Comparative analysis of thrombin generation platforms for patients with coagulation factor deficiencies: A comprehensive assessment.

INTRODUCTION: Thrombin generation assays (TGAs) assess the overall functionality of the hemostatic system and thereby provide a reflection of the hemostatic capacity of patients with disorders in this system. Currently, four (semi-)automated TGA platforms are available: the Calibrated Automated Thrombogram, Nijmegen Hemostasis Assay, ST Genesia and Ceveron s100. In this study, we compared their performance for detecting patients with congenital single coagulation factor deficiencies. MATERIALS AND METHODS: Pooled patient samples, healthy control samples and normal pooled plasma were tested on all four platforms, using the available reagents that vary in tissue factor and phospholipid concentrations. The TGA parameters selected for analysis were peak height and thrombin potential. Results were normalized by using the calculated mean of healthy controls and a correction for between-run variation. Outcomes were presented as relative values, with the mean of healthy controls standardized to 100 %. RESULTS: Across all platforms and reagents used, thrombin potentials and peak heights of samples with coagulation factor deficiencies were lower than those of healthy controls. Reagents designed for bleeding tendencies yielded the lowest values on all platforms (relative median peak height 19-32 %, relative median thrombin potential 19-45 %). Samples representing more severe coagulation factor deficiencies generally exhibited lower relative peak heights and thrombin potentials. CONCLUSIONS: Thrombin generation assays prove effective in differentiating single coagulation factor deficient samples from healthy controls, with modest discrepancies observed between the platforms. Reagents designed for assessing bleeding tendencies, featuring the lowest tissue factor and phospholipid concentrations, emerged as the most suitable option for detecting coagulation factor deficiencies.

The spectrum of neutralizing and non-neutralizing anti-FVIII antibodies in a nationwide cohort of 788 persons with hemophilia A.

Objectives: Anti-factor VIII (FVIII) antibodies have been reported to exhibit both neutralizing and non-neutralizing characteristics. This is the first study investigating the full spectrum of FVIII-specific antibodies, including non-neutralizing antibodies, very-low titer inhibitors, and inhibitors, in a large nationwide population of persons with hemophilia A of all severities. Methods: All persons with hemophilia A (mild (FVIII > 5-40 IU/dL)/moderate [FVIII 1-5 IU/dL)/severe (FVIII < 1 IU/dL)] with an available plasma sample who participated in the sixth Hemophilia in the Netherlands study between 2018 and 2019 were included. The presence of anti-FVIII antibodies of the immunoglobulin A, M, and G isotypes and IgG subclasses, along with antibody titer levels, were assessed using direct-binding ELISAs. FVIII specificity was assessed using a competition-based ELISA approach. The inhibitor status was determined using the Nijmegen ultra-sensitive Bethesda assay (NusBA) and the Nijmegen Bethesda assay (NBA). Results: In total, 788 persons with hemophilia A (336 (42.6%) mild, 123 (15.6%) moderate, 329 (41.8%) severe hemophilia) were included. The median age was 45 years (IQR 24-60), and the majority (50.9%) had over 150 exposure days to FVIII concentrates. Within our population, 144 (18.3%) individuals had non-neutralizing FVIII-specific antibodies, 10 (1.3%) had very low-titer inhibitors (NusBA positive; NBA negative), and 13 (1.6%) had inhibitors (both NusBA and NBA positive). IgG1 was the most abundant FVIII-specific antibody subclass, and the highest titer levels were found for IgG4. In individuals without a reported history of inhibitor development, no clear differences were observed in antibody patterns between those who were minimally or highly exposed to FVIII concentrates. IgG4 subclass antibodies were only observed in persons with a reported history of FVIII inhibitor or in those with a currently detected (very low-titer) inhibitor. Conclusion: In this cross-sectional study, we identified non-neutralizing antibodies in a relatively large proportion of persons with hemophilia A. In contrast, in our population, consisting of persons highly exposed to FVIII concentrates, (very low-titer) inhibitors were detected only in a small proportion of persons, reflecting a well-tolerized population. Hence, our findings suggest that only a small subpopulation of non-neutralizing FVIII-specific antibodies is associated with clinically relevant inhibitors.

The Nijmegen ultra-sensitive Bethesda Assay detects very low-titer factor VIII inhibitors in patients with congenital and acquired hemophilia A.

BACKGROUND: An inhibitor can develop in congenital hemophilia A (HA) patients against exogenous infused factor (F)VIII, whereas in acquired HA (AHA) inhibitors initially develop against endogenous FVIII. Inhibitors can be detected with the Nijmegen Bethesda Assay (NBA), which has an international cut-off level of 0.60 Nijmegen Bethesda Units/mL (NBU/mL). Thereby, very low-titer inhibitors may remain undetected. AIM: To describe the design and validation of the Nijmegen ultra-sensitive Bethesda Assay (NusBA) for the detection of very low-titer inhibitors. METHODS: The NusBA is a modification of the NBA in which the ratio of patient plasma to normal pooled plasma is changed from 1:1 to 9:1. Analytical validation was performed according to the CLSI EP10 guideline in order to determine trueness and reproducibility. Clinical validation was performed in two cohorts of congenital HA patients (82 adults) with pharmacokinetic data and four AHA patients. The limit of quantitation (LOQ) was determined by measuring plasma samples spiked with inhibitor levels in the low range (0.05-0.80 NBU/mL). RESULTS: The LOQ for the NusBA was 0.10 NusBU/mL, with a coefficient of variation of 24.2 %. Seven (8.5 %) congenital HA patients had a positive NusBA result, of which only one was detected with the NBA. There was no correlation between NusBA and FVIII half-life. In three of the AHA patients the NusBA remained positive, when the NBA became negative. DISCUSSION: The NusBA is able to detect very low-titer FVIII inhibitors of ≥0.10 NBU/mL. Thereby, it may have added value in early inhibitor detection and therapy adjustments in patients with congenital HA and AHA.

In patients with hemophilia, a decreased thrombin generation profile is associated with a severe bleeding phenotype.

Background: Heterogeneity in clinical bleeding phenotype has been observed in hemophilia patients with similar FVIII or FIX activity levels. Thrombin generation and plasmin generation, as a global hemostasis assay, may contribute to a better prediction of which patients are at an increased risk of bleeding. Objectives: The objective of this study was to describe the association between clinical bleeding phenotype and thrombin generation and plasmin generation profiles in patients with hemophilia. Methods: The Nijmegen Hemostasis Assay, which simultaneously measures thrombin and plasmin generation, was performed in plasma samples of patients with hemophilia participating in the sixth Hemophilia in the Netherlands study (HiN6). Patients receiving prophylaxis underwent a washout period. A severe clinical bleeding phenotype was defined as a self-reported annual bleeding rate of ≥5, a self-reported annual joint bleeding rate of ≥3, or the use of secondary/tertiary prophylaxis. Results: In total, 446 patients, with a median age of 44 years, were included in this substudy. Thrombin generation and plasmin generation parameters differed between patients with hemophilia and healthy individuals. The median thrombin peak height was 1.0 nM, 25.9 nM, 47.1 nM, and 143.9 nM in patients with severe, moderate, and mild hemophilia and healthy individuals, respectively. A severe bleeding phenotype was observed in patients with a thrombin peak height of <49% and a thrombin potential of <72% compared to healthy individuals, and was independent of the hemophilia severity. The median thrombin peak height was 0.70% in patients with a severe clinical bleeding phenotype and 30.3% in patients with a mild clinical bleeding phenotype. The median thrombin potentials for these patients were 0.06% and 59.3%, respectively. Conclusion: A decreased thrombin generation profile is associated with a severe clinical bleeding phenotype in patients with hemophilia. Thrombin generation in combination with bleeding severity may be a better tool to personalize prophylactic replacement therapy irrespective of hemophilia severity.

Thrombin generation assays to personalize treatment in bleeding and thrombotic diseases.

Treatment of bleeding and thrombotic disorders is highly standardized and based on evidence-based medicine guidelines. These evidence-based treatment schemes are well accepted but may lead to either insufficient treatment or over-dosing, because the individuals' hemostatic properties are not taken into account. This can potentially introduce bleeding or thrombotic complications in individual patients. With the incorporation of pharmacokinetic (PK) and pharmacodynamic (PK-PD) parameters, based on global assays such as thrombin generation assays (TGAs), a more personalized approach can be applied to treat either bleeding or thrombotic disorders. In this review, we will discuss the recent literature about the technical aspects of TGAs and the relation to diagnosis and management of bleeding and thrombotic disorders. In patients with bleeding disorders, such as hemophilia A or factor VII deficiency, TGAs can be used to identify patients with a more severe bleeding phenotype and also in the management with non-replacement therapy and/or bypassing therapy. These assays have also a role in patients with venous thrombo-embolism, but the usage of TGAs in patients with arterial thrombosis is less clear. However, there is a potential role for TGAs in the monitoring of (long-term) antithrombotic therapy, for example with the use of direct oral anticoagulants. Finally this review will discuss controversies, limitations and knowledge gaps in relation to the introduction of TGAs to personalize medicine in daily medical practice.

Fibrinolytic assays in bleeding of unknown cause: Improvement in diagnostic yield.

Introduction: Analysis of fibrinolytic disorders is challenging and may potentially lead to underdiagnosis of patients with an increased bleeding tendency. Aim: To compare clinical characteristics, laboratory measurements, and treatment modalities in a monocenter cohort of patients in whom fibrinolytic studies were performed. Methods: Retrospective study of patients in whom fibrinolytic studies were performed between January 2016 and February 2020 in the Hemophilia Treatment Center, Nijmegen-Eindhoven-Maastricht, the Netherlands. Plasminogen activator inhibitor type 1 (PAI-1) antigen and activity level, α2-antiplasmin activity, tissue plasminogen activator, and euglobulin clot lysis time (ECLT) before and after venous compression were determined in all patients. Data of bleeding assessment tool (BAT) score, clinical characteristics, results of primary and secondary hemostasis assays, and general treatment plans were collected. Results: In total, 160 patients were included: 97 (61%) without and 63 (39%) with a laboratory-based fibrinolytic disorder. Mean BAT score did not differ between the groups (9.3 vs 9.8, respectively). The presumptive fibrinolytic disorders were distributed as follows: 34 patients had an increased ECLT ratio or low baseline ECLT, 25 patients had low PAI-1 antigen and activity level, and four patients had both. The majority of these patients were treated with tranexamic acid monotherapy (60%) with only 40% additional treatment options, whereas 80% of patients without a presumptive fibrinolytic disorder had multiple treatment modalities. Discussion: Analysis of fibrinolytic disorders in selected patients has a high diagnostic yield. General incorporation of fibrinolytic analysis in the diagnostic workup of patients with bleeding of unknown cause can improve diagnosis and management of their bleeding episodes.

Von Willebrand disease type 2M: Correlation between genotype and phenotype.

BACKGROUND: An appropriate clinical diagnosis of von Willebrand disease (VWD) can be challenging because of a variable bleeding pattern and laboratory phenotype. Genotyping is a powerful diagnostic tool and may have an essential role in the diagnostic field of VWD. OBJECTIVES: To unravel the clinical and laboratory heterogeneity of genetically confirmed VWD type 2M patients and to investigate their relationship. METHODS: Patients with a confirmed VWD type 2M genetic variant in the A1 or A3 domain of von Willebrand factor (VWF) and normal or only slightly aberrant VWF multimers were selected from all subjects genotyped at the Radboud university medical center because of a high suspicion of VWD. Bleeding scores and laboratory results were analyzed. RESULTS: Fifty patients had a clinically relevant genetic variant in the A1 domain. Median bleeding score was 5. Compared with the nationwide Willebrand in the Netherlands study type 2 cohort, bleeding after surgery or delivery was reported more frequently and mucocutaneous bleedings less frequently. Median VWF activity/VWF antigen (VWF:Act/VWF:Ag) ratio was 0.32, whereas VWF collagen binding activity/VWF antigen (VWF:CB/VWF:Ag) ratio was 0.80. Variants in the A3 domain were only found in two patients with low to normal VWF:Act/VWF:Ag ratios (0.45, 1.03) and low VWF:CB/VWF:Ag ratios (0.45, 0.63). CONCLUSION: Genetically confirmed VWD type 2M patients have a relatively mild clinical phenotype, except for bleeding after surgery and delivery. Laboratory phenotype is variable and depends on the underlying genetic variant. Addition of genotyping to the current phenotypic characterization may improve diagnosis and classification of VWD.

ChAdOx1 vaccination, blood coagulation, and inflammation: No effect on coagulation but increased interleukin-6.

BACKGROUND: Vaccination is the leading approach in combatting the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. ChAdOx1 nCoV-19 vaccination (ChAdOx1) has been linked to a higher frequency of rare thrombosis and thromboembolism. This study aimed to explore markers related to the blood coagulation system activation and inflammation, before and after ChAdOx1 vaccination. PATIENTS AND METHODS: An observational cohort study including 40 health care workers. Whole blood samples were collected before, and either 1 or 2 days after vaccination. Activated coagulation factors in complex with their natural inhibitors were determined by custom ELISAs, including thrombin:antithrombin (T:AT), kallikrein:C1-esterase-inhibitor (PKa:C1Inh), factor(F)IXa:AT, FXa:AT, FXIaAT, FXIa:alpha-1-antitrypsin (α1AT), FXIa:C1inh, and FVIIa:AT. Plasma concentrations of interleukin (IL)-6 and IL-18 were quantified via ELISA. Analyses were performed using Wilcoxon signed-rank test. RESULTS: Levels of FVIIa:AT decreased with a median (IQR) of 707 (549-1028) pg/ml versus 598 (471-996) pg/ml, p = 0.01; and levels of IL-6 increased, 4.0 (1.9-6.8) pg/ml versus 6.9 (3.6-12.2) pg/ml, p = 0.02, after vaccination. No changes were observed in T:AT, PKa:C1Inh, FIXa:AT, FXa:AT, FXIaAT, FXIa:α1AT, FXIa:C1inh, and IL-18. CONCLUSION: ChAdOx1 leads to an inflammatory response with increased levels of IL-6. We did not observe activation of the blood coagulation system 1-2 days following vaccination.

A multi-center evaluation of TECHNOSCREEN® ADAMTS-13 activity assay as a screening tool for detecting deficiency of ADAMTS-13.

BACKGROUND: Quantifying A disintegrin-like and metalloprotease with thrombospondin type 1 motif, member 13 (ADAMTS-13) activity enhances thrombotic thrombocytopenic purpura (TTP) diagnosis but most assays are time consuming, technically demanding, and mainly available in reference centers. OBJECTIVE: Evaluate a simple, semiquantitative ADAMTS-13 activity screening test for early identification/exclusion of TTP. PATIENTS/METHODS: Plasma from 220 patients with suspected thrombotic microangiopathy at three reference centers were tested with TECHNOSCREEN® ADAMTS13 activity screening test in comparison with TECHNOZYM® ADAMTS-13 activity ELISA at two centers, and in-house fluorescence resonance energy transfer assay at the third center. The screening test indicates if ADAMTS-13 activity is at one of four level-indicator points: 0, 0.1, 0.4, or 0.8 IU/mL. RESULTS: Screen results were interpreted as binary data in that ADAMTS-13 activity was above or below the 0.1 IU/mL TTP clinical threshold. Combining all sites' data, the screen exhibited 88.7% sensitivity, 90.4% specificity, 74.6% positive predictive value, and 96.2% negative predictive value, comparable to published data for quantitative assays. Five samples with quantitative results below the threshold gave screen readings of 0.1 IU/mL and seven marginally above the threshold gave screen readings of zero. All would warrant plasma exchange while the level is quantified. Nine samples with normal/near normal results gave screens of zero and confirmatory quantifications would prompt early treatment withdrawal, as is current practice. One sample generated screen/quantitative results of 0.4/0.00 IU/mL respectively and was the only clear false-negative. CONCLUSIONS: The screening test provides more rapid ADAMTS-13 level evaluation than most currently available assays. Its simple operation renders it suitable for adoption in routine or specialist laboratory environments.

An orthotopic mouse model for chondrosarcoma of bone provides an in vivo tool for drug testing.

Chondrosarcoma is a malignant cartilaginous tumor of the bone. Recently, mutations in isocitrate dehydrogenase-1 (IDH1) and isocitrate dehydrogenase-2 (IDH2) were identified in central chondrosarcomas. As chondrosarcomas are notoriously resistant to conventional treatment modalities, the need for model systems to screen new treatment options is high. We used two chondrosarcoma cell lines (CH2879 and SW1353) to generate a bioluminescent orthotopic chondrosarcoma mouse model. Cell lines were stably transduced with a lentiviral luciferase expression vector, and after clonal selection, luciferase-expressing clones were subcutaneously and orthotopically implanted in nude mice. Mice injected with CH2879 cells were treated with doxorubicin over a period of 6 weeks. Both cell lines resulted in tumor growth. CH2879 tumors were consistently larger than SW1353 tumors. No difference in size could be observed between subcutaneous and orthotopic tumors. Tumor growth could be monitored over time through assessment of luciferase activity, without harming the mice. Using this model, we show that doxorubicin does not have a significant effect on in vivo tumor growth. We describe an orthotopic chondrosarcoma mouse model that can be used to test new treatment strategies evolving from in vitro research.

Label-free LC-MSe in tissue and serum reveals protein networks underlying differences between benign and malignant serous ovarian tumors.

PURPOSE: To identify proteins and (molecular/biological) pathways associated with differences between benign and malignant epithelial ovarian tumors. EXPERIMENTAL PROCEDURES: Serum of six patients with a serous adenocarcinoma of the ovary was collected before treatment, with a control group consisting of six matched patients with a serous cystadenoma. In addition to the serum, homogeneous regions of cells exhibiting uniform histology were isolated from benign and cancerous tissue by laser microdissection. We subsequently employed label-free liquid chromatography tandem mass spectrometry (LC-MSe) to identify proteins in these serum and tissues samples. Analyses of differential expression between samples were performed using Bioconductor packages and in-house scripts in the statistical software package R. Hierarchical clustering and pathway enrichment analyses were performed, as well as network enrichment and interactome analysis using MetaCore. RESULTS: In total, we identified 20 and 71 proteins that were significantly differentially expressed between benign and malignant serum and tissue samples, respectively. The differentially expressed protein sets in serum and tissue largely differed with only 2 proteins in common. MetaCore network analysis, however inferred GCR-alpha and Sp1 as common transcriptional regulators. Interactome analysis highlighted 14-3-3 zeta/delta, 14-3-3 beta/alpha, Alpha-actinin 4, HSP60, and PCBP1 as critical proteins in the tumor proteome signature based on their relative overconnectivity. The data have been deposited to the ProteomeXchange with identifier PXD001084. DISCUSSION: Our analysis identified proteins with both novel and previously known associations to ovarian cancer biology. Despite the small overlap between differentially expressed protein sets in serum and tissue, APOA1 and Serotransferrin were significantly lower expressed in both serum and cancer tissue samples, suggesting a tissue-derived effect in serum. Pathway and subsequent interactome analysis also highlighted common regulators in serum and tissue samples, suggesting a yet unknown role for PCBP1 in ovarian cancer pathophysiology.

Screening for potential targets for therapy in mesenchymal, clear cell, and dedifferentiated chondrosarcoma reveals Bcl-2 family members and TGFß as potential targets.

The mesenchymal, clear cell, and dedifferentiated chondrosarcoma subtypes are extremely rare, together constituting 10% to 15% of all chondrosarcomas. Their poor prognosis and lack of efficacious treatment emphasizes the need to elucidate the pathways playing a pivotal role in these tumors. We constructed tissue microarrays containing 42 dedifferentiated, 23 clear cell, and 23 mesenchymal chondrosarcomas and performed immunohistochemistry to study the expression of growth plate-signaling molecules and molecules shown to be involved in conventional chondrosarcoma. We observed high expression of SOX-9 and FGFR-3, as well as aberrant cellular localization of heparan sulfate proteoglycans, in all subtypes. TGFß signaling through p-SMAD2 and PAI-1 was highly active in all chondrosarcoma subtypes, which suggests that TGFß inhibitors as a possible therapeutic strategy in rare chondrosarcoma subtypes. As in conventional chondrosarcoma, antiapoptotic proteins (Bcl-2, and/or Bcl-xl) were highly expressed in all subtypes. Inhibition with the BH-3 mimetic ABT-737 rendered dedifferentiated chondrosarcoma cell lines sensitive to doxorubicin or cisplatin. Our data indicate that antiapoptotic proteins may play an important role in chemoresistance, suggesting a promising role for targeting Bcl-2 family members in chondrosarcoma treatment, irrespective of the subtype.

A critical assessment of SELDI-TOF-MS for biomarker discovery in serum and tissue of patients with an ovarian mass.

BACKGROUND: Less than 25% of patients with a pelvic mass who are presented to a gynecologist will eventually be diagnosed with epithelial ovarian cancer. Since there is no reliable test to differentiate between different ovarian tumors, accurate classification could facilitate adequate referral to a gynecological oncologist, improving survival. The goal of our study was to assess the potential value of a SELDI-TOF-MS based classifier for discriminating between patients with a pelvic mass. METHODS: Our study design included a well-defined patient population, stringent protocols and an independent validation cohort. We compared serum samples of 53 ovarian cancer patients, 18 patients with tumors of low malignant potential, and 57 patients with a benign ovarian tumor on different ProteinChip arrays. In addition, from a subset of 84 patients, tumor tissues were collected and microdissection was used to isolate a pure and homogenous cell population. RESULTS: Diagonal Linear Discriminant Analysis (DLDA) and Support Vector Machine (SVM) classification on serum samples comparing cancer versus benign tumors, yielded models with a classification accuracy of 71-81% (cross-validation), and 73-81% on the independent validation set. Cancer and benign tissues could be classified with 95-99% accuracy using cross-validation. Tumors of low malignant potential showed protein expression patterns different from both benign and cancer tissues. Remarkably, none of the peaks differentially expressed in serum samples were found to be differentially expressed in the tissue lysates of those same groups. CONCLUSION: Although SELDI-TOF-MS can produce reliable classification results in serum samples of ovarian cancer patients, it will not be applicable in routine patient care. On the other hand, protein profiling of microdissected tumor tissue may lead to a better understanding of oncogenesis and could still be a source of new serum biomarkers leading to novel methods for differentiating between different histological subtypes.

Genetic characterization of mesenchymal, clear cell, and dedifferentiated chondrosarcoma.

Clear cell, mesenchymal, and dedifferentiated chondrosarcoma are rare, cartilaginous tumors with limited treatment options other than surgery. Conventional chondrosarcomas have been extensively studied at the genetic level, but for rare chondrosarcoma subtypes, this is merely restricted to case reports. Information on the genetics of rare chondrosarcomas may provide insight into the etiology of these specific disease subtypes and possible alternative treatment strategies. Therefore, the aim of this study was to genetically characterize this subset of rare tumors. Using array CGH, we gathered genomic information of 30 rare cartilaginous tumors. In addition, we constructed tissue microarrays with 2 mm cores of 23 clear cell, 23 mesenchymal, and 45 dedifferentiated chondrosarcomas, in triplicate. Using immunohistochemistry, we investigated expression of R132H IDH1, and p53 and retinoblastoma pathways. Results were verified and further investigated with a methylation assay and MLPA for CDKN2A/p16, and IDH1/2, and TP53 mutation analysis. Array-CGH showed numerous genomic alterations in all subtypes. However, only a limited number of recurrent alterations were detected, none of which seemed to be associated with the subtypes. The IDH1/2, p53, and retinoblastoma pathways were affected in 0, 9, and 95% of clear cell chondrosarcomas, in 0, 39, and 70% in mesenchymal chondrosarcomas, and in 50, 59, and 85% of dedifferentiated chondrosarcomas, respectively. Our results suggest an important role for the retinoblastoma pathway in all three rare chondrosarcoma subtypes investigated.

Somatic mosaic IDH1 and IDH2 mutations are associated with enchondroma and spindle cell hemangioma in Ollier disease and Maffucci syndrome.

Ollier disease and Maffucci syndrome are non-hereditary skeletal disorders characterized by multiple enchondromas (Ollier disease) combined with spindle cell hemangiomas (Maffucci syndrome). We report somatic heterozygous mutations in IDH1 (c.394C>T encoding an R132C substitution and c.395G>A encoding an R132H substitution) or IDH2 (c.516G>C encoding R172S) in 87% of enchondromas (benign cartilage tumors) and in 70% of spindle cell hemangiomas (benign vascular lesions). In total, 35 of 43 (81%) subjects with Ollier disease and 10 of 13 (77%) with Maffucci syndrome carried IDH1 (98%) or IDH2 (2%) mutations in their tumors. Fourteen of 16 subjects had identical mutations in separate lesions. Immunohistochemistry to detect mutant IDH1 R132H protein suggested intraneoplastic and somatic mosaicism. IDH1 mutations in cartilage tumors were associated with hypermethylation and downregulated expression of several genes. Mutations were also found in 40% of solitary central cartilaginous tumors and in four chondrosarcoma cell lines, which will enable functional studies to assess the role of IDH1 and IDH2 mutations in tumor formation.

Characterization of BCAR4, a novel oncogene causing endocrine resistance in human breast cancer cells.

Resistance to the antiestrogen tamoxifen remains a major problem in the management of estrogen receptor-positive breast cancer. Knowledge on the resistance mechanisms is needed to develop more effective therapies. Breast cancer antiestrogen resistance 4 (BCAR4) was identified in a functional screen for genes involved in tamoxifen resistance. BCAR4 is expressed in 27% of primary breast tumors. In patients treated with tamoxifen for metastized disease high BCAR4 mRNA levels are associated with reduced clinical benefit and progression-free survival. Regarding tumor aggressiveness high BCAR4 mRNA levels are associated with a shorter metastasis free survival and overall survival. In the present study, we investigated the role of BCAR4 in endocrine resistance. Forced expression of BCAR4 in human ZR-75-1 and MCF7 breast cancer cells resulted in cell proliferation in the absence of estrogen and in the presence of various antiestrogens. Inhibition of estrogen receptor 1 (ESR1) expression with small interfering RNA (siRNA), implied that the BCAR4-induced mechanism of resistance is independent of ESR1. Highly conserved BCAR4 homologues of rhesus monkey, green monkey, and the less conserved common marmoset gene induced tamoxifen-resistant cell proliferation, in contrast to the distant BCAR4 homologues of bovine and rabbit. Injection of BCAR4-expressing ZR-75-1 cells into nude mice resulted in rapidly growing tumors. In silico analysis showed that BCAR4 mRNA is highly expressed in human placenta and oocyte, and absent in other normal tissues. In conclusion, BCAR4 is a strong transforming gene causing estrogen-independent growth and antiestrogen resistance, and induces tumor formation in vivo. Due to its restricted expression, BCAR4 may be a good target for treating antiestrogen-resistant breast cancer.

Opening the archives for state of the art tumour genetic research: sample processing for array-CGH using decalcified, formalin-fixed, paraffin-embedded tissue-derived DNA samples.

BACKGROUND: Molecular genetic studies on rare tumour entities, such as bone tumours, often require the use of decalcified, formalin-fixed, paraffin-embedded tissue (dFFPE) samples. Regardless of which decalcification procedure is used, this introduces a vast breakdown of DNA that precludes the possibility of further molecular genetic testing. We set out to establish a robust protocol that would overcome these intrinsic hurdles for bone tumour research. FINDINGS: The goal of our study was to establish a protocol, using a modified DNA isolation procedure and quality controls, to select decalcified samples suitable for array-CGH testing. Archival paraffin blocks were obtained from 9 different pathology departments throughout Europe, using different fixation, embedding and decalcification procedures, in order to preclude a bias for certain lab protocols. Isolated DNA samples were subjected to direct chemical labelling and enzymatic labelling systems and were hybridised on a high resolution oligonucleotide chip containing 44,000 reporter elements.Genomic alterations (gains and losses) were readily detected in most of the samples analysed. For example, both homozygous deletions of 0.6 Mb and high level of amplifications of 0.7 Mb were identified. CONCLUSIONS: We established a robust protocol for molecular genetic testing of dFFPE derived DNA, irrespective of fixation, decalcification or sample type used. This approach may greatly facilitate further genetic testing on rare tumour entities where archival decalcified, formalin fixed samples are the only source.

Expression of aromatase and estrogen receptor alpha in chondrosarcoma, but no beneficial effect of inhibiting estrogen signaling both in vitro and in vivo.

BACKGROUND: Chondrosarcomas are malignant cartilage-forming tumors which are highly resistant to conventional chemotherapy and radiotherapy. Estrogen signaling is known to play an important role in proliferation and differentiation of chondrocytes and in growth plate regulation at puberty. Our experiments focus on unraveling the role of estrogen signaling in the regulation of neoplastic cartilage growth and on interference with estrogen signaling in chondrosarcomas in vitro and in vivo. METHODS: We investigated the protein expression of estrogen receptor alpha (ESR1), androgen receptor (AR), and aromatase in tumor specimens of various chondrosarcoma subtypes, and (primary) chondrosarcoma cultures. Dose-response curves were generated of conventional central chondrosarcoma cell lines cultured in the presence of 17-beta-estradiol, dihydrotestosterone, 4-androstene-3,17dione, 4-hydroxytamoxifen, fulvestrant and aromatase inhibitors. In a pilot series, the effect of anastrozole (n=4) or exemestane (n=2) treatment in 6 chondrosarcoma patients with progressive disease was explored. RESULTS: We showed protein expression of ESR1 and aromatase in a large majority of all subtypes. Only a minority of the tumors showed few AR positive cells. The dose-response assays showed no effect of any of the compounds on proliferation of conventional chondrosarcoma in vitro. The median progression-free survival of the patients treated with aromatase inhibitors did not significantly deviate from untreated patients. CONCLUSIONS: The presence of ESR1 and aromatase in chondrosarcoma tumors and primary cultures supports a possible role of estrogen signaling in chondrosarcoma proliferation. However, our in vitro and pilot in vivo studies have shown no effect of estrogen-signaling inhibition on tumor growth.

Selective recruitment of breast cancer anti-estrogen resistance genes and relevance for breast cancer progression and tamoxifen therapy response.

Although endocrine treatment of breast cancer is effective and common practice, in advanced disease the development of resistance is nearly inevitable. To get more insight into individual genes that account for resistance against hormonal agents, we have executed functional genetic screens and subsequently evaluated the clinical relevance of several identified genes with respect to tumor aggressiveness and tamoxifen resistance in estrogen receptor-positive patients. Estrogen-dependent human breast cancer cells were transduced with different retroviral cDNA expression libraries and subjected to selective cultures with various anti-estrogens. From a total of 264 resistant cell clones, 132 different genes were recovered by PCR. By applying stringent selection criteria, we identified 15 breast cancer anti-estrogen resistance (BCAR) genes individually yielding resistance. BCAR genes were recovered with differential frequencies for the diverse culture conditions and anti-estrogen drugs. Analysis of the relation of BCAR genes (EIF1, FBXL10, HRAS, NRG1, PDGFRA, PDGFRB, RAD21, and RAF1) with tamoxifen treatment in patients with advanced disease showed significant association with clinical benefit and progression-free survival for EIF1 and PDGFRA mRNA levels. Furthermore, PDGFRA and HRAS mRNA levels were significantly associated with tumor aggressiveness in lymph node-negative patients who had not received adjuvant systemic therapy. In conclusion, our functional genetic screens showed that BCAR genes differ in their ability to confer resistance towards distinct anti-estrogens. Based on the clinical relevance of several BCAR genes, further studies are warranted to characterize the underlying mechanisms, which may ultimately lead to the development of novel treatments and more individualized management of breast cancer patients.

TSC22D1 and PSAP predict clinical outcome of tamoxifen treatment in patients with recurrent breast cancer.

Purpose Two genes, TSC22 domain family, member 1 (TSC22D1) and prosaposin (PSAP) were identified in an in vitro functional screen for genes having a causative role in tamoxifen resistance. These genes were also present in our previously established 81-gene signature for resistance to first-line tamoxifen therapy. The aim of this study was to investigate the predictive value of these genes for tamoxifen therapy failure in patients with recurrent breast cancer. Experimental Design The mRNA levels of TSC22D1 and PSAP were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR) in 223 estrogen receptor-positive primary breast tumors of patients with recurrent disease treated with first-line tamoxifen therapy. The main objective of this study was the length of progression-free survival (PFS). Results High mRNA levels of TSC22D1 and PSAP were significantly associated with shorter PFS and both were independent of the traditional predictive factors (HR = 1.30, 95% CI = 1.04-1.64 P = 0.023; and HR = 1.40, 95% CI = 1.03-1.88, P = 0.029, respectively). In multivariate analysis, patients with high mRNA levels of both genes associated significantly with no clinical benefit (OR = 0.19, 95% CI = 0.06-0.62, P = 0.006) and had the shortest PFS (HR = 2.05, 95% CI = 1.29-3.25, P = 0.002). Conclusion These results confirm our previous in vitro and tumor-related findings and are indicative for the failure of tamoxifen treatment in breast-cancer patients. Both TSC22D1 and PSAP are associated with clinical outcome and may have a functional role in therapy resistance.