Angiosarcoma is an aggressive malignancy that arises spontaneously or secondarily to ionising radiation or chronic lymphoedema1. Previous work has identified aberrant angiogenesis, including occasional somatic mutations in angiogenesis signalling genes, as a key driver of angiosarcoma1. Here, we employed whole genome, exome, and targeted sequencing to study the somatic changes underpinning primary and secondary angiosarcoma. We identified recurrent mutations in two genes, PTPRB and PLCG1, which are intimately linked to angiogenesis. The endothelial phosphatase PTPRB, a negative regulator of vascular growth factor tyrosine kinases, harboured predominantly truncating mutations in 10/39 (26%) tumours. PLCG1, a signal transducer of tyrosine kinases, presented with a recurrent, likely activating R707Q missense variant in 3/34 cases (9%). Overall, 15/39 (38%) tumours harboured at least one driver mutation in angiogenesis signalling genes. Our findings inform and reinforce current therapeutic efforts to target angiogenesis signalling in angiosarcoma.

Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive sarcomas that can show overlapping features with benign neurofibromas as well as high-grade sarcomas. Additional diagnostic markers are needed to aid in this often challenging differential diagnosis. Recently mutations in two critical components of the polycomb repressor 2 (PRC2) complex, SUZ12 and EED, were reported to occur specifically in MPNSTs while such mutations are absent in neurofibromas, both in the setting of neurofibromatosis (NF) and sporadic cases. Furthermore, both SUZ12 and EED mutations in MPNSTs were associated with loss of H3K27 tri-methylation, a downstream target of PRC2. Therefore we tested whether H3K27me3 immunohistochemistry is useful as a diagnostic and prognostic marker for MPNSTs. We performed H3K27me3 immunohistochemistry in 162 primary MPNSTs, 97 neurofibromas and 341 other tumors using tissue microarray. We observed loss of H3K27me3 in 34% (55/162) of all MPNSTs while expression was retained in all neurofibromas including atypical (n=8) and plexiform subtypes (n=24). Within other tumors we detected loss of H3K27me3 in only 7% (24/341). Surprisingly, 60% (9/15) of synovial sarcomas and 38% (3/8) of fibrosarcomatous dermatofibrosarcoma protuberans (DFSP) showed loss of H3K27 trimethylation. Only 1 out of 44 schwannomas showed loss of H3K27me3 and all 4 perineuriomas showed intact H3K27me3. Furthermore, MPNSTs with loss of H3K27 tri-methylation showed inferior survival compared to MPNSTs with intact H3K27 tri-methylation, which was validated in two independent cohorts. Our results indicate that H3K27me3 immunohistochemistry is useful as a diagnostic marker in which loss of H3K27me3 favours MPNST above neurofibroma. However H3K27me3 immunohistochemistry is not suitable to distinguish MPNST from its morphological mimicker synovial sarcoma or fibrosarcomatous DFSP. Since loss of H3K27 tri-methylation was related to poorer survival in MPNST, chromatin modification mediated by this specific histone seems to orchestrate more aggressive tumour biology.

Structured Abstract Objective MPNSTs are an aggressive group of soft tissue sarcomas that can arise sporadically, in the context of NF1, or at a site of prior irradiation. Large series profiling the features and outcomes of sporadic, neurofibromatosis type 1 (NF1)-associated, and radiation (RT)-associated malignant peripheral nerve sheath tumor (MPNST) are limited. The goal of this study was to elucidate differences between MPNST etiologies in a large single-institution retrospective study. Methods Patients (n = 317) were identified through our institutional tumor registry. Clinicopathologic features were retrospectively collected. Features were compared among MPNST subtypes for patients who had sufficient clinical history (n = 289), and clinicopathologic features were used to identify adverse predictors of recurrence and survival outcomes. Results Five-year local recurrence-free survival (LRFS), distant recurrence-free survival (DRFS), and disease-specific survival (DSS) estimates were 56.6%, 49.6%, and 53.6% for the high-grade MPNST cohort, respectively. Five-year DSS was lower in NF1-associated and RT-associated compared to sporadic MPNST (48.7%, 40.9%, and 63.0%, respectively; p = 0.140). RT-associated MPNST had worse LRFS than sporadic and NF1-associated subtypes (p = 0.047). Truncally located tumors, positive surgical margins, local recurrence, and metastasis were predictors of adverse DSS in multivariate analysis. Conclusion RT-associated MPNSTs demonstrate poorer local recurrence-free and disease-specific survival than sporadic and NF1-associated tumors. NF1-associated MPNSTs may have worse survival outcomes owing to large tumor size, compromising truncal location, and lower rate of negative resection margins compared to sporadic tumors.

Background Radiation therapy is used increasingly as a component of multidisciplinary treatment for many solid tumors. One complication of such treatment is the development of radiation-associated sarcoma (RAS). Undifferentiated pleomorphic sarcoma (UPS), previously termed “malignant fibrous histiocytoma” (MFH) is the most common histologic subtype of RAS. This study investigated the clinical outcomes for patients with radiation-associated UPS (RA-UPS/MFH). Methods The study identified 1068 patients with UPS/MFH treated at the authors’ institution. Patient and tumor factors were collected and compared. Regression analysis was performed to identify independent predictors of survival. A matched-cohort survival and recurrence analysis was performed for radiation-associated and sporadic UPS/MFH. Results The findings showed that RA-UPS/MFH comprised 5.1 % of the UPS population. The median latency to the development of RA-UPS/MFH was 9.3 years. The 5-year disease-specific survival (DSS) was 52.2 % for patients identified with RA-UPS/MFH (n = 55) compared with 76.4 % for patients with unmatched sporadic UPS/MFH (n = 1,013; p < 0.001). A matched-cohort analysis also demonstrated that the 5-year DSS was significantly worse for RA-UPS/MFH (52.2 vs 73.4 %; p = 0.002). Furthermore, higher local recurrence rates were observed for patients with RA-UPS/MFH than for patients with sporadic lesions (54.5 vs 23.5 %; p < 0.001). Radiation-associated status and incomplete resection were identified as independent predictors of local recurrence. Conclusion This study demonstrated worse clinical outcomes for patients with RA-UPS/MFH than for patients with sporadic UPS/MFH. Local recurrence was significantly higher for patients with RA-UPS/MFH, suggesting a unique tumor biology for this challenging disease.

Malignant peripheral nerve sheath tumours (MPNSTs), which develop sporadically or from neurofibromatosis, recur frequently with high metastatic potential and poor outcome. The polycomb group protein enhancer of zeste homologue 2 (EZH2) is an important regulator for various human malignancies. However, the function of EZH2 in MPNSTs is unknown. Here we report that the EZH2–miR-30d–KPNB1 signalling pathway is critical for MPNST tumour cell survival in vitro and tumourigenicity in vivo. Up-regulated EZH2 in MPNST inhibits miR-30d transcription via promoter binding activity, leading to enhanced expression of the nuclear transport receptor KPNB1 that is inhibited by miR-30d targeting of KPNB1 3′ UTR region. Furthermore, inhibition of EZH2 or KPNB1, or miR-30d over-expression, induces MPNST cell apoptosis in vitro and suppresses tumourigenesis in vivo. More importantly, forced over-expression of KPNB1 rescues MPNST cell apoptosis induced by EZH2 knockdown. Immunohistochemical analyses show that EZH2 and KPNB1 over-expression is observed in human MPNST specimens and is negatively associated with miR-30d expression. Our findings identify a novel signalling pathway involved in MPNST tumourigenesis, and also suggest that EZH2–miR-30d–KPNB1 signalling represents multiple potential therapeutic targetable nodes for MPNST.

BACKGROUNDDesmoid tumors (DTs) are rare mesenchymal lesions that can recur repeatedly. When it is feasible, DTs are surgically resected; however, this often results in high recurrence rates. Recently, treatment with PF‐03084014, a potent γ‐secretase inhibitor, has been shown to have antitumor activity in several tumor types by affecting the WNT/β‐catenin pathway. Consequently, Notch pathway inhibition by PF‐03084014 might be a promising approach for DT treatment.METHODSThe expression of Notch pathway components was analyzed in DT tissues and cell strains with immunohistochemistry and Western blotting, respectively. A panel of DT cell strains was exposed to PF‐03084014 and evaluated for cell proliferation. Antitumor effects were assessed via cell cycle, apoptosis, and migration and invasion analysis. Cells treated with PF‐03084014 were characterized with a gene array analysis combined with Ingenuity Pathway Analysis.RESULTSThe results showed that Notch pathway components were expressed at different levels in DTs. Hes1 (Hes Family BHLH Transcription Factor 1) was overexpressed in DT tumors versus dermal scar tissue, and PF‐03084014 caused significant decreases in Notch intracellular domain and Hes1 expression in DT cell strains. PF‐03084014 decreased DT cell migration and invasion and also caused cell growth inhibition in DT cell strains, most likely through cell cycle arrest. Gene array analysis combined with Ingenuity Pathway Analysis showed that Wnt1‐inducible signaling pathway protein 2 possibly regulated Notch and WNT pathways after treatment with PF‐03084014 through integrin.CONCLUSIONOur findings suggest that the Notch pathway is an important DT therapeutic target. Furthermore, PF‐03084014 has significant antitumor activity against DTs, and it may be an alternative strategy for DT treatment. Cancer 2015;121:4088–4096. © 2015 American Cancer Society.

Undifferentiated sarcoma was the most common source of brain metastasis. Most cases showed evidence of prior metastatic disease. Surgical resection is employed to manage symptoms, but prognosis remains dismal.

Background Undifferentiated pleomorphic sarcomas (UPS) present a diagnostic and therapeutic challenge. Identification of prognostic molecular markers is required for the discovery of novel treatment approaches. The aim of this study was to correlate clinicopathologic variables, expression of tyrosine kinase receptors, and markers of cell cycle progression and survival with oncologic outcomes. Methods A tissue microarray containing 208 primary UPS samples was analyzed by immunohistochemistry for protein markers and in situ hybridization for microRNA. Staining results were correlated with clinicopathologic features and oncologic outcomes. Univariate and multivariate analyses were conducted to assess associations between expression of protein markers, mi-RNA and outcome. Results At a median follow-up of 3.9 years (9 years for survivors), 5-year disease-specific survival (DSS) was 63%. Clinical variables associated with improved DSS included age < 61 years, tumor size < 10 cm, margin-negative resection and sporadic-tumor status. At the protein level, loss of cyclin D1 (p=0.06), pEGFR (p=0.023), pIGF-1R (p=0.022), and PTEN (p<0.001) and overexpression of AXL (p=0.015) were associated with reduced DSS on univariate analysis. Ki67, PCNA and pEGFR were more highly expressed in sporadic UPS than radiation-associated (RA-UPS) while RA-UPS samples expressed higher levels of both phosphorylated and total IGF-1R. Discussion Cyclin D1, AXL and PTEN are associated with cancer-specific outcomes and warrant further investigation in UPS. The differences in protein expression in sporadic versus RA-UPS may indicate that the activated molecular signaling nodes may be different for each specific histology and could also explain the aggressive phenotype seen in RA-UPS when compared to the sporadic lesions.