosfamide, significantly increased cell death in SK-UT-1 and CP0024 cell lines. MRP-1 is an adverse predictive factor in localized high-risk patients with STS treated with neoadjuvant anthracyclines plus ifosfamide followed by surgery. In vitro findings support the clinical assessment of the combination of chemotherapy and MRP-1 inhibitors as a promising strategy to overcome the drug ceiling effect for chemotherapy.

Relative Expression shows the expression levels of ABCB1 and ABCC1 determined in FFPE samples after treatment (post-treatment) relatively to baseline levels (pre-treatment) in two cases (Relative expression = post-treatment/ pre-treatment). These results are in line with the expression of both genes determined in patient blood samples and with protein expression by immunohistochemistry. Patient 07 (leiomyosarcoma) displayed the highest radiological progression.

Pre-Clinical studies and Phase I clinical study supplementary methods.

SW982 cells were treated with vehicle (DMSO), nilotinib (10 µM) or doxorubicin (0.1 µM). For sequential treatment, cells were pre-treated with nilotinib (10 µM) for 72 h, and then doxorubicin (0.1 µM) was added. Cell growth was continuously monitored using the RTCA MP Instrument. Cell Index (CI) values were normalized to the CI value at the time point of compound addition indicated by the black solid line. The CI profiles of treated cells reflect the initial cell attachment, logarithmic growth phase and response to the respective treatments. Error bars show the standard deviation of the mean of triplicates.

C) Values of the kinetic parameters (Vmax and Km) in the absence (vehicle, DMSO) or presence of different concentrations of nilotinib. The constants were estimated with the Michaelis-Menten equation using the GraphPad Prism program. Each value represents the mean {plus minus} SD of three independent experiments. 1The maximal rate, Vmax reveals the number of substrate molecules being catalyzed per second. 2Km is that concentration of substrate at which half the active sites of the enzyme are filled.

[Background] Solitary fibrous tumour (SFT) is a rare mesenchymal malignancy that lacks robust prognostic and predictive biomarkers. Interferon-stimulated gene 15 (ISG15) is a ubiquitin-like modifier, associated with tumour progression, and with poor survival of SFT patients, as previous published by our group. Here, we describe the role of ISG15 in the biology of this rare tumour., [Methods] ISG15 expression was assessed by immunohistochemistry in tissue microarrays from SFT patients and tested for correlation with progression-free survival and overall survival (OS). The effects of ISG15 knockdown or induction were investigated for cancer stem cell (CSC) characteristics and for drug sensitivity in unique in vitro models of SFT., [Results] The prognostic value of ISG15 for OS was validated at protein level in malignant SFT patients, prospectively treated with pazopanib and enrolled in GEIS-32 trial. In SFT in vitro models, ISG15 knockdown lead to a decrease in the expression of CSC-related genes, including SOX2, NANOG, ALDH1A1, ABCB1 and ABCC1. Likewise, ISG15 downregulation decreased the clonogenic/ tumoursphere-forming ability of SFT cells, while enhancing apoptotic cell death after doxorubicin, pazopanib or trabectedin treatment in 3D cell cultures. The regulation of CSC-related genes by ISG15 was confirmed after inducing its expression with interferon-β1; ISG15 induction upregulated 1.28- to 451-fold the expression of CSC-associated genes., [Conclusions] ISG15 is a prognostic factor in malignant SFT, regulating the expression of CSC-related genes and CSCs maintenance. Our results suggest that ISG15 could be a novel therapeutic target in SFT, which could improve the efficacy of the currently available treatments., The project was partially funded by the Instituto de Salud Carlos III (ISCIII)–Fondo Europeo de Desarrollo Regional (FEDER), project reference PI18/01728. The project was also funded by SELNET project. SELNET has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 825806. DSM. is the recipient of a Sara Borrell postdoctoral fellowship funded by the National Institute of Health Carlos III (ISCIII) (CD20/00155). JLMH is the recipient of a PFIS predoctoral fellowship funded by the National Institute of Health Carlos III (ISCIII) (FI19/00184).

Although the overall survival of advanced soft-tissue sarcoma (STS) patients has increased in recent years, the median progression-free survival is lower than 5 months, meaning that there is an unmet need in this population. Among second-line treatments for advanced STS, eribulin is an anti-microtubule agent that has been approved for liposarcoma. Here, we tested the combination of eribulin with gemcitabine in preclinical models of L-sarcoma. The effect in cell viability was measured by MTS and clonogenic assay. Cell cycle profiling was studied by flow cytometry, while apoptosis was measured by flow cytometry and Western blotting. The activity of eribulin plus gemcitabine was evaluated in in vivo patient-derived xenograft (PDX) models. In L-sarcoma cell lines, eribulin plus gemcitabine showed to be synergistic, increasing the number of hypodiploid events (increased subG1 population) and the accumulation of DNA damage. In in vivo PDX models of L-sarcomas, eribulin combined with gemcitabine was a viable scheme, delaying tumour growth after one cycle of treatment, being more effective in leiomyosarcoma. The combination of eribulin and gemcitabine was synergistic in L-sarcoma cultures and it showed to be active in in vivo studies. This combination deserves further exploration in the clinical context., Eribulin and funding was kindly provided by Eisai. The authors would also like to thank the SELNET project. SELNET has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 825806. J. Martin-Broto, D.S. Moura and N. Hindi would like to thank the International Accelerator Award funded by Cancer Research UK [C56167/A29363]. DSM is the recipient of a Sara Borrell postdoctoral fellowship funded by the National Institute of Health Carlos III (ISCIII) (CD20/00155). JLMH is the recipient of a PFIS predoctoral fellowship funded by the National Institute of Health Carlos III (ISCIII) (FI19/00184). The authors thank HUVR-IBiS Biobank (Andalusian Public Health System Biobank and ISCIII-Red de Biobancos PT17/0015/0041) for the processing and staining of PDX samples used in this study.

Rhabdomyosarcoma (RMS) in adults is a rare and aggressive disease, which lacks standard therapies for relapsed or advanced disease. This retrospective study aimed to describe the activity of BOMP-EPI (bleomycin, vincristine, methotrexate and cisplatin alternating with etoposide, cisplatin and ifosfamide), an alternative platinum-based regimen, in adult patients with relapsed/metastatic RMS. In the study, 10 patients with RMS with a median age at diagnosis of 20.8 years and a female/male distribution of 6/4 received a mean of 2.5 cycles of BOMP-EPI. The best RECIST response was a complete response in 1/10 (10%) patients, a partial response in 5/10 (50%), stable disease in 3/10 (30%) and progression in 1/10 (10%). With a median follow-up in the alive patients from the start of therapy of 30.5 months (15.7–258), all patients progressed with a median progression-free survival of 8.47 months (95% CI 8.1–8.8), and 7/10 patients died with a median overall survival of 24.7 months (95% CI 13.7–35.6). BOMP-EPI was an active chemotherapy regimen in adults with pediatric-type metastatic RMS, with outcomes in terms of survival that seem superior to what was expected for this poor-prognosis population. Low HMGB1 expression level was identified as a predictive factor of better response to this treatment.

MRP-1 is implicated in multidrug resistance and was described as prognostic in high-risk patients with soft-tissue sarcoma (STS) in a previous study. The current research aimed to validate MRP-1 prognostic/predictive value in localized sarcomas treated with anthracyclines plus ifosfamide within the ISG-1001 phase III study. In addition, the inhibitory activity on MRP-1 was investigated in preclinical studies to identify new combinations able to increase the efficacy of standard chemotherapy in STS. MRP-1 expression was assessed by IHC in tissue microarrays from patients with STS and tested for correlation with disease-free survival (DFS) and overall survival (OS). In vitro studies tested the efficacy of MRP-1 inhibitors (nilotinib, ripretinib, selumetinib, and avapritinib) in sarcoma cell lines. The effect of combinations of the most active MRP-1 inhibitors and chemotherapy was measured on the basis of apoptosis. MRP-1 was evaluable in 231 of 264 cases who entered the study. MRP-1 expression (strong intensity) was independently associated with worse DFS [HR, 1.78; 95% confidence interval (CI), 1.11–2.83; P = 0.016], in the multivariate analysis, with a trend for a worse OS (HR, 1.78; 95% CI, 0.97–3.25; P = 0.062). In vitro studies showed that the addition of MRP-1 inhibitors (nilotinib or avapritinib) to doxorubicin plus palifosfamide, significantly increased cell death in SK-UT-1 and CP0024 cell lines. MRP-1 is an adverse predictive factor in localized high-risk patients with STS treated with neoadjuvant anthracyclines plus ifosfamide followed by surgery. In vitro findings support the clinical assessment of the combination of chemotherapy and MRP-1 inhibitors as a promising strategy to overcome the drug ceiling effect for chemotherapy., The study was partially funded through a European Union grant (EUROSARC FP7 278472). The authors would like to thank Patricio Ledesma Figueroa for Data Management. J. Martin-Broto, D.S. Moura and N. Hindi would like to thank the International Accelerator Award funded by Cancer Research UK [C56167/A29363], Associazione Italiana per la Ricerca sul Cancro [AIRC - 24297] and Fundacion Científica – Asociacion Espanola Contra el Cancer [Foundation AECC - GEACC19007MA]. D.S. Moura was supported by a Sara Borrell grant (CD20/00155) funded by the Instituto de Salud Carlos III. C. Romagosa was supported by a grant from the “Programa d'impuls del talent i de l'ocupabilitat del PERIS 2016–2020.” J-Y. Blay would like to express gratitude for the support from NetSARC (INCA and DGOS) EURACAN (EC 739521) and LYRICAN (INCA-DGOS-INSERM 12563). The ISH1001 study was supported by Eurosarc (FP7–278742).

Altres ajuts: Fondo Europeo de Desarrollo Regional (FEDER). Solitary fibrous tumor is a rare subtype of soft-tissue sarcoma with a wide spectrum of histopathological features and clinical behaviors, ranging from mildly to highly aggressive tumors. The defining genetic driver alteration is the gene fusion NAB2-STAT6, resulting from a paracentric inversion within chromosome 12q, and involving several different exons in each gene. STAT6 (sig-nal transducer and activator of transcription 6) nuclear immunostaining and/or the identification of NAB2-STAT6 gene fusion is required for the diagnostic confirmation of solitary fibrous tumor. In the present study, a new gene fusion consisting of Nuclear Factor I X (NFIX), mapping to 19p13.2 and STAT6, mapping to 12q13.3 was identified by targeted RNA-Seq in a 74-year-old female patient diagnosed with a deep-seated solitary fibrous tumor in the pelvis. Histopathologically, the neo-plasm did not display nuclear pleomorphism or tumor necrosis and had a low proliferative index. A total of 378 unique reads spanning the NFIXexon8-STAT6exon2 breakpoint with 55 different start sites were detected in the bioinformatic analysis, which represented 59.5% of the reads intersecting the genomic location on either side of the breakpoint. Targeted RNA-Seq results were validated by RT-PCR/ Sanger sequencing. The identification of a new gene fusion partner for STAT6 in solitary fibrous tumor opens intriguing new hypotheses to refine the role of STAT6 in the sarcomatogenesis of this entity.

[Simple Summary] Solitary fibrous tumor (SFT) is a malignant condition that exhibits different clinical behaviors ranging from low to high aggressive SFT, with dedifferentiated SFT (DD-SFT) being the fastest-growing subtype. Even when surgery alone provides curation rates above 60%, recurrences do occur in a fraction of patients where surgery is unable to provide disease control. Among the systemic therapeutic options, antiangiogenic compounds have shown higher efficacy than chemotherapy by indirect comparisons. Furthermore, rotating different antiangiogenics, at the progression time, has been shown to be effective. The exception is DD-SFT since it is resistant to antiangiogenics but can respond to chemotherapy. This comprehensive review also analyzes the underlying molecular components that play a key role in SFT origin and aggressiveness. The discovery in 2013 of anomalous fusion genes between NAB2 and STAT6 was determinant to increase the knowledge on the molecular drivers in SFT that could be potential targets for future therapies., Solitary fibrous tumor (SFT) is a rare mesenchymal, ubiquitous tumor, with an incidence of 1 new case/million people/year. In the 2020 WHO classification, risk stratification models were recommended as a better tool to determine prognosis in SFT, to the detriment of “typical” or “malignant” classic terms. The risk for metastasis is up to 35–45%, or even greater, in series with a longer follow-up. Over the last few decades, advances in immunohistochemistry and molecular diagnostics identified STAT6 nuclear protein expression and the NAB2–STAT6 fusion gene as more precise tools for SFT diagnosis. Recent evidence taken from retrospective series and from two prospective phase II clinical trials showed that antiangiogenics are active and their sequential use from first line should be considered, except for dedifferentiated SFT for which chemotherapy is the best option. Since the fusion transcript driver’s first description in 2013, new insights have been brought on key molecular events in SFT. This comprehensive review mainly focuses on the superior efficacy of antiangiogenics over chemotherapeutic agents in SFT, provides the current knowledge of key molecules that could co-drive the SFT behavior, and suggests new target candidates that deserve to be explored in preclinical and clinical research in SFT., The authors would also like to thank the SELNET project. SELNET has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 825806. Furthermore, the authors would like to thank the Instituto de Salud Carlos III (ISCIII)—Fondo Europeo de Desarrollo Regional (FEDER), project reference PI18/01728. David S. Moura is the recipient of a Sara Borrell postdoctoral fellowship funded by the National Institute of Health Carlos III (ISCIII) (CD20/00155). José L. Mondaza-Hernandez is the recipient of a PFIS predoctoral fellowship funded by the National Institute of Health Carlos III (ISCIII) (FI19/00184).

The aim of this study was to identify an easily reliable prognostic score that selects the subset of advanced soft tissue sarcoma (ASTS) patients with a higher benefit with trabectedin in terms of time to progression and overall survival. A retrospective series of 357 patients with ASTS treated with trabectedin as second- or further-line in 19 centers across Spain was analyzed. First, it was confirmed that patients with high growth modulation index (GMI &gt, 1.33) were associated with the better clinical outcome. Univariate and multivariate analyses were performed to identify factors associated with a GMI &gt, 1.33. Thus, GEISTRA score was based on metastasis free-interval (MFI ≤ 9.7 months), Karnofsky &lt, 80%, Non L-sarcomas and better response in the previous systemic line. The median GMI was 0.82 (0–69), with 198 patients (55%) with a GMI &lt, 1, 41 (11.5%) with a GMI 1–1.33 and 118 (33.1%) with a GMI &gt, 1.33. The lowest GEISTRA score showed a median of time-to-progression (TTP) and overall survival (OS) of 5.7 and 19.5 months, respectively, whereas it was 1.8 and 3.1 months for TTP and OS, respectively, for the GEISTRA 4 score. This prognostic tool can contribute to better selecting candidates for trabectedin treatment in ASTS.

This article belongs to the Special Issue New Therapeutic Advances in Rare Tumors., Symptomatic control and tumoral shrinkage is an unmet need in advanced soft-tissue sarcoma (STS) patients beyond first-line. The combination of trabectedin and radiotherapy showed activity in a recently reported clinical trial in this setting. This retrospective series aims to analyze our experience with the same regimen in the real-life setting. We retrospectively reviewed advanced sarcoma patients treated with trabectedin concomitantly with radiotherapy with palliative intent. Growth-modulation index (GMI) was calculated as a surrogate of efficacy. Forty metastatic patients were analyzed. According to RECIST, there was one (2.5%) complete response, 12 (30%) partial responses, 18 (45%) disease stabilizations, and nine (22.5%) progressions. After a median follow-up of 15 months (range 2–38), median progression-free survival (PFS) and overall survival (OS) were 7.5 months (95% CI 2.8–12.2) and 23.5 months (95% CI 1.1–45.8), respectively. Median GMI was 1.42 (range 0.19–23.76), and in 16 (53%) patients, it was >1.33. In patients with GMI >1.33, median OS was significantly longer than in those with GMI 0–1.33 (median OS 52.1 months (95% CI not reached) vs. 8.9 months (95% CI 6.3–11.6), p = 0.028). The combination of trabectedin plus radiotherapy is an active therapeutic option in patients with advanced STS, especially when tumor shrinkage for symptomatic relief is needed., [Simple Summary] Active therapeutic options in advanced sarcomas, able to induce durable objective responses, are scarce beyond first line. New strategies for disease and symptomatic control are thus needed. Our aim was to analyze the activity of the combination of trabectedin and palliative radiotherapy in the real-life setting, in patients with pretreated metastatic sarcoma. Our findings on 40 pretreated metastatic soft-tissue sarcoma patients, in terms of objective responses (overall response rate by RECIST of 32.5%) and outcome (median progression-free survival of 7.5 months and median overall survival of 23.5 months), confirm the activity of this regimen, which is a valuable option to consider, especially in patients in which a dimensional response could help for symptomatic control.

Symptomatic control and tumoral shrinkage is an unmet need in advanced soft-tissue sarcoma (STS) patients beyond first-line. The combination of trabectedin and radiotherapy showed activity in a recently reported clinical trial in this setting. This retrospective series aims to analyze our experience with the same regimen in the real-life setting. We retrospectively reviewed advanced sarcoma patients treated with trabectedin concomitantly with radiotherapy with palliative intent. Growth-modulation index (GMI) was calculated as a surrogate of efficacy. Forty metastatic patients were analyzed. According to RECIST, there was one (2.5%) complete response, 12 (30%) partial responses, 18 (45%) disease stabilizations, and nine (22.5%) progressions. After a median follow-up of 15 months (range 2&ndash, 38), median progression-free survival (PFS) and overall survival (OS) were 7.5 months (95% CI 2.8&ndash, 12.2) and 23.5 months (95% CI 1.1&ndash, 45.8), respectively. Median GMI was 1.42 (range 0.19&ndash, 23.76), and in 16 (53%) patients, it was &gt, 1.33. In patients with GMI &gt, 1.33, median OS was significantly longer than in those with GMI 0&ndash, 1.33 (median OS 52.1 months (95% CI not reached) vs. 8.9 months (95% CI 6.3&ndash, 11.6), p = 0.028). The combination of trabectedin plus radiotherapy is an active therapeutic option in patients with advanced STS, especially when tumor shrinkage for symptomatic relief is needed.

Sarcomas are mesenchymal tumors, encompassing more than 175 subtypes, each one with their own genetic complexities. As a result, immunotherapy approaches have not been universally successful across the wide range of diverse subtypes. The actual state of science and the current clinical data utilizing immunotherapy within the soft-tissue sarcomas (STS) will be detailed in this review. More precisely, the review will focus on: (i) the role of the immune microenvironment in the development and activity of new therapeutic approaches; (ii) the recent identification of the sarcoma immune class (SIC) groups, especially group SIC E with its B-cell signature that predicts immunotherapy response; (iii) the clinical trials using PD-1 and/or CTLA-4 inhibitors, which serves as reference for response data, (iv) the promising clinical activity from the combination of anti-angiogenics agents with PD-1 inhibitors, (v) the adapted T-cell therapies for synovial sarcoma that target either NY-ESO or MAGEA4; and (vi) the role for localized therapy using the virotherapy T-VEC with PD-1 inhibitors. Herein, we present the facts and the hopes for the patients with sarcoma, as the field is rapidly advancing its understanding of what and where to use the various types of immunotherapies., B.A. Van Tine was supported by the NCI (RO1CA227115).

MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression at the post-transcriptional level, and they have been described as being associated with tumor prognosis. Here, miRNA profiling was planned to explore new molecular prognostic biomarkers in localized intestinal high-risk GIST. Paraffin tumor blocks of 14 and 86 patients were used in the discovery and expansion sets, respectively. GeneChip miRNA v3.0 was employed to identify the miRNAs differentially expressed between relapsed and non-relapsed patient samples, which were validated in the expansion set, by qRT-PCR. RT2 Profiler PCR Array was used for the screening of let-7e targets. Expression levels were correlated with relapse-free survival and overall survival. In the discovery set, 39 miRNAs were significantly deregulated, let-7e and miR-550 being the most underexpressed and overexpressed miRNAs in the relapsed group, respectively. In the expansion set, the underexpression of let-7e or the overexpression of 4 of its target genes (ACVR1B, CASP3, COL3A1, and COL5A2) were statistically associated with worse relapse-free survival. The expression of let-7e and 4 of its target genes are potential prognostic biomarkers in high-risk localized intestinal GIST. The expression of these genes is a potential molecular tool useful for a more accurate prognosis in this subset of GIST patients.

Simple Summary For intestinal localized high-risk gastrointestinal stromal tumors (GIST) patients’ new molecular biomarkers are urgently needed for a more accurate prognosis. In our study, miRNA profiling analyses was planned to explore new molecular biomarkers with potential prognostic role in this clinical context. Our data, revealed that 39 microRNAs (miRNAs) were significantly deregulated when comparing patients with disease relapsed versus non-relapsed cases. The underexpression of a specific miRNA let-7e and the overexpression of 4 of its target genes (ACVR1B, CASP3, COL3A1 and COL5A2) correlated significantly with worse relapse-free survival. Overall, our results suggest that miRNA profiling is a potential molecular tool useful for a more accurate prognosis for intestinal localized high-risk GIST patients. Abstract MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate gene expression at the post-transcriptional level, and they have been described as being associated with tumor prognosis. Here, miRNA profiling was planned to explore new molecular prognostic biomarkers in localized intestinal high-risk GIST. Paraffin tumor blocks of 14 and 86 patients were used in the discovery and expansion sets, respectively. GeneChip miRNA v3.0 was employed to identify the miRNAs differentially expressed between relapsed and non-relapsed patient samples, which were validated in the expansion set, by qRT-PCR. RT2 Profiler PCR Array was used for the screening of let-7e targets. Expression levels were correlated with relapse-free survival and overall survival. In the discovery set, 39 miRNAs were significantly deregulated, let-7e and miR-550 being the most underexpressed and overexpressed miRNAs in the relapsed group, respectively. In the expansion set, the underexpression of let-7e or the overexpression of 4 of its target genes (ACVR1B, CASP3, COL3A1, and COL5A2) were statistically associated with worse relapse-free survival. The expression of let-7e and 4 of its target genes are potential prognostic biomarkers in high-risk localized intestinal GIST. The expression of these genes is a potential molecular tool useful for a more accurate prognosis in this subset of GIST patients.

[Purpose of review] Tyrosine kinase inhibitors (TKIs) are the backbone for advanced gastrointestinal stromal tumor (GIST) treatment. The increasing knowledge concerning the structure and the changing conformational status because of some mutations in KIT and PDGFRα, allowed the development of new efficient compounds, with the main goal to overcome resistance in GIST. This review summarizes the latest developments in the treatment of GIST patients., [Recent findings] Amongst the several TKIs currently being studied in GIST, ripretinib, avapritinib and crenolanib had shown promising potent activity in preclinical studies and clinical trials. Ripretinib is a type II inhibitor that exerts its main action in the switch pocket of the activation loop, by mimicking the inhibition exerted by the regulatory region in this domain. Ripretinib is considered the new standard in the fourth line in advanced GIST. Avapritinib is a type I inhibitor synthesized to exerts its activity in the active conformation of the activation loop of KIT and PDFGRα. The relevant activity reported with avapritinib in patients carrying the D842 v mutation represents, for first time, an active therapeutic option in this resistant mutant. Crenolanib is a type I selective inhibitor of PDGFRα-resistant mutants, mainly D842 V, which is currently under clinical trial., [Summary] New potent TKIs are being approved, adding value to the already three registered drugs. Other agents, such as MEK inhibitors, immunotherapy and TRK-targeted therapy are potential new options in specific subsets of GIST patients.

A translational study was designed to analyze the expression of nucleotide excision repair (NER) and homologous recombination (HR) genes as potential predictive biomarkers for trabectedin in soft-tissue sarcoma (STS). This study is part of a randomized phase II trial comparing trabectedin plus doxorubicin versus doxorubicin in advanced STS. Gene expression levels were evaluated by qRT-PCR, while CUL4A protein levels were quantified by immunohistochemistry. Expression levels were correlated with patients&rsquo, progression-free survival (PFS) and overall survival (OS). Gene expression was also evaluated in cell lines and correlated with trabectedin sensitivity. In doxorubicin arm and in the whole series, which includes samples from both arms, no significant differences in terms of PFS were observed amongst the analyzed genes. In the group treated with trabectedin plus doxorubicin, the median of PFS was significantly longer in cases with CUL4A, ERCC1, or ERCC5 overexpression, while BRCA1 expression did not correlated with PFS. Gene expression had no prognostic influence in OS. CUL4A protein levels correlated with worse PFS in doxorubicin arm and in the whole series. In cell lines, only overexpression of ERCC1 was significantly correlated with trabectedin sensitivity. In conclusion, CUL4A, ERCC5, and mainly ERCC1 acted as predictive factors for trabectedin efficacy in advanced STS.

Purpose: Nilotinib plus doxorubicin showed to be synergistic regarding apoptosis in several sarcoma cell lines. A phase I/II trial was thus designed to explore the feasibility of nilotinib as coadjuvant of doxorubicin by inhibiting MRP-1/P-gp efflux activity. The phase I part of the study is presented here. Patients and Methods: Nilotinib 400 mg/12 hours was administered in fixed dose from day 1 to 6, and doxorubicin on day 5 of each cycle. Three dose escalation levels for doxorubicin at 60, 65, and 75 mg/m2 were planned. Cycles were repeated every 3 weeks for a total of 4 cycles. Eligible subtypes were retroperitoneal liposarcoma, leiomyosarcoma, and unresectable/metastatic high-grade chondrosarcoma. Results: Thirteen patients were enrolled: 7 chondrosarcoma, 4 liposarcoma, and 2 leiomyosarcoma. In 46 cycles administered, the most relevant grade 3/4 adverse effects per patient were neutropenia 54%, febrile neutropenia 15%, and asthenia 8%. No cardiac toxicity was observed. Only one dose-limiting toxicity (febrile neutropenia) was reported in the third dose level. With regard to efficacy, 1 partial response (1 liposarcoma), 9 stable diseases (5 chondrosarcoma, 2 liposarcoma, 1 leiomyosarcoma), and 3 progressive diseases (2 chondrosarcoma and 1 leiomyosarcoma) were present. ABCB1 and ABCC1 RNA expression levels decreased by 58.47-fold and 1.47-fold, respectively, on day 5 of the cycle. Conclusions: Combination of MRP-1/P-gp inhibitor, nilotinib, as coadjuvant with doxorubicin is feasible; it appears not to add substantial toxicity compared with doxorubicin alone. Pharmacodynamic study supports this concept. The recommended dose for the phase II part for doxorubicin was 75 mg/m2. Clin Cancer Res; 24(21); 5239–49. ©2018 AACR.

Background: Around 15% of adult GIST are wild type for KIT/PDGFRA mutations (KPWT), usually have SDH deficiencies, and are resistant to imatinib (IM). The underlying mechanisms include overexpression of HIF1α in SDH deficient-GIST, high IGFR signaling through MAPK, BRAF mutation or STAT3 activation. Regorafenib (RE), targeting these pathways, could be more active as upfront therapy in KPWT GIST. Methods: Patients (pts) >18, with advanced non pretreated KPWT GIST were eligible after central confirmation by next-generation sequencing (NGS). Eligible pts received RE at 160mg/d for 21/28d cycles. Primary end-point was disease control rate (DCR) at 12 weeks (RECIST 1.1 ) by central radiological assessment (CRA). Secondary objectives were PFS, OS, ORR (RECIST,Choi), safety and QoL. An amendment allowed previous IM (adjuvant). Statistical assumptions [H0 73% and H1 90% (α 0.1 and β 0.2)], defined a sample size of 20 pts. Results: From May 2016 to October 2020, 30pts with KPWT GIST (by Sanger) underwent central molecular screening. Among the 15 non-eligible pts, 8 harbored KIT exon 11 mutations, 3 exon 9 and 3 PDGFRA exon 18 by NGS. The remaining 16 (53.3%) molecularly eligible pts were enrolled and started RE except one pt due to COVID-19 pandemic. The trial was prematurely closed due to low recruitment, especially after COVID outbreak. Demographics and treatment details in the table. Based on CRA, 12w-DCR was 86.7%. With a median (m) FU of 26 (5-44) months (mo), 10/15 pts progressed, with a mPFS of 10.8 mo (95% CI 6.9-14.8). 6 mo, 9 mo and 12 mo PFS rates were 65%, 48% and 29% respectively. 2 pts were PD-free at 25 and 43 mo from start of RE. 6/15 pts died, with a mOS of 33.5 mo (95% CI NR). [Formula presented] Conclusions: The study results approach the prespecified activity threshold. The low recruitment rate could have affected this attainment. Other analysis of secondary endpoints are ongoing. The high percentage of overlooked mutant GIST by Sanger raises the need of NGS in presumed KPWT GIST. Clinical trial identification: NCT02638766. Legal entity responsible for the study: Spanish Group for Research on Sarcoma (GEIS). Funding: Bayer. Disclosure: J. Martin Broto: Financial Interests, Personal, Expert Testimony, Honoraria: Lilly;Financial Interests, Personal, Expert Testimony, Honoraria: PharmaMar;Financial Interests, Personal, Expert Testimony, Honoraria: Eisai;Financial Interests, Personal, Expert Testimony, Honoraria: Bayer;Financial Interests, Personal, Invited Speaker: PharmaMar;Financial Interests, Institutional, Invited Speaker: PharmaMar;Financial Interests, Institutional, Invited Speaker: Eisai;Financial Interests, Institutional, Invited Speaker: Novartis;Financial Interests, Institutional, Invited Speaker: IMMIX Biopharma;Financial Interests, Institutional, Invited Speaker: Lixte;Financial Interests, Institutional, Invited Speaker: Karyopharm;Financial Interests, Institutional, Invited Speaker: Bayer;Financial Interests, Institutional, Invited Speaker: Celgene;Financial Interests, Institutional, Invited Speaker: Pfizer;Financial Interests, Institutional, Invited Speaker: BMS;Financial Interests, Institutional, Invited Speaker: Blueprint;Financial Interests, Institutional, Invited Speaker: Deciphera;Financial Interests, Institutional, Invited Speaker: Nektar;Financial Interests, Institutional, Invited Speaker: FORMA;Financial Interests, Institutional, Invited Speaker: Amgen;Financial Interests, Institutional, Invited Speaker: Daiichi Sankyo;Financial Interests, Institutional, Invited Speaker: Lilly;Financial Interests, Institutional, Invited Speaker: AROG;Financial Interests, Institutional, Invited Speaker: Adaptimmune;Financial Interests, Institutional, Invited Speaker: GSK. N. Hindi: Financial Interests, Personal, Invited Speaker: PharmaMar;Financial Interests, Personal, Advisory Board: PharmaMar;Financial Interests, Institutional, Research Grant: PharmaMar;Financial Interests, Institutional, Sponsor/Funding: PharmaMar;Financial Interests, Institutional, Research Grant: Nova tis;Financial Interests, Institutional, Research Grant: Eisai;Financial Interests, Institutional, Research Grant: Immix Bio;Financial Interests, Institutional, Sponsor/Funding: Bayer;Financial Interests, Institutional, Sponsor/Funding: Deciphera;Financial Interests, Institutional, Sponsor/Funding: Daychii;Financial Interests, Institutional, Sponsor/Funding: Blueprint;Financial Interests, Institutional, Sponsor/Funding: Adaptimmune;Financial Interests, Institutional, Sponsor/Funding: GSK;Financial Interests, Institutional, Sponsor/Funding: Karyopharm;Financial Interests, Institutional, Sponsor/Funding: Celgene;Financial Interests, Institutional, Sponsor/Funding: AROG. J. Lavernia: Financial Interests, Personal, Invited Speaker: PharmaMar;Financial Interests, Personal, Invited Speaker: BMS. C. Serrano: Financial Interests, Personal, Invited Speaker: Bayer;Financial Interests, Institutional, Research Grant: Bayer. D. Moura: Financial Interests, Institutional, Research Grant: Novartis;Financial Interests, Institutional, Research Grant: Eisai;Financial Interests, Institutional, Research Grant: PharmaMar;Financial Interests, Institutional, Research Grant: Immix Bio. J. Blay: Financial Interests, Institutional, Research Grant: Bayer;Financial Interests, Personal, Invited Speaker: Bayer;Financial Interests, Institutional, Research Grant: Novartis;Financial Interests, Personal, Invited Speaker: Novartis;Financial Interests, Institutional, Research Grant: Roche;Financial Interests, Personal, Invited Speaker: Roche;Financial Interests, Institutional, Research Grant: Deciphera;Financial Interests, Personal, Research Grant: Deciphera. E.R. Fumagalli: Financial Interests, Institutional, Research Grant: Bayer. All other authors have declared no conflicts of interest.

[Background] Solitary fibrous tumour is an ultra-rare sarcoma, which encompasses different clinicopathological subgroups. The dedifferentiated subgroup shows an aggressive course with resistance to pazopanib, whereas in the malignant subgroup, pazopanib shows higher activity than in previous studies with chemotherapy. We designed a trial to test pazopanib activity in two different cohorts of solitary fibrous tumour: the malignant-dedifferentiated cohort, which was previously published, and the typical cohort, which is presented here., [Methods] In this single-arm, phase 2 trial, adult patients (aged ≥18 years) diagnosed with confirmed metastatic or unresectable typical solitary fibrous tumour of any location, who had progressed in the previous 6 months (by Choi criteria or Response Evaluation Criteria in Solid Tumors [RECIST]) and an Eastern Cooperative Oncology Group (ECOG) performance status of 0–2 were enrolled at 11 tertiary hospitals in Italy, France, and Spain. Patients received pazopanib 800 mg once daily, taken orally, until progression, unacceptable toxicity, withdrawal of consent, non-compliance, or a delay in pazopanib administration of longer than 3 weeks. The primary endpoint was proportion of patients achieving an overall response measured by Choi criteria in patients who received at least 1 month of treatment with at least one radiological assessment. All patients who received at least one dose of the study drug were included in the safety analyses. This study is registered in ClinicalTrials.gov, NCT02066285, and with the European Clinical Trials Database, EudraCT 2013-005456-15., [Findings] From June 26, 2014, to Dec 13, 2018, of 40 patients who were assessed, 34 patients were enrolled and 31 patients were included in the response analysis. Median follow-up was 18 months (IQR 14–34), and 18 (58%) of 31 patients had a partial response, 12 (39%) had stable disease, and one (3%) showed progressive disease according to Choi criteria and central review. The proportion of overall response based on Choi criteria was 58% (95% CI 34–69). There were no deaths caused by toxicity, and the most frequent adverse events were diarrhoea (18 [53%] of 34 patients), fatigue (17 [50%]), and hypertension (17 [50%])., [Interpretation] To our knowledge, this is the first prospective trial of pazopanib for advanced typical solitary fibrous tumour. The manageable toxicity and activity shown by pazopanib in this cohort suggest that this drug could be considered as first-line treatment for advanced typical solitary fibrous tumour., Spanish Group for Research on Sarcomas (GEIS), Italian Sarcoma Group (ISG), French Sarcoma Group (FSG), GlaxoSmithKline, and Novartis.

[Background] Sarcomas exhibit low expression of factors related to immune response, which could explain the modest activity of PD-1 inhibitors. A potential strategy to convert a cold into an inflamed microenvironment lies on a combination therapy. As tumor angiogenesis promotes immunosuppression, we designed a phase Ib/II trial to test the double inhibition of angiogenesis (sunitinib) and PD-1/PD-L1 axis (nivolumab)., [Methods] This single-arm, phase Ib/II trial enrolled adult patients with selected subtypes of sarcoma. Phase Ib established two dose levels: level 0 with sunitinib 37.5 mg daily from day 1, plus nivolumab 3 mg/kg intravenously on day 15, and then every 2 weeks; and level −1 with sunitinib 37.5 mg on the first 14 days (induction) and then 25 mg per day plus nivolumab on the same schedule. The primary endpoint was to determine the recommended dose for phase II (phase I) and the 6-month progression-free survival rate, according to Response Evaluation Criteria in Solid Tumors 1.1 (phase II)., [Results] From May 2017 to April 2019, 68 patients were enrolled: 16 in phase Ib and 52 in phase II. The recommended dose of sunitinib for phase II was 37.5 mg as induction and then 25 mg in combination with nivolumab. After a median follow-up of 17 months (4–26), the 6-month progression-free survival rate was 48% (95% CI 41% to 55%). The most common grade 3–4 adverse events included transaminitis (17.3%) and neutropenia (11.5%)., [Conclusions] Sunitinib plus nivolumab is an active scheme with manageable toxicity in the treatment of selected patients with advanced soft tissue sarcoma, with almost half of patients free of progression at 6 months., [Trial registration number] NCT03277924., This work was supported by GEIS and ISG. BMS and Pfizer provided drug supply and partial funding for shipping. Translational studies were partially funded by Beca Buesa from the GEIS group.

11511 Background: Pazopanib (P) was assessed prospectively in a phase 2 study in SFT resulting in a longer progression free survival (PFS) and overall survival (OS) compared to historical controls treated with chemotherapy. No statistical correlation was found between angiogenic factors and P in its pivotal phase III sarcoma trial. In the last two years, a soaring interest on the prognostic and predictive value of inflammatory indexes such as neutrophil/lymphocyte (NLR) and platelet/lymphocyte (PLR) is emerging in sarcomas. A retrospective analysis of inflammatory indexes of patients who entered the GEIS-32 (NCT02066285) trial was performed. In that trial advanced SFT patients were treated with P from front-line. Methods: All eligible patients who entered in the typical- and malignant-SFT cohort of the GEIS-32 trial were included in this analysis. To determine NLR and PLR, baseline values of platelets (10e9/L), neutrophils (10e9/L) and lymphocytes (10e9/L) were obtained from complete blood count tests. Additionally, RDW (standardized as 1 = upper value of normal range) values at baseline were also determined. The impact of NLR, PLR and RDW on OS, PFS and Choi response were analyzed by univariate and multivariate analysis. MAXSTAT was used to determine optimal cut-off points for overall survival. Metastasis free interval (MFI), mitotic count and ECOG were also analyzed, among others. Results: Sixty-seven out of 70 enrolled SFT patients, median age 63-y and 57% female, were considered for this analysis. The median follow-up from treatment initiation was 20.0 months. High standardized RDW value at baseline (cut-off 1.03) was significantly associated with worse OS [10.7 months (95% CI 3.8-17.5) vs 49.8 months (95% CI 9.4-90.2), p < 0.001] and worse PFS [8.8 months (95% CI 0.9-7.0) vs 9.8 months (7.4-12.3), p = 0.001]. High PLR (cut-off 242) significantly correlated with worse OS [10.7 months (95% CI 5.2-16.2) vs 49.8 months (95% CI 14.6-85.0), p < 0.001] and worse PFS [4.5 months (95% CI 2.0-7.0) vs 10.1 months (95% CI 6.3-13.9), p = 0.005], and high NLR (cut-off 3.78) was significantly associated with worse OS [11.7 months (95% CI 3.5-19.8) vs NA, p < 0.001] and worse PFS [4.5 months (95% CI 1.9-7.0) vs 10.8 months (95% CI 8.7-12.9), p = 0.010]. Independent variables in multivariate analysis were NLR, RDW, MFI and mitosis for PFS; while RDW and ECOG for OS (see table). Further, NLR and mitosis were independent factors for Choi progressive disease (as best response). Conclusions: High NLR and RDW values were independent biomarkers of worse outcome in advanced SFT patients treated with pazopanib.[Table: see text]

11546 Background: Despite several second-line options are accessible for the treatment of advanced STS, there is a lack of predictive biomarkers available to support the rational selection of these drugs. Trabectedin specifically targets mononuclear cell lineage (macrophages and monocytes) that ultimately could inhibit tumor angiogenesis. Moreover, trabectedin seems to induce the expression of immune-checkpoint proteins (e.g. PD-L1); however, the predictive value of these factors remains unknown. We present the analyses of immune-checkpoint genes ( CD274, CD86, CTLA4, HAVCR2, LAG3 and PDCD1) and CD163, CD4, CD68 and CD8A expression as potential predictive factors of response to trabectedin in a subset of STS patients of the GEIS registry. Methods: Selection criteria included patients with STS, pretreated with at least 2 lines in the advanced setting (one line being trabectedin), with paraffin block available and ethic committee’s approval. Direct transcriptomics was performed using HTG Molecular Oncology Biomarker Pathway panel (HTG Molecular Diagnostics, Inc.; Tucson, AZ, USA), following manufacturers’ instructions. Data analyses were performed taking into account the median Log2 of expression of each gene and by correlating it with progression-free survival (PFS) for trabectedin, and overall survival measured from the starting date of trabectedin treatment (OS). Results: Among 387 registered patients, fitting with the inclusions criteria, 139 cases were used for gene expression analyses, as the discovery set. Patients had median age of 52 years, 54% were females and had a median follow-up from diagnosis of 44 months. High expression of CD274 (PD-L1) was significantly associated with better PFS of trabectedin (5.4 vs. 3.0 months; p= 0.006). Similar results were obtained with high expression of CTLA4 and LAG3: 6.0 vs 3.1 months; p = 0.005 and 5.4 vs 2.7 months; p = 0.042, respectively. Expression of CTLA4 and LAG3 showed no significant impact in OS; whereas CD274 high expression showed a trend towards better OS (17.9 vs 10.2 months; p = 0.077). Also, no significant correlation was achieved for CD163, CD4, CD68, CD8A, CD86 and HAVCR2; PDCD1 (PD-1) showed a trend towards better PFS of trabectedin, p = 0.114. Conclusions: The expression of selected immune-checkpoint genes exhibited a potential predictive value for trabectedin in advanced STS. Validation studies (at the transcriptional and protein level) are currently ongoing to confirm their potential predictive role.

11543 Background: The ceiling-drug effect seen for most active drugs in STS could be related, partially, to multidrug resistance mechanisms (MDRM). We previously reported the independent prognostic role for RFS and OS of MRP1 in high-risk localized STS of limbs and trunk-wall treated with epirubicin and ifosfamide (Mol Cancer Ther.2014 13(1):249-59). A translational study was carried out within the randomized phase III trial of epirubicin plus ifosfamide vs histotype-tailored neoadjuvant chemotherapy (NCT01710176), to investigate MRP1 prognostic value using the trial population as validation set. Methods: Patients enrolled in the trial were invited to participate, through the informed consent, to this analysis. IHC used QCRL-1 (Santa Cruz biotechnology) MRP1 monoclonal antibody. TMAs were built on the highest-grade area of each tumor, being the procedure blinded for clinical data. MRP1 expression was grouped as low (≤ 25% positive cells) vs high ( > 25% positive cells) expression. For data analysis, patients were grouped as A) epirubicin plus ifosfamide control arm and B) histotype-tailored experimental arm. Drugs used in group B were: gemcitabine-docetaxel (UPS), gemcitabine-DTIC (LMS), trabectedin (High-grade (HG) myxoid LPS), ifosfamide-etoposide (MPNST) and high-dose ifosfamide (SS). Prognostic value of MRP1’s extension was analyzed using Cox’s proportional hazard regression. A p-value < 0.05 was considered statistically significant. Results: 175 patients were analyzed (median age 49; males 61%) with median follow-up of 4.66 y. Group A (n = 88) included HG-myxoid LPS (27%), SS (25%), UPS (24%), LMS (12%) MPNST (10%) and others (2%); group B (n = 87) included UPS (38%), SS (24%), HG-myxoid LPS (20%), LMS (10%) and MPNST (8%). MRP1 high extension was distributed as follows: 48% (A) and 57% (B). High MRP-1 expression showed significantly worse prognosis for disease-free survival (DFS) (HR 2.71 (1.31-5.62) p = 0.007) and a trend towards worse OS (HR = 2.75 (0.97-7.81) p = 0.058) in group A. No correlation was seen between MRP-1 expression and DFS (p = 0.384) or OS (p = 0.665), in group B. Conclusions: MRP1 overexpression was related to significant worse prognosis in 2 prospective randomized series of high-risk, localized, STS treated with neoadjuvant epirubicin and ifosfamide. These agents are both substrate of MRP1; this could add rationale for a possible predictive role, as MDRM, for the two most active drugs in STS. A trial combining epirubicin, ifosfamide and MRP1 inhibitor is currently under design.

[Background] A solitary fibrous tumour is a rare soft-tissue tumour with three clinicopathological variants: typical, malignant, and dedifferentiated. Preclinical experiments and retrospective studies have shown different sensitivities of solitary fibrous tumour to chemotherapy and antiangiogenics. We therefore designed a trial to assess the activity of pazopanib in a cohort of patients with malignant or dedifferentiated solitary fibrous tumour. The clinical and translational results are presented here., [Methods] In this single-arm, phase 2 trial, adult patients (aged ≥ 18 years) with histologically confirmed metastatic or unresectable malignant or dedifferentiated solitary fibrous tumour at any location, who had progressed (by RECIST and Choi criteria) in the previous 6 months and had an ECOG performance status of 0–2, were enrolled at 16 third-level hospitals with expertise in sarcoma care in Spain, Italy, and France. Patients received pazopanib 800 mg once daily, taken orally without food, at least 1 h before or 2 h after a meal, until progression or intolerance. The primary endpoint of the study was overall response measured by Choi criteria in the subset of the intention-to-treat population (patients who received at least 1 month of treatment with at least one radiological assessment). All patients who received at least one dose of the study drug were included in the safety analyses. This study is registered with ClinicalTrials.gov, number NCT02066285, and with the European Clinical Trials Database, EudraCT number 2013-005456-15., [Findings] From June 26, 2014, to Nov 24, 2016, of 40 patients assessed, 36 were enrolled (34 with malignant solitary fibrous tumour and two with dedifferentiated solitary fibrous tumour). Median follow-up was 27 months (IQR 16–31). Based on central radiology review, 18 (51%) of 35 evaluable patients had partial responses, nine (26%) had stable disease, and eight (23%) had progressive disease according to Choi criteria. Further enrolment of patients with dedifferentiated solitary fibrous tumour was stopped after detection of early and fast progressions in a planned interim analysis. 51% (95% CI 34–69) of 35 patients achieved an overall response according to Choi criteria. Ten (29%) of 35 patients died. There were no deaths related to adverse events and the most frequent grade 3 or higher adverse events were hypertension (11 [31%] of 36 patients), neutropenia (four [11%]), increased concentrations of alanine aminotransferase (four [11%]), and increased concentrations of bilirubin (three [8%])., [Interpretation] To our knowledge, this is the first trial of pazopanib for treatment of malignant solitary fibrous tumour showing activity in this patient group. The manageable toxicity profile and the activity shown by pazopanib suggests that this drug could be an option for systemic treatment of advanced malignant solitary fibrous tumour, and provides a benchmark for future trials., Spanish Group for Research on Sarcomas (GEIS), Italian Sarcoma Group (ISG), French Sarcoma Group (FSG), GlaxoSmithKline, and Novartis.

Background Soft-tissue sarcomas (STS) are life-threatening diseases, for which more efficient therapeutic options are necessary. Trabectedin (T) is an anti-tumor drug approved for the treatment of advanced STS. Synergistic drug combinations could improve T results in STS patients. Rapamycin (R) is an mTOR pathway inhibitor. Synergy with T has been described in ovary clear cell carcinoma. Of note, R suppresses DNA double-strand breaks repair, thus generating the perfect set-up for T activity. Altogether, we hypothesize that T+R combination (T+R) is synergistic in STS, and that mTOR inhibition enhances T activity. Methods Human STS cell lines (n = 9) were treated with increasing doses of T (1x10-7M to 1x10-11M) and/ or R (1x10-9 to 1x10-11) to determine IC50 and combination index (CI) values. Cells were initially exposed to R, 2 hours later T was added, under the assumption that R pre-treatment favors T cytotoxicity. Cell viability, at 72 h, was measured by MTS assay. Apoptosis was determined by Western Blot for PARP and Caspase 3 cleavage. In vivo experiments were performed in immunocompetent 3-methylcolanthrene fibrosarcoma mice: T was administrated via IV (0.15 mg/kg; q7dx1) and R via IP (0.50 mg/kg; q7dx2). Body weight and tumor volume were measured every 2 days for 15 days of treatment. Tumors were collected for analysis (snap frozen and paraffin embedding). Results T+R was synergistic in all STS cell lines: CP0024 primary leiomyosarcoma and 93T449 liposarcoma cell lines showed strong synergism with CI at the ED50 of 0.129 and 0.027, respectively. This synergy was followed by an increase of PARP and Caspase 3 cleavage. The synergism was confirmed in vivo: mice treated with R+T showed tumor growth delay in comparison to the drugs alone (p Conclusions R+T is synergic in STS and deserves exploration in clinical setting. Further research will reveal the mechanisms underlying this synergy. Legal entity responsible for the study Javier Martin Broto. Funding PharmaMar. Disclosure D.S. Moura: Research grant / Funding (institution): PharmaMar; Research grant / Funding (institution): Eisai; Research grant / Funding (institution): Novartis; Travel / Accommodation / Expenses: PharmaMar; Travel / Accommodation / Expenses: Eisai. M. Lopez-Alvarez: Travel / Accommodation / Expenses: Eisai. N. Hindi: Travel / Accommodation / Expenses: PharmaMar; Research grant / Funding (institution): Eisai; Research grant / Funding (institution): Novartis; Research grant / Funding (institution): PharmaMar; Honoraria (self): PharmaMar. J. Martin-Broto: Research grant / Funding (institution): PharmaMar; Research grant / Funding (institution): Eisai; Research grant / Funding (institution): Novartis; Honoraria (self): PharmaMar; Honoraria (self): Lilly; Honoraria (self): Novartis; Speaker Bureau / Expert testimony: PharmaMar. All other authors have declared no conflicts of interest.

This is an Open Access article distributed under the terms of the Creative Commons Attribution-Non-Commercial License., All types of DNA damage cause a local alteration and relaxation of chromatin structure. Sensing and reacting to this initial chromatin alteration is a necessary trigger for any type of DNA damage response (DDR). In this context, chromatin kinases are likely candidates to participate in detection and reaction to a locally altered chromatin as a consequence of DNA damage and, thus, initiate the appropriate cellular response. In this work, we demonstrate that VRK1 is a nucleosomal chromatin kinase and that its depletion causes loss of histones H3 and H4 acetylation, which are required for chromatin relaxation, both in basal conditions and after DNA damage, independently of ATM. Moreover, VRK1 directly and stably interacts with histones H2AX and H3 in basal conditions. In response to DNA damage induced by ionizing radiation, histone H2AX is phosphorylated in Ser139 by VRK1. The phosphorylation of H2AX and the formation of gH2AX foci induced by ionizing radiation (IR), are prevented by VRK1 depletion and are rescued by kinase-active, but not kinase-dead, VRK1. In conclusion, we found that VRK1 is a novel chromatin component that reacts to its alterations and participates very early in DDR, functioning by itself or in cooperation with ATM., DMM and M S-G were supported by JAE-CSIC-Fondo Social Europeo fellowships. DSM was supported by a Ministerio de Ciencia e Innovación-FPI predoctoral fellowship. This work was funded by grants from Ministerio de Econom ıa y Competitividad (SAF2010-14935, SAF2013-44810R, SAF2014-57791-REDC) and Consejerıa de Educacion de la Junta de Castilla y Leon (CSI002U14) to PAL.

[Introduction] There are limited findings available on KIT-negative GIST-like (KNGL) population. Also, KIT expression may be post-transcriptionally regulated by miRNA221 and miRNA222. Hence, the aim of this study is to characterize KNGL population, by differential gene expression, and to analyze miRNA221/222 expression and their prognostic value in KNGL patients., [Methods] KIT, PDGFRA, DOG1, IGF1R, MIR221 and MIR222 expression levels were determined by qRT-PCR. We also analyzed KIT and PDGFRA mutations, DOG1 expression, by immunohistochemistry, along with clinical and pathological data. Disease-free survival (DFS) and overall survival (OS) differences were calculated using Log-rank test., [Results] Hierarchical cluster analyses from gene expression data identified two groups: group I had KIT, DOG1 and PDGFRA overexpression and IGF1R underexpression and group II had overexpression of IGF1R and low expression of KIT, DOG1 and PDGFRA. Group II had a significant worse OS (p = 0.013) in all the series, and showed a tendency for worse OS (p = 0.11), when analyzed only the localized cases. MiRNA222 expression was significantly lower in a control subset of KIT-positive GIST (p < 0.001). OS was significantly worse in KNGL cases with higher expression of MIR221 (p = 0.028) or MIR222 (p = 0.014)., [Conclusions] We identified two distinct KNGL subsets, with a different prognostic value. Increased levels of miRNA221/222, which are associated with worse OS, could explain the absence of KIT protein expression of most KNGL tumors., The project was funded by the Instituto de Salud Carlos III (ISCIII) - Fondo Europeo de Desarrollo Regional (FEDER), through a public competitive call (project reference PI15/01254; principal Investigator Javier Martín Broto), and the Spanish Group for Research on Sarcoma (GEIS).

© The Author(s) 2018., Regulation of cell division requires the integration of signals implicated in chromatin reorganization and coordination of its sequential changes in mitosis. Vaccinia-related kinase 1 (VRK1) and Aurora B (AURKB) are two nuclear kinases involved in different steps of cell division. We have studied whether there is any functional connection between these two nuclear kinases, which phosphorylate histone H3 in Thr3 and Ser10, respectively. VRK1 and AURKB are able to form a stable protein complex, which represents only a minor subpopulation of each kinase within the cell and is detected following nocodazole release. Each kinase is able to inhibit the kinase activity of the other kinase, as well as inhibit their specific phosphorylation of histone H3. In locations where the two kinases interact, there is a different pattern of histone modifications, indicating that there is a local difference in chromatin during mitosis because of the local complexes formed by these kinases and their asymmetric intracellular distribution. Depletion of VRK1 downregulates the gene expression of BIRC5 (survivin) that recognizes H3-T3ph, both are dependent on the activity of VRK1, and is recovered with kinase active murine VRK1, but not with a kinase-dead protein. The H3–Thr3ph–survivin complex is required for AURB recruitment, and their loss prevents the localization of ACA and AURKB in centromeres. The cross inhibition of the kinases at the end of mitosis might facilitate the formation of daughter cells. A sequential role for VRK1, AURKB, and haspin in the progression of mitosis is proposed., This work was funded by grants from Ministerio de Economía y Competitividad (SAF2013-44810-R, SAF2014-57791-REDC), Agencia Estatal de Investigación (SAF2016-75744-R), and Consejería de Educación de la Junta de Castilla y León (CSI001U16 and UIC-17) to P.A.L.

VRK1 is a nuclear chromatin Ser-Thr kinase functionally associated with different processes that require chromatin remodeling. The VRK1 activity is regulated by entry in cell cycle, and this kinase is also required for nuclear envelope dynamics, chromatin condensation, and Golgi fragmentation. Among its substrates, there are several transcription factors: p53, c-Jun, ATF2, CREB1, and SOX2. VRK1 probably acts cooperating with other signaling pathways that also phosphorylate these transcription factors. VRK1 stabilizes p53 by a specific phosphorylation in Thr18 and after induction of p53 responses, there is a VRK1 downregulation in the lysosome, in which the autophagic pathway participates in a p53-dependent manner. VRK1 also contributes to chromatin condensation, nuclear envelop kinetics by phosphorylation of histone H3 and BAF, and the regulation of Cajal bodies by phosphorylation of coilin. In DNA-damage responses, VRK1 actively participates in chromatin remodeling and regulates H2AX, NBS1, and 53BP1. VRK1 is downstream of MEK1 and Plk3 in the induction of Golgi fragmentation during mitosis. Furthermore, VRK1 is expressed in most tissues, is necessary in the early G1 phase for entry in cell cycle, and is associated with proliferation markers.

[Background] Patients with relapsed unresectable osteosarcoma represents an unmet need, so active and safe systemic treatments are required. Fas cell surface death receptor and mammalian target of rapamycin pathways are implicated in progressing osteosarcoma, and we had preclinical and clinical experience with a scheme that targets both pathways. Therefore, we designed a phase II trial with gemcitabine plus rapamycin, to determine the efficacy and safety, in this subset of patients., [Patients and methods] A multicenter, single-arm phase II trial was sponsored by the Spanish Group for Research on Sarcoma. Osteosarcoma patients, relapsed or progressing after standard chemotherapy and unsuitable for metastasectomy received gemcitabine and rapamycin p.o. 5 mg/day except for the same day of gemcitabine administration, and the day before. The main end point was 4-month progression-free survival rate (PFSR), with the assumption that rates higher than 40% would be considered as an active regimen. Translational research aimed to correlate biomarkers with the clinical outcome., [Results] Thirty-five patients were enrolled and received at least one cycle. PFSR at 4 months was 44%, and after central radiologic assessment, 2 partial responses and 14 stabilizations (48.5%) were reported from 33 assessable patients. The most frequent grade 3–4 adverse events were: neutropenia (37%), thrombocytopenia (20%), anemia (23%), and fatigue (15%); however, only three patients had febrile neutropenia. Positive protein expression of RRM1 significantly correlated with worse PFS and overall survival, while positivity of P-ERK1/2 was correlated with significant better overall survival., [Conclusion] Gemcitabine plus sirolimus exhibits satisfactory antitumor activity and safety in this osteosarcoma population, exceeding the prespecified 40% of 4-month PFSR. The significant correlation of biomarkers with clinical outcome encourages further prospective investigation., This work was funded by the Ministry of Health, Social Policy and Equality of Spain, through a public competitive call (project reference EC11-444) and by the Spanish Group for Research on Sarcoma (GEIS), which sponsored the trial (no grant numbers apply).