Clonal hemopoiesis driven by leukemia-associated gene mutations can occur without evidence of a blood disorder. To investigate this phenomenon, we interrogated 15 mutation hot spots in blood DNA from ...4,219 individuals using ultra-deep sequencing. Using only the hot spots studied, we identified clonal hemopoiesis in 0.8% of individuals under 60, rising to 19.5% of those ≥90 years, thus predicting that clonal hemopoiesis is much more prevalent than previously realized. DNMT3A-R882 mutations were most common and, although their prevalence increased with age, were found in individuals as young as 25 years. By contrast, mutations affecting spliceosome genes SF3B1 and SRSF2, closely associated with the myelodysplastic syndromes, were identified only in those aged >70 years, with several individuals harboring more than one such mutation. This indicates that spliceosome gene mutations drive clonal expansion under selection pressures particular to the aging hemopoietic system and explains the high incidence of clonal disorders associated with these mutations in advanced old age.
Display omitted
•Clonal hemopoiesis is an almost inevitable consequence of aging in humans•Spliceosome gene mutations drove clonal hemopoiesis only in persons aged ≥70 years•NPM1 mutations behave as gatekeepers for leukemogenesis
McKerrell et al. employ ultra-deep sequencing to show that age-related clonal hemopoiesis is much more common than previously realized. They find that clonal hemopoiesis, driven by mutations in spliceosome genes SF3B1 and SRSF2, was noted exclusively in individuals aged 70 years or older and that NPM1 mutations are not seen in association with this phenomenon, endorsing their close association with leukemogenesis.
Acute myeloid leukaemia (AML) is an uncontrolled clonal proliferation of abnormal myeloid progenitor cells in the bone marrow and blood. Advances in cancer genomics have revealed the spectrum of ...somatic mutations that give rise to human AML and drawn our attention to its molecular evolution and clonal architecture. It is now evident that most AML genomes harbour small numbers of mutations, which are acquired in a stepwise manner. This characteristic, combined with our ability to identify mutations in individual leukaemic cells and our detailed understanding of normal human and murine haematopoiesis, makes AML an excellent model for understanding the principles of cancer evolution. Furthermore, a better understanding of how AML evolves can help us devise strategies to improve the therapy and prognosis of AML patients. Here, we draw from recent advances in genomics, clinical studies and experimental models to describe the current knowledge of the clonal evolution of AML and its implications for the biology and treatment of leukaemias and other cancers.
NPM1 mutations define the commonest subgroup of acute myeloid leukemia (AML) and frequently co-occur with FLT3 internal tandem duplications (ITD) or, less commonly, NRAS or KRAS mutations. ...Co-occurrence of mutant NPM1 with FLT3-ITD carries a significantly worse prognosis than NPM1-RAS combinations. To understand the molecular basis of these observations, we compare the effects of the 2 combinations on hematopoiesis and leukemogenesis in knock-in mice. Early effects of these mutations on hematopoiesis show that compound Npm1cA/+;NrasG12D/+ or Npm1cA;Flt3ITD share a number of features: Hox gene overexpression, enhanced self-renewal, expansion of hematopoietic progenitors, and myeloid differentiation bias. However, Npm1cA;Flt3ITD mutants displayed significantly higher peripheral leukocyte counts, early depletion of common lymphoid progenitors, and a monocytic bias in comparison with the granulocytic bias in Npm1cA/+;NrasG12D/+ mutants. Underlying this was a striking molecular synergy manifested as a dramatically altered gene expression profile in Npm1cA;Flt3ITD, but not Npm1cA/+;NrasG12D/+, progenitors compared with wild-type. Both double-mutant models developed high-penetrance AML, although latency was significantly longer with Npm1cA/+;NrasG12D/+. During AML evolution, both models acquired additional copies of the mutant Flt3 or Nras alleles, but only Npm1cA/+;NrasG12D/+ mice showed acquisition of other human AML mutations, including IDH1 R132Q. We also find, using primary Cas9-expressing AMLs, that Hoxa genes and selected interactors or downstream targets are required for survival of both types of double-mutant AML. Our results show that molecular complementarity underlies the higher frequency and significantly worse prognosis associated with NPM1c/FLT3-ITD vs NPM1/NRAS-G12D-mutant AML and functionally confirm the role of HOXA genes in NPM1c-driven AML.
•Npm1c and Nras-G12D co-mutation in mice leads to AML with a longer latency and a more mature phenotype than the Npm1c/Flt3-ITD combination.•Mutant Flt3 or Nras allele amplification is the dominant mode of progression in both Npm1c/Flt3-ITD and Npm1c/Nras-G12D murine AML.
Summary
Marrow fibrosis is a significant complication of myeloproliferative neoplasms (MPN) that affects up to 20% of patients and is associated with a poor prognosis. The pathological processes that ...lead to fibrotic progression are not well understood, but megakaryocytes have been implicated in the process. The aim of this study was to determine whether platelets, derived from megakaryocytes, have transcriptomic alterations associated with fibrosis. Platelets from MPN patients with and without fibrosis and non‐malignant control individuals were assessed using next generation sequencing. Results from the initial training cohort showed discrete changes in platelet transcripts in the presence of marrow fibrosis. We identified more than 1000 differentially expressed transcripts from which a putative 3‐gene fibrotic platelet signature (CCND1, H2AX previously termed H2AFX and CEP55) could be identified. This fibrosis‐associated signature was assessed blinded on platelets from an independent test MPN patient cohort. The 3‐gene signature was able to discriminate between patients with and without marrow fibrosis with a positive predictive value of 71% (93% specificity, 71% sensitivity). This demonstrates that assessment of dysregulated transcripts in platelets may be a useful monitoring tool in MPN to identify progression to marrow fibrosis. Further, sequential monitoring could have clinical applications for early prediction of progression to fibrosis.
Transcription factor 3 (TCF3) is a DNA transcription factor that modulates megakaryocyte development. Although abnormal TCF3 expression has been identified in a range of hematological malignancies, ...to date, it has not been investigated in myelofibrosis (MF). MF is a Philadelphia-negative myeloproliferative neoplasm (MPN) that can arise
or progress from essential thrombocythemia ET and polycythemia vera PV and where dysfunctional megakaryocytes have a role in driving the fibrotic progression. We aimed to examine whether TCF3 is dysregulated in megakaryocytes in MPN, and specifically in MF. We first assessed TCF3 protein expression in megakaryocytes using an immunohistochemical approach analyses and showed that TCF3 was reduced in MF compared with ET and PV. Further, the TCF3-negative megakaryocytes were primarily located near trabecular bone and had the typical "MF-like" morphology as described by the WHO. Genomic analysis of isolated megakaryocytes showed three mutations, all predicted to result in a loss of function, in patients with MF; none were seen in megakaryocytes isolated from ET or PV marrow samples. We then progressed to transcriptomic sequencing of platelets which showed loss of
in MF. These proteomic, genomic and transcriptomic analyses appear to indicate that TCF3 is downregulated in megakaryocytes in MF. This infers aberrations in megakaryopoiesis occur in this progressive phase of MPN. Further exploration of this pathway could provide insights into TCF3 and the evolution of fibrosis and potentially lead to new preventative therapeutic targets.
•Does treatment for 90 days with 5 mg oral doses of the myeloperoxidase inhibitor AZD4831 decrease myeloperoxidase specific activity in patients with heart failure and a left ventricular ejection ...fraction of at least 40%, with acceptable safety and tolerability?•AZD4831 reduced normalized ex vivo myeloperoxidase specific activity by more than 50% from baseline and by 75% vs placebo in this randomized, double-blind, phase 2a trial in 41 patients, with few treatment-related adverse events and no safety signals of concern.•The level of myeloperoxidase inhibition and the safety profile observed with AZD4831 warrant further clinical investigation of the efficacy and safety of this first-in-class myeloperoxidase inhibitor in patients with heart failure and preserved or mildly reduced left ventricular ejection fraction.
Inflammation is a key driver of heart failure with preserved left ventricular ejection fraction. AZD4831 inhibits extracellular myeloperoxidase, decreases inflammation, and improves microvascular function in preclinical disease models.
In this double-blind phase 2a study (Safety and Tolerability Study of AZD4831 in Patients With Heart Failure SATELLITE; NCT03756285), patients with symptomatic heart failure, left ventricular ejection fraction of ≥40%, and elevated B-type natriuretic peptides were randomized 2:1 to once-daily oral AZD4831 5 mg or placebo for 90 days. We aimed to assess target engagement (primary end point: myeloperoxidase specific activity) and safety of AZD4831. Owing to coronavirus disease 2019, the study was terminated early after randomizing 41 patients (median age 74.0 years, 53.7% male). Myeloperoxidase activity was decreased by more than 50% from baseline to day 30 and day 90 in the AZD4831 group, with a placebo-adjusted decreased of 75% (95% confidence interval, 48, 88, nominal P < .001). No improvements were noted in secondary or exploratory end points, apart from a trend in Kansas City Cardiomyopathy Questionnaire overall summary score. No deaths or treatment-related serious adverse events occurred. AZD4831 treatment-related adverse events were generalized maculopapular rash, pruritus, and diarrhea (all n = 1).
AZD4831 inhibited myeloperoxidase and was well tolerated in patients with heart failure and left ventricular ejection fraction of 40% or greater. Efficacy findings were exploratory owing to early termination, but warrant further clinical investigation of AZD4831.
Few treatments are available for patients with the forms of heart failure known as heart failure with preserved or mildly reduced ejection fraction. Current treatments do not target inflammation, which may play an important role in this condition. We tested a new drug called AZD4831 (mitiperstat), which decreases inflammation by inhibiting the enzyme myeloperoxidase. Among the 41 patients in our clinical trial, AZD4831 had a good safety profile and inhibited myeloperoxidase by the expected amount. Results mean we can conduct further trials to see whether AZD4831 decreases the symptoms of heart failure and improves patients’ ability to participate in physical exercise.
Display omitted
B-cell lymphoma (BCL) is the most common hematologic malignancy. While sequencing studies gave insights into BCL genetics, identification of non-mutated cancer genes remains challenging. Here, we ...describe PiggyBac transposon tools and mouse models for recessive screening and show their application to study clonal B-cell lymphomagenesis. In a genome-wide screen, we discover BCL genes related to diverse molecular processes, including signaling, transcriptional regulation, chromatin regulation, or RNA metabolism. Cross-species analyses show the efficiency of the screen to pinpoint human cancer drivers altered by non-genetic mechanisms, including clinically relevant genes dysregulated epigenetically, transcriptionally, or post-transcriptionally in human BCL. We also describe a CRISPR/Cas9-based in vivo platform for BCL functional genomics, and validate discovered genes, such as Rfx7, a transcription factor, and Phip, a chromatin regulator, which suppress lymphomagenesis in mice. Our study gives comprehensive insights into the molecular landscapes of BCL and underlines the power of genome-scale screening to inform biology.
Systemic microvascular dysfunction and inflammation are postulated to play a pathophysiologic role in heart failure with preserved ejection fraction (HFpEF).
This study aimed to identify biomarker ...profiles associated with clinical outcomes in HFpEF and investigate how inhibition of the neutrophil-derived reactive oxygen species–producing enzyme, myeloperoxidase, affects these biomarkers.
Using supervised principal component analyses, the investigators assessed the associations between baseline plasma proteomic Olink biomarkers and clinical outcomes in 3 independent observational HFpEF cohorts (n = 86, n = 216, and n = 242). These profiles were then compared with the biomarker profiles discriminating patients treated with active drug vs placebo in SATELLITE (Safety and Tolerability Study of AZD4831 in Patients With Heart Failure), a double-blind randomized 3-month trial evaluating safety and tolerability of the myeloperoxidase inhibitor AZD4831 in HFpEF (n = 41). Pathophysiological pathways were inferred from the biomarker profiles by interrogation of the Ingenuity Knowledge Database.
TNF-R1, TRAIL-R2, GDF15, U-PAR, and ADM were the top individual biomarkers associated with heart failure hospitalization or death, and FABP4, HGF, RARRES2, CSTB, and FGF23 were associated with lower functional capacity and poorer quality of life. AZD4831 downregulated many markers (most significantly CDCP1, PRELP, CX3CL1, LIFR, VSIG2). There was remarkable consistency among pathways associated with clinical outcomes in the observational HFpEF cohorts, the top canonical pathways being associated with tumor microenvironments, wound healing signaling, and cardiac hypertrophy signaling. These pathways were predicted to be downregulated in AZD4831 relative to placebo-treated patients.
Biomarker pathways that were most strongly associated with clinical outcomes were also the ones reduced by AZD4831. These results support the further investigation of myeloperoxidase inhibition in HFpEF.
Display omitted
PDF
