Patient perspectives on testing for clonal hematopoiesis of indeterminate potential

Clonal haematopoiesis in cardiovascular disease: prognostic role and novel therapeutic target

Clonal haematopoiesis is the clonal expansion of blood stem cells with acquired mutations. Clonal haematopoiesis of indeterminate potential (CHIP), traditionally defined as clonal haematopoiesis driven by a pre-leukaemic mutation in at least 2% of sequenced alleles, affects 10-20% of individuals aged >70 years. Although CHIP is considered a precursor condition for haematological malignancies, population-based data suggest that the majority of CHIP-associated mortality is attributable to non-malignant conditions, such as cardiovascular disease. Observational human studies have shown that CHIP is a strong and independent predictor of the onset and progression of atherosclerotic cardiovascular disease, heart failure and arrhythmia. In addition, findings from animal experiments suggest that CHIP is causally involved in these diseases and might be a risk factor that can be targeted with therapeutics. As our understanding of the cardiovascular implications of CHIP and other types of clonal haematopoiesis rapidly expands, it has become increasingly clear that clonal haematopoiesis subtypes have substantial heterogeneity with respect to magnitude of effect and underlying mechanisms for different cardiovascular diseases. In this Review, we discuss clonal haematopoiesis as a prognostic factor for numerous cardiovascular diseases, highlight its potential as a therapeutic target and propose a potential role for CHIP in cardiovascular precision medicine.

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.

Clonal hematopoiesis of indeterminate potential and cardiovascular diseases: A review

Cardiovascular disease (CVD) is a major driver of mortality and declining health worldwide. Cardiovascular diseases (CVD) is the most common cause of morbidity and mortality globally. Although dyslipidemia, smoking, diabetes, hypertension and obesity are some well-known causes of CVD, the overlapping genetic pathways between other diseases and those affecting cardiovascular health have been overlooked. In the past decade, mutations in TET2, DNMT3A, ASXL1, and JAK2 are found to cause clonal hematopoiesis of intermediate potential (CHIP), a disease associated with age-related haematological malignancies without the presence of cytopenias or dysplasia. Coronary artery disease, heart failure, aortic stenosis, and arrhythmias have been shown to be associated with the presence of CHIP mutations. Addressing the association between CHIP could significantly reduce residual risk patients with CVD. The link between CHIP and CVD can potentially be addressed through inhibitors of inflammasomes, antagonists in the interleukin pathway, or direct antagonists of CHIP mutations.

Helping ourselves, helping others: the Young Women's Breast Cancer Study (YWS) - a multisite prospective cohort study to advance the understanding of breast cancer diagnosed in women aged 40 years and younger

PURPOSE

Compared with older women diagnosed with breast cancer, younger women are more likely to die of breast cancer and more likely to suffer psychosocially in both the short-term and long term. The Young Women's Breast Cancer Study (YWS) is a multisite prospective cohort study established to address gaps in our knowledge about this vulnerable and understudied population.

PARTICIPANTS

The YWS enrolled 1302 women newly diagnosed with stages 0-IV breast cancer at age 40 years or younger at 13 academic and community sites in North America between 2006 and 2016. Longitudinal patient-reported outcome data are complemented by clinical data abstraction and biospecimen collection at multiple timepoints.

FINDINGS TO DATE

Key findings related to fertility include that nearly 40% of participants were interested in pregnancy following diagnosis; of those who reported interest, 10% pursued fertility preservation. Overall, approximately 10% of YWS participants became pregnant in the first 5 years after diagnosis; follow-up is ongoing for pregnancies after 5 years. Studies focused on psychosocial outcomes have characterised quality of life, post-traumatic stress and fear of recurrence, with findings detailing the factors associated with the substantial psychosocial burden many young women face during and following active treatment. Multiple studies have leveraged YWS biospecimens, including whole-exome sequencing of tumour analyses that revealed that select somatic alterations occur at different frequencies in young (age≤35) versus older women with luminal A breast cancer, and a study that explored clonal hematopoiesis of indeterminate potential found it to be rare in young survivors.

FUTURE PLANS

With a median follow-up of approximately 10 years, the cohort is just maturing for many relevant long-term outcomes and provides outstanding opportunities to further study and build collaborations to address gaps in our knowledge, with the ultimate objective to improve care and outcomes for young women with breast cancer.

TRIAL REGISTRATION NUMBER

NCT01468246.

Clonal hematopoiesis in the setting of hematopoietic cell transplantation

Clonal hematopoiesis (CH) in autologous transplant recipients and allogeneic transplant donors has genetic features and clinical associations that are distinct from each other and from non-cancer populations. CH in the setting of autologous transplant is enriched for mutations in DNA damage response pathway genes and is associated with adverse outcomes, including an increased risk of therapy-related myeloid neoplasm and inferior overall survival. Studies of CH in allogeneic transplant donors have yielded conflicting results but have generally shown evidence of potentiated alloimmunity in recipients, with some studies showing an association with favorable recipient outcomes.

Molecular and clinical aspects relevant for counseling individuals with clonal hematopoiesis of indeterminate potential

Clonal hematopoiesis of indeterminate potential (CHIP) has fascinated the medical community for some time. Discovered about a decade ago, this phenomenon links age-related alterations in hematopoiesis not only to the later development of hematological malignancies but also to an increased risk of early-onset cardiovascular disease and some other disorders. CHIP is detected in the blood and is characterized by clonally expanded somatic mutations in cancer-associated genes, predisposing to the development of hematologic neoplasms such as MDS and AML. CHIP-associated mutations often involve DNA damage repair genes and are frequently observed following prior cytotoxic cancer therapy. Genetic predisposition seems to be a contributing factor. It came as a surprise that CHIP significantly elevates the risk of myocardial infarction and stroke, and also contributes to heart failure and pulmonary hypertension. Meanwhile, evidence of mutant clonal macrophages in vessel walls and organ parenchyma helps to explain the pathophysiology. Besides aging, there are some risk factors promoting the appearance of CHIP, such as smoking, chronic inflammation, chronic sleep deprivation, and high birth weight. This article describes fundamental aspects of CHIP and explains its association with hematologic malignancies, cardiovascular disorders, and other medical conditions, while also exploring potential progress in the clinical management of affected individuals. While it is important to diagnose conditions that can lead to adverse, but potentially preventable, effects, it is equally important not to stress patients by confronting them with disconcerting findings that cannot be remedied. Individuals with diagnosed or suspected CHIP should receive counseling in a specialized outpatient clinic, where professionals from relevant medical specialties may help them to avoid the development of CHIP-related health problems. Unfortunately, useful treatments and clinical guidelines for managing CHIP are still largely lacking. However, there are some promising approaches regarding the management of cardiovascular disease risk. In the future, strategies aimed at restoration of gene function or inhibition of inflammatory mediators may become an option.

Clonal Hematopoiesis in Young Women Treated for Breast Cancer

PURPOSE

Young women treated for breast cancer with cytotoxic therapies are at risk for clonal hematopoiesis of indeterminate potential (CHIP), a condition in which blood cells carrying a somatic mutation associated with hematologic malignancy comprise at least 4% of the total blood system. CHIP has primarily been studied in older patient cohorts with limited clinical phenotyping.

EXPERIMENTAL DESIGN

We performed targeted sequencing on longitudinal blood samples to characterize the clonal hematopoietic landscape of 878 women treated for breast cancer enrolled in the prospective Young Women's Breast Cancer Study.

RESULTS

We identified somatic driver mutations in 252 study subjects (28.7%), but only 24 (2.7%) had clones large enough to meet criteria for CHIP. The most commonly mutated genes were DNMT3A and TET2, similar to mutations observed in noncancer cohorts. At 9-year median follow-up, we found no association between the presence of a somatic blood mutation (regardless of clone size) and adverse breast cancer (distant relapse-free survival) or non-breast cancer-related outcomes in this cohort. A subset of paired blood samples obtained over 4 years showed no evidence of mutant clonal expansion, regardless of genotype. Finally, we identified a subset of patients with likely germline mutations in genes known to contribute to inherited cancer risk, such as TP53 and ATM.

CONCLUSIONS

Our data show that for young women with early-stage breast cancer, CHIP is uncommon after cytotoxic exposure, is unlikely to contribute to adverse outcomes over the decade-long follow-up and may not require additional monitoring if discovered incidentally.