A new next-generation sequencing strategy for the simultaneous analysis of mutations and chromosomal rearrangements at DNA level in acute myeloid leukemia patients

Acute myeloid leukemias (AMLs) are currently genomically characterized by karyotype, fluorescence in situ hybridization (FISH), real-time quantitative PCR, and DNA sequencing. Next-generation sequencing offers the promise of detecting all genomic lesions in a single run. However, technical limitations have hampered the detection of chromosomal rearrangements, so most studies are limited to somatic mutation assessment or require the use of RNA-based strategies. To overcome these limitations, we designed a targeted-DNA capture next-generation sequencing approach associated with easy-to-perform public bioinformatic tools for one-step identification of translocations, inversions, and somatic mutations in AML. Thirty well-characterized newly diagnosed myeloid leukemia patients (27 AML and 3 chronic myeloid leukemia) were tested with the panel. Twenty-three of 24 known rearrangements, as well as one novel fusion gene that could not be detected by karyotype/fluorescence in situ hybridization/real-time quantitative PCR, were detected. This strategy also identified all chromosomal breakpoints as potential targets for future high-sensitive minimal residual disease studies. In addition, mutation analysis revealed the presence of missense protein-coding alterations in at least 1 of the 32 genes evaluated in 21 of 30 patients (70%). This strategy may represent a time- and cost-effective diagnostic method for molecular characterization in AML.Supported by the Fundación Española de Hematología y Hemoterapia (FEHH) (M.I.P.-C. and M.G.-A.); the Spanish Association Against Cancer Scientific Foundation (AECC) (M.C.C.); Miguel Servet program CP13/00080 from the Instituto de Salud Carlos III (ISCIII), Ministerio de Ciencia, Innovación y Universidades, Spain (M.E.S.); and the “Beca de investigación FEHH-CRIS 2018” (C.J.). Partially supported by ISCIII research grants PI15/01706, CIBERONCCB16/12/00233, and “Una manera de hacer Europa” Innocampus, CEI-2010-1-0010.Peer reviewe

Molecular profiling of immunoglobulin heavychain gene rearrangements unveils new potential prognostic markers for multiple myeloma patients

Multiple myeloma is a heterogeneous disease whose pathogenesis has not been completely elucidated. Although B-cell receptors play a crucial role in myeloma pathogenesis, the impact of clonal immunoglobulin heavy-chain features in the outcome has not been extensively explored. Here we present the characterization of complete heavychain gene rearrangements in 413 myeloma patients treated in Spanish trials, including 113 patients characterized by next-generation sequencing. Compared to the normal B-cell repertoire, gene selection was biased in myeloma, with significant overrepresentation of IGHV3, IGHD2 and IGHD3, as well as IGHJ4 gene groups. Hypermutation was high in our patients (median: 8.8%). Interestingly, regarding patients who are not candidates for transplantation, a high hypermutation rate (≥7%) and the use of IGHD2 and IGHD3 groups were associated with improved prognostic features and longer survival rates in the univariate analyses. Multivariate analysis revealed prolonged progression-free survival rates for patients using IGHD2/IGHD3 groups (HR: 0.552, 95% CI: 0.361−0.845, p = 0.006), as well as prolonged overall survival rates for patients with hypermutation ≥7% (HR: 0.291, 95% CI: 0.137−0.618, p = 0.001). Our results provide new insights into the molecular characterization of multiple myeloma, highlighting the need to evaluate some of these clonal rearrangement characteristics as new potential prognostic markers

Molecular profiling of immunoglobulin heavychain gene rearrangements unveils new potential prognostic markers for multiple myeloma patients

Multiple myeloma is a heterogeneous disease whose pathogenesis has not been completely elucidated. Although B-cell receptors play a crucial role in myeloma pathogenesis, the impact of clonal immunoglobulin heavy-chain features in the outcome has not been extensively explored. Here we present the characterization of complete heavychain gene rearrangements in 413 myeloma patients treated in Spanish trials, including 113 patients characterized by next-generation sequencing. Compared to the normal B-cell repertoire, gene selection was biased in myeloma, with significant overrepresentation of IGHV3, IGHD2 and IGHD3, as well as IGHJ4 gene groups. Hypermutation was high in our patients (median: 8.8%). Interestingly, regarding patients who are not candidates for transplantation, a high hypermutation rate (≥7%) and the use of IGHD2 and IGHD3 groups were associated with improved prognostic features and longer survival rates in the univariate analyses. Multivariate analysis revealed prolonged progression-free survival rates for patients using IGHD2/IGHD3 groups (HR: 0.552, 95% CI: 0.361−0.845, p = 0.006), as well as prolonged overall survival rates for patients with hypermutation ≥7% (HR: 0.291, 95% CI: 0.137−0.618, p = 0.001). Our results provide new insights into the molecular characterization of multiple myeloma, highlighting the need to evaluate some of these clonal rearrangement characteristics as new potential prognostic markers

Richter transformation driven by Epstein-Barr virus reactivation during therapy-related immunosuppression in chronic lymphocytic leukemia

The increased risk of Richter transformation (RT) in patients with chronic lymphocytic leukemia (CLL) due to Epstein-Barr virus (EBV) reactivation during immunosuppressive therapy with fludarabine or other targeted agents remains controversial. Among 31 RT cases classified as diffuse large B-cell lymphoma (DLBCL), seven (23%) showed EBV expression. In comparison to EBV-negative tumors, EBV+ DLBCLs derived predominantly from IGVH-hypermutated CLL and exhibited CLL-unrelated IGVH sequences more frequently. Intriguingly, despite having different cellular origins, clonally related and unrelated EBV+ DLBCLs shared a previous history of immunosuppressive chemo-immunotherapy, a non-germinal center DLBCL phenotype, EBV latency programs type II/III, and a very short survival. These data suggested that EBV reactivation during therapy-related immunosuppression can transform either CLL cells or non-tumoral B lymphocytes into EBV+ DLBCL. To investigate this hypothesis, xenogeneic transplantation of blood cells from 31 patients with CLL and monoclonal B-cell lymphocytosis (MBL) was performed in Rag2-/-IL2γc-/-mice. Remarkably, the recipients' impaired immunosurveillance favored the spontaneous outgrowth of EBV+ B-cell clones from 95% of CLL and 64% of MBL patients, but not from healthy donors. Eventually, these cells generated monoclonal tumors (mostly CLL-unrelated but also CLL-related) recapitulating the principal features of EBV+ DLBCL in patients. Accordingly, clonally related and unrelated EBV+ DLBCL xenografts exhibited indistinguishable cellular, virological and molecular features, and synergistically responded to combined inhibition of EBV replication with ganciclovir and BCR signaling with ibrutinib in vivo. Our study underscores the risk of RT driven by EBV in CLL patients receiving immunosuppressive therapies, and provides the scientific rationale for testing ganciclovir and ibrutinib in EBV+ DLBCL