Prediction of risk for myeloid malignancy in clonal hematopoiesis

Clonal hematopoiesis in patients with autoimmune thrombocytopenia: an international multicenter study

ABSTRACT

Diagnostic boundaries between immune thrombocytopenia (ITP) and other thrombocytopenic states, such as thrombocytopenic myelodysplastic syndromes, may be difficult to establish, and the detection of somatic mutations by next-generation sequencing (NGS) may be of aid. Here, we aimed at characterizing the prevalence and clinical significance of clonal hematopoiesis in ITP. In this multicentric retrospective observational study, we enrolled 167 adult patients with ITP, followed at 13 centers in Italy, United Kingdom, and the United States. Patients underwent NGS evaluation after a median of 3.6 years from ITP onset, and 83% had received at least 1 therapy line, for a median of 2 lines (range, 0-9); 51 of 167 patients (30%) had at least 1 mutation. After exclusion of germ line variants and polymorphisms, 31 of 167 (18.5%) were defined as having clonal hemopoiesis. Most commonly mutated genes were TET2, DNMT3A, SRSF2, and ASXL1 (median variant allele frequency, 29%); 19 of 31 patients (68%) had high-risk variants, and 8 had multiple mutations. Mutated patients were more frequently older males and showed a shorter time from first to second-line therapy, particularly with thrombopoietin receptor agonist (TPO-RA). Additionally, clonal hematopoiesis was associated with increased thrombotic risk (26% vs 8% in NGS-negative cases; P = .01), independently from TPO-RA exposure, though with an age effect. These data demonstrated the prevalence of clonal hematopoiesis in 18% of adult patients with ITP, which is associated with older age, relapsed/refractory disease, and high risk of thrombotic complications.

MDM2 inhibition is associated with the emergence of TP53-altered clonal hematopoiesis

Murine double minute 2 (MDM2) inhibitors have shown promising activity in TP53-wild type tumors and are under active investigation across a spectrum of malignancies. Herein, we report a 51-year-old female with MDM2-amplified, TP53-wild type adenoid cystic carcinoma who was treated with a MDM2 inhibitor and developed persistent pancytopenia despite drug discontinuation. Her pancytopenia was associated with 20 distinct pathogenic TP53 mutations in peripheral blood and bone marrow not present in drug-resistant tumor tissue. Plasma TP53 mutations were similarly detected among 4 other patients treated at our institution, with the number of mutations correlating strongly with duration of treatment. This case suggests that MDM2 inhibitors are associated with TP53 clonal hematopoiesis, which may confer a risk of subsequent myeloid malignancy. As multiple MDM2 inhibitor trials are ongoing, our findings underscore the need for further investigation into the potential long-term deleterious effects of these inhibitors in the hematopoietic stem and progenitor compartment.

Clonal Hematopoiesis of Indeterminate Potential and Cardiovascular Health

Clonal hematopoiesis of indeterminate potential (CHIP) is an age-related phenomenon in which somatic mutations lead to clonal expansion of hematopoietic stem cells without the development of hematologic abnormalities. A growing body of literature demonstrates an association between CHIP and cardiovascular disease. This pathophysiology demonstrates a novel connection between global inflammation and cardiovascular morbidity. While there is limited consensus addressing the cardiovascular care of these patients, risk factor optimization and disease surveillance are advisable. Investigation into possible therapies is ongoing and provides promise for the treatment of inflammation contributing to cardiovascular disease in patients with and without CHIP.

Genome sequencing in the management of myelodysplastic syndromes and related disorders

Myeloid neoplasms originate from the clonal proliferation of hematopoietic stem cells, which is driven by the acquisition of somatic genetic mutations. Within these disorders, myelodysplastic syndromes (MDS) are specifically characterized by morphological abnormalities (dysplasia) and impaired maturation of myeloid precursors (ineffective hematopoiesis), resulting in peripheral blood cytopenia. Several studies have advanced the field of MDS, with a few landmark papers leading to a paradigm shift, opening new avenues of research and enabling a molecular revolution. These seminal papers include the first description of the 5q- syndrome, the identification of somatic mutations of TET2 in myeloid neoplasms, the detection of common pathway mutations in the splicing machinery, and the discovery of clonal hematopoiesis. The somatic genomic landscape of MDS is now well defined. Genes that are recurrently mutated include epigenetic regulators, as well as genes of RNA splicing machinery, transcription regulation, DNA repair control, cohesin complex, and signal transduction. Furthermore, several disorders with a germline genetic predisposition to MDS have been identified, collectively accounting for up to 15% of all MDS cases. Genomic profiling can significantly improve the diagnostic approach to MDS, allowing the identification of distinct nosological entities such as SF3B1-mutant or TP53-mutant MDS. The Molecular International Prognostic Scoring System for MDS has already proven to be a valuable tool for individualized risk assessment and treatment decisions. In addition, the recently developed molecular taxonomy of MDS will likely facilitate the implementation of precision medicine approaches for these disorders. This will necessitate the establishment of specialized infrastructures within public health systems, involving close collaboration between healthcare institutions, academia, and the life-sciences industry.

Clonal Hematopoiesis Is Associated With Adverse Clinical Outcomes and Left Ventricular Remodeling in Aortic Stenosis

Background

Clonal hematopoiesis of indeterminate potential (CHIP) has been linked to intensified systemic inflammation and represents a novel risk factor for atherosclerotic cardiovascular diseases, including aortic stenosis (AS).

Objectives

This study aimed to assess the clinical impact of CHIP in a cohort of severe AS patients undergoing transcatheter aortic valve implantation (TAVI).

Methods

We enrolled 110 severe AS patients in this retrospective study. Targeted next-generation sequencing was employed to detect somatic mutations with a variant allele frequency >2% in 16 genes most frequently associated with CHIP. Correlative analyses on clinical, laboratory, and echocardiographic parameters were also performed. The primary endpoint was post-TAVI heart failure hospitalization. Multivariate Cox regression model was used to account for confounding effects of relevant clinical factors.

Results

CHIP was detected in 40 (36.4%) patients in our cohort. The most commonly mutated genes were DNMT3A, TET2, and ASXL1. With a median follow-up of 55.2 months, patients carrying CHIP had a significantly higher heart failure hospitalization rate (adjusted HR: 3.060; 95% CI: 1.090-8.589; P = 0.034) than those without CHIP. Additionally, patients harboring CHIP had higher serum ferritin levels, as well as echocardiographic evidence of left ventricular hypertrophy and diastolic dysfunction.

Conclusions

Our study supports the adverse clinical impact of CHIP in AS patients undergoing TAVI, which could be attributed to systemic inflammation and maladaptive LV remodeling. Prospective trials are anticipated to validate our findings and provide further evidence that CHIP holds the potential of being an actionable therapeutic target in AS.

CHIP away at the marrow-clot connection: inflammation, clonal hematopoiesis, and thromboembolic disease

ABSTRACT

Both the incidence and prognosis of arterial atherothrombosis and venous thromboembolism are strongly correlated with increasing age. Over the past decade, clonal hematopoiesis of indeterminate potential (CHIP) has been identified as a novel biomarker for cardiovascular disease. Driven by somatic mutations in the hematopoietic system, the epidemiology of CHIP is highly age dependent: among individuals aged ≥70 years in the general population, estimated prevalence of CHIP exceeds 10%. Several additional risk factors for CHIP have emerged in recent years, including smoking, receipt of anticancer therapy, and germ line predispositions. CHIP carriers consistently have higher risk of incident arterial atherothrombosis, even after accounting for traditional cardiovascular risk factors. However, the magnitude of this association varies across studies. In addition, individuals with established cardiovascular disease and CHIP have higher risks of recurrence and all-cause mortality than their non-CHIP counterparts. An association between CHIP carriership and incident venous thromboembolism has recently been made, although additional studies are needed to confirm this finding. No approved therapy exists to modify the cardiovascular risk among CHIP carriers. However, canakinumab showed promise in a post-hoc analyses of patients with TET2-mutated CHIP, and other anti-inflammasome agents are actively under development or evaluation. In this review, we provide an overview of CHIP as a mediator of thromboembolic diseases and discuss emerging therapeutics aimed at intervening on this thrombo-inflammatory nexus.

Clonal Hematopoiesis in Women With Breast Cancer

PURPOSE

Clonal hematopoiesis (CH) has been associated with a variety of adverse outcomes, most notably hematologic malignancy and ischemic cardiovascular disease. A series of recent studies also suggest that CH may play a role in the outcomes of patients with solid tumors, including breast cancer. Here, we review the clinical and biological data that underlie potential connections between CH, inflammation, and breast cancer, with a focus on the prevalence and impact of clonal hematopoiesis of indeterminate potential in patients with breast cancer.

METHODS

We summarize data from multiple studies, including a series of cohorts of patients with breast cancer, to assess the prevalence of CH, the relationship between CH and exposure to cytotoxic therapy, and the correlation between CH and breast cancer-specific outcomes.

RESULTS

Our findings indicate that CH is prevalent among patients with breast cancer, particularly those treated with cytotoxic therapies. However, there are no definitive data to support an association between the presence of CH and breast cancer-specific outcomes.

CONCLUSION

Current data do not support routine CH testing in patients with breast cancer, nor should the presence of CH influence decisions regarding breast cancer therapy in most patients. However, larger, long-term studies are necessary to further define the implications of CH in patients with breast cancer and guide clinical decision making.

Correlates and Consequences of Clonal Hematopoiesis Expansion Rate: A 15-Year Longitudinal Study of 6,986 Women

Clonal hematopoiesis of indeterminate potential (CHIP) is associated with increased mortality and malignancy risk, yet the determinants of clonal expansion remain poorly understood. We performed sequencing at >4,000x depth of coverage for CHIP mutations in 6,986 postmenopausal women from the Women's Health Initiative at two timepoints approximately 15 years apart. Among 3,685 mutations detected at baseline (VAF ≥ 0.5%), 50% progressed to CHIP (VAF ≥ 2%) at follow-up. We confirmed that clonal expansion is highly dependent on initial clone size and CHIP driver gene, with SF3B1 and JAK2 mutations exhibiting the fastest growth rate. We identified germline variants in TERT , IL6R , TCL1A , and MSI2 that modulate clonal expansion rate. Measured baseline leukocyte telomere length showed differential effects on incident CHIP risk, with shorter baseline leukocyte telomere length predisposing to incident PPM1D mutations and longer baseline leukocyte telomere length favoring incident DNMT3A mutations. We discovered that the IL6R missense variant p.Asp358Ala specifically impairs TET2 clonal expansion, supported by direct measurements of soluble interleukin-6 receptor and interleukin-6. Faster clonal growth rate was associated with increased risk of cytopenia, leukemia, and all-cause mortality. Notably, CHIP clonal expansion rate mediated 34.4% and 43.7% of the Clonal Hematopoiesis Risk Score's predictive value for leukemia and all-cause mortality, respectively. These findings reveal key biological determinants of CHIP progression and suggest that incorporating growth rate measurements could enhance risk stratification.

Clonal Hematopoiesis of Indeterminate Potential in Crohn's Disease and Ulcerative Colitis

BACKGROUND

Clonal hematopoiesis of indeterminate potential (CHIP) is the presence of somatic mutations in myeloid and lymphoid malignancy genes in the blood cells of individuals without a hematologic malignancy. Inflammation is hypothesized to be a key mediator in the progression of CHIP to hematologic malignancy and patients with CHIP have a high prevalence of inflammatory diseases. This study aimed to identify the prevalence and characteristics of CHIP in patients with inflammatory bowel disease (IBD).

METHODS

We analyzed whole-exome sequencing data from 587 Crohn's disease (CD), 441 ulcerative colitis (UC), and 293 non-IBD controls to assess CHIP prevalence and used logistic regression to study associations with clinical outcomes.

RESULTS

Older UC patients (age > 45) harbored increased myeloid-CHIP mutations compared to younger patients (age ≤ 45) (P = .01). Lymphoid-CHIP was more prevalent in older IBD patients (P = .007). Young CD patients were found to have myeloid-CHIP with high-risk features. Inflammatory bowel disease patients with CHIP exhibited unique mutational profiles compared to controls. Steroid use was associated with increased CHIP (P = .05), while anti-TNF therapy was associated with decreased myeloid-CHIP (P = .03). Pathway enrichment analyses indicated an overlap between CHIP genes, IBD phenotypes, and inflammatory pathways.

CONCLUSIONS

Our findings underscore a connection between IBD and CHIP pathophysiology. Patients with IBD and CHIP had unique risk profiles, especially among older UC patients and younger CD patients. These findings suggest distinct evolutionary pathways for CHIP in IBD and necessitate awareness among IBD providers and hematologists to identify patients potentially at risk for CHIP-related complications including malignancy, cardiovascular disease, and acceleration of their inflammatory disease.

Genetic and environmental risks for clonal hematopoiesis and cancer

Somatic variants accumulate in all organs with age, with a positive selection of clonal populations that provide a fitness advantage during times of heightened cellular stress leading to clonal expansion. Easily measured within the hematopoietic compartment, clonal hematopoiesis (CH) is now recognized as a common process in which hematopoietic clones with somatic variants associated with hematopoietic neoplasms exist within the blood or bone marrow of individuals without evidence of malignancy. Most cases of CH involve a limited number of genes, most commonly DNMT3A, TET2, and ASXL1. CH confers risk for solid and hematopoietic malignancies as well as cardiovascular and numerous inflammatory diseases and offers opportunities for cancer prevention. Here, we explore the genetic and environmental factors that predispose individuals to CH with unique variant signatures and discuss how CH drives cancer progression with the goals of improving individual cancer risk stratification, identifying key intervention opportunities, and understanding how CH impacts therapeutic strategies and outcomes.

Can molecular patterns help to classify overlapping entities in myeloid neoplasms?

Myeloid neoplasms include myeloproliferative and myelodysplastic neoplasms and acute myeloid leukaemia. Historically, these diseases have been diagnosed based on clinicopathological features with sometimes arbitrary thresholds that have persisted even as molecular features were gradually incorporated into their classification. As such, although current diagnostic approaches can classify the majority of myeloid neoplasms accurately using a combination of molecular and clinicopathological features, some areas of overlap persist and occasionally pose diagnostic challenges. These include overlap across BCR::ABL1-negative myeloproliferative neoplasms; between clonal cytopenia of undetermined significance and myelodysplastic neoplasms; myelodysplastic/myeloproliferative neoplasms; and, detection of KIT mutations in myeloid neoplasms other than mastocytosis, raising the prospect of systemic mastocytosis. Molecular testing has become state of the art in the diagnostic work-up of myeloid neoplasms, and molecular patterns can inherently help to classify overlapping entities if considered within a framework of haematological presentations. For future development, molecular testing will likely include whole genome and transcriptome sequencing, and primarily molecular classifications of myeloid neoplasms have already been suggested. As such, genetically defined groups should still constitute the basis for our understanding of disease development from early onset to progression, while clinicopathological features could then be used to describe the stage of the disease rather than the specific type of myeloid neoplasm.

Predicting therapy-related myeloid neoplasms after CAR-T with the Clonal Haematopoiesis Risk Score (CHRS)

The clonal haematopoiesis risk score (CHRS) was proposed to predict the rate of progression from clonal haemopoiesis of indeterminate potential (CHIP)/clonal cytopenia with unknown significance (CCUS) to myeloid neoplasms in the general population. CHRS encompasses the type and VAF of the mutation, the presence of a single DNMT3A mutation, cytopenia, age, red cell distribution width (RDW) and mean corpuscular volume (MCV). We studied clonal haematopoiesis in a cohort of 55 consecutive patients treated with CD19-directed CAR-T cells: CHIP and CCUS were present in 7% and 33% of patients before CAR-T. Three therapy-related myeloid neoplasms (t-MN) were observed after treatment with CAR-T (2 MDS and 1 AML). Only patients with an intermediate-high baseline CHRS developed a t-MN. Patients with an intermediate-high CHRS had more than a twofold increased risk of developing a t-MN within the first 9 months after CAR-T (odds ratio 2.89, 95% C.I. 1.98-4.19, p < 0.001). Overall, CHRS was able to predict the occurrence of t-MN after CAR-T with good specificity.

Future directions in myelodysplastic syndromes/neoplasms and acute myeloid leukaemia classification: from blast counts to biology

Myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukaemia (AML) are neoplastic haematopoietic cell proliferations that are diagnosed and classified based on a combination of morphological, clinical and genetic features. Specifically, the percentage of myeloblasts in the blood and bone marrow is a key feature that has historically separated MDS from AML and, together with several other morphological parameters, defines distinct disease entities within MDS. Both MDS and AML have recurrent genetic abnormalities that are increasingly influencing their definitions and subclassification. For example, in 2022, two new MDS entities were recognised based on the presence of SF3B1 mutation or bi-allelic TP53 abnormalities. Genomic information is more objective and reproducible than morphological analyses, which are subject to interobserver variability and arbitrary numeric cut-offs. Nevertheless, the integration of genomic data with traditional morphological features in myeloid neoplasm classification has proved challenging by virtue of its sheer complexity; gene expression and methylation profiling also can provide information regarding disease pathogenesis, adding to the complexity. New machine-learning technologies have the potential to effectively integrate multiple diagnostic modalities and improve on historical classification systems. Going forward, the application of machine learning and advanced statistical methods to large patient cohorts can refine future classifications by advancing unbiased and robust previously unrecognised disease subgroups. Future classifications will probably incorporate these newer technologies and higher-level analyses that emphasise genomic disease entities over traditional morphologically defined entities, thus promoting more accurate diagnosis and patient risk stratification.

Clonal haemopoiesis and venous thromboembolism risk

Many cases of venous thromboembolism (VTE) are idiopathic and clonal haemopoiesis, a risk factor for atherosclerotic vascular disease, may be a contributing factor to VTE. The report by Englisch and colleagues suggests that clonal haemopoiesis is a risk factor for recurrent VTE, especially in people without identifiable thrombotic predisposition. Commentary on: Englisch et al. Association of clonal hematopoiesis with recurrent venous thromboembolism: A case-control study. Br J Haematol 2025; 206:263-271.

Understanding Human Oncogene Function and Cooperativity in Myeloid Malignancy Using iPSCs

Myeloid malignancies are a spectrum of clonal disorders driven by genetic alterations that cooperatively confer aberrant self-renewal and differentiation of hematopoietic stem and progenitor cells (HSPCs). Induced pluripotent stem cells (iPSCs) can be differentiated into HSPCs and have been widely explored for modeling hematologic disorders and cell therapies. More recently, iPSCs models have been applied to study the origins and pathophysiology of myeloid malignancies, motivated by the appreciation for the differences in human oncogene function and the need for genetically defined models that recapitulate leukemia development. In this review, we will provide a broad overview of the rationale, the challenges, practical aspects, history, and recent advances of iPSC models for modeling myeloid neoplasms. We will focus on the insights into the previously unknown aspects of human oncogene function and cooperativity gained through the use of these models. It is now safe to say that iPSC models are a mainstay of leukemia modeling "toolbox" alongside primary human cells from normal and patient sources.

Myeloid clonal hematopoiesis of indeterminate potential in patients with chronic lymphocytic leukemia

ABSTRACT

Clonal hematopoiesis of indeterminate potential (CHIP) in patients with chronic lymphocytic leukemia (CLL) has not been extensively characterized. The objective of this study was to describe the prevalence of myeloid CHIP (M-CHIP) in patients with CLL, and to determine its association with time to first treatment (TTFT) and overall survival (OS). We retrospectively analyzed data from patients participating in a prospective CLL database at the Dana-Farber Cancer Institute who had standard-of-care targeted 95-gene next-generation sequencing (NGS) performed. A schema was devised to classify mutations as M-CHIP related. M-CHIP was analyzed as a binary (present/absent) and categorical (≥2 vs 1 vs 0 mutations) predictor. We included 966 patients (median age at time of NGS, 65 years; 38% female). Overall, 747 (77%) patients had NGS performed before CLL treatment, whereas 219 (23%) had it performed after receiving treatment. Median follow-up time from NGS was 1.9 years. The prevalence of M-CHIP in untreated (12%) and treated (24%) patients with CLL was similar to that described in previous literature. M-CHIP prevalence appeared to increase with age in untreated patients, but appeared consistent across age in treated patients, suggesting that treatment (85% had prior chemotherapy) may have an impact on M-CHIP emergence even in younger patients. The presence of ≥2 M-CHIP mutations was associated with OS, even accounting for prior treatment and age, but was driven by a small subset of patients (n = 28). M-CHIP was not associated with TTFT. These findings support continued work into characterizing the effects of M-CHIP in patients with CLL.

Implications of Clonal Hematopoiesis in Hematological and Non-Hematological Disorders

Clonal hematopoiesis (CH) is associated with an increased risk of developing myeloid neoplasms (MNs) such as myelodysplastic neoplasm (MDS) and acute myeloid leukemia (AML). In general, CH comprises clonal hematopoiesis of indeterminate potential (CHIP) and clonal cytopenia of undetermined significance (CCUS). It is an age-related phenomenon characterized by the presence of somatic mutations in hematopoietic stem cells (HSCs) and hematopoietic stem and progenitor cells (HSPCs) that acquire a fitness advantage under selection pressure. Individuals with CHIP have an absolute risk of 0.5-1.0% per year for progressing to MDS or AML. Inflammation, smoking, cytotoxic therapy, and radiation can promote the process of clonal expansion and leukemic transformation. Of note, exposure to chemotherapy or radiation for patients with solid tumors or lymphomas can increase the risk of therapy-related MN. Beyond hematological malignancies, CH also serves as an independent risk factor for heart disease, stroke, chronic obstructive pulmonary disease, and chronic kidney disease. Prognostic models such as the CH risk score and MN-prediction models can provide a framework for risk stratification and clinical management of CHIP/CCUS and identify high-risk individuals who may benefit from close surveillance. For CH or related disorders, therapeutic strategies targeting specific CH-associated mutations and specific selection pressure may have a potential role in the future.

Molecular profiling in MPN: who should have it and why?

Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs) are a group of blood cancers that result from somatic mutations in hematopoietic stem cells, causing constitutive activation of JAK-STAT signaling pathways with consequent overproduction of 1 or more myeloid lineages. The initiating event in MPN pathogenesis is a genetic mutation, and consequently molecular profiling is central to the diagnosis, risk stratification, and, increasingly, monitoring of therapy response in persons with MPN. In this review we summarize current approaches to molecular profiling of classical MPNs (essential thrombocythemia, polycythemia vera, and myelofibrosis), using illustrative clinical case histories to demonstrate how genetic analysis is already fully integrated into MPN diagnostic classification and prognostic risk stratification. Molecular profiling can also be used in MPN to measure response to therapy both in clinical trials and increasingly in routine clinical practice. Taking a forward look, we discuss how molecular profiling in MPN might be used in the future to select specific molecularly targeted therapies and the role of additional genetic methodologies beyond mutation analysis.

Contemporary Approach to the Diagnosis and Classification of Myelodysplastic Neoplasms/Syndromes-Recommendations From the International Consortium for Myelodysplastic Neoplasms/Syndromes (MDS [icMDS])

Myelodysplastic neoplasms/syndromes (MDS) are a heterogeneous group of biologically distinct entities characterized by variable degrees of ineffective hematopoiesis. Recently, 2 classification systems (the 5th edition of the World Health Organization Classification of Haematolymphoid tTumours and the International Consensus Classification) further subcharacterized MDS into morphologically and genetically defined groups. Accurate diagnosis and subclassification of MDS require a multistep systemic approach. The International Consortium for MDS (icMDS) summarizes a contemporary, practical, and multimodal approach to MDS diagnosis and classification.

Therapy-related myelodysplastic syndromes and acute myeloid leukemia

Progress always comes at a price: the field of oncology has seen unprecedented progress in treatment options recently for many solid and hematologic cancers. Unfortunately, these long-term survivors of prior cancer and cytotoxic therapy exposure are at higher risk of therapy-related myelodysplastic syndromes/acute myeloid leukemia (t-MDS/AML.) T-MDS/AML is a myeloid malignancy which occur after exposure to chemotherapy or radiation therapy for unrelated malignancy. T-MDS/AML is associated with adverse cytogenomic features and poor prognosis. While advances in the field of clonal hematopoiesis and germline variants has unraveled the molecular underpinnings of t-MDS/AML, we have miles to go in terms of t-MDS/AML directed therapy and improvement in outcomes. In this review, we discuss the epidemiology of t-MDS/AML, clinical and biological insights, evolution of t-MDS/AML and available treatment options.

Inflammation in myelodysplastic syndrome pathogenesis

Inflammation is a key driver of the progression of preleukemic myeloid conditions, such as clonal hematopoiesis of indeterminate potential (CHIP) and clonal cytopenia of undetermined significance (CCUS), to myelodysplastic syndromes (MDS). Inflammation is a critical mediator in the complex interplay of the genetic, epigenetic, and microenvironmental factors contributing to clonal evolution. Under inflammatory conditions, somatic mutations in TET2, DNMT3A, and ASXL1, the most frequently mutated genes in CHIP and CCUS, induce a competitive advantage to hematopoietic stem and progenitor cells, which leads to their clonal expansion in the bone marrow. Chronic inflammation also drives metabolic reprogramming and immune system deregulation, further promoting the expansion of malignant clones. This review underscores the urgent need to fully elucidate the role of inflammation in MDS initiation and highlights the potential of the therapeutical targeting of inflammatory pathways as an early intervention in MDS.

The prognostic effect of blast count in TP53 mutant myeloid neoplasms -the Minnesota experience

In 2022, the World Health Organization (WHO) and International Consensus Classification (ICC) recognized TP53 as an entity-defining alteration in myeloid neoplasms, yet with differing criteria that could lead to discrepant diagnoses and affect clinical trial eligibility. We studied 67 patients with TP53 mutant myeloid neoplasms, reclassifying them using both criteria. While most cases fulfill the criteria for TP53 mutant defined entities, most discrepancies were found in cases with ≥20% blasts. Patients were stratified into three groups based on blast count (<10%, 10-19%, and ≥20%) which revealed comparable clinicopathologic features, genetic characteristics, and outcomes. Notably, patients with ≥10% blasts had shorter overall survival compared to those with <10% blasts (8.1 vs. 12.4 months; p = 0.03). This study is among the few to examine TP53 mutant myeloid neoplasms as a single entity and suggests that the 10% blast count threshold could serve as a gateway to a more harmonized classification for these patients.

Detection and Interpretation of Clonal Hematopoiesis Variants during Routine Solid Tumor Next-Generation Sequencing: A Single-Institution Experience

Clonal hematopoiesis (CH) and clonal cytopenia of undetermined significance (CCUS) are recently recognized diagnostic entities that serve as independent risk factors for cardiovascular disease and myeloid malignancy. CH is an incidental finding, and evaluation of the incidence of CH/CCUS-associated mutations in solid tumor next-generation sequencing samples was undertaken to better understand the prevalence of mutations in this population. A retrospective review of clinical sequencing data for solid tumor malignancies diagnosed between February 2022 and April 2023 on next-generation sequencing data was performed. Cases were reviewed for variants in genes associated with CH/CCUS. Variant allele frequencies and other factors of the sequencing data were assessed for determining risk of CH/CCUS. A total of 2479 cases were evaluated during the study period. Of these, 29 cases demonstrated potential CH/CCUS-associated mutations, with a total of 33 variants identified. These were identified in a variety of tumor types, with gliomas being the most common. Significant cardiac histories were found in over half of cases identified, and few cases had abnormal blood counts. Detailed criteria for flagging variants as suspicious for CH and recommendations for these criteria as future guidelines for reporting are described. These variants are incidental findings that require more extensive follow-up or change in therapy management using a single institutional cohort.

Clonal Hematopoiesis in Chronic Thromboembolic Pulmonary Hypertension

BACKGROUND

The cause of chronic thromboembolic pulmonary hypertension (CTEPH) remains largely unknown. Recently, clonal hematopoiesis (CH) has been reported to be associated with cardiovascular and thromboembolic diseases. Here, we investigated the prevalence and clinical impact of CH in patients with CTEPH.

METHODS AND RESULTS

Whole-exome sequencing and deep-panel sequencing were performed in 214 patients with CTEPH. Clinical data before and after treatment were compared between patients with and without CH. RNA sequencing and serum analysis were performed to explore the pathogenesis that CH contributes to CTEPH. Among the enrolled patients, 20.1%, notably 44.4% who were 80 to 89 years old, had variants in CH-associated genes. In regard to clinical impact, B-type natriuretic peptide levels and home oxygen therapy rate were significantly higher, and 6-minute walk distance was significantly shorter after treatment in patients with CH than in those without CH. Moreover, novel clot reformation in the pulmonary artery despite the use of anticoagulants and additional angioplasty events after treatment completion were more frequent in patients with CH. RNA sequencing analysis revealed that blood coagulation and neutrophil extracellular trap formation pathways were enriched in patients with CH. Additionally, serum citrullinated histone H3 levels were higher in patients with CH than those without CH. These results were consistent in the subgroup of patients who did not have the history of hematological disorders.

CONCLUSIONS

The findings in this study raise the possibility that CH will induce a more prothrombotic state through neutrophil activation and neutrophil extracellular trap formation, contributing to pathogenesis and poor treatment response in patients with CTEPH.

Inflammatory Mesenchymal Stromal Cells and IFN-responsive T cells are key mediators of human bone marrow niche remodeling in CHIP and MDS

Somatic mutations in hematopoietic stem/progenitor cells (HSPCs) can lead to clonal hematopoiesis of indeterminate potential (CHIP), potentially progressing to myelodysplastic syndromes (MDS). Here, we investigated how CHIP and MDS remodel the human bone marrow (BM) niche relative to healthy elderly donors, using single cell and anatomical analyses in a large BM cohort. We found distinct inflammatory remodeling of the BM in CHIP and MDS. Furthermore, the stromal compartment progressively lost its HSPC-supportive adipogenic CXCL12-abundant reticular cells while an inflammatory mesenchymal stroma cell (iMSCs) population emerged in CHIP, which expanded in MDS. iMSCs exhibited distinct functional signatures in CHIP and MDS, retaining residual HSPC-support and angiogenic activity in MDS, corresponding with an increase in microvasculature in the MDS niche. Additionally, an IFN-responsive T cell population was linked to fueling inflammation in the stroma. Overall, these findings open new avenues for early intervention in hematological malignancies.

Mitochondrial heteroplasmy improves risk prediction for myeloid neoplasms

Clonal hematopoiesis of indeterminate potential is the primary pathogenic risk factor for myeloid neoplasms, while heteroplasmy (mutations in a subset of cellular mitochondrial DNA) is another marker of clonal expansion associated with hematological malignancies. We explore how these two markers relate and influence myeloid neoplasms incidence, and their role in risk stratification. We find that heteroplasmy is more common in individuals with clonal hematopoiesis of indeterminate potential, particularly those with higher variant allele fractions, multiple mutations, or spliceosome machinery mutations. Individuals with both markers have a higher risk of myeloid neoplasms than those with either alone. Furthermore, heteroplasmic variants with higher predicted deleteriousness increase the risk of myeloid neoplasms. Incorporating heteroplasmy in an existing risk score model for individuals with clonal hematopoiesis of indeterminate potential significantly improves sensitivity and better identifies high-risk groups. This suggests heteroplasmy as a clonal expansion marker and potentially as a biomarker for myeloid neoplasms development.

JAK2-mutant clonal hematopoiesis is associated with venous thromboembolism

ABSTRACT

Venous thromboembolism (VTE) is common among older individuals, but provoking factors are not identified in many cases. Patients with myeloid malignancies, especially myeloproliferative neoplasms (MPNs), are at increased risk for venous thrombosis. Clonal hematopoiesis of indeterminate potential (CHIP), a precursor state to myeloid malignancies, is common among older individuals and may similarly predispose to venous thrombosis. We evaluated overall and genotype-specific associations between CHIP and prevalent and incident VTE in >400 000 samples from the UK Biobank. CHIP was modestly associated with incident VTE with a hazard ratio (HR) of 1.17 (95% confidence interval [CI], 1.09-1.3; P = .002) but was not significantly associated with prevalent VTE with an odds ratio (OR) of 1.02 (95% CI, 0.81-1.23; P = .81). TET2-mutant CHIP was associated with incident VTE with a HR of 1.33 (95% CI, 1.05-1.69; P = .02). JAK2 mutations were highly associated with both prevalent and incident VTE risk, with an OR of 6.58 (95% CI, 2.65-16.29; P = 4.7 × 10-5) and a HR of 4.2 (95% CI, 2.18-8.08; P = 1.7 × 10-5), respectively, consistent with the thrombophilia associated with JAK2-mutant MPN. The association between JAK2-mutant CHIP and VTE remained significant after excluding potential undiagnosed MPN based on laboratory parameters. JAK2-mutant CHIP was more strongly associated with VTE but was less common than heterozygous factor V Leiden and heterozygous prothrombin gene mutation. These results indicate that most individuals with CHIP do not have an altered risk of thrombosis, but individuals with JAK2-mutant CHIP have a significantly elevated risk of VTE.

Risk prediction for clonal cytopenia: multicenter real-world evidence

ABSTRACT

Clonal cytopenia of undetermined significance (CCUS) represents a distinct disease entity characterized by myeloid-related somatic mutations with a variant allele fraction of ≥2% in individuals with unexplained cytopenia(s) but without a myeloid neoplasm (MN). Notably, CCUS carries a risk of progressing to MN, particularly in cases featuring high-risk mutations. Understanding CCUS requires dedicated studies to elucidate its risk factors and natural history. Our analysis of 357 patients with CCUS investigated the interplay between clonality, cytopenia, and prognosis. Multivariate analysis identified 3 key adverse prognostic factors: the presence of splicing mutation(s) (score = 2 points), platelet count of <100 × 109/L (score = 2.5), and ≥2 mutations (score = 3). Variable scores were based on the coefficients from the Cox proportional hazards model. This led to the development of the clonal cytopenia risk score (CCRS), which stratified patients into low- (score of <2.5 points), intermediate- (score of 2.5 to <5), and high-risk (score of ≥5) groups. The CCRS effectively predicted 2-year cumulative incidence of MN for low- (6.4%), intermediate- (14.1%), and high-risk (37.2%) groups, respectively, by the Gray test (P < .0001). We further validated the CCRS by applying it to an independent CCUS cohort of 104 patients, demonstrating a c-index of 0.64 (P = .005) in stratifying the cumulative incidence of MN. Our study underscores the importance of integrating clinical and molecular data to assess the risk of CCUS progression, making the CCRS a valuable tool that is practical and easily calculable. These findings are clinically relevant, shaping the management strategies for CCUS and informing future clinical trial designs.

TP53 mutations in myeloid neoplasms: implications for accurate laboratory detection, diagnosis, and treatment

Genetic alterations that affect the function of p53 tumor suppressor have been extensively investigated in myeloid neoplasms, revealing their significant impact on disease progression, treatment response, and patient outcomes. The identification and characterization of TP53 mutations play pivotal roles in subclassifying myeloid neoplasms and guiding treatment decisions. Starting with the presentation of a typical case, this review highlights the complicated nature of genetic alterations involving TP53 and provides a comprehensive analysis of TP53 mutations and other alterations in myeloid neoplasms. Currently available methods used in clinical laboratories to identify TP53 mutations are discussed, focusing on the importance of establishing a robust testing protocol within clinical laboratories to ensure the delivery of accurate and reliable results. The treatment implications of TP53 mutations in myeloid neoplasms and clinical trial options are reviewed. Ultimately, we hope that this review provides valuable insights into the patterns of TP53 alterations in myeloid neoplasms and offers guidance to establish practical laboratory testing protocols to support the best practices of precision oncology.

Effects of donor-engrafted clonal hematopoiesis in allogeneic and autologous stem cell transplantation: a systematic review and meta-analysis

Donor stem cell health may be critically important to the success of hematopoietic stem cell transplantation (HSCT). Herein, we performed this systematic review and meta-analysis including meta-regression to assess the impact of donor-engrafted clonal hematopoiesis (CH) in allogeneic HSCT (allo-HSCT) and impact of pre-transplant CH in autologous HSCT (auto-HSCT). We applied random-effects models to analyze 5 allo-HSCT studies with 3192 donor-recipient pairs and 9 auto-HSCT studies with 2854 patients. We found that donor-engrafted CH after allo-HSCT decreased the risk of disease relapse [Hazard Ratio (HR) = 0.79, 95% Confidence Interval (CI): (0.67, 0.93)], but did not affect overall survival (OS) [HR = 0.91, 95% CI: (0.75, 1.11)], progression-free survival (PFS) [HR = 0.94, 95% CI: (0.63, 1.41)], or non-relapse mortality [HR = 1.06, 95% CI: (0.81, 1.39)]. In contrast, pre-transplant CH in auto-HSCT recipients resulted in inferior OS [HR = 1.30, 95% CI: (1.16, 1.46)], inferior PFS [HR = 1.35, 95% CI: (1.18, 1.54)], and higher risk for therapy-related myeloid neoplasm [HR = 4.85, 95% CI: (2.39, 9.82)] when compared to auto-HSCT recipients without CH. This study sheds light onto the debate about prospective "CHIP screening" for stem cell donors and addresses the impact of CH as a transmissible phenomenon.

Clonal hematopoiesis of indeterminate potential: the root cause of, and fertile ground for, hematological malignancies

Clonal hematopoiesis (CH) of indeterminate potential (CHIP), characterized by propagation of blood cell clones carrying somatic mutations in specific driver genes, is increasingly recognized as a critical factor in the development of hematological malignancies. This phenomenon, which often emerges with age, underscores the complex interplay between genetic predisposition and environmental influences in cancer initiation and progression. Recent years have witnessed significant advances in our understanding of the link between CHIP and hematological diseases. In this review, we provide a comprehensive overview of the features of CHIP and explore its role in promoting tumorigenesis and influencing treatment outcomes for blood cancers. Finally, we summarize current available tools for risk stratification and discuss management strategies for patients with CHIP.

Immune Checkpoint Inhibitor Therapy and Associations with Clonal Hematopoiesis

Cancer cohorts are now known to be associated with increased rates of clonal hematopoiesis (CH). We sort to characterize the hematopoietic compartment of patients with melanoma and non-small cell lung cancer (NSCLC) given our recent population level analysis reporting evolving rates of secondary leukemias. The advent of immune checkpoint blockade (ICB) has dramatically changed our understanding of cancer biology and has altered the standards of care for patients. However, the impact of ICB on hematopoietic myeloid clonal expansion remains to be determined. We studied if exposure to ICB therapy affects hematopoietic clonal architecture and if their evolution contributed to altered hematopoiesis. Blood samples from patients with melanoma and NSCLC (n = 142) demonstrated a high prevalence of CH. Serial samples (or post ICB exposure samples; n = 25) were evaluated in melanoma and NSCLC patients. Error-corrected sequencing of a targeted panel of genes recurrently mutated in CH was performed on peripheral blood genomic DNA. In serial sample analysis, we observed that mutations in DNMT3A and TET2 increased in size with longer ICB exposures in the melanoma cohort. We also noted that patients with larger size DNMT3A mutations with further post ICB clone size expansion had longer durations of ICB exposure. All serial samples in this cohort showed a statistically significant change in VAF from baseline. In the serial sample analysis of NSCLC patients, we observed similar epigenetic expansion, although not statistically significant. Our study generates a hypothesis for two important questions: (a) Can DNMT3A or TET2 CH serve as predictors of a response to ICB therapy and serve as a novel biomarker of response to ICB therapy? (b) As ICB-exposed patients continue to live longer, the myeloid clonal expansion may portend an increased risk for subsequent myeloid malignancy development. Until now, the selective pressure of ICB/T-cell activating therapies on hematopoietic stem cells were less known and we report preliminary evidence of clonal expansion in epigenetic modifier genes (also referred to as inflammatory CH genes).

Distinct landscape and clinical implications of therapy-related clonal hematopoiesis

Therapy-related clonal hematopoiesis (t-CH) is defined as clonal hematopoiesis detected in individuals previously treated with chemotherapy and/or radiation therapy. With the increased use of genetic analysis in oncological care, the detection of t-CH among cancer patients is becoming increasingly common. t-CH arises through the selective bottleneck imposed by chemotherapies and potentially through direct mutagenesis from chemotherapies, resulting in a distinct mutational landscape enriched with mutations in DNA damage-response pathway genes such as TP53, PPM1D, and CHEK2. Emerging evidence sheds light on the mechanisms of t-CH development and potential strategies to mitigate its emergence. Due to its unique characteristics that predominantly affect cancer patients, t-CH has clinical implications distinct from those of CH in the general population. This Review discusses the potential mechanisms of t-CH development, its mutational landscape, mutant-drug relationships, and its clinical significance. We highlight the distinct nature of t-CH and call for intensified research in this field.

Clonal hematopoiesis and atherosclerosis

Clonal hematopoiesis of indeterminate potential (CHIP) has emerged as a previously unrecognized, potent, age-related, and common risk factor for atherosclerosis. Somatic mutations in certain known leukemia driver genes give rise to clones of mutant cells in peripheral blood. The increased risk of developing hematologic malignancy does not, on its own, explain excess mortality in individuals with CHIP. Cardiovascular disease accounts for much of this gap. Experimental evidence supports the causality of certain CHIP mutations in accelerated atherosclerosis. CHIP due to mutations in different driver genes varies in their promotion of atherosclerotic events and in the region of augmented atherosclerotic involvement. For example, CHIP due to mutations in DNMT3a appears less atherogenic than CHIP that arises from TET2 or JAK2, forms of CHIP that incite inflammation. The recognition of certain CHIP mutations as promoters of atherosclerotic risk has opened new insights into understanding of the pathophysiology of this disease. The accentuated cardiovascular risk and involvement of distinct pathways of various forms of CHIP also inform novel approaches to allocation of targeted therapies, affording a step toward personalized medicine.

Clonal hematopoiesis and hematological malignancy

Clonal hematopoiesis (CH), the expansion of hematopoietic stem cells and their progeny driven by somatic mutations in leukemia-associated genes, is a common phenomenon that rises in prevalence with advancing age to affect most people older than 70 years. CH remains subclinical in most carriers, but, in a minority, it progresses to a myeloid neoplasm, such as acute myeloid leukemia, myelodysplastic syndrome, or myeloproliferative neoplasm. Over the last decade, advances in our understanding of CH, its molecular landscape, and the risks associated with different driver gene mutations have culminated in recent developments that allow for a more precise estimation of myeloid neoplasia risk in CH carriers. In turn, this is leading to the development of translational and clinical programs to intercept and prevent CH from developing into myeloid neoplasia. Here, we give an overview of the spectrum of CH driver mutations, what is known about their pathophysiology, and how this informs the risk of incident myeloid malignancy.

Variance quantitative trait loci reveal gene-gene interactions which alter blood traits

Gene-gene (GxG) interactions play an important role in human genetics, potentially explaining part of the "missing heritability" of polygenic traits and the variable expressivity of monogenic traits. Many GxG interactions have been identified in model organisms through experimental breeding studies, but they have been difficult to identify in human populations. To address this challenge, we applied two complementary variance QTL (vQTL)-based approaches to identify GxG interactions that contribute to human blood traits and blood-related disease risk. First, we used the previously validated genome-wide scale test for each trait in ~450,000 people in the UK Biobank and identified 4 vQTLs. Genome-wide GxG interaction testing of these vQTLs enabled discovery of novel interactions between (1) CCL24 and CCL26 for eosinophil count and plasma CCL24 and CCL26 protein levels and (2) HLA-DQA1 and HLA-DQB1 for lymphocyte count and risk of celiac disease, both of which replicated in ~140,000 NIH All of Us and ~70,000 Vanderbilt BioVU participants. Second, we used a biologically informed approach to search for vQTL in disease-relevant genes. This approach identified (1) a known interaction for hemoglobin between two pathogenic variants in HFE which cause hereditary hemochromatosis and alters risk of cirrhosis and (2) a novel interaction between the JAK2 46/1 haplotype and a variant on chromosome 14 which modifies platelet count, JAK2 V617F clonal hematopoiesis, and risk of polycythemia vera. This work identifies novel disease-relevant GxG interactions and demonstrates the utility of vQTL-based approaches in identifying GxG interactions relevant to human health at scale.

Genetic architecture of telomere length in 462,666 UK Biobank whole-genome sequences

Telomeres protect chromosome ends from damage and their length is linked with human disease and aging. We developed a joint telomere length metric, combining quantitative PCR and whole-genome sequencing measurements from 462,666 UK Biobank participants. This metric increased SNP heritability, suggesting that it better captures genetic regulation of telomere length. Exome-wide rare-variant and gene-level collapsing association studies identified 64 variants and 30 genes significantly associated with telomere length, including allelic series in ACD and RTEL1. Notably, 16% of these genes are known drivers of clonal hematopoiesis-an age-related somatic mosaicism associated with myeloid cancers and several nonmalignant diseases. Somatic variant analyses revealed gene-specific associations with telomere length, including lengthened telomeres in individuals with large SRSF2-mutant clones, compared with shortened telomeres in individuals with clonal expansions driven by other genes. Collectively, our findings demonstrate the impact of rare variants on telomere length, with larger effects observed among genes also associated with clonal hematopoiesis.

The role of clonal progression leading to the development of therapy-related myeloid neoplasms

Therapy-related myeloid neoplasms (t-MN) are characterized by aggressive features and a dismal prognosis. Recent evidence suggests a higher incidence of t-MN in individuals harboring clonal hematopoiesis of indeterminate potential (CHIP). In order to gain insight into CHIP-driven malignant progression, we gathered data from ten published reports with available detailed patient characteristics at the time of primary malignancy and t-MN development. Detailed clinical and molecular information on primary malignancy and t-MN were available for 109 patients: 43% harbored at least one somatic mutation at the time of the primary malignancy. TET2 and TP53 mutations showed an increasing variant allele frequency from CHIP to t-MN. ASXL1-associated CHIP significantly correlated with the emergence of TET2 and CEBPA mutations at t-MN, as well as U2AF1-driven CHIP with EZH2 mutation and both IDH2 and SRSF2-driven CHIP with FLT3 mutation. DNMT3A-driven CHIP correlated with a lower incidence of TP53 mutation at t-MN. In contrast, TP53-driven CHIP correlated with a complex karyotype and a lower tendency to acquire new mutations at t-MN. Patients with multiple myeloma as their first malignancy presented a significantly higher rate of TP53 mutations at t-MN. The progression from CHIP to t-MN shows different scenarios depending on the genes involved. A deeper knowledge of CHIP progression mechanisms will allow a more reliable definition of t-MN risk.

SOHO State of the Art Updates and Next Questions: An Update on Higher Risk Myelodysplastic Syndromes

Higher-risk myelodysplastic syndromes (HR-MDS) are clonal myeloid neoplasms that cause life-limiting complications from severe cytopenias and leukemic transformation. Efforts to better classify, prognosticate, and assess therapeutic responses in HR-MDS have resulted in publication of new clinical tools in the last several years. Given limited current treatment options and suboptimal outcomes, HR-MDS stands to benefit from the study of investigational agents.Higher-risk myelodysplastic syndromes (HR-MDS) are a heterogenous group of clonal myeloid-lineage malignancies often characterized by high-risk genetic lesions, increased blood transfusion needs, constitutional symptoms, elevated risk of progression to acute myeloid leukemia (AML), and therapeutic need for allogeneic bone marrow transplantation. Use of blast percentage and other morphologic features to define myelodysplastic neoplasm subtypes is rapidly shifting to incorporate genetics, resulting in a subset of former HR-MDS patients now being considered as AML in presence of leukemia-defining genetic alterations. A proliferation of prognostic tools has further focused use of genetic features to drive decision making in clinical management. Recently, criteria to assess response of HR-MDS to therapy were revised to incorporate more clinically meaningful endpoints and better match AML response criteria. Basic science investigations have resulted in improved understanding of the relationship between MDS genetic lesions, bone marrow stromal changes, germline predispositions, and disease phenotype. However, therapeutic advances have been more limited. There has been import of the IDH1 inhibitor ivosidenib, initially approved for AML; the Bcl-2 inhibitor venetoclax and liposomal daunorubicin/cytarabine (CPX-351) are under active investigation as well. Unfortunately, effective treatment of TP53-mutated disease remains elusive, though preliminary evidence suggests improved outcomes with oral decitabine/cedazuridine over parenteral hypomethylating agent monotherapy. Investigational agents with novel mechanisms of action may help expand the repertoire of treatment options for HR-MDS and trials continue to offer a hopeful therapeutic avenue for suitable patients.

The Clonal Hematopoiesis-associated Gene Srcap Plays an Essential Role in Hematopoiesis

Somatic mutations arising in hematopoietic stem cells (HSCs) may provide the latter with a fitness advantage, allowing the mutant HSC to clonally expand. Such mutations have been recurrently identified in the chromatin modifier, SRCAP, in both non-malignant and leukemic clones, suggesting that this gene plays a significant role in hematopoiesis. We generated a conditional Srcap loss of function murine model and determined the consequences of hematopoietic-specific loss of this gene. We show that Srcap is essential for normal fetal liver erythropoiesis and monocytopoiesis. In Srcap deficient fetal livers, the number of phenotypic HSCs is similar to that of controls, but these HSCs exhibit a profound repopulating defect. Likewise, conditional deletion of Srcap during adult hematopoiesis results in a rapid loss of HSCs. Loss of Srcap is associated with evidence of increased DNA damage in HSCs and lineage-restricted progenitors as assessed by y-H2AX expression. Consistent with this finding, we observed strong transcriptional upregulation of the p53 pathway in Srcap deficient erythroid precursors. Collectively our data highlight the importance of Srcap in maintaining HSC function and supporting hematopoietic differentiation and suggests that it plays an essential role in maintaining genomic integrity.

Clonal Hematopoiesis of Indeterminate Potential in Crohn's Disease and Ulcerative Colitis

Clonal hematopoiesis of indeterminate potential (CHIP) is the presence of somatic mutations in myeloid and lymphoid malignancy genes in the blood cells of individuals without a hematologic malignancy. Inflammation is hypothesized to be a key mediator in the progression of CHIP to hematologic malignancy and patients with CHIP have a high prevalence of inflammatory diseases. This study aimed to identify the prevalence and characteristics of CHIP in patients with inflammatory bowel disease (IBD). We analyzed whole exome sequencing data from 587 Crohn's disease (CD), 441 ulcerative colitis (UC), and 293 non-IBD controls to assess CHIP prevalence and used logistic regression to study associations with clinical outcomes. Older UC patients (age>45) harbored increased myeloid-CHIP mutations compared to younger patients (age≤45) (p=0.01). Lymphoid-CHIP was more prevalent in older IBD patients (p=0.007). Young CD patients were found to have myeloid-CHIP with high-risk features. IBD patients with CHIP exhibited unique mutational profiles compared to controls. Steroid use was associated with increased CHIP (p=0.05), while anti-TNF therapy was associated with decreased myeloid-CHIP (p=0.03). Pathway enrichment analyses indicated overlap between CHIP genes, IBD phenotypes, and inflammatory pathways. Our findings underscore a connection between IBD and CHIP pathophysiology. Patients with IBD and CHIP had unique risk profiles especially among older UC patients and younger CD patients. These findings suggest distinct evolutionary pathways for CHIP in IBD and necessitate awareness among IBD providers and hematologists to identify patients potentially at risk for CHIP-related complications including malignancy, cardiovascular disease and acceleration of their inflammatory disease.

CHIPing Away at Proteomics to Find Correlations with Myeloid Neoplasms

Plasma proteomic profiling to identify associations with myeloid neoplasm (MN) risk highlights the potential of integrating proteins and genetic biomarkers for the detection of individuals at high risk of developing MN. These proteins also offer valuable insights into biological pathways and inflammatory mechanisms involved in the progression of clonal hematopoiesis to MN. See related article by Tran et al., p. 3220.

CHIP: a clonal odyssey of the bone marrow niche

Clonal hematopoiesis of indeterminate potential (CHIP) is characterized by the selective expansion of hematopoietic stem and progenitor cells (HSPCs) carrying somatic mutations. While CHIP is typically asymptomatic, it has garnered substantial attention due to its association with the pathogenesis of multiple disease conditions, including cardiovascular disease (CVD) and hematological malignancies. In this Review, we will discuss seminal and recent studies that have advanced our understanding of mechanisms that drive selection for mutant HSPCs in the BM niche. Next, we will address recent studies evaluating potential relationships between the clonal dynamics of CHIP and hematopoietic development across the lifespan. Next, we will examine the roles of systemic factors that can influence hematopoietic stem cell (HSC) fitness, including inflammation, and exposures to cytotoxic agents in driving selection for CHIP clones. Furthermore, we will consider how - through their impact on the BM niche - lifestyle factors, including diet, exercise, and psychosocial stressors, might contribute to the process of somatic evolution in the BM that culminates in CHIP. Finally, we will review the role of old age as a major driver of selection in CHIP.

Plasma Proteomic Signature Predicts Myeloid Neoplasm Risk

PURPOSE

Clonal hematopoiesis (CH) is thought to be the origin of myeloid neoplasms (MN). Yet, our understanding of the mechanisms driving CH progression to MN and clinical risk prediction of MN remains limited. The human proteome reflects complex interactions between genetic and epigenetic regulation of biological systems. We hypothesized that the plasma proteome might predict MN risk and inform our understanding of the mechanisms promoting MN development.

EXPERIMENTAL DESIGN

We jointly characterized CH and plasma proteomic profiles of 46,237 individuals in the UK Biobank at baseline study entry. During 500,036 person-years of follow-up, 115 individuals developed MN. Cox proportional hazard regression was used to test for an association between plasma protein levels and MN risk.

RESULTS

We identified 115 proteins associated with MN risk, of which 30% (N = 34) were also associated with CH. These were enriched for known regulators of the innate and adaptive immune system. Plasma proteomics improved the prediction of MN risk (AUC = 0.85; P = 5×10-9) beyond clinical factors and CH (AUC = 0.80). In an independent group (N = 381,485), we used inherited polygenic risk scores (PRS) for plasma protein levels to validate the relevance of these proteins toMNdevelopment. PRS analyses suggest that most MN-associated proteins we identified are not directly causally linked toMN risk, but rather represent downstream markers of pathways regulating the progression of CH to MN.

CONCLUSIONS

These data highlight the role of immune cell regulation in the progression of CH to MN and the promise of leveraging multi-omic characterization of CH to improveMN risk stratification. See related commentary by Bhalgat and Taylor, p. 3095.

A practical approach on the classifications of myeloid neoplasms and acute leukemia: WHO and ICC

In 2022, two new classifications of myeloid neoplasms and acute leukemias were published: the 5th edition WHO Classification (WHO-HAEM5) and the International Consensus Classification (ICC). As with prior classifications, the WHO-HAEM5 and ICC made updates to the prior classification (revised 4th edition WHO Classification, WHO-HAEM4R) based on a consensus of groups of experts, who examined new evidence. Both WHO-HAEM5 and ICC introduced several new disease entities that are based predominantly on genetic features, superseding prior morphologic definitions. While it is encouraging that two groups independently came to similar conclusions in updating the classification of myeloid neoplasms and acute leukemias, there are several divergences in how WHO-HAEM5 and ICC define specific entities as well as differences in nomenclature of certain diseases. In this review, we highlight the similarities and differences between the WHO-HAEM5 and ICC handling of myeloid neoplasms and acute leukemias and present a practical approach to diagnosing and classifying these diseases in this current era of two divergent classification guidelines.

Clonal hematopoiesis of indeterminate potential as a prognostic factor: a systematic review and meta-analysis

ABSTRACT

With advances in sequencing, individuals with clonal hematopoiesis of indeterminate potential (CHIP) are increasingly being identified, making it essential to understand its prognostic implications. We conducted a systematic review of studies comparing the risk of clinical outcomes in individuals with and without CHIP. We searched MEDLINE and EMBASE and included original research reporting an outcome risk measure in individuals with CHIP, adjusted for the effect of age. From the 3305 studies screened, we included 88 studies with 45 to 470 960 participants. Most studies had a low-to-moderate risk of bias in all domains of the Quality in Prognostic Factor Studies tool. Random-effects meta-analyses were performed for outcomes reported in at least 3 studies. CHIP conferred an increased risk of all-cause mortality (hazard ratio [HR], 1.34; 95% confidence interval, 1.19-1.50), cancer mortality (HR, 1.46; 1.13-1.88), composite cardiovascular events (HR, 1.40; 1.19-1.65), coronary heart disease (HR, 1.76; 1.27-2.44), stroke (HR, 1.16; 1.05-1.28), heart failure (HR, 1.27; 1.15-1.41), hematologic malignancy (HR, 4.28; 2.29-7.98), lung cancer (HR, 1.40; 1.27-1.54), renal impairment (HR, 1.25; 1.18-1.33) and severe COVID-19 (odds ratio [OR], 1.46; 1.18-1.80). CHIP was not associated with cardiovascular mortality (HR, 1.09; 0.97-1.22), except in the subgroup analysis restricted to larger clones (HR, 1.31; 1.12-1.54). Isolated DNMT3A mutations did not increase the risk of myeloid malignancy, all-cause mortality, or renal impairment. The reasons for heterogeneity between studies included differences in definitions and measurements of CHIP and the outcomes, and populations studied. In summary, CHIP is associated with diverse clinical outcomes, with clone size, specific gene, and inherent patient characteristics important mediators of risk.