Publications by authors named "Guillem Clot"

Mantle cell lymphoma (MCL) is considered one of the most aggressive B-cell lymphoid neoplasms. The transcription factor SOX11 is aberrantly expressed in conventional aggressive MCL, while it is not or weakly expressed in the leukemic non-nodal MCL subtype with a predominantly indolent clinical evolution. SOX11 is a key driver of MCL through the regulation of several oncogenic mechanisms, suggesting that it may be interacting with different protein complexes to exert its multiple actions.

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Monoclonal B-cell lymphocytosis of marginal zone origin (MBL-MZ) is an indolent clonal disorder with potential progression to lymphoma. MYC rearrangements (MYCr), typically linked to aggressive B-cell lymphomas, have not been reported in MBL-MZ. We describe three MBL-MZ cases with MYCr and TP53 alterations, detected via karyotyping, FISH, and optical genome mapping.

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Recurrent mutations in the third base of U1 spliceosomal RNA responsible for marked splicing and expression abnormalities have been described in chronic lymphocytic leukemia (CLL) and some solid tumors. However, the clinical significance of these mutations in large and independent CLL cohorts as well as their presence in other B-cell neoplasms is unknown. Here we characterized U1 mutations in 1670 CLL and 363 mature B-cell lymphomas.

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Previous studies have reported that chronic lymphocytic leukemia (CLL) shows a de novo chromatin activation pattern compared with normal B cells. Here, we explored whether the level of chromatin activation is related to the clinical behavior of CLL. We identified that, in some regulatory regions, increased de novo chromatin activation is linked to clinical progression, whereas, in other regions, it is associated with an indolent course.

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Article Synopsis
  • * A study involving 61 TLBCL patients analyzed their genetic characteristics compared to nodal DLBCL and primary CNS large B-cell lymphomas; findings indicated that TLBCL has fewer copy number changes but more somatic mutations than nodal DLBCL.
  • * The results highlight a unique genetic profile for TLBCL, with most cases classified as MCD, indicating genetic diversity, suggesting that this lymphoma type warrants targeted treatment strategies due to its distinct biology.
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Targeted NGS allows a fast and efficient multi-gene analysis and the detection of key gene aberrations in melanoma. In this study, we aim to describe the genetic alterations in a series of 87 melanoma cases using the oncomine focus assay (OFA), relate these results with the clinicopathological features of the patients, and compare them with our previous study results in which we used a smaller panel, the oncomine solid tumor (OST) DNA kit. Patients diagnosed with advanced melanoma at our center from 2020 to 2022 were included and DNA and RNA were extracted for sequencing.

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Article Synopsis
  • SRY-related HMG-box gene 11 (SOX11) is overexpressed in certain types of lymphomas but absent in normal B cells, playing an oncogenic role in mantle cell lymphoma (MCL) while its role in Burkitt lymphoma (BL) is still unclear.
  • In EBV-negative BL cases, SOX11 expression is linked to specific genetic changes, such as IG∷MYC translocations, indicating an alternative pathogenic mechanism compared to SOX11-negative tumors.
  • Bladder cancer with SOX11 expression shows unique genetic mutations and a different cell behavior pattern, highlighting two subsets of EBV-negative BL cases based on SOX11 presence and suggesting SOX11's involvement in the early development
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Mantle cell lymphoma (MCL) is an incurable B-cell neoplasm characterized by an aggressive behavior, short responses to conventional therapies and SOX11 overexpression, which is associated with aggressive disease features and inferior clinical outcome of patients. Oxidative stress is known to induce tumorigenesis and tumor progression, whereas high expression levels of antioxidant genes have been associated with chemoresistance in different cancers. However, the role of oxidative stress in MCL pathogenesis and the involvement of SOX11 regulating redox homeostasis in MCL cells are largely unknown.

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Article Synopsis
  • Mantle cell lymphoma (MCL) shows diverse clinical and biological characteristics, complicating therapy choices, especially for older patients.
  • In a study of patients aged 60 and older treated with bendamustine and rituximab, key prognostic indicators included the simplified MCL international prognostic index (s-MIPI), MCL35 score, and blastoid cytology, which correlated with survival outcomes.
  • Combining robust proliferation assays like MCL35 with cytological evaluations and MIPI could help better classify and manage the risks of older MCL patients in future clinical trials.
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  • The t(14;19)(q32;q13) chromosomal rearrangement leads to the overexpression of the BCL3 gene through its juxtaposition with the immunoglobulin heavy chain (IGH) gene, affecting various lymphoid neoplasms.
  • An analysis of 13 lymphoid neoplasms with BCL3 rearrangement identified two distinct breakpoint clusters that result in different clinical outcomes: 5' breakpoints near an IGH enhancer causing overexpression of BCL3, and 3' breakpoints leading to no overexpression.
  • The study revealed that upstream BCL3-R tumors are related to atypical chronic lymphocytic leukemia while downstream BCL3-R tumors are linked to marginal zone lymphomas,
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The genetic mechanisms associated with splenic marginal zone lymphoma (SMZL) transformation are not well defined. We studied 41 patients with SMZL that eventually underwent large B-cell lymphoma transformation. Tumor material was obtained either only at diagnosis (9 patients), at diagnosis and transformation (18 patients), and only at transformation (14 patients).

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While some follicular lymphoma (FL) patients do not require treatment or experience prolonged responses, others relapse early, and little is known about genetic alterations specific to patients with a particular clinical behavior. We selected 56 grade 1-3A FL patients according to their need of treatment or timing of relapse: never treated (n = 7), non-relapsed (19), late relapse (14), early relapse or POD24 (11), and primary refractory (5). We analyzed 56 diagnostic and 12 paired relapse lymphoid tissue biopsies and performed copy number alteration (CNA) analysis and next generation sequencing (NGS).

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Article Synopsis
  • Richter transformation (RT) is a severe progression of chronic lymphocytic leukemia (CLL) into aggressive large B cell lymphoma with poor outcomes.
  • Researchers analyzed the genome and transcriptome of 19 CLL cases that developed RT, studying samples over nearly two decades to detect early subclones associated with RT features.
  • They found new genetic drivers and a specific mutational signature for RT, as well as identified a pathway that could be targeted for therapy by inhibiting oxidative phosphorylation in RT cells.
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Mantle cell lymphoma (MCL) is a phenotypically and genetically heterogeneous malignancy in which the genetic alterations determining clinical indications are not fully understood. Here, we performed a comprehensive whole-exome sequencing analysis of 152 primary samples derived from 134 MCL patients, including longitudinal samples from 16 patients and matched RNA-Seq data from 48 samples. We classified MCL into 4 robust clusters (C1-C4).

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Relapsed or refractory diffuse large B-cell lymphoma (DLBCL) cases have a poor outcome. Here we analysed clinico-biological features in 373 DLBCL patients homogeneously treated with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone (R-CHOP), in order to identify variables associated with early failure to treatment (EF), defined as primary refractoriness or relapse within 12 months from diagnosis. In addition to clinical features, mutational status of 106 genes was studied by targeted next-generation sequencing in 111 cases, copy number alterations in 87, and gene expression profile (GEP) in 39.

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Mantle cell lymphoma (MCL) is a mature B-cell neoplasm with a heterogeneous clinical and biological behavior. SOX11 oncogenic expression contributes to the aggressiveness of these tumors by different mechanisms, including tumor and stromal cell interactions. However, the precise composition of the immune cell microenvironment of MCL, its possible relationship to SOX11 expression, and how it may contribute to tumor behavior is not well known.

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We report a systematic analysis of the DNA methylation variability in 1,595 samples of normal cell subpopulations and 14 tumor subtypes spanning the entire human B-cell lineage. Differential methylation among tumor entities relates to differences in cellular origin and to epigenetic alterations, which allowed us to build an accurate machine learning-based diagnostic algorithm. We identify extensive patient-specific methylation variability in silenced chromatin associated with the proliferative history of normal and neoplastic B cells.

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Plasmablastic lymphoma (PBL) is an aggressive B-cell lymphoma with an immunoblastic/large-cell morphology and terminal B-cell differentiation. The differential diagnosis from Burkitt lymphoma, plasma cell myeloma and some variants of diffuse large B-cell lymphoma may be challenging because of the overlapping morphological, genetic and immunophenotypic features. Furthermore, the genomic landscape in PBL is not well known.

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To investigate the three-dimensional (3D) genome architecture across normal B cell differentiation and in neoplastic cells from different subtypes of chronic lymphocytic leukemia and mantle cell lymphoma patients, here we integrate in situ Hi-C and nine additional omics layers. Beyond conventional active (A) and inactive (B) compartments, we uncover a highly-dynamic intermediate compartment enriched in poised and polycomb-repressed chromatin. During B cell development, 28% of the compartments change, mostly involving a widespread chromatin activation from naive to germinal center B cells and a reversal to the naive state upon further maturation into memory B cells.

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Fifty-five cases of t(14;18)- follicular lymphoma (FL) were genetically characterized by targeted sequencing and copy number (CN) arrays. t(14;18)- FL predominated in women (M/F 1:2); patients often presented during early clinical stages (71%), and had excellent prognoses. Overall, t(14;18)- FL displayed CN alterations (CNAs) and gene mutations carried by conventional t(14;18)+ FL (cFL), but with different frequencies.

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B-cell receptor (BCR) signaling is crucial for chronic lymphocytic leukemia (CLL) biology. IGLV3-21-expressing B cells may acquire a single point mutation (R110) that triggers autonomous BCR signaling, conferring aggressive behavior. Epigenetic studies have defined 3 CLL subtypes based on methylation signatures reminiscent of naïve-like (n-CLL), intermediate (i-CLL), and memory-like (m-CLL) B cells with different biological features.

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