Breast cancer therapies and cardiomyopathy

Endothelin Receptor Blocker Reverses Breast Cancer-Induced Cardiac Remodeling

Background

Although some cancer therapies have overt and/or subclinical cardiotoxic effects that increase subsequent cardiovascular risk in breast cancer patients, we have recently shown that the breast tumor itself can also induce cardiac hypertrophy through the activation of the endothelin system to contribute to cardiovascular risk. However, the extent to which the suppression of the activation of the endothelin system could improve cardiac remodeling in breast cancer patients has yet to be investigated.

Objectives

We aimed to retrospectively assess the cardiac morphology/function in patients with breast cancer before receiving cancer chemotherapy and to investigate if the suppression of the activation of the endothelin system improves cardiac remodeling in a mouse model of breast cancer.

Methods

Our study involved 28 previously studied women with breast cancer (including 24 after tumor resection) before receiving adjuvant therapy and 17 control healthy women. In addition, we explored how the endothelin system contributed to breast cancer-induced cardiac remodeling using a mouse model of breast cancer.

Results

Our results indicate that before chemotherapy, breast cancer patients already exhibit relative cardiac remodeling and subclinical cardiac dysfunction, which was associated with the activation of the endothelin system. Importantly, our mouse data also show that the endothelin receptor blocker atrasentan significantly lessened cardiac remodeling and improved cardiac function in a preclinical model of breast cancer.

Conclusions

Although our findings should be further examined in other preclinical/clinical models, our data suggest that endothelin receptor blockers may play a role in cardiac health in individuals with breast cancer. (Understanding and Treating Heart Failure With Preserved Ejection Fraction: Novel Mechanisms, Diagnostics and Potential Therapeutics [Alberta HEART]; NCT02052804 and Multidisciplinary Team Intervention in Cardio-Oncology [TITAN]; NCT01621659).

Heart slice culture system reliably demonstrates clinical drug-related cardiotoxicity

The limited availability of human heart tissue and its complex cell composition are major limiting factors for the reliable testing of drug efficacy and toxicity. Recently, we developed functional human and pig heart slice biomimetic culture systems that preserve the viability and functionality of 300 μm heart slices for up to 6 days. Here, we tested the reliability of this culture system for testing the cardiotoxicity of anti-cancer drugs. We tested three anti-cancer drugs (doxorubicin, trastuzumab, and sunitinib) with known different mechanisms of cardiotoxicity at three concentrations and assessed the effect of these drugs on heart slice viability, structure, function and gene expression. Slices incubated with any of these drugs for 48 h showed diminished in viability as well as loss of cardiomyocyte structure and function. Mechanistically, RNA sequencing of doxorubicin-treated tissues demonstrated a significant downregulation of cardiac genes and upregulation of oxidative stress responses. Trastuzumab treatment downregulated cardiac muscle contraction-related genes consistent with its clinically known effect on cardiomyocytes. Interestingly, sunitinib treatment resulted in significant downregulation of angiogenesis-related genes, in line with its mechanism of action. Similar to hiPS-derived-cardiomyocytes, heart slices recapitulated the expected toxicity of doxorubicin and trastuzumab, however, slices were superior in detecting sunitinib cardiotoxicity and mechanism in the clinically relevant concentration range of 0.1-1 μM. These results indicate that heart slice culture models have the potential to become a reliable platform for testing and elucidating mechanisms of drug cardiotoxicity.

Breast cancer diagnosis is associated with relative left ventricular hypertrophy and elevated endothelin-1 signaling

BACKGROUND

The survival rates of women with breast cancer have improved significantly over the last four decades due to advances in breast cancer early diagnosis and therapy. However, breast cancer survivors have an increased risk of cardiovascular complications following chemotherapy. While this increased risk of later occurring structural cardiac remodeling and/or dysfunction has largely been attributed to the cardiotoxic effects of breast cancer therapies, the effect of the breast tumor itself on the heart prior to cancer treatment has been largely overlooked. Thus, the objectives of this study were to assess the cardiac phenotype in breast cancer patients prior to cancer chemotherapy and to determine the effects of human breast cancer cells on cardiomyocytes.

METHODS

We investigated left ventricular (LV) function and structure using cardiac magnetic resonance imaging in women with breast cancer prior to systemic therapy and a control cohort of women with comparable baseline factors. In addition, we explored how breast cancer cells communicate with the cardiomyocytes using cultured human cardiac and breast cancer cells.

RESULTS

Our results indicate that even prior to full cancer treatment, breast cancer patients already exhibit relative LV hypertrophy (LVH). We further demonstrate that breast cancer cells likely contribute to cardiomyocyte hypertrophy through the secretion of soluble factors and that at least one of these factors is endothelin-1.

CONCLUSION

Overall, the findings of this study suggest that breast cancer cells play a greater role in inducing structural cardiac remodeling than previously appreciated and that tumor-derived endothelin-1 may play a pivotal role in this process.

Survivorship, Version 2.2018, NCCN Clinical Practice Guidelines in Oncology

The NCCN Guidelines for Survivorship provide screening, evaluation, and treatment recommendations for common physical and psychosocial consequences of cancer and cancer treatment to help healthcare professionals who work with survivors of adult-onset cancer in the posttreatment period. This portion of the guidelines describes recommendations regarding the management of anthracycline-induced cardiotoxicity and lymphedema. In addition, recommendations regarding immunizations and the prevention of infections in cancer survivors are included.

New Myocyte Formation in the Adult Heart: Endogenous Sources and Therapeutic Implications

Death of adult cardiac myocytes and supportive tissues resulting from cardiovascular diseases such as myocardial infarction is the proximal driver of pathological ventricular remodeling that often culminates in heart failure. Unfortunately, no currently available therapeutic barring heart transplantation can directly replenish myocytes lost from the injured heart. For decades, the field has struggled to define the intrinsic capacity and cellular sources for endogenous myocyte turnover in pursuing more innovative therapeutic strategies aimed at regenerating the injured heart. Although controversy persists to this day as to the best therapeutic regenerative strategy to use, a growing consensus has been reached that the very limited capacity for new myocyte formation in the adult mammalian heart is because of proliferation of existing cardiac myocytes but not because of the activity of an endogenous progenitor cell source of some sort. Hence, future therapeutic approaches should take into consideration the fundamental biology of myocyte renewal in designing strategies to potentially replenish these cells in the injured heart.

Evaluating the Utility of Baseline Cardiac Function Screening in Early-Stage Breast Cancer Treatment

BACKGROUND

Cardiotoxicity can be a complication of anthracycline- or trastuzumab-based therapy for breast cancer patients. Screening echocardiograms (ECHOs) and radionuclide ventriculograms (RVGs) are often performed before administration of these agents to evaluate cardiac function. Limited evidence for the clinical utility of these screening tests is available.

METHODS

Early-stage breast cancer patients diagnosed from 2006 to 2011 (n = 1,067) with baseline ECHOs/RVGs were identified in a single institution prospective registry. Medical record review was performed to obtain pre- and post-ECHO/RVG treatment plans, baseline ECHO/RVG results, cardiac risk factors, and cardiac events. Patients with cardiac history were excluded. ECHO/RVG abnormalities were defined as ejection fraction (EF) <55%, valvular disease, left ventricular hypertrophy, and diastolic dysfunction. Cardiac events were defined as heart failure, myocardial infarction, arrhythmia, valvular disease, or angina during or after chemotherapy.

RESULTS

Among 600 eligible patients, abnormal ECHO/RVG results were observed in 13 (2.2%, 1.2%-3.7%), including 9 with baseline EF <55%. There were no detected changes in treatment plans, although more frequent cardiac monitoring was recommended for 2 patients. There were no significant differences in age, race, menopausal status, smoking history, alcohol use, body mass index, or medical comorbidities between patients with abnormal and normal results. In follow-up (mean, 4.0 years; range, 0-8.3), 15 patients developed cardiac events (none of whom had had abnormal baseline ECHOs/RVGs).

CONCLUSION

Baseline ECHO/RVG in patients without prior cardiac history rarely yields an abnormality that prompts change in planned anthracycline- and/or trastuzumab-based treatment. Moreover, few cardiac events developed in this screened population in follow-up.

IMPLICATIONS FOR PRACTICE

Baseline cardiac function screening with echocardiograms or radionuclide ventriculograms is frequently performed before administration of anthracycline- or trastuzumab-based chemotherapy in breast cancer patients due to the relatively low cost and risk to patients and the concern for potential cardiotoxicity. However, at a population level, these tests can take up time and can add up to significant costs for both patients and the health care system. This study finds that in patients with no history of cardiac disease, baseline cardiac function screening rarely identifies abnormalities that change treatment plans. Moreover, few cardiac events develop in an average of 4 years of follow-up, including none in patients with abnormal baseline cardiac function screening results. This suggests that baseline cardiac function screening may have limited utility in chemotherapy planning in young breast cancer patients with no history of cardiac disease.

Stem cell therapy and breast cancer treatment: review of stem cell research and potential therapeutic impact against cardiotoxicities due to breast cancer treatment

A new problem has emerged with the ever-increasing number of breast cancer survivors. While early screening and advances in treatment have allowed these patients to overcome their cancer, these treatments often have adverse cardiovascular side effects that can produce abnormal cardiovascular function. Chemotherapeutic and radiation therapy have both been linked to cardiotoxicity; these therapeutics can cause a loss of cardiac muscle and deterioration of vascular structure that can eventually lead to heart failure (HF). This cardiomyocyte toxicity can leave the breast cancer survivor with a probable diagnosis of dilated or restrictive cardiomyopathy (DCM or RCM). While current HF standard of care can alleviate symptoms, other than heart transplantation, there is no therapy that replaces cardiac myocytes that are killed during cancer therapies. There is a need to develop novel therapeutics that can either prevent or reverse the cardiac injury caused by cancer therapeutics. These new therapeutics should promote the regeneration of lost or deteriorating myocardium. Over the last several decades, the therapeutic potential of cell-based therapy has been investigated for HF patients. In this review, we discuss the progress of pre-clinical and clinical stem cell research for the diseased heart and discuss the possibility of utilizing these novel therapies to combat cardiotoxicity observed in breast cancer survivors.

Cardiac toxicity of anticancer agents

Modern cancer therapies are highly effective in the treatment of various malignancies, but their use is limited by the potential for cardiotoxicity. The most frequent and typical clinical manifestation of cardiotoxicity is left ventricular dysfunction, induced not only by cytotoxic conventional cancer therapy like anthracyclines, but also by new antitumor targeted therapy such as trastuzumab. The current standard for monitoring cardiac function, based on periodic assessment of left ventricular ejection fraction detects cardiotoxicity only when a functional impairment has already occurred, precluding any chance of preventing its development. A novel approach, based on the use of cardiac biomarkers has emerged in the last decade, resulting in a cost-effective diagnostic tool for early, real-time identification, assessment and monitoring of cardiotoxicity. In particular, prophylactic treatment with enalapril in patients with an early increase in troponin after chemotherapy has been shown to be very effective in preventing left ventricular dysfunction and associated cardiac events. In patients developing cancer treatment induced-cardiomyopathy, complete left ventricular ejection fraction recovery and a reduction of cardiac events may be achieved only when left ventricular dysfunction is detected early after the end of cancer treatment and treatment with angiotensin-converting enzyme inhibitors, possibly in combination with beta-blockers, is promptly initiated.