Shamzah Araf

EZH2 mutations are frequent and represent an early event in follicular lymphoma

Gain of function mutations in the H3K27 methyltransferase EZH2 represent a promising therapeutic target in germinal center lymphomas. In this study, we assessed the frequency and distribution of EZH2 mutations in a large cohort of patients with follicular lymphoma (FL) (n = 366) and performed a longitudinal analysis of mutation during the disease progression from FL to transformed FL (tFL) (n = 33). Mutations were detected at 3 recurrent mutation hot spots (Y646, A682, and A692) in 27% of FL cases with variant allele frequencies (VAF) ranging from 2% to 61%. By comparing VAF of EZH2 with other mutation targets (CREBBP, MLL2, TNFRSF14, and MEF2B), we were able to distinguish patients harboring clonal EZH2 mutation from rarer cases with subclonal mutations. Overall, the high incidence of EZH2 mutations in FL and their stability during disease progression makes FL an appropriate disease to evaluate EZH2 targeted therapy.

Disease evolution and outcomes in familial AML with germline CEBPA mutations.

In-depth molecular investigation of familial leukemia has been limited by the rarity of recognized cases. This study examines the genetic events initiating leukemia and details the clinical progression of disease across multiple families harboring germ-line CEBPA mutations. Clinical data were collected from 10 CEBPA-mutated families, representing 24 members with acute myeloid leukemia (AML). Whole-exome (WES) and deep sequencing were performed to genetically profile tumors and define patterns of clonal evolution. Germline CEBPA mutations clustered within the N-terminal and were highly penetrant, with AML presenting at a median age of 24.5 years (range, 1.75-46 years). In all diagnostic tumors tested (n = 18), double CEBPA mutations (CEBPAdm) were detected, with acquired (somatic) mutations preferentially targeting the C-terminal. Somatic CEBPA mutations were unstable throughout the disease course, with different mutations identified at recurrence. Deep sequencing of diagnostic and relapse paired samples confirmed that relapse-associated CEBPA mutations were absent at diagnosis, suggesting recurrence was triggered by novel, independent clones. Integrated WES and deep sequencing subsequently revealed an entirely new complement of mutations at relapse, verifying the presentation of a de novo leukemic episode. The cumulative incidence of relapse in familial AML was 56% at 10 years (n = 11), and 3 patients experienced ≥3 disease episodes over a period of 17 to 20 years. Durable responses to secondary therapies were observed, with prolonged median survival after relapse (8 years) and long-term overall survival (10-year overall survival, 67%). Our data reveal that familial CEBPA-mutated AML exhibits a unique model of disease progression, associated with favorable long-term outcomes.

Recurrent mTORC1-activating RRAGC mutations in follicular lymphoma

Follicular lymphoma is an incurable B cell malignancy characterized by the t(14;18) translocation and mutations affecting the epigenome. Although frequent gene mutations in key signaling pathways, including JAK-STAT, NOTCH and NF-κB, have also been defined, the spectrum of these mutations typically overlaps with that in the closely related diffuse large B cell lymphoma (DLBCL). Using a combination of discovery exome and extended targeted sequencing, we identified recurrent somatic mutations in RRAGC uniquely enriched in patients with follicular lymphoma (17%). More than half of the mutations preferentially co-occurred with mutations in ATP6V1B2 and ATP6AP1, which encode components of the vacuolar H+-ATP ATPase (V-ATPase) known to be necessary for amino acid−induced activation of mTORC1. The RagC variants increased raptor binding while rendering mTORC1 signaling resistant to amino acid deprivation. The activating nature of the RRAGC mutations, their existence in the dominant clone and their stability during disease progression support their potential as an excellent candidate for therapeutic targeting.

Epigenetic dysregulation in follicular lymphoma

The adoption of next-generation sequencing technologies has led to a remarkable shift in our understanding of the genetic landscape of follicular lymphoma. While the disease has been synonymous with the t(14;18), the prevalence of alterations in genes that regulate the epigenome has been established as a pivotal hallmark of these lymphomas. Giant strides are being made in unraveling the biological consequences of these alterations in tumorigenesis opening up new opportunities for directed therapies.

Pediatric-type FL: simply different

In this issue of Blood , the groups of [Louissaint et al][1][1][2] and [Schmidt et al][3][2][4] report on the genetic landscape of pediatric-type follicular lymphoma (PTFL). Their studies confirm suspicions that PTFL represents a biologically distinct form of lymphoma, with fewer recurrent genetic

Genomic profiling reveals spatial intra-tumor heterogeneity in follicular lymphoma.

We are indebted to the patients for donating tumor specimens as part of this study. The authors thank the Centre de Ressources Biologiques (CRB)-Sante of Rennes (BB-0033-00056) for patient samples, Queen Mary University of London Genome Centre for Illumina Miseq sequencing, and the support by the National Institute for Health Research (NIHR) Biomedical Research Centre at Guy’s and St Thomas’ NHS Foundation Trust and King’s College London for Illumina Hiseq sequencing. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, or the Department of Health. This work was supported by grants from the Kay Kendall Leukaemia Fund (KKL 757 awarded to J.O.), Cancer Research UK (22742 awarded to J.O., 15968 awarded to J.F., Clinical Research Fellowship awarded to S.A.), Bloodwise through funding of the Precision Medicine for Aggressive Lymphoma (PMAL) consortium, Centre for Genomic Health, Queen Mary University of London, Carte d’Identite des Tumeurs (CIT), Ligue National contre le Cancer, Pole de biologie hospital universitaire de Rennes, CRB-Sante of Rennes (BB-0033-00056), and CeVi/Carnot program.

Advances in the molecular diagnosis of diffuse large B-cell lymphoma in the era of precision medicine

ABSTRACT Introduction: The adoption of high-throughput technologies has led to a transformation in our ability to classify diffuse large B-cell lymphoma (DLBCL) into unique molecular subtypes. In parallel, the expansion of agents targeting key genetic and gene expression signatures has led to an unprecedented opportunity to personalize cancer therapies, paving the way for precision medicine. Areas covered: This review summarizes the key molecular subtypes of DLBCL and outlines the novel technology platforms in development to discriminate clinically relevant subtypes. Expert commentary: The application of emerging diagnostic tests into routine clinical practise is gaining momentum following the demonstration of subtype specific activity by novel agents. Co-ordinated efforts are required to ensure that these state of the art technologies provide reliable and clinically meaningful results accessible to the wider haematology community.

Transmission of diffuse large B cell lymphoma by an allogeneic stem-cell transplant

Cancer development is an evolutionary process driven by the acquisition of stochastic mutations, some of which increase cellular fitness in a co-evolving microenvironment.[1][1] Evidence across multiple cancer types demonstrates that this process is highly protracted, likely beginning years or even

Corrigendum: Recurrent mTORC1-activating RRAGC mutations in follicular lymphoma.

Nat. Genet.; 10.1038/ng.3473; corrected online 12 January 2016 In the version of this article initially published online, several funding sources were omitted from the Acknowledgments section. The error has been corrected for the print, PDF and HTML versions of this article.

Genomic analysis reveals epigenetic ‘addiction’ underpinning follicular lymphoma and its transformation – a rationale for targeted epigenetic therapies

Follicular lymphoma (FL) continues to pose a clinical challenge with a progressive disease course typified by multiple relapses, eventual resistance to standard therapies and transformation (tFL) in a subset of patients to the more aggressive diffuse large B cell lymphoma (DLBCL). WGS was performed on 6 paired FL-tFL patients and corresponding germ-lines to understand the clonal dynamics of progression and recurring genetic events in FL. We identified that the dominant pattern of FL evolution to transformation was consistent with the existence of a common origin, an ancestral common progenitor cell (CPC) population. Strikingly, the CPCs were enriched for mutations in chromatin regulatory genes with every case harbouring mutations in MLL2, a histone methyltransferase, concurrent with mutations in other methyltransferases (EZH2, MLL3, PRMT2), acetyltransferases (CREBBP, MEF2B), bromodomain proteins (BRD2, CECR2), core and linker histones. Targeted deep sequencing of EZH2 showed mutations in 27% of cases in an extension cohort of 366 cases, much higher than previously reported. All mutations targeted the catalytic SET domain leading to a gain-of-function thus offering the possibility of using EZH2 inhibitors. The plethora of genetic mutations in epigenetic regulators in FL shown in this study therefore offers a compelling model disease to strategically test epigenetically-targeted therapies.