[Gastrointestinal stromal tumors : Where do we stand?] / Gastrointestinale Stromatumoren : Wo stehen wir?

For more than 20 years gastrointestinal stromal tumors (GIST) have been a paradigm for a targeted treatment with tyrosine kinase inhibitors. A fundamental prerequisite for a neoadjuvant or adjuvant treatment of localized GIST or an additive treatment of metastatic GIST is the molecular typing of tumors, ideally at the initial diagnosis. In addition, the possibility of a hereditary or syndromic predisposition must be considered because this results in consequences for the treatment and a different follow-up strategy.

SS18-SSX drives CREB activation in synovial sarcoma.

PURPOSE: Synovial sarcoma (SySa) is a rare soft tissue tumor characterized by a reciprocal t(X;18) translocation. The chimeric SS18-SSX fusion protein represents the major driver of the disease, acting as aberrant transcriptional dysregulator. Oncogenic mechanisms whereby SS18-SSX mediates sarcomagenesis are incompletely understood, and strategies to selectively target SySa cells remain elusive. Based on results of Phospho-Kinase screening arrays, we here investigate the functional and therapeutic relevance of the transcription factor CREB in SySa tumorigenesis. METHODS: Immunohistochemistry of phosphorylated CREB and its downstream targets (Rb, Cyclin D1, PCNA, Bcl-xL and Bcl-2) was performed in a large cohort of SySa. Functional aspects of CREB activity, including SS18-SSX driven circuits involved in CREB activation, were analyzed in vitro employing five SySa cell lines and a mesenchymal stem cell model. CREB mediated transcriptional activity was modulated by RNAi-mediated knockdown and small molecule inhibitors (666-15, KG-501, NASTRp and Ro 31-8220). Anti-proliferative effects of the CREB inhibitor 666-15 were tested in SySa avian chorioallantoic membrane and murine xenograft models in vivo. RESULTS: We show that CREB is phosphorylated and activated in SySa, accompanied by downstream target expression. Human mesenchymal stem cells engineered to express SS18-SSX promote CREB expression and phosphorylation. Conversely, RNAi-mediated knockdown of SS18-SSX impairs CREB phosphorylation in SySa cells. Inhibition of CREB activity reduces downstream target expression, accompanied by suppression of SySa cell proliferation and induction of apoptosis in vitro and in vivo. CONCLUSION: In conclusion, our data underline an essential role of CREB in SySa tumorigenesis and provides evidence for molecular targeted therapies.

Low-density lipoprotein receptor (LDLR) is an independent adverse prognostic factor in acute myeloid leukaemia.

The low-density lipoprotein receptor (LDLR) is a membrane receptor that mediates the endocytosis of low-density lipoprotein (LDL). Uptake of LDL has been proposed to contribute to chemotherapy resistance of acute myeloid leukaemia (AML) cell lines in vitro. In the present study, we analysed LDLR expression and survival using bone marrow biopsies from 187 intensively treated patients with AML. Here, increasing LDLR expression was associated with decreasing overall (58·4%, 44·2%, and 24·4%; P = 0·0018), as well as event-free survival (41·7%, 18·1%, and 14·3%; P = 0·0077), and an increasing cumulative incidence of relapse (33·9%, 55·1%, and 71·4%; P = 0·0011). Associations of LDLR expression with survival were confirmed in 557 intensively treated patients from two international validation cohorts. In the analytic and validation cohorts, LDLR expression remained associated with outcome in multivariable regression analyses including the European LeukemiaNet genetic risk classification. Thus, LDLR predicts outcome of patients with AML beyond existing risk factors. Furthermore, we found low expression levels of LDLR in most healthy tissues, suggesting it as a promising target for antibody-based pharmacodelivery approaches in AML.

[Masquerade lacrimal duct stenosis: prevalence of lacrimal sac tumors]. / Maskerade Tränenwegsstenose: Prävalenz von Tränensacktumoren.

BACKGROUND: Tumors of the lacrimal sac are a rare entity. Malignancies are often associated with a high mortality rate. Lacrimal sac tumors often present as lacrimal duct stenosis with dacryocystitis and are often only diagnosed after an intraoperative biopsy. The aim of this study was a retrospective analysis of all cases with lacrimal sac tumors, which presented with a lacrimal duct stenosis at this medical center in the past 10 years. METHODS: All patients who were treated by external dacryocystorhinostomy (DCR) at the University Medical Center Münster during the period January 2009-December 2018 were retrospectively analyzed for the presence of a lacrimal sac tumor. Symptoms, clinical and histopathological findings, diagnostic and therapeutic procedures as well as long-term follow-up were analyzed. RESULTS: A total number of 878 patients underwent an external DCR at the University Medical Center Münster during the study period. Of these patients 13 were diagnosed with a lacrimal sac tumor and included 9 malignant lymphomas, 2 squamous cell carcinomas, 1 oncocytic adenoma and 1 transitional cell papilloma. CONCLUSION: Neoplasms of the lacrimal sac can masquerade as lacrimal duct stenosis or dacryocystitis and must be considered as a differential diagnosis in cases with an atypical clinical course. A lacrimal sac biopsy during an (external) DCR with subsequent histopathological examination is strongly recommended in such cases.

Prevalence of the Hippo Effectors YAP1/TAZ in Tumors of Soft Tissue and Bone.

Tumors of soft tissue and bone represent a heterogeneous group of neoplasias characterized by a wide variety of genetic aberrations. Albeit knowledge on tumorigenesis in mesenchymal tumors is continuously increasing, specific insights on altered signaling pathways as a basis for molecularly targeted therapeutic strategies are still sparse. The aim of this study was to determine the involvement of YAP1/TAZ-mediated signals in tumors of soft tissue and bone. Expression levels of YAP1 and TAZ were analyzed by immunohistochemistry in a large cohort of 486 tumor specimens, comprising angiosarcomas (AS), Ewing sarcomas, leiomyosarcomas, malignant peripheral nerve sheath tumors (MPNST), solitary fibrous tumors, synovial sarcomas (SySa), well-differentiated/dedifferentiated/pleomorphic and myxoid liposarcomas (MLS). Moderate to strong nuclear staining of YAP1 and TAZ was detected in 53% and 33%, respectively. YAP1 nuclear expression was most prevalent in MPNST, SySa and MLS, whereas nuclear TAZ was predominately detected in AS, MLS and MPNST. In a set of sarcoma cell lines, immunoblotting confirmed nuclear localization of YAP1 and TAZ, corresponding to their transcriptionally active pool. Suppression of YAP1/TAZ-TEAD mediated transcriptional activity significantly impaired sarcoma cell viability in vitro and in vivo. Our findings identify nuclear YAP1 and TAZ positivity as a common feature in subsets of sarcomas of soft tissue and bone and provide evidence of YAP1/TAZ-TEAD signaling as a specific liability to be considered as a new target for therapeutic intervention. Nuclear YAP1/TAZ expression may represent a biomarker suited to identify patients that could benefit from YAP1/TAZ-TEAD directed therapeutic approaches within future clinical trials.

SS18-SSX-Dependent YAP/TAZ Signaling in Synovial Sarcoma.

PURPOSE: Synovial sarcoma is a soft tissue malignancy characterized by a reciprocal t(X;18) translocation. The chimeric SS18-SSX fusion protein acts as a transcriptional dysregulator representing the major driver of the disease; however, the signaling pathways activated by SS18-SSX remain to be elucidated to define innovative therapeutic strategies. EXPERIMENTAL DESIGN: Immunohistochemical evaluation of the Hippo signaling pathway effectors YAP/TAZ was performed in a large cohort of synovial sarcoma tissue specimens. SS18-SSX dependency and biological function of the YAP/TAZ Hippo signaling cascade were analyzed in five synovial sarcoma cell lines and a mesenchymal stem cell model in vitro. YAP/TAZ-TEAD-mediated transcriptional activity was modulated by RNAi-mediated knockdown and the small-molecule inhibitor verteporfin. The effects of verteporfin were finally tested in vivo in synovial sarcoma cell line-based avian chorioallantoic membrane and murine xenograft models as well as a patient-derived xenograft. RESULTS: A significant subset of synovial sarcoma showed nuclear positivity for YAP/TAZ and their transcriptional targets FOXM1 and PLK1. In synovial sarcoma cells, RNAi-mediated knockdown of SS18-SSX led to significant reduction of YAP/TAZ-TEAD transcriptional activity. Conversely, SS18-SSX overexpression in SCP-1 cells induced aberrant YAP/TAZ-dependent signals, mechanistically mediated by an IGF-II/IGF-IR signaling loop leading to dysregulation of the Hippo effectors LATS1 and MOB1. Modulation of YAP/TAZ-TEAD-mediated transcriptional activity by RNAi or verteporfin treatment resulted in significant growth inhibitory effects in vitro and in vivo. CONCLUSIONS: Our preclinical study identifies an elementary role of SS18-SSX-driven YAP/TAZ signals, highlights the complex network of oncogenic signaling pathways in synovial sarcoma pathogenesis, and provides evidence for innovative therapeutic approaches.

[Treatment Options for Adenoid Cystic Lacrimal Gland Carcinoma - A Case Series and Literature Review]. / Therapieoptionen bei adenoidzystischem Tränendrüsenkarzinom ­ Fallserie und aktueller Literaturüberblick.

Adenoid cystic carcinoma of the lacrimal gland (ACC) is a rare malignant orbital tumour with a poor overall prognosis. Current therapeutic approaches like radical and local surgery, adjuvant radiation and neoadjuvant intra-arterial chemotherapy are controversial. We present three cases of patients with ACC with different therapy concepts and discuss these with current recommendations from the literature.

Diagnostic tools in the differential diagnosis of giant cell-rich lesions of bone at biopsy.

The diagnosis of giant cell-rich lesions of bone can be challenging if radiological findings are ambiguous and tissue of the biologically deciding component is underrepresented in biopsy specimens. The frequent association of giant cell tumor of bone (GCT) and chondroblastoma (CB) with (secondary) aneurysmal bone cysts (ABC) may further impede correct classification. The present study evaluates the potentials and limitations of mutation-specific histone H3.3 and DOG1 immunohistochemistry, Sanger-/next generation sequencing (NGS) and FISH analysis in the differential diagnosis of 23 GCT, 14 CB and 19 ABC. All morphologically typical GCT and CB harbored mutations in the H3F3A or H3F3B gene, respectively. These were, except for one uncommon G34L mutation in a GCT, reliably and specifically detected by mutation-specific H3.3 G34W or H3.3 K36M immunohistochemistry and DNA sequencing. In the diagnostic substantiation of CB, DOG1 staining was less sensitive compared to H3.3 K36M immunohistochemistry. 47% of ABC specifically showed translocations of the USP6 gene, while mutations in H3F3A/B were absent. Based on the results of this study, we conclude that mutation-specific H3.3 immunohistochemistry (selectively complemented with NGS-based DNA sequencing) and USP6 FISH analysis enable a reliable diagnostic distinction of GCT, CB and ABC of morphologically and radiologically difficult cases.

Adjuvant chemotherapy-Radiotherapy-Chemotherapy sandwich protocol in resectable soft tissue sarcoma: An updated single-center analysis of 104 cases.

Adjuvant therapy of local soft tissue sarcomas (STS) after wide surgical excision still is a topic under controversial scientific debate. In this single center report we have offered an adjuvant "sandwich" therapy protocol consisting of 4 cycles of doxorubicin (75 mg/m2 i.v. over 1 h on day 1) followed by ifosfamide (5 g/m2 i.v. over 24 h starting on day 1) and local radiotherapy scheduled between chemotherapy cycles 2 and 3 to 104 consecutive patients after wide surgical excision (R0) of histologically proven high-grade STS. After a mean follow-up of 39 months (range 5-194 months) relapse free survival (RFS) at 2 and 5 years was 68.1% (95% CI, 58.5-77.7%) and 61.2% (95% CI, 50.4-71.6%). When analyzing the 82 STS cases of the extremities only 2- and 5-year RFS was 74.0% (95% CI, 64.0-84.0%) and 65.3% (95% CI, 53.7-76.9%). By intent-to-treat analysis, the overall survival (OS) at 2 years was 87.3% (95% CI, 80.5-94.1%) and 75.6% (95% CI, 65.2-86.0%) at 5 years, while OS for STS of the extremities only cohort was 90.5% (95% CI, 83.7-97.3%) and 79.0% (95% CI, 68.4-89.6%), respectively. Tolerability of the treatment was good. This analysis demonstrates the feasibility of adjuvant chemoradiotherapy and reflects the results of the long lasting intensive multidisciplinary team approach at our "high-volume" sarcoma center. The long-term survival in our patients is among the highest reported and the low local and distant recurrence rate in high-risk STS is at least comparable to the published data.

Prospective evaluation of the SeptiFAST multiplex real-time PCR assay for surveillance and diagnosis of infections in haematological patients after allogeneic stem cell transplantation compared to routine microbiological assays and an in-house real-time PCR method.

We prospectively evaluated a multiplex real-time PCR assay (SeptiFast, SF) in a cohort of patients undergoing allo-BMT in comparison to an in-house PCR method (IH-PCR). Overall 847 blood samples (mean 8 samples/patient) from 104 patients with haematological malignancies were analysed. The majority of patients had acute leukaemia (62%) with a mean age of 52 years (54% female). Pathogens could be detected in 91 of 847 (11%) samples by SF compared to 38 of 205 (18.5%) samples by BC, and 57 of 847 (6.7%) samples by IH-PCR. Coagulase-negative staphylococci (n=41 in SF, n=29 in BC) were the most frequently detected bacteria followed by Escherichia coli (n=9 in SF, n=6 in BC). Candida albicans (n=17 in SF, n=0 in BC, n=24 in IH-PCR) was the most frequently detected fungal pathogen. SF gave positive results in 5% of samples during surveillance vs in 26% of samples during fever episodes. Overall, the majority of blood samples gave negative results in both PCR methods resulting in 93% overall agreement resulting in a negative predictive value of 0.96 (95% CI: 0.95-0.97), and a positive predictive value of 0.10 (95% CI: -0.01 to 0.21). SeptiFast appeared to be superior over BC and the IH-PCR method.

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

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

Characterization of pancreatic glucagon-producing tumors and pituitary gland tumors in transgenic mice overexpressing MYCN in hGFAP-positive cells.

Amplification or overexpression of MYCN is involved in development and maintenance of multiple malignancies. A subset of these tumors originates from neural precursors, including the most aggressive forms of the childhood tumors, neuroblastoma and medulloblastoma. In order to model the spectrum of MYCN-driven neoplasms in mice, we transgenically overexpressed MYCN under the control of the human GFAP-promoter that, among other targets, drives expression in neural progenitor cells. However, LSL-MYCN;hGFAP-Cre double transgenic mice did neither develop neural crest tumors nor tumors of the central nervous system, but presented with neuroendocrine tumors of the pancreas and, less frequently, the pituitary gland. Pituitary tumors expressed chromogranin A and closely resembled human pituitary adenomas. Pancreatic tumors strongly produced and secreted glucagon, suggesting that they derived from glucagon- and GFAP-positive islet cells. Interestingly, 3 out of 9 human pancreatic neuroendocrine tumors expressed MYCN, supporting the similarity of the mouse tumors to the human system. Serial transplantations of mouse tumor cells into immunocompromised mice confirmed their fully transformed phenotype. MYCN-directed treatment by AuroraA- or Brd4-inhibitors resulted in significantly decreased cell proliferation in vitro and reduced tumor growth in vivo. In summary, we provide a novel mouse model for neuroendocrine tumors of the pancreas and pituitary gland that is dependent on MYCN expression and that may help to evaluate MYCN-directed therapies.

Thyroid cartilage invasion in laryngeal and hypopharyngeal squamous cell carcinoma treated with total laryngectomy.

The objective of this study is to analyze the accuracy of computed tomography in detecting malignant thyroid cartilage invasion. In a retrospective chart review, 120 patients with carcinoma of the larynx and hypopharynx underwent computed tomography before total laryngectomy. These data were compared with the histological specimens. Multidetector computed tomography (MDCT) scan had a positive predictive value (PPV) of 76 % and a negative predictive value (NPV) of 69 %. The specificity of MDCT was 89 % and sensitivity was 46 %. Comparison between radiologic suspected cartilage invasion and histologic results showed a significant correlation (p < 0.02). We found no significant impact of cartilage invasion concerning survival rates (5-year overall survival p = 0.683; 5-year disease-free survival p = 0.711). Preoperative CT scan is an important instrument in detecting neoplastic cartilage invasion.

Classification of KIT/PDGFRA wild-type gastrointestinal stromal tumors: implications for therapy.

Gastrointestinal stromal tumors (GIST) are driven mostly by oncogenic KIT or PDGFRA mutations. However, in 10-15% of all GIST, no such activating mutations can be found and these tumors are classified as 'wild-type GIST' (KIT/PDGFRA wt-GIST). Subgroups of KIT/PDGFRA wt-GIST are driven by other sporadic mutations involving the RAS/RAF/MAP-kinase pathway, such as BRAF or KRAS mutations. Furthermore, KIT/PDGFRA wt-GIST are observed in the context of hereditary syndromes, such as neurofibromatosis Type 1, in which the lack of neurofibromin 1 also leads to the activation of the RAS/RAF/MAP-kinase pathway. Finally, the deficiency succinate dehydrogenase seems to play a major role in KIT/PDGFRA wt-GIST. In conclusion, KIT/PDGFRA wt-GIST belong to different subgroups defined by diverse underlying genetic alterations leading to different biological phenotypes. The vast majority of KIT/PDGFRA wt-GIST will not respond to imatinib. Further research to unravel the pathogenesis of KIT/PDGFRA wt-GIST is prerequisite to the development of effective treatment strategies.