Publications by authors named "Karim Labreche"

Purpose: Patients with IDH-mutant 1p/19q-codeleted grade 3 oligodendroglioma (O3) benefit from adding alkylating agent chemotherapy to radiotherapy (RT). However, the optimal chemotherapy regimen between procarbazine, 1-(2-Chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), and vincristine (PCV) and temozolomide (TMZ) remains unclear given the lack of randomized trial data comparing both regimens.

Methods: The objective was to assess the overall survival (OS) and progression-free survival (PFS) associated with first-line PCV/RT versus TMZ/RT in patients newly diagnosed with O3.

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  • Microsatellite instability (MSI), often linked to mismatch repair deficiency in colorectal cancer (CRC), leads to numerous noncoding DNA mutations, particularly affecting RNA splicing sites.
  • This research shows that these noncoding mutations happen early in tumor development, even before the cancer cells become mutated in their coding regions, and are associated with altered splicing patterns in mRNA.
  • The altered RNA splicing impacts cellular differentiation and promotes the initiation of MSI CRC, indicating that these noncoding changes are significant for cancer progression before traditional coding mutations occur.
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Non-Hodgkin lymphomas (NHL) commonly occur in immunodeficient patients, both those infected by human immunodeficiency virus (HIV) and those who have been transplanted, and are often driven by Epstein-Barr virus (EBV) with cerebral localization, raising the question of tumor immunogenicity, a critical issue for treatment responses. We investigated the immunogenomics of 68 lymphoproliferative disorders from 51 immunodeficient (34 post-transplant, 17 HIV+) and 17 immunocompetent patients. Overall, 72% were large B-cell lymphoma and 25% were primary central nervous system lymphoma, while 40% were EBV+.

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Some patients with Lynch syndrome (LS) have extreme phenotypes, i.e. cancer before the recommended screening age, or cancer for which there are no screening guidelines.

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Activation-induced cytidine deaminase, AICDA or AID, is a driver of somatic hypermutation and class-switch recombination in immunoglobulins. In addition, this deaminase belonging to the APOBEC family may have off-target effects genome-wide, but its effects at pan-cancer level are not well elucidated. Here, we used different pan-cancer datasets, totaling more than 50,000 samples analyzed by whole-genome, whole-exome, or targeted sequencing.

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  • Cell-free DNA (cfDNA) analysis is a blood-based method that helps identify genetic abnormalities, especially beneficial for immunosuppressed patients who cannot undergo traditional biopsies.
  • In our study, we analyzed cfDNA from 36 patients with rare cancers, revealing tumor fractions (TF) in 29% of immunosuppressed patients with specific cancers, and successfully correlated cfDNA profiles with tumor tissue.
  • The use of low-coverage whole genome sequencing (LC-WGS) proved to be an efficient approach for detecting genetic content in cfDNA, aiding in the molecular analysis for better treatment strategies.
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Background: Cerebral cavernous malformations (CCMs) are common sporadic and inherited vascular malformations of the central nervous system. Although familial CCMs are linked to loss-of-function mutations in (), , or (), the genetic cause of sporadic CCMs, representing 80% of cases, remains incompletely understood.

Methods: We developed two mouse models harboring mutations identified in human meningiomas with the use of the prostaglandin D2 synthase (PGDS) promoter.

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B-cell non-Hodgkin's lymphoma (NHL) risk associations had been mainly attributed to family history of the disease, inflammation, and immune components including human leukocyte antigen (HLA) genetic variations. Nevertheless, a broad range of genome-wide association studies (GWAS) have shed light into the identification of several genetic variants presumptively associated with B-cell NHL etiologies, survival or shared genetic risk with other diseases. The present review aims to overview HLA structure and diversity and summarize the evidence of genetic variations, by GWAS, on five NHL subtypes (diffuse large B-cell lymphoma DLBCL, follicular lymphoma FL, chronic lymphocytic leukemia CLL, marginal zone lymphoma MZL, and primary central nervous system lymphoma PCNSL).

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Background: We characterised the phenotypic consequence of genetic variation at the PCSK9 locus and compared findings with recent trials of pharmacological inhibitors of PCSK9.

Methods: Published and individual participant level data (300,000+ participants) were combined to construct a weighted PCSK9 gene-centric score (GS). Seventeen randomized placebo controlled PCSK9 inhibitor trials were included, providing data on 79,578 participants.

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A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

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Background: Primary central nervous system lymphoma (PCNSL) is a rare form of extra-nodal non-Hodgkin lymphoma. PCNSL is a distinct subtype of non-Hodgkin lymphoma, with over 95% of tumors belonging to the diffuse large B-cell lymphoma (DLBCL) group. We have conducted a genome-wide association study (GWAS) on immunocompetent patients to address the possibility that common genetic variants influence the risk of developing PCNSL.

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Genome-wide association studies (GWAS) have so far identified 25 loci associated with glioma risk, with most showing specificity for either glioblastoma (GBM) or non-GBM tumors. The majority of these GWAS susceptibility variants reside in noncoding regions and the causal genes underlying the associations are largely unknown. Here we performed a transcriptome-wide association study to search for novel risk loci and candidate causal genes at known GWAS loci using Genotype-Tissue Expression Project (GTEx) data to predict -predicted gene expression in relation to GBM and non-GBM risk in conjunction with GWAS summary statistics on 12,488 glioma cases (6,183 GBM and 5,820 non-GBM) and 18,169 controls.

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Background: An inverse relationship between allergies with glioma risk has been reported in several but not all epidemiological observational studies. We performed an analysis of genetic variants associated with atopy to assess the relationship with glioma risk using Mendelian randomisation (MR), an approach unaffected by biases from temporal variability and reverse causation that might have affected earlier investigations.

Methods: Two-sample MR was undertaken using genome-wide association study data.

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Background: Obesity and related factors have been implicated as possible aetiological factors for the development of glioma in epidemiological observation studies. We used genetic markers in a Mendelian randomisation framework to examine whether obesity-related traits influence glioma risk. This methodology reduces bias from confounding and is not affected by reverse causation.

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Recent genome-wide association studies of glioma have led to the discovery of single nucleotide polymorphisms (SNPs) at 25 loci influencing risk. Gliomas are heterogeneous, hence to investigate the relationship between risk SNPs and glioma subtype we analysed 1659 tumours profiled for IDH mutation, TERT promoter mutation and 1p/19q co-deletion. These data allowed definition of five molecular subgroups of glioma: triple-positive (IDH mutated, 1p/19q co-deletion, TERT promoter mutated); TERT-IDH (IDH mutated, TERT promoter mutated, 1p/19q-wild-type); IDH-only (IDH mutated, 1p/19q wild-type, TERT promoter wild-type); triple-negative (IDH wild-type, 1p/19q wild-type, TERT promoter wild-type) and TERT-only (TERT promoter mutated, IDH wild-type, 1p/19q wild-type).

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Background: Primary central nervous system lymphoma (PCNSL) represents a particular entity within non-Hodgkin lymphomas and is associated with poor outcome. The present study addresses the potential clinical relevance of chimeric transcripts in PCNSL discovered by using RNA sequencing (RNA-seq).

Methods: Seventy-two immunocompetent and newly diagnosed PCNSL cases were included in the present study.

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To examine for a causal relationship between vitamin D and glioma risk we performed an analysis of genetic variants associated with serum 25-hydroxyvitamin D (25(OH)D) levels using Mendelian randomisation (MR), an approach unaffected by biases from confounding. Two-sample MR was undertaken using genome-wide association study data. Single nucleotide polymorphisms (SNPs) associated with 25(OH)D levels were used as instrumental variables (IVs).

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Molecular classification of cancer has entered clinical routine to inform diagnosis, prognosis, and treatment decisions. At the same time, new tumor entities have been identified that cannot be defined histologically. For central nervous system tumors, the current World Health Organization classification explicitly demands molecular testing, e.

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Genome-wide association studies (GWAS) have transformed our understanding of glioma susceptibility, but individual studies have had limited power to identify risk loci. We performed a meta-analysis of existing GWAS and two new GWAS, which totaled 12,496 cases and 18,190 controls. We identified five new loci for glioblastoma (GBM) at 1p31.

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Background: The 1p19q non-codeleted gliomas with IDH mutation, defined as "molecular astrocytomas," display frequent TP53 mutations and have an intermediate prognosis. We investigated the prognostic impact of copy number-neutral loss of heterozygosity (CNLOH) in 17p in this population.

Methods: We analyzed 793 gliomas (206 grade II, 377 grade III, and 210 grade IV) by single nucleotide polymorphism array and for TP53 mutations.

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Anaplastic oligodendroglioma (AO) are rare primary brain tumours that are generally incurable, with heterogeneous prognosis and few treatment targets identified. Most oligodendrogliomas have chromosomes 1p/19q co-deletion and an IDH mutation. Here we analysed 51 AO by whole-exome sequencing, identifying previously reported frequent somatic mutations in CIC and FUBP1.

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Testicular germ cell tumours (TGCTs) are the most common cancer in young men. Here we perform whole-exome sequencing (WES) of 42 TGCTs to comprehensively study the cancer's mutational profile. The mutation rate is uniformly low in all of the tumours (mean 0.

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Little is known about the genomic basis of primary central nervous system lymphoma (PCNSL) tumorigenesis. To investigate the mutational profile of PCNSL, we analyzed nine paired tumor and germline DNA samples from PCNSL patients by high throughput exome sequencing. Eight genes of interest have been further investigated by focused resequencing in 28 additional PCNSL tumors to better estimate their incidence.

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