Clonal Hematopoiesis of Indeterminate Potential: an Expanding Genetic Cause of Cardiovascular Disease

A roadmap for modelling radiation-induced cardiac disease

Cardiac risk mitigation is a major priority in improving outcomes for cancer survivors as advances in cancer screening and treatments continue to decrease cancer mortality. More than half of adult cancer patients will be treated with radiotherapy (RT); therefore it is crucial to develop a framework for how to assess and predict radiation-induced cardiac disease (RICD). Historically, RICD was modelled solely using whole heart metrics such as mean heart dose. However, data over the past decade has identified cardiac substructures which outperform whole heart metrics in predicting for significant cardiac events. Additionally, non-RT factors such as pre-existing cardiovascular risk factors and toxicity from other therapies contribute to risk of future cardiac events. In this review, we aim to discuss the current evidence and knowledge gaps in predicting RICD and provide a roadmap for the development of comprehensive models based on three interrelated components, (1) baseline CV risk assessment, (2) cardiac substructure radiation dosimetry linked with cardiac-specific outcomes and (3) novel biomarker development.

Ovarian Insufficiency: Clinical Spectrum and Management Challenges

The term "ovarian insufficiency" describes the decline of ovarian function resulting in fertility loss and the marked decrease of ovarian steroid hormone production. From a clinical standpoint, ovarian insufficiency presents in three different settings. The first is natural menopause at midlife occurring at the average age of 51 years. The second arises after surgical oophorectomy owing to disease or elective cancer prophylaxis. Finally, primary or premature ovarian insufficiency is characterized by menopause occurring before age 40, often of undetermined etiology, but at times linked with genetic mutations, autoimmune syndromes, metabolic conditions, iatrogenic etiologies, and toxic exposures. Each clinical situation presents unique concerns and management challenges. The majority of women with intact ovaries who live to age 51 experience natural menopause, with early menopause <45 years. In the United States, surgical menopause with bilateral oophorectomy occurs in ∼600,000 women per year. The timing and specific clinical indication for oophorectomy alters management. Primary ovarian insufficiency occurs in 1% of women, although recent estimates suggest the prevalence may be increasing. Symptoms of ovarian insufficiency include hot flashes or vasomotor symptoms, mood disorders, sleep disruption, and vaginal/urinary symptoms. Health concerns include bone, cardiovascular, and cognitive health. Management of symptoms and preventive strategies varies depending upon the age, clinical situation, and specific health concerns of each individual. Treatment options for symptom relief include cognitive behavior therapy and hypnosis, nonhormonal prescription therapies, and hormone therapy. Tailoring the therapeutic approach over time in response to age, emerging medical issues, and patient desires constitutes individualized care.

Novel therapeutic targets and emerging treatments for atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of morbidity and mortality worldwide. Even with excellent control of low-density lipoprotein cholesterol (LDL-C) levels, adverse cardiovascular events remain a significant clinical problem worldwide, including among those without any traditional ASCVD risk factors. It is necessary to identify novel sources of residual risk and to develop targeted strategies that address them. Lipoprotein(a) has become increasingly recognized as a new cardiovascular risk determinant. Large-scale clinical trials have also signalled the potential additive cardiovascular benefits of decreasing triglycerides beyond lowering LDL-C levels. Since CANTOS (Anti-inflammatory Therapy with Canakinumab for Atherosclerotic Disease) demonstrated that antibodies against interleukin-1β may decrease recurrent cardiovascular events in secondary prevention, various anti-inflammatory medications used for rheumatic conditions and new monoclonal antibody therapeutics have undergone rigorous evaluation. These data build towards a paradigm shift in secondary ASCVD prevention, underscoring the value of targeting multiple biological pathways in the management of both lipid levels and systemic inflammation. Evolving knowledge of the immune system, and the gut microbiota may result in opportunities for modifying previously unrecognized sources of residual inflammatory risk. This review provides an overview of novel therapeutic targets for ASCVD and emerging treatments with a focus on mechanisms, efficacy, and safety.

Clonal Hematopoiesis of Indeterminate Potential From a Heart Failure Specialist's Point of View

Clonal hematopoiesis of indeterminate potential (CHIP) is a common bone marrow abnormality induced by age-related DNA mutations, which give rise to proinflammatory immune cells. These immune cells exacerbate atherosclerotic cardiovascular disease and may induce or accelerate heart failure. The mechanisms involved are complex but point toward a central role for proinflammatory macrophages and an inflammasome-dependent immune response (IL-1 [interleukin-1] and IL-6 [interleukin-6]) in the atherosclerotic plaque or directly in the myocardium. Intracardiac inflammation may decrease cardiac function and induce cardiac fibrosis, even in the absence of atherosclerotic cardiovascular disease. The pathophysiology and consequences of CHIP may differ among implicated genes as well as subgroups of patients with heart failure, based on cause (ischemic versus nonischemic) and ejection fraction (reduced ejection fraction versus preserved ejection fraction). Evidence is accumulating that CHIP is associated with cardiovascular mortality in ischemic and nonischemic heart failure with reduced ejection fraction and involved in the development of heart failure with preserved ejection fraction. CHIP and corresponding inflammatory pathways provide a highly potent therapeutic target. Randomized controlled trials in patients with well-phenotyped heart failure, where readily available anti-inflammatory therapies are used to intervene with clonal hematopoiesis, may pave the way for a new area of heart failure treatment. The first clinical trials that target CHIP are already registered.

Somatic Mutations and Clonal Hematopoiesis as Drivers of Age-Related Cardiovascular Risk

Purpose of Review

Clonal hematopoiesis of indeterminate potential (CHIP) has been identified as a novel cardiovascular risk factor. Here we review the relationship of lifestyle and environmental risk factors predisposing to somatic mutations and CHIP and provide an overview on age-related cardiovascular outcomes.

Recent Findings

CHIP has been associated with accelerated atherosclerosis and cardiovascular disease in both epidemiological and experimental studies. The most commonly mutated candidate driver genes are DNMT3A, TET2, JAK2, and ASXL1. The underlying mechanisms appear predominantly related to inflammatory pathways. Although age is the dominant risk factor for developing CHIP, emerging evidence suggests that other factors such as smoking, obesity/type 2 diabetes, or an unhealthy diet play a role in the occurrence of somatic mutations.

Summary

Evidence suggests a strong link between vascular risk factors, somatic hematopoietic mutations, and age-related cardiovascular disease. Further studies on CHIP biology are required to identify targeted interventions for risk reduction in patients with CHIP and inform the utility of screening strategies.

Liquid biopsies in pediatric oncology: opportunities and obstacles

PURPOSE OF REVIEW

Liquid biopsies have emerged as a noninvasive alternative to tissue biopsy with potential applications during all stages of pediatric oncology care. The purpose of this review is to provide a survey of pediatric cell-free DNA (cfDNA) studies, illustrate their potential applications in pediatric oncology, and to discuss technological challenges and approaches to overcome these hurdles.

RECENT FINDINGS

Recent literature has demonstrated liquid biopsies' ability to inform treatment selection at diagnosis, monitor clonal evolution during treatment, sensitively detect minimum residual disease following local control, and provide sensitive posttherapy surveillance. Advantages include reduced procedural anesthesia, molecular profiling unbiased by tissue heterogeneity, and ability to track clonal evolution. Challenges to wider implementation in pediatric oncology, however, include blood volume restrictions and relatively low mutational burden in childhood cancers. Multiomic approaches address challenges presented by low-mutational burden, and novel bioinformatic analyses allow a single assay to yield increasing amounts of information, reducing blood volume requirements.

SUMMARY

Liquid biopsies hold tremendous promise in pediatric oncology, enabling noninvasive serial surveillance with adaptive care. Already integrated into adult care, recent advances in technologies and bioinformatics have improved applicability to the pediatric cancer landscape.

Clonal hematopoiesis and cardiovascular disease: deciphering interconnections

Cardiovascular and oncological diseases represent the global major causes of death. For both, a novel and far-reaching risk factor has been identified: clonal hematopoiesis (CH). CH is defined as clonal expansion of peripheral blood cells on the basis of somatic mutations, without overt hematological malignancy. The most commonly affected genes are TET2, DNMT3A, ASXL1 and JAK2. By the age of 70, at least 20-50% of all individuals carry a CH clone, conveying a striking clinical impact by increasing all-cause mortality by 40%. This is due predominantly to a nearly two-fold increase of cardiovascular risk, but also to an elevated risk of malignant transformation. Individuals with CH show not only increased risk for, but also worse outcomes after arteriosclerotic events, such as stroke or myocardial infarction, decompensated heart failure and cardiogenic shock. Elevated cytokine levels, dysfunctional macrophage activity and activation of the inflammasome suggest that a vicious cycle of chronic inflammation and clonal expansion represents the major functional link. Despite the apparently high impact of this entity, awareness, functional understanding and especially clinical implications still require further research. This review provides an overview of the current knowledge of CH and its relation to cardiovascular and hematological diseases. It focuses on the basic functional mechanisms in the interplay between atherosclerosis, inflammation and CH, identifies issues for further research and considers potential clinical implications.