Barbara Dessars

Genotypic and Gene Expression Studies in Congenital Melanocytic Nevi: Insight into Initial Steps of Melanotumorigenesis

Large congenital melanocytic nevi (CMNs) are said to have a higher propensity to malignant transformation compared with acquired nevi. Thus, they represent a good model for studying initial steps of melanotumorigenesis. We have performed genotypic (karyotype, fluorescence in situ hybridization, and mutational analyses) and differential expression studies on a large cohort of medium (n=3) and large (n=24) CMN. Chromosomal abnormalities were rare and single, a feature probably reflecting the benignity of these lesions. Mutational screening showed a high frequency of NRAS mutations in our series (19/27 cases, 70%), whereas BRAF mutations were less common (4/27 cases, 15%). Differential did not show significant alterations of cellular processes such as cell proliferation, cell migration/invasion, angiogenesis, apoptosis, and immune/inflammatory responses. However, significant downregulation of genes involved in pigmentation and upregulation of genes playing a role in DNA protection were observed. Lastly, our microarrays displayed upregulation of genes mediating chemoresistance in cancer. As alteration of pigmentation mechanisms can trigger oxidative damage, increased expression of genes involved in maintenance of DNA integrity might reflect the ability of nevocytic cells to self-protect against cellular stress. Furthermore, the observed alterations linked to chemoresistance might partially account for the well-known inefficacy of chemotherapy in malignant melanoma.

Clinical Validation of Targeted Next Generation Sequencing for Colon and Lung Cancers

Objective Recently, Next Generation Sequencing (NGS) has begun to supplant other technologies for gene mutation testing that is now required for targeted therapies. However, transfer of NGS technology to clinical daily practice requires validation. Methods We validated the Ion Torrent AmpliSeq Colon and Lung cancer panel interrogating 1850 hotspots in 22 genes using the Ion Torrent Personal Genome Machine. First, we used commercial reference standards that carry mutations at defined allelic frequency (AF). Then, 51 colorectal adenocarcinomas (CRC) and 39 non small cell lung carcinomas (NSCLC) were retrospectively analyzed. Results Sensitivity and accuracy for detecting variants at an AF >4% was 100% for commercial reference standards. Among the 90 cases, 89 (98.9%) were successfully sequenced. Among the 86 samples for which NGS and the reference test were both informative, 83 showed concordant results between NGS and the reference test; i.e. KRAS and BRAF for CRC and EGFR for NSCLC, with the 3 discordant cases each characterized by an AF <10%. Conclusions Overall, the AmpliSeq colon/lung cancer panel was specific and sensitive for mutation analysis of gene panels and can be incorporated into clinical daily practice.

Evaluation of a new generation of plastic evacuated blood-collection tubes in clinical chemistry, therapeutic drug monitoring, hormone and trace metal analysis.

Abstract Polyethylene terephthalate (PET) tubes have several advantages over glass tubes: they are unbreakable, lighter and more easily disposed of. Despite a steady increase in their use and an expansion of the range of available tubes, few studies validating their use have been published in the literature. This paper describes the various studies that have been performed to compare VENOJECT glass, VENOSAFE PET and VENOSAFE PET/heparin tubes for the assay of a panel of analytes in routine clinical chemistry, immunochemistry, hormone and tumor marker analysis and trace metal determination. These studies demonstrate that VENOSAFE PET tubes are a suitable alternative to glass tubes.

Rational use of the EAC real-time quantitative PCR protocol in chronic myelogenous leukemia: report of three false-negative cases at diagnosis

Rational use of the EAC real-time quantitative PCR protocol in chronic myelogenous leukemia: report of three false-negative cases at diagnosis

A Familial Heterozygous Null Mutation of MET in Autism Spectrum Disorder

Autism spectrum disorder (ASD) results from interactions of genetic and environmental factors. The MET proto‐oncogene has been identified as a candidate gene for autism susceptibility, and is implicated in neurodevelopment and social brain circuitry. Here, we describe the first case of a familial mutation of MET, consisting of an interstitial genomic deletion removing exons 12 through 15, causing a frameshift and premature stop codon, with evidence of nonsense‐mediated mRNA decay. On the other allele, patients carried the C allele of the MET promoter rs1858830 polymorphism, known to decrease MET expression and previously associated with autism susceptibility. The heterozygous mutation was associated with autism in one patient, and language and social impairment in a sibling. Our observations delineate the phenotypic spectrum associated with a clearly defined, very likely complete loss of function mutation of MET. Incomplete penetrance in this family was consistent with MET as a partial susceptibility gene for ASD. Implication of MET in normal and pathological brain development opens new perspectives for understanding the pathophysiology of autism and for eventual therapeutical clues. Autism Res 2014, 7: 617–622.

Global histone deacetylase enzymatic activity is an independent prognostic marker associated with a shorter overall survival in chronic lymphocytic leukemia patients

Histone deacetylases (HDAC) play a crucial role in transcriptional regulation and are often deregulated in many cancers. However, global HDAC enzymatic activity has never been investigated in Chronic Lymphocytic Leukemia (CLL). We measured HDAC activity in protein extracts from CD19+ B-cells purified from 114 CLL patients with a median follow-up of 91 months (range: 11–376). HDAC activity was equivalent in CLL and normal B-cells but higher in patients who died during the study than in living patients (152.1 vs. 65.04 pmol; P = 0.0060). Furthermore, HDAC activity correlated with treatment-free survival (TFS; P = 0.0156) and overall survival (OS; P < 0.0001): patients with low HDAC activity (n = 75) had a median TFS and OS of 101 and >376 months, respectively, whereas patients with high HDAC activity (n = 39) had a median TFS and OS of 47 and 137 months, respectively. Multivariate analyses indicated that HDAC activity is an independent predictor of OS (hazard ratio = 7.68; P = 0.0017). Finally, HDAC activity increased after B-cell receptor stimulation using IgM, suggesting a role for microenvironment stimuli (n = 10; P = 0.0371). In conclusion, high HDAC activity in CLL B-cells is associated with shorter TFS and OS and is an independent marker of OS, refining the use of other prognostic factors. This work provides a biological base for the use of HDAC inhibitors in CLL treatment.

Identification of chronic myeloid leukemia patients treated with imatinib who are potentially eligible for treatment discontinuation by assessing real-life molecular responses on the international scale in a EUTOS-certified lab

A retrospective study was performed to describe molecular responses (MR) on the international scale (IS) in patients with chronic myeloid leukemia (CML) treated with imatinib in routine clinical practice in Belgium and to identify patients potentially eligible for treatment discontinuation. The analysis included 116 patients with CML in chronic phase at treatment centers sending blood samples for molecular follow-up to a single EUTOS-certified laboratory. IS MR from the last patient visit between October 2014 and April 2015 were retrospectively collected. Most patients (93.1%) had an IS MR corresponding to an optimal response per European LeukemiaNet 2013 guidelines; 53.4% (62/116) of patients were in deep molecular responses ≥MR4.5 at their last visit (mean treatment duration: 91.0 months) among whom 36.2% (42/116) had been receiving imatinib for >5.8 years and 26.7% (31/116) for >8 years (margins of error: 8.74% and 8.05%, respectively). These patients would likely have the highest chance of staying in treatment-free remission (TFR) upon discontinuation, based on published TFR trial data. Although our study only provides a snapshot in time of a patients last MR reported, without precise information regarding MR duration, the study settings could nevertheless support the feasibility of attempting TFR outside clinical trials in the future.