CHIP, CCUS, and Other Acronyms: Definition, Implications, and Impact on Practice

Multiomic profiling of human clonal hematopoiesis reveals genotype and cell-specific inflammatory pathway activation

ABSTRACT

Clonal hematopoiesis (CH) is an age-associated phenomenon that increases the risk of hematologic malignancy and cardiovascular disease. CH is thought to enhance disease risk through inflammation in the peripheral blood.1 Here, we profile peripheral blood gene expression in 66 968 single cells from a cohort of 17 patients with CH and 7 controls. Using a novel mitochondrial DNA barcoding approach, we were able to identify and separately compare mutant Tet methylcytosine dioxygenase 2 (TET2) and DNA methyltransferase 3A (DNMT3A) cells with nonmutant counterparts. We discovered the vast majority of mutated cells were in the myeloid compartment. Additionally, patients harboring DNMT3A and TET2 CH mutations possessed a proinflammatory profile in CD14+ monocytes through previously unrecognized pathways such as galectin and macrophage inhibitory factor. We also found that T cells from patients with CH, although mostly unmutated, had decreased expression of GTPase of the immunity associated protein genes, which are critical to T-cell development, suggesting that CH impairs T-cell function.

Clonal hematopoiesis and inflammation in the vasculature: CHIVE, a prospective, longitudinal clonal hematopoiesis cohort and biorepository

ABSTRACT

Clonal hematopoiesis (CH) is an age-associated phenomenon leading to an increased risk of both hematologic malignancy and nonmalignant organ dysfunction. Increasingly available genetic testing has made the incidental discovery of CH clinically common yet evidence-based guidelines and effective management strategies to prevent adverse CH health outcomes are lacking. To address this gap, the prospective CHIVE (clonal hematopoiesis and inflammation in the vasculature) registry and biorepository was created to identify and monitor individuals at risk, support multidisciplinary CH clinics, and refine taxonomy and standards of practice for CH risk mitigation. Data from the first 181 patients enrolled in this prospective registry recapitulate the molecular epidemiology of CH from biobank-scale retrospective studies, with DNMT3A, TET2, ASXL1, and TP53 as the most commonly mutated genes. Blood counts across all hematopoietic lineages trended lower in patients with CH. In addition, patients with CH had higher rates of end organ dysfunction, in particular chronic kidney disease. Among patients with CH, variant allele frequency was independently associated with the presence of cytopenias and progression to hematologic malignancy, whereas other common high-risk CH clone features were not clear. Notably, accumulation of multiple distinct high-risk clone features was also associated with cytopenias and hematologic malignancy progression, supporting a recently published CH risk score. Surprisingly, ∼30% of patients enrolled in CHIVE from CH clinics were adjudicated as not having clonal hematopoiesis of indeterminate potential, highlighting the need for molecular standards and purpose-built assays in this field. Maintenance of this well-annotated cohort and continued expansion of CHIVE to multiple institutions are underway and will be critical to understanding how to thoughtfully care for this patient population.

DNMT3A/TET2/ASXL1 Mutations are an Age-independent Thrombotic Risk Factor in Polycythemia Vera Patients: An Observational Study

BACKGROUND

 Polycythemia vera (PV) patients are classified as high or low thrombotic risk based on age and prior history of thrombosis. Despite adherence to treatment recommendations, vascular events remain frequent, leading us to question whether thrombotic risk stratification could be improved. We previously reported an association between thrombotic events and mutations in DTA genes (DNMT3A, TET2, and ASXL1). The objective of this study was to confirm this observation in a larger series of PV patients.

METHODS

 PV patients with a minimum follow-up of 3 years were recruited from 8 European centers. Medical history was searched for thrombotic event recorded at any time and next-generation sequencing carried out with a myeloid panel. Multivariable logistic regression evaluated the impact of variables on thrombotic risk. Kaplan-Meier thrombosis-free survival curves were compared by the log rank test. Associations in the total cohort were confirmed in a case-control study to exclude selection bias.

RESULTS

 Of the 136 patients recruited, 74 (56.1%) had a thrombotic event, with an incidence density of 2.83/100 person-years. In multivariable analysis, DTA mutation was a risk factor for thrombotic event, being predictive for shorter thrombosis-free survival in the whole cohort (p = 0.007), as well as in low-risk patients (p = 0.039) and older patients (p = 0.009), but not for patients with a prediagnostic event. A gender- and age-matched case-control study confirmed the increased risk of thrombotic event for PV patients with a DTA mutation.

CONCLUSION

 Our results support the use of molecular testing at diagnosis to help predict which PV patients are at higher risk of developing thrombosis.

Clonal Hematopoiesis in Patients With Neuroendocrine Tumor Treated With Lutetium-177 and the Risk of Thrombocytopenia: A Prospective Study

PURPOSE

Thrombocytopenia is a relatively common dose-limiting toxicity during peptide receptor radionuclide therapy (PRRT) in patients with NET. Although uncommon, some patients develop persistent cytopenia and eventually therapy-related myeloid neoplasm (t-MN), which has a dismal prognosis. As the indications for PRRT are expanding, it is important to investigate factors that may predict cytopenias during/after PRRT. We prospectively evaluated the prevalence of clonal hematopoiesis (CH) and cytopenia in patients with NET undergoing PRRT.

MATERIALS AND METHODS

Patients with metastatic NET with plan to receive four cycles of lutetium-177 were enrolled. CH was evaluated before PRRT using a panel of 220 genes with a targeted depth of ≥1,000×. Patients were followed during PRRT and every 3 months thereafter.

RESULTS

Of 37 patients enrolled, the median age was 68 years and 51.4% were male. Previous treatment exposures included alkylating agents in 30%, platinum agents in 8%, and external radiation in 13%. CH was detected in 35.1% using a variant allele frequency (VAF) cutoff of ≥2% and 45.9% with a VAF of ≥1%. The most common mutations were in age-related genes (DNMT3A, TET2). CH was not associated with anemia or neutropenia; however, it was associated with lower platelet count at baseline and more time spent in a thrombocytopenic state during/after PRRT. Five patients had bone marrow biopsies (BMBs) because of sustained hematologic dysfunction post-PRRT, and of those, diagnoses included clonal cytopenia of undetermined significance (CCUS) in three and idiopathic cytopenia of undetermined significance (ICUS) in two.

CONCLUSION

CH is present in 35.1% of patients with NET and is associated with thrombocytopenia risk during PRRT. Future studies with long-term follow-up will delineate whether CH might be a predictor for higher risk of t-MN after PRRT.

Malignant progression of preleukemic disorders

ABSTRACT

The spectrum of myeloid disorders ranges from aplastic bone marrow failure characterized by an empty bone marrow completely lacking in hematopoiesis to acute myeloid leukemia in which the marrow space is replaced by undifferentiated leukemic blasts. Recent advances in the capacity to sequence bulk tumor population as well as at a single-cell level has provided significant insight into the stepwise process of transformation to acute myeloid leukemia. Using models of progression in the context of germ line predisposition (trisomy 21, GATA2 deficiency, and SAMD9/9L syndrome), premalignant states (clonal hematopoiesis and clonal cytopenia of unknown significance), and myelodysplastic syndrome, we review the mechanisms of progression focusing on the hierarchy of clonal mutation and potential roles of transcription factor alterations, splicing factor mutations, and the bone marrow environment in progression to acute myeloid leukemia. Despite major advances in our understanding, preventing the progression of these disorders or treating them at the acute leukemia phase remains a major area of unmet medical need.

Abdominal venous thromboses: detection of the JAK2 p.V617F mutation by next-generation ultradeep sequencing-A prevalence study of patients in Mecklenburg-West Pomerania (2017-2021)

Background

Abdominal venous thromboses are rare thrombotic events with heterogeneous etiologies. They are related to myeloproliferative neoplasms (MPNs) in some patients and can occur as first signs of the disease. MPNs are characterized by mutations in the genes of Janus kinase 2 (JAK2), myeloproliferative leukemia virus oncogene (MPL), and calreticulin (CALR).

Methods

Within the prospective trial "Prevalence of JAK2 mutations in patients with abdominal venous thromboses" (JAK2 MV study; German Clinical Trials Register: DRKS00026943), the peripheral blood of patients with abdominal venous thromboses in Mecklenburg-West Pomerania, a federal state located in north-east Germany, was analyzed by next-generation ultradeep sequencing for MPN-associated mutations. Clinical characteristics and blood cell counts were also of interest. The primary endpoint was the detection of the mutation JAK2 p.V617F. Secondary endpoints were the detection of other acquired variants of JAK2, as well as MPL and CALR.

Results

A total of 68 patients with abdominal venous thromboses were included from February 2017 to January 2021, with splanchnic veins affected in 65 patients. The mutation JAK2 p.V617F was present in 13 patients (19%), with four patients showing low variant allele frequencies (VAF 0.1% to 1.9%). The time interval from the thrombotic event to analysis was longer for patients with the mutation. The mutation MPL p.W515R was detected in three cases, all of them with low VAF. One patient among them had a concurrent mutation of JAK2 p.V617F. The mutations CALR type I or type II were not found.

Discussion

By analyzing peripheral blood for the mutation JAK2 p.V617F, an important cause of these rare thrombotic events can be identified. The development of a diagnostic workup with next-generation ultradeep sequencing for the analysis of the JAK2 p.V617F mutation and further mutations has the potential to better understand the etiology of abdominal venous thromboses in individual patients in regional clinical care, as abdominal venous thromboses are diagnosed by various medical disciplines.

Clonal Hematopoiesis and Cardiovascular Disease in Patients With Multiple Myeloma Undergoing Hematopoietic Cell Transplant

Importance

There is a paucity of information on the association between clonal hematopoiesis of indeterminate potential (CHIP) and cardiovascular disease (CVD) in patients with cancer, including those with multiple myeloma (MM) undergoing hematopoietic cell transplant (HCT), a population at high risk of developing CVD after HCT.

Objective

To examine the association between CHIP and CVD in patients with MM and to describe modifiers of CVD risk among those with CHIP.

Design, Setting, and Participants

This was a retrospective cohort study of patients with MM who underwent HCT between 2010 and 2016 at City of Hope Comprehensive Cancer Center in Duarte, California, and had pre-HCT mobilized peripheral blood stem cell (PBSC) products cryopreserved and accessible for CHIP analyses. The study team performed targeted panel DNA sequencing to detect the presence of CHIP (variant allele frequency 2% or more).

Main Outcomes and Measures

The primary end point was the 5-year cumulative incidence and risk for developing de novo CVD (heart failure, coronary artery disease, or stroke) after HCT.

Results

Of 1036 consecutive patients with MM (580 male [56%]; median age, 60.0 years) who underwent a first autologous HCT, 201 patients had at least 1 CHIP variant (19.4%) and 35 patients had 2 or more variants (3.4%). The 5-year incidence of CVD was significantly higher in patients with CHIP (21.1% vs 8.4%; P < .001) compared with those without CHIP; the 5-year incidence among those with 2 or more variants was 25.6%. In the multivariable model, CHIP was associated with increased risk of CVD (hazard ratio [HR], 2.72; 95% CI, 1.70-4.39), as well as of individual outcomes of interest, including heart failure (HR, 4.02; 95% CI, 2.32-6.98), coronary artery disease (HR, 2.22; 95% CI, 1.06-4.63), and stroke (HR, 3.02; 95% CI, 1.07-8.52). Patients who had both CHIP and preexisting hypertension or dyslipidemia were at nearly 7-fold and 4-fold increased risk of CVD, respectively (reference: no CHIP, no hypertension, or dyslipidemia).

Conclusion and Relevance

CHIP was significantly and independently associated with risk of CVD in patients with MM undergoing HCT and may serve as a novel biologically plausible biomarker for CVD in this cohort. Patients with MM and both CHIP and cardiovascular risk factors had an exceptionally high risk of CVD. Additional studies are warranted to determine if cardiovascular preventive measures can reduce CHIP-associated CVD risk.

Effects of IL-1β inhibition on anemia and clonal hematopoiesis in the randomized CANTOS trial

Canakinumab, a monoclonal antibody targeting proinflammatory cytokine interleukin-1β (IL-1β), improved hemoglobin levels while preventing recurrent cardiovascular events in the Canakinumab Anti-inflammatory Thrombosis Outcomes Study (CANTOS). This cardiovascular (CV) preventive effect was greater in patients with TET2 mutations associated with clonal hematopoiesis (CH). The current proteogenomic analysis aimed to understand the clinical response to canakinumab and underlying proteomic profiles in the context of CH and anemia. The analysis included 4595 patients from the CANTOS study who received either canakinumab or placebo and evaluated multiplexed proteomics (4785 proteins) using SomaScan and targeted deep sequencing for CH mutations. Incident anemia was more common in the presence of CH mutations but reduced by canakinumab treatment. Canakinumab treatment was significantly associated with higher hemoglobin increment in patients with concurrent CH mutations and anemia than patients with CH mutations without anemia or without CH mutations. Compared with those without CH mutations, the presence of CH mutations was associated with proteomic signatures of inflammation and defense response to infection, as well as markers of high-risk CV disease which was further enhanced by the presence of anemia. Canakinumab suppressed hepcidin, proinflammatory cytokines, myeloid activation, and complement pathways, and reversed pathologically deregulated pathways to a greater extent in patients with CH mutations and anemia. These molecular findings provide evidence of the clinical use of IL-1β blockade and support further study of canakinumab for patients with concurrent anemia and CH mutations. This study was registered at www.clinicaltrials.gov as #NCT01327846.

Pre-operative clonal hematopoiesis is related to adverse outcome in lung cancer after adjuvant therapy

BACKGROUND

Clonal hematopoiesis (CH) frequently progresses after chemotherapy or radiotherapy. We evaluated the clinical impact of preoperative CH on the survival outcomes of patients with non-small cell lung cancer (NSCLC) who underwent surgical resection followed by adjuvant therapy.

METHODS

A total of 415 consecutive patients with NSCLC who underwent surgery followed by adjuvant therapy from 2011 to 2017 were analyzed. CH status was evaluated using targeted deep sequencing of blood samples collected before surgery. To minimize the possible selection bias between the two groups according to CH status, a propensity score matching (PSM) was adopted. Early-stage patients were further analyzed with additional matched cohort of patients who did not receive adjuvant therapy.

RESULTS

CH was detected in 21% (86/415) of patients with NSCLC before adjuvant therapy. Patients with CH mutations had worse overall survival (OS) than those without (hazard ratio [95% confidence interval] = 1.56 [1.07-2.28], p = 0.020), which remained significant after the multivariable analysis (1.58 [1.08-2.32], p = 0.019). Of note, the presence of CH was associated with non-cancer mortality (p = 0.042) and mortality of unknown origin (p = 0.018). In patients with stage IIB NSCLC, there was a significant interaction on OS between CH and adjuvant therapy after the adjustment with several cofactors through the multivariable analysis (HR 1.19, 95% CI 1.00-1.1.41, p = 0.041).

CONCLUSIONS

In resected NSCLC, existence of preoperative CH might amplify CH-related adverse outcomes through adjuvant treatments, resulting in poor survival results.

Targeted NGS on sequential bone marrow biopsies aids in the evaluation of cytopenias and monocytosis and documents clonal evolution-a proof of principle study

Differential diagnosis of clonal versus reactive cytopenia and monocytosis, respectively, frequently presents a diagnostic challenge. With the two recent classifications of myeloid disorders, mutational analysis has gained importance as a diagnostic tool. However, reports on its utility on trephine bone marrow biopsies (BMB) are sparse. The aim of our proof of principle study was to determine the suitability of targeted sequencing for the longitudinal evaluation of cytopenia and monocytosis and demonstration of clonal evolution on sequential BMB. Seventy-seven EDTA-decalcified BMB of 33 patients with peripheral cytopenia and/or monocytosis, including at least one follow-up biopsy/patient, were included. Initial morphological diagnoses were idiopathic cytopenia of undetermined significance (ICUS, 8 cases), MDS (without blast increase, 7 cases), MDS with increased blasts/excess blasts (MDS-IB/EB) (11 cases), and CMML (7 cases). Thirty-one genes relevant for myeloid disorders were examined using two custom AmpliSeq NGS panels. Mutations were found in the initial BMB of 5/8 cases of ICUS, thus changing the diagnosis to clonal cytopenia of unknown significance (CCUS), 5/7 MDS, 10/11 MDS-IB/EB, and 7/7 CMML. Clonal evolution was observed in 14/33 (42%) cases, mostly associated with disease progression. None of the wild-type patients acquired mutations during follow-up. NGS-based mutation profiling is a robust diagnostic tool for BMB and provides valuable additional information, especially for cases with no/minimal dysplasia, and for better risk stratification of MDS. Tracking variant allele frequency and appearance of mutations over time allows for observing clonal evolution or relapse.

Premalignant Clonal Hematopoiesis (Clonal Hematopoiesis of Indeterminate Potential and Clonal Cytopenia of Undetermined Significance)

Premalignant clonal hematopoiesis is the presence of somatic alterations in the blood of otherwise healthy individuals. Although the condition is not considered as a cancer, it carries an increased risk of developing a hematologic malignancy, particularly in those with large neoplastic clones, multiple pathogenic mutations, and high-risk mutations. In addition to the increased risk of malignancy, clonal hematopoiesis carries a markedly increased risk of cardiovascular events and death. Appropriate identification of this entity is critical to mitigate cardiovascular risk factors and ensure appropriate monitoring for the emergence of blood cancer.

Clinical impact of the genomic landscape and leukemogenic trajectories in non-intensively treated elderly acute myeloid leukemia patients

To characterize the genomic landscape and leukemogenic pathways of older, newly diagnosed, non-intensively treated patients with AML and to study the clinical implications, comprehensive genetics analyses were performed including targeted DNA sequencing of 263 genes in 604 patients treated in a prospective Phase III clinical trial. Leukemic trajectories were delineated using oncogenetic tree modeling and hierarchical clustering, and prognostic groups were derived from multivariable Cox regression models. Clonal hematopoiesis-related genes (ASXL1, TET2, SRSF2, DNMT3A) were most frequently mutated. The oncogenetic modeling algorithm produced a tree with five branches with ASXL1, DDX41, DNMT3A, TET2, and TP53 emanating from the root suggesting leukemia-initiating events which gave rise to further subbranches with distinct subclones. Unsupervised clustering mirrored the genetic groups identified by the tree model. Multivariable analysis identified FLT3 internal tandem duplications (ITD), SRSF2, and TP53 mutations as poor prognostic factors, while DDX41 mutations exerted an exceptionally favorable effect. Subsequent backwards elimination based on the Akaike information criterion delineated three genetic risk groups: DDX41 mutations (favorable-risk), DDX41wildtype/FLT3-ITDneg/TP53wildtype (intermediate-risk), and FLT3-ITD or TP53 mutations (high-risk). Our data identified distinct trajectories of leukemia development in older AML patients and provide a basis for a clinically meaningful genetic outcome stratification for patients receiving less intensive therapies.

Cytogenetics in the management of clonal chromosomal abnormalities of undetermined significance and persistent polyclonal B-cell lymphocytosis: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Acquired clonal chromosomal abnormalities (CAs) are usually considered to be disease-related. However, when a CA of this type is the only abnormality present (and especially in small clones), the clinical significance is unclear. Here, we review the literature on recurrent CAs whose significance is regularly subject to debate. Our objective was to help with their interpretation and develop guidelines for sex chromosome loss, trisomy 15, trisomy 8, deletion 20q and other isolated non-myelodysplastic neoplasm (MDS)-defining CAs. We suggest that non-MDS-defining CAs correspond to clonal hematopoiesis of indeterminate potential (CHIP) in the absence of cytopenia and clonal cytopenia of undetermined significance (CCUS) in the presence of cytopenia. Lastly, we review the literature on persistent polyclonal binucleated B-cell lymphocytosis; although usually benign, this condition may correspond to a premalignant state.

Myelodysplastic syndromes with ring sideroblasts

Myelodysplastic syndromes (MDS) are acquired bone marrow malignant disorders characterized by ineffective hematopoiesis, resulting from a complex interaction between genetic and epigenetic mutations, alterations of the marrow microenvironment, and the immune system. In 2001, the World Health Organization (WHO) proposed a classification that integrates morphologic and genetic information, considering the MDS with ring sideroblasts (MDS-RS) as a distinct entity. Considering the strong association between MDS-RS and SF3B1 mutation and its importance in the development of MDS, the last WHO classification replaced the prior entity of MDS-RS with MDS with SF3B1 mutation. Several studies were performed to explore this genotype-phenotype correlation. Mutant SF3B1 protein deregulates the expression of genes implicated in developing hematopoietic stem and progenitor cells. Of paramount importance are PPOX and ABCB7 involved in iron metabolism. Another essential role in hemopoiesis is played by the transforming growth factor-beta (TGF-β) receptor. This gene exerts its effects on SMAD pathways, regulating hematopoiesis through effects on balancing proliferation and apoptosis cell inactivity, differentiation, and migration. Luspatercept (ACE-536) is a soluble fusion protein that inhibits molecules in the TGF-β superfamily. Since its structure resembles the TGF-β family receptor, it catches TGF-β superfamily ligands before binding to the receptor, resulting in reduced activation of SMAD signaling, thus enabling erythroid maturation. Luspatercept was investigated in the phase III trial MEDALIST, showing promising efficacy in treating anemia compared to placebo. Nowadays, further studies are needed to explore the real potential of luspatercept, investigating the biological features likely associated with treatment response, the potential use in combination treatments, and its role in the treatment of naïve MDS.

Unveiling the Genetic Footprint: Exploring Somatic Mutations in Peripheral Arterial Disease Progression

Peripheral arterial diseases (PADs) are complex cardiovascular conditions influenced by environmental factors and somatic mutations in multiple genes involved in hematopoiesis and inflammation. While traditional risk factors, such as smoking, hypercholesterolemia, and hypertension, have been extensively studied, the role of somatic mutations in PAD progression remains underexplored. The present article intends to provide a comprehensive commentary of the molecular mechanisms, genetic landscape, prognostic significance, and clinical implications of somatic mutations in PADs. The expansion of clonal hematopoiesis of indeterminate potential (CHIP) clones in the circulating blood, named clonal hematopoiesis (CH), leads to the infiltration of these clones into atherosclerotic plaques and the production of inflammatory cytokines, increasing the risk of cardiovascular diseases, including PADs. Furthermore, recent experimental evidence has demonstrated the involvement of somatically mutated TP53 genes with a high variant allele frequency (VAF) in PAD development and prognosis. This review delves into the relationship between CH and PADs, elucidating the prevalence, impact, and underlying mechanisms of this association. This understanding paves the way for novel therapeutic approaches targeting CHIP to promote tissue regeneration and improve outcomes in PAD patients. It emphasizes the need for further research to fully unravel the genetic footprint of the disease and highlights potential clinical implications. The findings presented in this article lay the foundation for personalized medicine approaches and open avenues for the development of targeted therapies based on somatic mutation profiling.

The Times, They Are A-Changing: The Impact of Next-Generation Sequencing on Diagnosis, Classification, and Prognostication of Myeloid Malignancies With Focus on Myelodysplastic Syndrome, AML, and Germline Predisposition

Myeloid malignancies are a manifestation of clonal expansion of hematopoietic cells driven by somatic genetic alterations that may arise in a potential background of deleterious germline variants. As next-generation sequencing technology has become more accessible, real-world experience has allowed integration of molecular genomic data with morphology, immunophenotype, and conventional cytogenetics to refine our understanding of myeloid malignancies. This has prompted revisions in the classification and the prognostication schema of myeloid malignancies and germline predisposition to hematologic malignancies. This review provides an overview of significant changes in the recently published classifications of AML and myelodysplastic syndrome, emerging prognostic scoring, and the role of germline deleterious variants in predisposing to MDS and AML.

How Great Is the Threat of Clonal Hematopoiesis? Let This New Risk Score Be Your Guide

The recent expanding compendium of sequencing analysis has offered insight into the pathobiology of myeloid neoplasms. This molecular evidence of clonal hematopoiesis provides information to allow earlier identification of predisposition states to myeloid neoplasms, such as clonal hematopoiesis of indeterminate potential (CHIP) and clonal cytopenia of unknown significance (CCUS). The ability to risk-stratify cases of clonal hematopoiesis that may evolve to frank myeloid neoplasms is essential to manage expectations for patients and providers alike.

A Lower Frequency of Spliceosome Mutations Distinguishes Clonal Cytopenias of Undetermined Significance From Low-Risk Myelodysplastic Syndromes, Despite Inherent Similarities in Genomic, Laboratory, and Clinical Features

Clonal cytopenias of undetermined significance (CCUS) are associated with an increased risk of developing a myelodysplastic syndrome (MDS); however, the mechanism and factors associated with evolution remain unclear. We propose that next-generation sequencing (NGS) of cytopenic cases with equivocal morphologic dysplasia will improve patient clinical care and that serial sequencing of such equivocal cases could identify the factors that predict evolution to MDS. We performed targeted NGS of samples from 193 individuals with confirmed or suspected MDS or MDS/myeloproliferative neoplasm, including sequential investigation for 28 individuals at the time of diagnosis and during follow-up. NGS facilitated the diagnosis of all suspicious cases as myeloid neoplasm (21%), CCUS (34%), or idiopathic cytopenias of undetermined significance (45%) when no variants were detected. We found that there was no significant difference in most measured clinical features or clonal phenotypes, such as cell counts, number of variants, variant allele frequencies, and overall survival, between CCUS and International Prognostic Scoring System-Revised-defined low-risk MDS. However, there was a significant difference in the types of variants between CCUS and low-risk MDS, with a significantly lower number of splicing factor mutations in CCUS cases (P < .001). Moreover, we observed an increased probability of evolution to MDS of individuals with CCUS compared with that in those with idiopathic cytopenias of undetermined significance over the first 5 years (P = .045). Our analyses revealed no conclusive pattern associating clonal expansion or the number of variants with the evolution of CCUS to MDS, perhaps further supporting the similarity of these diseases and the clinical importance of recognizing and formally defining CCUS as a category of precursor myeloid disease state in the next revision of the World Health Organization guidelines.

Comparison of the International Consensus and 5th WHO edition classifications of adult myelodysplastic syndromes and acute myeloid leukemia

Several editions of the World Health Organization (WHO) classifications of lympho-hemopoietic neoplasms in 2001, 2008, and 2016 served as the international standard for diagnosis. Since the 4th WHO edition, here referred as WHO-HAEM4, significant clinico-pathological, immunophenotypic, and molecular advances have been made in the field of myeloid neoplasms, which have contributed to refine diagnostic criteria, to upgrade entities previously defined as provisional and to identify new entities. This process has resulted in two recent classification proposals of myeloid neoplasms: the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, with a focus on adult myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukemia (AML). The goal is to provide a tool to facilitate the work of pathologists, hematologists and researchers involved in the diagnosis and treatment of these hematological malignancies.

The Secondary Myelodysplastic Neoplasms (MDS) Jigsaw

There is a great deal of controversy in the hematologic community regarding the classification of secondary myelodysplastic neoplasms (MDSs). Current classifications are based on the presence of genetic predisposition and MDS post-cytotoxic therapy (MDS-pCT) etiologies. However, since these risk factors are not exclusive for secondary MDSs and there are multiple overlapping scenarios, a comprehensive and definitive classification is yet to come. In addition, a sporadic MDS might arise after a primary tumor fulfills the diagnostic criteria of MDS-pCT without a causative cytotoxicity. In this review, we describe the triggering pieces of a secondary MDS jigsaw: previous cytotoxic therapy, germline predisposition and clonal hematopoiesis. Epidemiological and translational efforts are needed to put these pieces together and ascertain the real weight of each of these pieces in each MDS patient. Future classifications must contribute to understanding the role of secondary MDS jigsaw pieces in different concomitant or independent clinical scenarios associated with the primary tumor.

Human Immunodeficiency Virus and Clonal Hematopoiesis

The evolution of antiretroviral therapies (ART) has tremendously improved the life expectancy of people living with human immunodeficiency virus (HIV) (PLWH), which is currently similar to the general population. However, as PLWH are now living longer, they exhibit various comorbidities such as a higher risk of cardiovascular disease (CVD) and non-acquired immunodeficiency syndrome (AIDS)-defined malignancies. Clonal hematopoiesis (CH) is the acquisition of somatic mutations by the hematopoietic stem cells, rendering them survival and growth benefit, thus leading to their clonal dominance in the bone marrow. Recent epidemiologic studies have highlighted that PLWH have a higher prevalence of CH, which in turn is associated with increased CVD risk. Thus, a link between HIV infection and a higher risk for CVD might be explained through the induction of inflammatory signaling in the monocytes carrying CH mutations. Among the PLWH, CH is associated with an overall poorer control of HIV infection; an association that requires further mechanistic evaluation. Finally, CH is linked to an increased risk of progression to myeloid neoplasms including myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML), which are associated with particularly poor outcomes among patients with HIV infection. These bidirectional associations require further molecular-level understanding, highlighting the need for more preclinical and prospective clinical studies. This review summarizes the current literature on the association between CH and HIV infection.

Association between peripheral blood cytopenia and cancer mortality: A race-specific risk factor for cancer death

BACKGROUND

Cytopenia is associated with cancer through mechanisms including clonal hematopoiesis and chronic inflammation. Cytopenia is more prevalent in Black people but its relationship with racial disparities in cancer mortality is unknown.

METHODS

Cytopenia was defined in 19,028 Black and White participants recruited between 2003 and 2007 for the REasons for Geographic and Racial Differences in Stroke cohort, based on age-, sex-, and race-adjusted ranges for blood counts. Cancer death was ascertained from Social Security Death and National Death Indexes. Multivariable Cox models estimated the risk of cancer mortality associated with cytopenia, adjusting for demographics (model1), anemia and cancer risk factors (model2), and socioeconomics (model3). Racial differences in the cytopenia-cancer death association were tested by cross-product interaction terms.

RESULTS

Cytopenia was identified in 383 (2%) participants, 250 (65%) White, and 113 (35%) Black people. With median follow-up 11.3 years, 1,224 (6.4%) cancer deaths occurred. Cytopenia was associated with increased risk of cancer mortality in model1 (HR = 1.57, 95%CI 1.15-2.24), model2 (HR = 1.67, 95%CI 1.22-2.30), and model3 (HR = 1.59, 95%CI 1.17-2.17). Participants with cytopenia had twofold increased cumulative incidence of cancer death (13% vs. 6.5%, p < 0.01). Race by cytopenia interaction terms showed higher HR for cancer death in Black compared to White participants: 2.01 versus 1.41 (p_interaction  = 0.016, model1), 2.12 versus 1.45 (p_interaction  = 0.009, model2), and 1.82 versus 1.44 (p_interaction  = 0.04, model3).

CONCLUSION

In this large, observational biracial prospective study, cytopenia was a risk factor for cancer death, with stronger association in Black than White people. Though race impacted the association of cytopenia with cancer mortality, cytopenia was not a mediator of the racial disparity in cancer mortality.

Circulating tumor DNA in early-stage colon cancer: ready for prime time or needing refinement?

Liquid biopsies are the detection of molecular information in fluids from patients with cancer. In colorectal cancer (CRC), the most promising liquid biopsy strategy is the use of circulating tumor DNA (ctDNA) from plasma. In early-stage CRC, the potential for ctDNA to impact care stems from the detection of minimal residual disease (MRD) to guide adjuvant therapy after curative intent treatment and in identifying recurrences during surveillance. As for any new diagnostic test, ctDNA assays must overcome pre-analytical and analytical challenges before clinical implementation. We will discuss important logistical and assay considerations that clinicians and patients should understand when assessing ctDNA assays. We will also delve into important concepts to aid in interpreting ctDNA results and potential incidental findings that may arise. Sequencing errors, germline variants, and clonal hematopoiesis of indeterminate potential (CHIP) must be addressed to properly interpret results. CHIP is also an important consideration that impacts patient prognosis through association with cardiovascular and hematologic diseases. With this background in place, we next review the best available evidence for the use of ctDNA in early-stage colon cancer. Observational cohorts have established MRD after surgery as a significant prognostic factor for recurrence in stage II and III colon cancer. It also has the ability to anticipate clinical recurrence before standard investigations when used in surveillance. The first and only interventional randomized trial to date evaluating ctDNA is DYNAMIC. The study demonstrated the noninferiority of a MRD detection-guided approach in selecting patients with stage II colon cancer for adjuvant treatment. Notwithstanding the important results, there are still important questions to be answered before ctDNA enters prime time in the clinic. However, future appears bright and ongoing trials will help clarify how to best use this technology in early-stage colon cancer.

Myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a family of myeloid cancers with diverse genotypes and phenotypes characterized by ineffective haematopoiesis and risk of transformation to acute myeloid leukaemia (AML). Some epidemiological data indicate that MDS incidence is increasing in resource-rich regions but this is controversial. Most MDS cases are caused by randomly acquired somatic mutations. In some patients, the phenotype and/or genotype of MDS overlaps with that of bone marrow failure disorders such as aplastic anaemia, paroxysmal nocturnal haemoglobinuria (PNH) and AML. Prognostic systems, such as the revised International Prognostic Scoring System (IPSS-R), provide reasonably accurate predictions of survival at the population level. Therapeutic goals in individuals with lower-risk MDS include improving quality of life and minimizing erythrocyte and platelet transfusions. Therapeutic goals in people with higher-risk MDS include decreasing the risk of AML transformation and prolonging survival. Haematopoietic cell transplantation (HCT) can cure MDS, yet fewer than 10% of affected individuals receive this treatment. However, how, when and in which patients with HCT for MDS should be performed remains controversial, with some studies suggesting HCT is preferred in some individuals with higher-risk MDS. Advances in the understanding of MDS biology offer the prospect of new therapeutic approaches.

Navigating the contested borders between myelodysplastic syndrome and acute myeloid leukemia

Myelodysplastic syndrome and acute myeloid leukemia are heterogeneous myeloid neoplasms which arise from the accumulation of mutations in a myeloid stem cell or progenitor that confer survival or growth advantages. These disease processes are formally differentiated by clinical, laboratory, and morphological presentations, especially with regard to the preponderance of blasts in the peripheral blood or bone marrow (AML); however, they are closely associated through their shared lineage as well as their existence on a spectrum with some cases of MDS displaying increased blasts, a feature that reflects more AML-like behavior, and the propensity for MDS to transform into AML. It is increasingly recognized that the distinctions between these two entities result from the divergent patterns of genetic alterations that drive each of them. Mutations in genes related to chromatin-remodeling and the spliceosome are seen in both MDS and AML arising out of antecedent MDS, while mutations in genes related to signaling pathways such as RAS or FLT3 are more typically seen in AML or otherwise are a harbinger of transformation. In this review, we focus on the insights into the biological and genetic distinctions and similarities between MDS and AML that are now used to refine clinical prognostication, guide disease management, and to inform development of novel therapeutic approaches.

Clonal Hematopoiesis: Role in Hematologic and Non-Hematologic Malignancies

Hematopoietic stem cells (HSCs) ensure the coordinated and balanced production of all hematopoietic cell types throughout life. Aging is associated with a gradual decline of the self-renewal and regenerative potential of HSCs and with the development of clonal hematopoiesis. Clonal hematopoiesis of indeterminate potential (CHIP) defines the clonal expansion of genetically variant hematopoietic cells bearing one or more gene mutations and/or structural variants (such as copy number alterations). CHIP increases exponentially with age and is associated with cancers, including hematologic neoplasia, cardiovascular and other diseases. The presence of CHIP consistently increases the risk of hematologic malignancy, particularly in individuals who have CHIP in association with peripheral blood cytopenia.

Molecular Diagnostic Testing for Hematopoietic Neoplasms: Linking Pathogenic Drivers to Personalized Diagnosis

Molecular diagnostics inhabit an increasingly central role in characterizing hematopoietic malignancies. This brief review summarizes the genomic targets important for many major categories of hematopoietic neoplasia by focusing on disease pathogenesis. In myeloid disease, recurrent mutations in key functional classes drive clonal hematopoiesis, on which additional variants can specify clinical presentation and accelerate progression. Lymphoblastic leukemias are frequently initiated by oncogenic fusions that block lymphoid maturation while, in concert with additional mutations, driving proliferation. The links between genetic aberrations and lymphoma patient outcomes have been clarified substantially through the clustering of genomic profiles. Finally, the addition of next-generation sequencing strategies to cytogenetics is refining risk stratification for plasma cell myeloma. In all categories, molecular diagnostics shed light on the unique mechanistic underpinnings of each individual malignancy, thereby empowering more rational, personalized care for these patients.

Mechanisms shared between cancer, heart failure, and targeted anti-cancer therapies

Heart failure (HF) and cancer are the leading causes of death worldwide and accumulating evidence demonstrates that HF and cancer affect one another in a bidirectional way. Patients with HF are at increased risk for developing cancer, and HF is associated with accelerated tumour growth. The presence of malignancy may induce systemic metabolic, inflammatory, and microbial alterations resulting in impaired cardiac function. In addition to pathophysiologic mechanisms that are shared between cancer and HF, overlaps also exist between pathways required for normal cardiac physiology and for tumour growth. Therefore, these overlaps may also explain the increased risk for cardiotoxicity and HF as a result of targeted anti-cancer therapies. This review provides an overview of mechanisms involved in the bidirectional connection between HF and cancer, specifically focusing upon current 'hot-topics' in these shared mechanisms. It subsequently describes targeted anti-cancer therapies with cardiotoxic potential as a result of overlap between their anti-cancer targets and pathways required for normal cardiac function.

Therapy-related clonal cytopenia as a precursor to therapy-related myeloid neoplasms

Therapy-related myeloid neoplasms (t-MN) are aggressive leukemia that develops as a complication of prior exposure to DNA-damaging agents. Clonal cytopenia of undetermined significance (CCUS) is a precursor of de novo myeloid neoplasms. Characteristics of CCUS that develop following cytotoxic therapies (therapy-related clonal cytopenia, t-CC) and outcomes following t-CC have not been described. We identified 33 patients with t-CC and compared to a cohort of the WHO-defined t-MN (n = 309). t-CC had a distinct genetic and cytogenetic profile: pathogenic variants (PV) in TET2 and SRSF2 were enriched in t-CC, whereas TP53 PV was more common in t-MN. Ten (30%) t-CC patients developed a subsequent t-MN, with a cumulative incidence of 13%, 23%, and 50% at 6 months, 1, and 5 years, respectively. At t-MN progression, 44% of evaluable patients had identifiable clonal evolution. The median survival following t-CC was significantly superior compared all t-MN phenotype including t-MDS with <5% bone marrow blasts (124.5 vs. 16.3 months, P < 0.001) respectively. The presence of cytogenetic abnormality and the absence of variants in DNMT3A, TET2, or ASXL1 (DTA-genes) were associated with a higher likelihood of developing a subsequent t-MN and an inferior survival. We describe a putative precursor entity of t-MN with distinct features and outcomes.

Diagnosis of Myelodysplastic Syndromes: From Immunological Observations to Clinical Applications

Myelodysplastic syndromes (MDS) constitute a very heterogeneous group of diseases with a high prevalence in elderly patients and a propensity for progression to acute myeloid leukemia. The complexity of these hematopoietic malignancies is revealed by the multiple recurrent somatic mutations involved in MDS pathogenesis and the paradoxical common phenotype observed in these patients characterized by ineffective hematopoiesis and cytopenia. In the context of population aging, the incidence of MDS will strongly increase in the future. Thus, precise diagnosis and evaluation of the progression risk of these diseases are imperative to adapt the treatment. Dysregulations of both innate and adaptive immune systems are frequently detected in MDS patients, and their critical role in MDS pathogenesis is now commonly accepted. However, different immune dysregulations and/or dysfunctions can be dynamically observed during the course of the disease. Monitoring the immune system therefore represents a new attractive tool for a more precise characterization of MDS at diagnosis and for identifying patients who may benefit from immunotherapy. We review here the current knowledge of the critical role of immune dysfunctions in both MDS and MDS precursor conditions and discuss the opportunities offered by the detection of these dysregulations for patient stratification.

Clonal Hematopoiesis and Myeloid Neoplasms in the Context of Telomere Biology Disorders

Purpose of Review

Telomere biology disorders (TBDs) are cancer-predisposing multisystemic diseases that portend a higher risk of transforming into myeloid neoplasms (MNs). Due to the rarity and high variability of clinical presentations, TBD-specific characteristics of MN and the mechanisms behind this predisposition are not well defined. Herein, we review recent studies on TBD patient cohorts describing myeloid transformation events and summarize efforts to develop screening and treatment guidelines for these patients.

Recent Findings

Preliminary studies have indicated that TBD patients have a higher prevalence of somatic genetic alterations in hematopoietic cells, an age-related phenomenon, also known as clonal hematopoiesis; increasing predisposition to MN. The CH mutational landscape in TBD differs from that observed in non-TBD patients and preliminary data suggest a higher frequency of somatic mutations in the DNA repair mechanism pathway. Although initial studies did not observe specific features of MN in TBD patients, certain events are common in TBD, such as hypocellular bone marrows. The mechanisms of MN development need further elucidation.

Summary

Current management options for MN-TBD patients need to be individualized and tailored as per the clinical context. Because of the high sensitivity to alkylator chemotherapy and radiation conferred by short telomeres, non-cytotoxic targeted therapies and immunotherapy are ideal therapeutic options, but these therapies are still being tested in clinical trials. Defining the mechanisms of CH evolution in TBD and identifying risk factors leading to MN evolution will allow for the development of screening and treatment guidelines for these patients.

Morphologic, immunophenotypic, and molecular genetic comparison study in patients with clonal cytopenia of undetermined significance, myelodysplastic syndrome, and acute myeloid leukemia with myelodysplasia-related changes: A single institution experience

INTRODUCTION

Next-generation sequencing (NGS) analysis showed clonal cytopenia of undetermined significance (CCUS) as an immediate precursor to myelodysplastic syndrome (MDS).

METHODS

We evaluated and compared morphologic, multiparametric flow cytometry (MFC), and molecular genetic findings in patients with CCUS (n = 37), MDS (n = 75), and acute myeloid leukemia with myelodysplasia-related changes (AML-MRC, n = 24).

RESULTS

CCUS patients showed variable MFC abnormalities including >2% CD34+ myeloblasts (5.8%), altered antigen expression on myeloblasts, monocytes, and granulocytes (1.2, 1.5, and 0.2/case), abnormal maturation of myeloblasts (45.8%), decreased hematogones (17.6%), and decreased side scatter (SSC) of granulocytes (11.4%). CCUS patients with high-risk mutations showed significantly more MFC abnormalities. However, CCUS patients with >20% variant allelic fraction (VAF) did not show more MFC aberrations than the rest of the group. MDS patients showed significantly more MFC abnormalities compared with CCUS patients (p = 7.8E-05-0.047). Low-grade MDS patients showed significantly fewer MFC abnormalities compared with high-grade MDS or AML-MRC patients (p = 1.89E-05-0.04). AML-MRC patients showed significantly elevated blast counts, more antigen aberrations, decreased hematogones, and decreased SSC of granulocytes compared with CCUS patients (p = 2.0E-05-0.01). CCUS patients carried predominantly TET2/DNMT3A/ASXL1 mutations. They harbored fewer mutations in gene coding splicing factors compared with MDS patients (p = .0001-.02) and fewer mutations in tumor suppressor and transcription factor genes compared with AML-MRC patients (p = .0006-.02).

CONCLUSIONS

CCUS is an immediate precursor to low-grade MDS. The progression from CCUS to MDS to AML-MRC is a stepwise process that requires acquisition of mutations in splicing, transcription factor, and tumor suppressor genes with accumulations of additional MFC abnormalities.

Flow Cytometric Findings in Clonal Cytopenia of Undetermined Significance

OBJECTIVES

To examine flow cytometric (FCM) findings in clonal cytopenia of undetermined significance (CCUS) in relation to variant allele fraction (VAF) and mutation risk.

METHODS

Nine FCM parameters, including 5 FCM metrics (Meyerson-Alayed scoring scheme [MASS] parameters) we previously used to identify myelodysplastic syndromes (MDS), were compared among 96 CCUS samples, 100 low-grade MDS samples and 100 samples from patients without somatic alterations (controls).

RESULTS

FCM findings did not differ between CCUS samples with less than 20% VAF and controls. CCUS samples with more than 20% VAF (CCUS >20% VAF) demonstrated more than 1 abnormal FCM parameter at a frequency between MDS and controls. Abnormalities in CCUS with high-risk alterations (CCUS(hi)) were similar to MDS, with no statistical difference in the percentage of cases with more than 1 FCM abnormality or a positive MASS score. The positive predictive value (PPV) for clinically significant myeloid processes; MDS, CCUS(hi), and CCUS >20% VAF compared with other CCUS samples and controls was 94.8%, with 96.5% specificity and 61% sensitivity using a modified MASS score. A subset of MDS (43%) was distinguished from CCUS(hi) and CCUS >20% VAF using 3 parameters, with a 93.5% PPV and 83.3% specificity.

CONCLUSIONS

FCM abnormalities can distinguish high-risk CCUS based on VAF or alteration type from low-risk CCUS and MDS in many cases. The findings are of potential utility in the evaluation of patients with cytopenias.

CHIP: is clonal hematopoiesis a surrogate for aging and other disease?

Somatic mutations are an unavoidable consequence of aging tissues. Even though most mutations are functionally silent, some may affect genes critical to proper tissue self-renewal and differentiation, resulting in the outgrowth of affected cells, also known as clonal expansion. In hematopoietic tissue such clonal dominance is known as clonal hematopoiesis (CH). Sporadic CH is frequent in aging and affects over 10% of individuals beyond the fifth decade of life. It has been associated with an increased risk of hematologic malignancies and cardiovascular disease. In addition to aging, CH has been observed in other hematologic conditions and confers an adaptation of hematopoietic stem cells (HSCs) to various environmental stressors and cell-intrinsic defects. In the presence of extrinsic stressors such as genotoxic therapies, T-cell-mediated immune attack, or inflammation, somatic mutations may result in augmentation of HSC fitness. Such attuned HSCs can evade the environmental insults and outcompete their unadapted counterparts. Similarly, in inherited bone marrow failures, somatic mutations in HSCs frequently lead to the reversion of inherited defects. This may occur via the direct correction of germline mutations or indirect compensatory mechanisms. Occasionally, such adaptation may involve oncogenes or tumor suppressors, resulting in malignant transformation. In this brief article, we focus on the mechanisms of clonal dominance in various clinical and biological contexts.

Clonal cytogenetic abnormalities in donor-derived cells after sex mismatched allogeneic stem cell transplantation

Clonal cytogenetic abnormalities (CCA) in donor-derived cells after stem cell transplant (SCT) are typically reported in donor-derived cell neoplasms, but CCA also may reflect a constitutional abnormality in the donor or may be present in a recipient without overt hematological malignancy. We reviewed 8515 tests on 2035 patients, who had allogenic sex mismatched SCT and underwent serial cytogenetic analysis between 2006 and 2020 in our institution. A constitutional CCA was observed in 3 patients: inv(10), t(1;5), and t(13;14). A somatic CCA without overt neoplasia was detected in 12 patients: del(7q) (n = 6), del(20q) (n = 3), der(11)t(11;11) (n = 1), t(1;9) (n = 1), dup(6p)(n = 1). In this group, four patients with cytopenia had del(7q), and an association between del(7q) and an adverse overall survival (OS) was observed [HR:5.99; 95%CI 1.23-29.92). Four patients had a donor-derived cell neoplasm: myelodysplastic syndrome (n = 3) and acute myeloid leukemia (n = 1), and all four neoplasms had loss of 7q. In our cohort, ∼1% of the patients (19/2,035) had CCA in donor-derived cells. Balanced constitutional CCA can pose a reproductive risk to donor. Loss of 7q is the most common somatic CCA, in donor-derived cells.

Myelodysplastic syndromes: Biological and therapeutic consequences of the evolving molecular aberrations landscape

Myelodysplastic syndromes (MDS) are clonal hematopoietic disorders with heterogeneous presentation, ranging from indolent disease courses to aggressive diseases similar to acute myeloid leukemia (AML). Approximately 90% of MDS patients harbor recurrent mutations , which – with the exception of mutated SF3B1 –have not (yet) been included into the diagnostic criteria or risk stratification for MDS. Accumulating evidence suggests their utility for diagnostic workup, treatment indication and prognosis. Subsequently, in patients with unexplained cytopenia or dysplasia identification of these mutations may lead to earlier diagnosis. The acquisition and expansion of additional driver mutations usually antecedes further disease progression to higher risk MDS or secondary AML and thus, can be clinically helpful to detect individuals that may benefit from aggressive treatment approaches. Here, we review our current understanding of somatic gene mutations, gene expression patterns and flow cytometry regarding their relevance for disease evolution from pre-neoplastic states to MDS and potentially AML.

Clonal hematopoiesis and bone marrow failure syndromes

Bone marrow failure syndromes (BMF) are a group of conditions characterized by inefficient hematopoiesis frequently associated with extra-hematopoietic phenotypes and variable risk of progression to myeloid malignancies. They can be acquired or inherited and mediated by either cell extrinsic factors or cell intrinsic impairment of hematopoietic stem cell (HSC) function. The pathophysiology includes immune-mediated attack (e.g., acquired BMFs) or germline defects in DNA damage repair machinery, telomeres maintenance or ribosomes biogenesis. (e.g., inherited BMF). Clonal hematopoiesis (CH) that frequently accompanies BMF may provide a mechanism of improved HSC fitness through the evasion of extracellular pressure or somatic reversion of germline defects. The mechanism for the CH selective advantage differs depending on the condition in which it occurs. However, this adaptation mechanism, particularly when involving putative oncogenes or tumor suppressors, may lead to increased risk of myeloid malignancies. Surveillance and early detection of leukemogenic clones may lead to timely implementation of curative therapies and improved survival.

Chronic infection drives Dnmt3a-loss-of-function clonal hematopoiesis via IFNγ signaling

Age-related clonal hematopoiesis (CH) is a risk factor for malignancy, cardiovascular disease, and all-cause mortality. Somatic mutations in DNMT3A are drivers of CH, but decades may elapse between the acquisition of a mutation and CH, suggesting that environmental factors contribute to clonal expansion. We tested whether infection provides selective pressure favoring the expansion of Dnmt3a mutant hematopoietic stem cells (HSCs) in mouse chimeras. We created Dnmt3a-mosaic mice by transplanting Dnmt3a-/- and WT HSCs into WT mice and observed the substantial expansion of Dnmt3a-/- HSCs during chronic mycobacterial infection. Injection of recombinant IFNγ alone was sufficient to phenocopy CH by Dnmt3a-/- HSCs upon infection. Transcriptional and epigenetic profiling and functional studies indicate reduced differentiation associated with widespread methylation alterations, and reduced secondary stress-induced apoptosis accounts for Dnmt3a-/- clonal expansion during infection. DNMT3A mutant human HSCs similarly exhibit defective IFNγ-induced differentiation. We thus demonstrate that IFNγ signaling induced during chronic infection can drive DNMT3A-loss-of-function CH.

Innate immune pathways and inflammation in hematopoietic aging, clonal hematopoiesis, and MDS

With a growing aged population, there is an imminent need to develop new therapeutic strategies to ameliorate disorders of hematopoietic aging, including clonal hematopoiesis and myelodysplastic syndrome (MDS). Cell-intrinsic dysregulation of innate immune- and inflammatory-related pathways as well as systemic inflammation have been implicated in hematopoietic defects associated with aging, clonal hematopoiesis, and MDS. Here, we review and discuss the role of dysregulated innate immune and inflammatory signaling that contribute to the competitive advantage and clonal dominance of preleukemic and MDS-derived hematopoietic cells. We also propose how emerging concepts will further reveal critical biology and novel therapeutic opportunities.

Advances in therapeutic options for newly diagnosed, high-risk AML patients

Acute myeloid leukemia (AML) is an aggressive malignancy characterized by clonal proliferation of neoplastic immature precursor cells. AML impacts older adults and has a poor prognosis. Despite recent advances in treatment, AML is complex, with both genetic and epigenetic aberrations in the malignant clone and elaborate interactions with its microenvironment. We are now able to stratify patients on the basis of specific clinical and molecular features in order to optimize individual treatment strategies. However, our understanding of the complex nature of these molecular abnormalities continues to expand the defining characteristics of high-risk mutations. In this review, we focus on genetic and microenvironmental factors in adverse risk AML that play critical roles in leukemogenesis, including those not described in an European LeukemiaNet adverse risk group, and describe therapies that are currently in the clinical arena, either approved or under development.

Clonal haematopoiesis of indeterminate potential: intersections between inflammation, vascular disease and heart failure

Ageing is a major risk factor for the development of cardiovascular disease (CVD) and cancer. Whilst the cumulative effect of exposure to conventional cardiovascular risk factors is important, recent evidence highlights clonal haematopoiesis of indeterminant potential (CHIP) as a further key risk factor. CHIP reflects the accumulation of somatic, potentially pro-leukaemic gene mutations within haematopoietic stem cells over time. The most common mutations associated with CHIP and CVD occur in genes that also play central roles in the regulation of inflammation. While CHIP carriers have a low risk of haematological malignant transformation (<1% per year), their relative risk of mortality is increased by 40% and this reflects an excess of cardiovascular events. Evidence linking CHIP, inflammation and atherosclerotic disease has recently become better defined. However, there is a paucity of information about the role of CHIP in the development and progression of heart failure, particularly heart failure with preserved ejection fraction (HFpEF). While systemic inflammation plays a role in the pathophysiology of both heart failure with reduced and preserved ejection fraction (EF), it may be of greater relevance in the pathophysiology of HFpEF, which is also strongly associated with ageing. This review describes CHIP and its pathogenetic links with ageing, inflammation and CVD, while providing insight into its putative role in HFpEF.

Sex-Related Differences in Chronic Myeloid Neoplasms: From the Clinical Observation to the Underlying Biology

Chronic myeloid neoplasms are clonal diseases with variable clinical course and outcomes and despite the introduction of novel therapies, patients with high-risk disease continue to have overall poor outcomes. Different groups have highlighted that men have overall worse survival and higher incidence of transformation to acute leukemia compared to women across neoplasms such as myelodysplastic syndrome (MDS), myeloproliferative neoplasms (MPN), MDS/MPN overlap neoplasms, and CML. More recent studies evaluating the genomic profile of patients with these neoplasms demonstrated a male predominance for mutations in high-risk genes including ASXL1, U2AF1, SRSF2 and ZRSR2. The understanding of the underlying biology is limited but a number of hypotheses have been developed and are currently being investigated. This review summarizes the current knowledge about sex-related differences in the clinical outcomes and genomic profile of patients with chronic myeloid neoplasms and discusses the hypothesized biologic mechanisms as an attempt to explain these observations.

Prognostic Markers of Myelodysplastic Syndromes

Myelodysplastic syndrome (MDS) is a clonal disease characterized by multilineage dysplasia, peripheral blood cytopenias, and a high risk of transformation to acute myeloid leukemia. In theory, from clonal hematopoiesis of indeterminate potential to hematologic malignancies, there is a complex interplay between genetic and epigenetic factors, including miRNA. In practice, karyotype analysis assigns patients to different prognostic groups, and mutations are often associated with a particular disease phenotype. Among myeloproliferative disorders, secondary MDS is a group of special entities with a typical spectrum of genetic mutations and cytogenetic rearrangements resembling those in de novo MDS. This overview analyzes the present prognostic systems of MDS and the most recent efforts in the search for genetic and epigenetic markers for the diagnosis and prognosis of MDS.