Inhibition of Cyp1a Protects Mice against Anthracycline Cardiomyopathy

Background

Anthracyclines such as doxorubicin (Dox) are highly effective anti-tumor agents, but their use is limited by dose-dependent cardiomyopathy and heart failure. Our laboratory previously reported that induction of cytochrome P450 family 1 (Cyp1) enzymes contributes to acute Dox cardiotoxicity in zebrafish and in mice, and that potent Cyp1 inhibitors prevent cardiotoxicity. However, the role of Cyp1 enzymes in chronic Dox cardiomyopathy, as well as the mechanisms underlying cardioprotection associated with Cyp1 inhibition, have not been fully elucidated.

Methods

The Cyp1 pathway was evaluated using a small molecule Cyp1 inhibitor in wild-type (WT) mice, or Cyp1-null mice ( Cyp1a1/1a2 -/- , Cyp1b1 -/- , and Cyp1a1/1a2/1b1 -/- ). Low-dose Dox was administered by serial intraperitoneal or intravenous injections, respectively. Expression of Cyp1 isoforms was measured by RT-qPCR, and myocardial tissue was isolated from the left ventricle for RNA sequencing. Cardiac function was evaluated by transthoracic echocardiography.

Results

In WT mice, Dox treatment was associated with a decrease in Cyp1a2 and increase in Cyp1b1 expression in the heart and in the liver. Co-treatment of WT mice with Dox and the novel Cyp1 inhibitor YW-130 protected against cardiac dysfunction compared to Dox treatment alone. Cyp1a1/1a2 -/- and Cyp1a1/1a2/1b1 -/- mice were protected from Dox cardiomyopathy compared to WT mice. Male, but not female, Cyp1b1 -/- mice had increased cardiac dysfunction following Dox treatment compared to WT mice. RNA sequencing of myocardial tissue showed upregulation of Fundc1 and downregulation of Ccl21c in Cyp1a1/1a2 -/- mice treated with Dox, implicating changes in mitophagy and chemokine-mediated inflammation as possible mechanisms of Cyp1a-mediated cardioprotection.

Conclusions

Taken together, this study highlights the potential therapeutic value of Cyp1a inhibition in mitigating anthracycline cardiomyopathy.

Priorities in Cardio-Oncology Basic and Translational Science: GCOS 2023 Symposium Proceedings: JACC: CardioOncology State-of-the-Art Review

Despite improvements in cancer survival, cancer therapy-related cardiovascular toxicity has risen to become a prominent clinical challenge. This has led to the growth of the burgeoning field of cardio-oncology, which aims to advance the cardiovascular health of cancer patients and survivors, through actionable and translatable science. In these Global Cardio-Oncology Symposium 2023 scientific symposium proceedings, we present a focused review on the mechanisms that contribute to common cardiovascular toxicities discussed at this meeting, the ongoing international collaborative efforts to improve patient outcomes, and the bidirectional challenges of translating basic research to clinical care. We acknowledge that there are many additional therapies that are of significance but were not topics of discussion at this symposium. We hope that through this symposium-based review we can highlight the knowledge gaps and clinical priorities to inform the design of future studies that aim to prevent and mitigate cardiovascular disease in cancer patients and survivors.

Sex Differences in the Development of Anthracycline-Associated Heart Failure

BACKGROUND

Female sex is frequently cited as a risk factor for anthracycline cardiotoxicity based on pediatric data, but the role of sex in the development of cardiotoxicity has not been clearly established in adults.

OBJECTIVES

To assess the effect of female sex on the development of incident heart failure (HF) in adult patients treated with anthracyclines.

METHODS

This was a retrospective cohort study of 1525 adult patients with no prior history of HF or cardiomyopathy who were treated with anthracyclines between 1992 and 2019. The primary outcome was new HF within 5 years of the first dose of anthracyclines. The effect of sex was assessed using Cox proportional hazards and competing risk models.

RESULTS

Over a median (IQR) follow-up of 1.02 (0.30-3.01) years, 4.78% of patients developed HF (44 men and 29 women). Female sex was not associated with the primary outcome in a multivariable Cox proportional hazards model (HR 0.87; 95% CI 0.53-1.43; P = 0.58). Similar results were observed in a multivariable model accounting for the competing risk of death (HR 0.94; 95% CI 0.39-2.25; P = 0.88). Age, coronary artery disease and hematopoietic stem cell transplant were associated with the primary outcome in a multivariable Cox proportional hazards model. Age and body mass index were associated with the primary outcome in a multivariable competing risk model.

CONCLUSIONS

In this large, single-center, retrospective cohort study, female sex was not associated with incident HF in adult patients treated with anthracyclines.

CONDENSED ABSTRACT

Female sex is frequently cited as a risk factor for anthracycline cardiotoxicity based on pediatric data, but the role of sex in the development of cardiotoxicity has not been clearly established in adults. In this retrospective cohort study, we assessed the effect of female sex on the development of incident heart failure in adult patients treated with anthracyclines. Using Cox proportional hazards and competing risk regression models, we found that there was no association between female sex and heart failure after treatment with anthracyclines.

Atorvastatin for Anthracycline-Associated Cardiac Dysfunction: The STOP-CA Randomized Clinical Trial

Importance

Anthracyclines treat a broad range of cancers. Basic and retrospective clinical data have suggested that use of atorvastatin may be associated with a reduction in cardiac dysfunction due to anthracycline use.

Objective

To test whether atorvastatin is associated with a reduction in the proportion of patients with lymphoma receiving anthracyclines who develop cardiac dysfunction.

Design, Setting, and Participants

Double-blind randomized clinical trial conducted at 9 academic medical centers in the US and Canada among 300 patients with lymphoma who were scheduled to receive anthracycline-based chemotherapy. Enrollment occurred between January 25, 2017, and September 10, 2021, with final follow-up on October 10, 2022.

Interventions

Participants were randomized to receive atorvastatin, 40 mg/d (n = 150), or placebo (n = 150) for 12 months.

Main Outcomes and Measures

The primary outcome was the proportion of participants with an absolute decline in left ventricular ejection fraction (LVEF) of ≥10% from prior to chemotherapy to a final value of <55% over 12 months. A secondary outcome was the proportion of participants with an absolute decline in LVEF of ≥5% from prior to chemotherapy to a final value of <55% over 12 months.

Results

Of the 300 participants randomized (mean age, 50 [SD, 17] years; 142 women [47%]), 286 (95%) completed the trial. Among the entire cohort, the baseline mean LVEF was 63% (SD, 4.6%) and the follow-up LVEF was 58% (SD, 5.7%). Study drug adherence was noted in 91% of participants. At 12-month follow-up, 46 (15%) had a decline in LVEF of 10% or greater from prior to chemotherapy to a final value of less than 55%. The incidence of the primary end point was 9% (13/150) in the atorvastatin group and 22% (33/150) in the placebo group (P = .002). The odds of a 10% or greater decline in LVEF to a final value of less than 55% after anthracycline treatment was almost 3 times greater for participants randomized to placebo compared with those randomized to atorvastatin (odds ratio, 2.9; 95% CI, 1.4-6.4). Compared with placebo, atorvastatin also reduced the incidence of the secondary end point (13% vs 29%; P = .001). There were 13 adjudicated heart failure events (4%) over 24 months of follow-up. There was no difference in the rates of incident heart failure between study groups (3% with atorvastatin, 6% with placebo; P = .26). The number of serious related adverse events was low and similar between groups.

Conclusions and Relevance

Among patients with lymphoma treated with anthracycline-based chemotherapy, atorvastatin reduced the incidence of cardiac dysfunction. This finding may support the use of atorvastatin in patients with lymphoma at high risk of cardiac dysfunction due to anthracycline use.

Trial Registration

ClinicalTrials.gov Identifier: NCT02943590.

Sustained alternate-day fasting potentiates doxorubicin cardiotoxicity

Fasting strategies are under active clinical investigation in patients receiving chemotherapy. Prior murine studies suggest that alternate-day fasting may attenuate doxorubicin cardiotoxicity and stimulate nuclear translocation of transcription factor EB (TFEB), a master regulator of autophagy and lysosomal biogenesis. In this study, human heart tissue from patients with doxorubicin-induced heart failure demonstrated increased nuclear TFEB protein. In mice treated with doxorubicin, alternate-day fasting or viral TFEB transduction increased mortality and impaired cardiac function. Mice randomized to alternate-day fasting plus doxorubicin exhibited increased TFEB nuclear translocation in the myocardium. When combined with doxorubicin, cardiomyocyte-specific TFEB overexpression provoked cardiac remodeling, while systemic TFEB overexpression increased growth differentiation factor 15 (GDF15) and caused heart failure and death. Cardiomyocyte TFEB knockout attenuated doxorubicin cardiotoxicity, while recombinant GDF15 was sufficient to cause cardiac atrophy. Our studies identify that both sustained alternate-day fasting and a TFEB/GDF15 pathway exacerbate doxorubicin cardiotoxicity.

Efficacy and safety of catheter ablation for atrial fibrillation in patients with history of cancer

BACKGROUND

Though the incidence of atrial fibrillation (AF) is increased in patients with cancer, the effectiveness of catheter ablation (CA) for AF in patients with cancer is not well studied.

METHODS

We conducted a retrospective cohort study of patients who underwent CA for AF. Patients with a history of cancer within 5-years prior to, or those with an exposure to anthracyclines and/or thoracic radiation at any time prior to the index ablation were compared to patients without a history of cancer who underwent AF ablation. The primary outcome was freedom from AF [with or without anti-arrhythmic drugs (AADs), or need for repeat CA at 12-months post-ablation]. Secondary endpoints included freedom from AF at 12 months post-ablation with AADs and without AADs. Safety endpoints included bleeding, pulmonary vein stenosis, stroke, and cardiac tamponade. Multivariable regression analysis was performed to identify independent risk predictors of the primary outcome.

RESULTS

Among 502 patients included in the study, 251 (50%) had a history of cancer. Freedom from AF at 12 months did not differ between patients with and without cancer (83.3% vs 72.5%, p 0.28). The need for repeat ablation was also similar between groups (20.7% vs 27.5%, p 0.29). Multivariable regression analysis did not identify a history of cancer or cancer-related therapy as independent predictors of recurrent AF after ablation. There was no difference in safety endpoints between groups.

CONCLUSION

CA is a safe and effective treatment for AF in patients with a history of cancer and those with exposure to potentially cardiotoxic therapy.

Apolipoprotein M Attenuates Anthracycline Cardiotoxicity and Lysosomal Injury

Apolipoprotein M (ApoM) binds sphingosine-1-phosphate (S1P) and is inversely associated with mortality in human heart failure (HF). Here, we show that anthracyclines such as doxorubicin (Dox) reduce circulating ApoM in mice and humans, that ApoM is inversely associated with mortality in patients with anthracycline-induced heart failure, and ApoM heterozygosity in mice increases Dox-induced mortality. In the setting of Dox stress, our studies suggest ApoM can help sustain myocardial autophagic flux in a post-transcriptional manner, attenuate Dox cardiotoxicity, and prevent lysosomal injury.

Prolactin Inhibition in Peripartum Cardiomyopathy: Systematic Review and Meta-analysis

Heart failure (HF) is one of the leading causes of maternal mortality and morbidity in the United States. Peripartum cardiomyopathy (PPCM) constitutes up to 70% of all HF in pregnancy. Cardiac angiogenic imbalance caused by cleaved 16kDa prolactin has been hypothesized to contribute to the development of PPCM, fueling investigation of prolactin inhibitors for the management of PPCM. We conducted a systematic review and meta-analysis to assess the impact of prolactin inhibition on left ventricular (LV) function and mortality in patients with PPCM. We included English language articles from PubMed and EMBASE published upto March 2022. We pooled the mean difference (MD) for left ventricular ejection fraction (LVEF) at follow-up, odds ratio (OR) for LV recovery and risk ratio (RR) for all-cause mortality using random-effects meta-analysis. Among 548 studies screened, 10 studies (3 randomized control trials (RCTs), 2 retrospective and 5 prospective cohorts) were included in the systematic review. Patients in the Bromocriptine + standard guideline directed medical therapy (GDMT) group had higher LVEF% (pMD 12.56 (95% CI 5.84-19.28, I2=0%) from two cohorts and pMD 14.25 (95% CI 0.61-27.89, I2=88%) from two RCTs) at follow-up compared to standard GDMT alone group. Bromocriptine group also had higher odds of LV recovery (pOR 3.55 (95% CI 1.39-9.1, I2=62)). We did not find any difference in all-cause mortality between the groups. Our analysis demonstrates that the addition of Bromocriptine to standard GDMT was associated with a significant improvement in LVEF% and greater odds of LV recovery, without significant reduction in all-cause mortality.

Circulating hemopexin modulates anthracycline cardiac toxicity in patients and in mice

Anthracyclines such as doxorubicin (Dox) are effective chemotherapies, but their use is limited by cardiac toxicity. We hypothesized that plasma proteomics in women with breast cancer could identify new mechanisms of anthracycline cardiac toxicity. We measured changes in 1317 proteins in anthracycline-treated patients (n = 30) and replicated key findings in a second cohort (n = 31). An increase in the heme-binding protein hemopexin (Hpx) 3 months after anthracycline initiation was associated with cardiac toxicity by echocardiography. To assess the functional role of Hpx, we administered Hpx to wild-type (WT) mice treated with Dox and observed improved cardiac function. Conversely, Hpx-/- mice demonstrated increased Dox cardiac toxicity compared to WT mice. Initial mechanistic studies indicate that Hpx is likely transported to the heart by circulating monocytes/macrophages and that Hpx may mitigate Dox-induced ferroptosis to confer cardioprotection. Together, these observations suggest that Hpx induction represents a compensatory response during Dox treatment.

Cardiovascular Drug Interactions With Nirmatrelvir/Ritonavir in Patients With COVID-19: JACC Review Topic of the Week

Nirmatrelvir-ritonavir (NMVr) is used to treat symptomatic, nonhospitalized patients with coronavirus disease-2019 (COVID-19) who are at high risk of progression to severe disease. Patients with cardiovascular risk factors and cardiovascular disease are at a high risk of developing adverse events from COVID-19 and as a result have a higher likelihood of receiving NMVr. Ritonavir, the pharmaceutical enhancer used in NMVr, is an inhibitor of the enzymes of CYP450 pathway, particularly CYP3A4 and to a lesser degree CYP2D6, and affects the P-glycoprotein pump. Co-administration of NMVr with medications commonly used to manage cardiovascular conditions can potentially cause significant drug-drug interactions and may lead to severe adverse effects. It is crucial to be aware of such interactions and take appropriate measures to avoid them. In this review, we discuss potential drug-drug interactions between NMVr and commonly used cardiovascular medications based on their pharmacokinetics and pharmacodynamic properties.

Impact of Social Vulnerability on Comorbid Cancer and Cardiovascular Disease Mortality in the United States

Background

Racial and social disparities exist in outcomes related to cancer and cardiovascular disease (CVD).

Objectives

The aim of this cross-sectional study was to study the impact of social vulnerability on mortality attributed to comorbid cancer and CVD.

Methods

The Centers for Disease Control and Prevention Wide-Ranging Online Data for Epidemiologic Research database (2015-2019) was used to obtain county-level mortality data attributed to cancer, CVD, and comorbid cancer and CVD. County-level social vulnerability index (SVI) data (2014-2018) were obtained from the CDC's Agency for Toxic Substances and Disease Registry. SVI percentiles were generated for each county and aggregated to form SVI quartiles. Age-adjusted mortality rates (AAMRs) were estimated and compared across SVI quartiles to assess the impact of social vulnerability on mortality related to cancer, CVD, and comorbid cancer and CVD.

Results

The AAMR for comorbid cancer and CVD was 47.75 (95% CI: 47.66-47.85) per 100,000 person-years, with higher mortality in counties with greater social vulnerability. AAMRs for cancer and CVD were also significantly greater in counties with the highest SVIs. However, the proportional increase in mortality between the highest and lowest SVI counties was greater for comorbid cancer and CVD than for either cancer or CVD alone. Adults <45 years of age, women, Asian and Pacific Islanders, and Hispanics had the highest relative increase in comorbid cancer and CVD mortality between the fourth and first SVI quartiles, without significant urban-rural differences.

Conclusions

Comorbid cancer and CVD mortality increased in counties with higher social vulnerability. Improved education, resource allocation, and targeted public health interventions are needed to address inequities in cardio-oncology.

Abstract P3114: Intermittent Fasting Potentiates Anthracycline Cardiotoxicity

Background: Anthracyclines such as doxorubicin (Dox) cause cardiotoxicity and associated autophagic impairment, though controversy exists increasing autophagy ameliorates or exacerbates Dox cardiotoxicity. Because intermittent fasting (IF), a potent stimulus of autophagy, is presently under clinical investigation in multiple human clinical trials of cancer patients receiving chemotherapy, we tested whether IF would ameliorate or exacerbate Dox cardiotoxicity in multiple murine models.

Methods: Chow-fed C57BL/6 mice (n=150) were randomized to ad libitum feeding ( adlib ) or IF (every other day) and treated with vehicle or Dox (5 mg/kg IP x 4 doses). Alternatively, to stimulate autophagy and lysosomal biogenesis transcriptionally, we employed adeno-associated virus 9 (AAV9)-driven overexpression of transcription factor EB (TFEB) vs null, followed by vehicle or Dox (n=40). We further analyzed TFEB nuclear content in myocardial tissue from patients with anthracycline cardiomyopathy vs non-failing donors and patients with other non-ischemic cardiomyopathies (n=17).

Results: In Dox-treated mice (but not in vehicle controls), IF significantly reduced survival (18% absolute reduction or AR) ( figure A ), left ventricular ejection fraction (LVEF) (8% AR) ( figure B ) and heart weight index (12% relative reduction) ( figure C ) compared to adlib group. Mechanistically, in Dox-treated mice, IF significantly decreased phosphorylation of mammalian target of rapamycin, increased active, nuclear TFEB content, and increased levels of the atrophy factor muscle RING-finger protein-1. In myocardial tissue from patients with anthracycline cardiomyopathy, we observed a 3.5-fold increase (p<0.01) in nuclear TFEB content compared to both tissues from donors without heart failure and tissues from patients with other non-ischemic cardiomyopathies. Overexpression of TFEB exacerbated Dox-induced cardiotoxicity, including significant decreases in LVEF, left ventricular mass index, and survival.

Conclusions: IF exacerbates Dox-related mortality and cardiomyopathy, likely by stimulating the autophagy-lysosomal transcriptional regulator TFEB. Our data raise concerns about the safety of IF and augmentation of TFEB activity in the context of anthracycline chemotherapy.

Understanding Myocardial Metabolism in the Context of Cardio-Oncology

Cardiovascular events, ranging from arrhythmias to decompensated heart failure, are common during and after cancer therapy. Cardiovascular complications can be life-threatening, and from the oncologist's perspective, could limit the use of first-line cancer therapeutics. Moreover, an aging population increases the risk for comorbidities and medical complexity among patients who undergo cancer therapy. Many have established cardiovascular diagnoses or risk factors before starting these therapies. Therefore, it is essential to understand the molecular mechanisms that drive cardiovascular events in patients with cancer and to identify new therapeutic targets that may prevent and treat these 2 diseases. This review will discuss the metabolic interaction between cancer and the heart and will highlight current strategies of targeting metabolic pathways for cancer treatment. Finally, this review highlights opportunities and challenges in advancing our understanding of myocardial metabolism in the context of cancer and cancer treatment.

Genetics of Anthracycline-Associated Cardiotoxicity

Anthracyclines are a major component of chemotherapies used in many pediatric and adult malignancies. Anthracycline-associated cardiotoxicity (ACT) is a dose-dependent adverse effect that has substantial impact on morbidity and mortality. Therefore, the identification of genetic variants associated with increased risk of ACT has the potential for significant clinical impact to improve patient care. The goal of this review is to summarize the current evidence supporting genetic variants associated with ACT, identify gaps and limitations in current knowledge, and propose future directions for incorporating genetics into clinical practice for patients treated with anthracyclines. We will discuss mechanisms of ACT that could be illuminated by genetics and discuss clinical applications for the cardiologist/cardio-oncologist.

Excess heme upregulates heme oxygenase 1 and promotes cardiac ferroptosis in mice with sickle cell disease

Sickle cell disease (SCD) is characterized by increased hemolysis, which results in plasma heme overload and ultimately cardiovascular complications. Here, we hypothesized that increased heme in SCD causes upregulation of heme oxygenase 1 (Hmox1), which consequently drives cardiomyopathy through ferroptosis, an iron-dependent non-apoptotic form of cell death. First, we demonstrated that the Townes SCD mice had higher levels of hemopexin-free heme in the serum and increased cardiomyopathy, which was corrected by hemopexin supplementation. Cardiomyopathy in SCD mice was associated with upregulation of cardiac Hmox1, and inhibition or induction of Hmox1 improved or worsened cardiac damage, respectively. Because free iron, a product of heme degradation through Hmox1, has been implicated in toxicities including ferroptosis, we evaluated the downstream effects of elevated heme in SCD. Consistent with Hmox1 upregulation and iron overload, levels of lipid peroxidation and ferroptotic markers increased in SCD mice, which were corrected by hemopexin administration. Moreover, ferroptosis inhibitors decreased cardiomyopathy, whereas a ferroptosis inducer erastin exacerbated cardiac damage in SCD and induced cardiac ferroptosis in nonsickling mice. Finally, inhibition or induction of Hmox1 decreased or increased cardiac ferroptosis in SCD mice, respectively. Together, our results identify ferroptosis as a key mechanism of cardiomyopathy in SCD.

Gender Differences in Medicare Payments Among Cardiologists

Importance

Women cardiologists receive lower salaries than men; however, it is unknown whether US Centers for Medicare & Medicaid Services (CMS) reimbursement also differs by gender and contributes to the lower salaries.

Objective

To determine whether gender differences exist in the reimbursements, charges, and reimbursement per charge from CMS.

Design, Setting, and Participants

This cross-sectional analysis used the CMS database to obtain 2016 reimbursement data for US cardiologists. These included reimbursements to cardiologists, charges submitted, and unique billing codes. Gender differences in reimbursement for evaluation and management and procedural charges from both inpatient and outpatient settings were also assessed. Analysis took place between April 2019 and December 2020.

Main Outcomes and Measures

Outcomes included median CMS payments received and median charges submitted in the inpatient and outpatient settings in 2016.

Results

In 2016, 17 524 cardiologists (2312 women [13%] and 15 212 men [87%]) received CMS payments in the inpatient setting, and 16 929 cardiologists (2151 women [13%] and 14 778 men [87%]) received CMS payments in the outpatient setting. Men received higher median payments in the inpatient (median [interquartile range], $62 897 [$30 904-$104 267] vs $45 288 [$21 371-$73 191]; P < .001) and outpatient (median [interquartile range], $91 053 [$34 820-$196 165] vs $51 975 [$15 622-$120 175]; P < .001) practice settings. Men submitted more median charges in the inpatient (median [interquartile range], 1190 [569-2093] charges vs 959 [569-2093] charges; P < .001) and outpatient settings (median [interquartile range], 1685 [644-3328] charges vs 870 [273-1988] charges; P < .001). In a multivariable-adjusted linear regression analysis, women received less CMS payments compared with men (log-scale β = -0.06; 95% CI, -0.11 to -0.02) after adjustment for number of charges, number of unique billing codes, complexity of patient panel, years since graduation of physicians, and physician subspecialty. Payment by billing codes, both inpatient and outpatient, did not differ by gender.

Conclusions and Relevance

There may be potential differences in CMS payments between men and women cardiologists, which appear to stem from gender differences in the number and types of charges submitted. The mechanisms behind these differences merit further research, both to understand why such gender differences exist and also to facilitate reductions in pay disparities.

Preclinical Models of Cancer Therapy-Associated Cardiovascular Toxicity: A Scientific Statement From the American Heart Association

Although cardiovascular toxicity from traditional chemotherapies has been well recognized for decades, the recent explosion of effective novel targeted cancer therapies with cardiovascular sequelae has driven the emergence of cardio-oncology as a new clinical and research field. Cardiovascular toxicity associated with cancer therapy can manifest as a broad range of potentially life-threatening complications, including heart failure, arrhythmia, myocarditis, and vascular events. Beyond toxicology, the intersection of cancer and heart disease has blossomed to include discovery of genetic and environmental risk factors that predispose to both. There is a pressing need to understand the underlying molecular mechanisms of cardiovascular toxicity to improve outcomes in patients with cancer. Preclinical cardiovascular models, ranging from cellular assays to large animals, serve as the foundation for mechanistic studies, with the ultimate goal of identifying biologically sound biomarkers and cardioprotective therapies that allow the optimal use of cancer treatments while minimizing toxicities. Given that novel cancer therapies target specific pathways integral to normal cardiovascular homeostasis, a better mechanistic understanding of toxicity may provide insights into fundamental pathways that lead to cardiovascular disease when dysregulated. The goal of this scientific statement is to summarize the strengths and weaknesses of preclinical models of cancer therapy-associated cardiovascular toxicity, to highlight overlapping mechanisms driving cancer and cardiovascular disease, and to discuss opportunities to leverage cardio-oncology models to address important mechanistic questions relevant to all patients with cardiovascular disease, including those with and without cancer.

5-FU Cardiotoxicity: Vasospasm, Myocarditis, and Sudden Death

PURPOSE OF REVIEW

5-fluorouracil (5-FU) is one of the most common causes of cardiotoxicity associated with chemotherapy. The manifestations of 5-FU cardiotoxicity are diverse, and there are no established clinical guidelines addressing the diagnosis and management of this condition. Here we summarize the mechanistic and clinical data available to guide clinicians in caring for patients with suspected 5-FU cardiotoxicity.

RECENT FINDINGS

The decision to resume 5-FU treatment in patients with suspected cardiovascular toxicity remains challenging. Testing for predisposing genetic variants may be helpful, particularly in patients with other signs of 5-FU toxicity. Uridine triacetate is a recently approved antidote that can improve clinical outcomes in patients with life-threatening fluoropyrimidine cardiotoxicity. 5-FU cardiotoxicity remains poorly understood, with limited mechanistic or prospective clinical trial data available to define risk factors or effective management strategies. Risk stratification and therapeutic decisions should be individualized, based on the risk-benefit ratio of continuing 5-FU therapy for each patient.

Zebrafish Models of Cancer Therapy-Induced Cardiovascular Toxicity

Purpose of review: Both traditional and novel cancer therapies can cause cardiovascular toxicity in patients. In vivo models integrating both cardiovascular and cancer phenotypes allow for the study of on- and off-target mechanisms of toxicity arising from these agents. The zebrafish is the optimal whole organism model to screen for cardiotoxicity in a high throughput manner, while simultaneously assessing the role of cardiotoxicity pathways on the cancer therapy’s antitumor effect. Here we highlight established zebrafish models of human cardiovascular disease and cancer, the unique advantages of zebrafish to study mechanisms of cancer therapy-associated cardiovascular toxicity, and finally, important limitations to consider when using the zebrafish to study toxicity. Recent findings: Cancer therapy-associated cardiovascular toxicities range from cardiomyopathy with traditional agents to arrhythmias and thrombotic complications associated with newer targeted therapies. The zebrafish can be used to identify novel therapeutic strategies that selectively protect the heart from cancer therapy without affecting antitumor activity. Advances in genome editing technology have enabled the creation of several transgenic zebrafish lines valuable to the study of cardiovascular and cancer pathophysiology. Summary: The high degree of genetic conservation between zebrafish and humans, as well as the ability to recapitulate cardiotoxic phenotypes observed in patients with cancer, make the zebrafish an effective model to study cancer therapy-associated cardiovascular toxicity. Though this model provides several key benefits over existing in vitro and in vivo models, limitations of the zebrafish model include the early developmental stage required for most high-throughput applications.

Niacinamide May Be Associated with Improved Outcomes in COVID-19-Related Acute Kidney Injury: An Observational Study

Background

AKI is a significant complication of coronavirus disease 2019 (COVID-19), with no effective therapy. Niacinamide, a vitamin B3 analogue, has some evidence of efficacy in non-COVID-19-related AKI. The objective of this study is to evaluate the association between niacinamide therapy and outcomes in patients with COVID-19-related AKI.

Methods

We implemented a quasi-experimental design with nonrandom, prospective allocation of niacinamide in 201 hospitalized adult patients, excluding those with baseline eGFR <15 ml/min per 1.73 m² on or off dialysis, with COVID-19-related AKI by Kidney Disease Improving Global Outcomes (KDIGO) criteria, in two hospitals with identical COVID-19 care algorithms, one of which additionally implemented treatment with niacinamide for COVID-19-related AKI. Patients on the niacinamide protocol (B3 patients) were compared against patients at the same institution before protocol commencement and contemporaneous patients at the non-niacinamide hospital (collectively, non-B3 patients). The primary outcome was a composite of death or RRT.

Results

A total of 38 out of 90 B3 patients and 62 out of 111 non-B3 patients died or received RRT. Using multivariable Cox proportional hazard modeling, niacinamide was associated with a lower risk of RRT or death (HR, 0.64; 95% CI, 0.40 to 1.00; P=0.05), an association driven by patients with KDIGO stage-2/3 AKI (HR, 0.29; 95% CI, 0.13 to 0.65; P=0.03; P interaction with KDIGO stage=0.03). Total mortality also followed this pattern (HR, 0.17; 95% CI, 0.05 to 0.52; in patients with KDIGO stage-2/3 AKI, P=0.002). Serum creatinine after AKI increased by 0.20 (SEM, 0.08) mg/dl per day among non-B3 patients with KDIGO stage-2/3 AKI, but was stable among comparable B3 patients (+0.01 [SEM, 0.06] mg/dl per day; P interaction=0.03).

Conclusions

Niacinamide was associated with lower risk of RRT/death and improved creatinine trajectory among patients with severe COVID-19-related AKI. Larger randomized studies are necessary to establish a causal relationship.

Outcomes of COVID-19 in Patients With a History of Cancer and Comorbid Cardiovascular Disease

BACKGROUND

Cancer and cardiovascular disease (CVD) are independently associated with adverse outcomes in patients with COVID-19. However, outcomes in patients with COVID-19 with both cancer and comorbid CVD are unknown.

METHODS

This retrospective study included 2,476 patients who tested positive for SARS-CoV-2 at 4 Massachusetts hospitals between March 11 and May 21, 2020. Patients were stratified by a history of either cancer (n=195) or CVD (n=414) and subsequently by the presence of both cancer and CVD (n=82). We compared outcomes between patients with and without cancer and patients with both cancer and CVD compared with patients with either condition alone. The primary endpoint was COVID-19-associated severe disease, defined as a composite of the need for mechanical ventilation, shock, or death. Secondary endpoints included death, shock, need for mechanical ventilation, need for supplemental oxygen, arrhythmia, venous thromboembolism, encephalopathy, abnormal troponin level, and length of stay.

RESULTS

Multivariable analysis identified cancer as an independent predictor of COVID-19-associated severe disease among all infected patients. Patients with cancer were more likely to develop COVID-19-associated severe disease than were those without cancer (hazard ratio [HR], 2.02; 95% CI, 1.53-2.68; P<.001). Furthermore, patients with both cancer and CVD had a higher likelihood of COVID-19-associated severe disease compared with those with either cancer (HR, 1.86; 95% CI, 1.11-3.10; P=.02) or CVD (HR, 1.79; 95% CI, 1.21-2.66; P=.004) alone. Patients died more frequently if they had both cancer and CVD compared with either cancer (35% vs 17%; P=.004) or CVD (35% vs 21%; P=.009) alone. Arrhythmias and encephalopathy were also more frequent in patients with both cancer and CVD compared with those with cancer alone.

CONCLUSIONS

Patients with a history of both cancer and CVD are at significantly higher risk of experiencing COVID-19-associated adverse outcomes. Aggressive public health measures are needed to mitigate the risks of COVID-19 infection in this vulnerable patient population.

Predictors of steroid-refractory immune checkpoint inhibitor associated myocarditis

Background/Introduction

Immune checkpoint inhibitor (ICI)-associated myocarditis has a high mortality rate of approximately 50%. Clinical decompensation often occurs despite first-line treatment with corticosteroids. Factors associated with steroid failure are currently unknown.

Purpose

To identify predictors of steroid failure in patients with ICI-associated myocarditis.

Methods

We developed a web-based registry to collect and study 157 cases with clinical manifestations of ICI-associated myocarditis across 16 countries. Steroid failure was defined as patients who were escalated to immunomodulators after ≥1mg/kg daily dose of prednisone or had in-hospital death due to myocarditis despite ≥1mg/kg daily dose of prednisone. Steroid response was defined as all other patients treated with steroids without escalation to immunomodulators and without death due to myocarditis. A multivariate logistic model accounting for age and sex was used to predict association with steroid failure.

Results

Compared to steroid responsive cases, steroid failure was more likely to result in fulminant myocarditis (56.7% vs 19.6%, OR=5.37 [2.62–10.98] p&lt;0.001) and all-cause in-hospital mortality (49.1% vs 12.9%, OR=6.50 [2.86–14.73] p&lt;0.001) with shorter time from presentation to death (27.5 vs 43.0 days HR: 2.56 [1.45–4.50] p=0.001). When adjusting for age and sex, cases were more likely to be steroid-refractory if they were female (46.7% vs 30.1%, OR=2.77 [1.31–5.85] p=0.007), higher body mass index (27.2 vs 22.0, OR=1.09 [1.01–1.18] p=0.012), had higher intake creatine kinase (2800.5 vs 528.0 U/L, OR=1.48 [1.14–1.90] p=0.003) had higher intake troponin T (1.40 vs 0.25 ng/mL OR=1.63 [1.00–2.64] p=0.049), or had one or more concomitant non-cardiac immune-related adverse event (90.0% vs 74.2%, OR=3.10 [1.14–8.25] p&lt;0.026). The only immune-related adverse events independently associated with steroid failure in myocarditis were myasthenia gravis-like syndrome (26.7% vs 8.2%, OR=3.84 [1.47–10.10] p=0.006) and myositis (45.0% vs 24.7%, OR=2.38 [1.16–4.92] p=0.018). Steroid failure was not significantly associated with cardiovascular or autoimmune history but was associated with a history of thymoma (12.0% vs 2.6%, OR=18.86 [0.10–356.7] p=0.05)

Conclusion(s)

Features such as female sex, high body mass index, and pre-existing thymoma as well as findings of elevated cardiac biomarkers and other non-cardiac immune-related adverse events – particularly myositis and myasthenia gravis-like syndrome – may represent a steroid-refractory phenotype of ICI-associated myocarditis. These results suggest that a multidisciplinary approach to diagnosing concomitant non-cardiac immune related adverse events is key to risk-stratifying ICI-associated myocarditis.

Forrest Plot

Funding Acknowledgement

Type of funding source: Private hospital(s). Main funding source(s): National Institutes of Health

Management of Cardiovascular Disease During Coronavirus Disease (COVID-19) Pandemic

Patients with pre-existing cardiovascular disease and risk factors are more likely to experience adverse outcomes associated with the novel coronavirus disease-2019 (COVID-19). Additionally, consistent reports of cardiac injury and de novo cardiac complications, including possible myocarditis, arrhythmia, and heart failure in patients without prior cardiovascular disease or significant risk factors, are emerging, possibly due to an accentuated host immune response and cytokine release syndrome. As the spread of the virus increases exponentially, many patients will require medical care either for COVID-19 related or traditional cardiovascular issues. While the COVID-19 pandemic is dominating the attention of the healthcare system, there is an unmet need for a standardized approach to deal with COVID-19 associated and other traditional cardiovascular issues during this period. We provide consensus guidance for the management of various cardiovascular conditions during the ongoing COVID-19 pandemic with the goal of providing the best care to all patients and minimizing the risk of exposure to frontline healthcare workers.

Changes in Citric Acid Cycle and Nucleoside Metabolism Are Associated with Anthracycline Cardiotoxicity in Patients with Breast Cancer

Anthracyclines and HER2-targeted antibodies are very effective for the treatment of breast cancer, but their use is limited by cardiotoxicity. In this nested case-control study, we assessed the role of intermediary metabolism in 38 women with breast cancer treated with anthracyclines and trastuzumab. Using targeted mass spectrometry to measure 71 metabolites in the plasma, we identified changes in citric acid and aconitic acid that differentiated patients who developed cardiotoxicity from those who did not. In patients with cardiotoxicity, the magnitude of change in citric acid at three months correlated with the change in left ventricular ejection fraction (LVEF) and absolute LVEF at nine months. Patients with cardiotoxicity also demonstrated more pronounced changes in purine and pyrimidine metabolism. Early metabolic changes may therefore provide insight into the mechanisms associated with the development of chemotherapy-associated cardiotoxicity.

Cardioprotection in cancer therapy: novel insights with anthracyclines

Anthracyclines are a class of antineoplastic agents that remain critical to modern-day cancer treatment. However, their propensity to cause cardiotoxic effects limits their use and can cause increased morbidity and mortality among patients with cancer. Currently available methods to minimize the impact of anthracycline cardiotoxicity have not been widely successful. While it is largely accepted that the generation of oxygen radicals contributes to the development of anthracycline cardiotoxicity, the exact mechanisms of cardiomyocyte injury remain unclear. In this review, we discuss the current state of basic and translational research on the cardiotoxic mechanisms of anthracyclines that have led to the discovery of new therapeutic targets. Pending validation in patient populations, these recent advances have the potential to be translated into clinical approaches that will minimize anthracycline cardiotoxicity and improve outcomes in cancer survivors.

Gender differences in industry payments among cardiologists

BACKGROUND

There is a wage gap among men and women practicing cardiology. Differences in industry funding can be both a consequence of and a contributor to gender differences in salaries. We sought to determine whether gender differences exist in the distribution, types, and amounts of industry payments among men and women in cardiology.

METHODS

In this cross-sectional analysis, we used the Centers for Medicare & Medicaid Services Open Payment program database to obtain 2016 industry payment data for US cardiologists. We also used UK Disclosure data to obtain 2016 industry payments to UK cardiologists. Outcomes included the proportions of male and female cardiologists receiving industry funding and the mean industry payment amounts received by male and female cardiologists. Where possible, we also assessed 2014 and 2015 data in both locations.

RESULTS

Of the 22,848 practicing Centers for Medicare & Medicaid Services US cardiologists in 2016, 20,037 (88%) were men and 2,811 (12%) were women. Proportionally more men than women received industry payments in 2016 (78.0% vs 68.5%, respectively; P < .001). Men received higher overall mean industry payments than women ($6,193.25 vs. $2,501.55, P < .001). Results were similar in 2014 and 2015. Among UK cardiologists, more men (24.4%) than women (13.5%) received industry payments in 2016 (P < .001). However, although the difference in overall industry payments was numerically larger among men compared to women, this did not achieve statistical significance (£2,348.31 vs £1,501.37, respectively, P = .35).

CONCLUSIONS

Industry payments to cardiologists are common, and there are gender differences in these payments on both sides of the Atlantic.

Cyp1 Inhibition Prevents Doxorubicin-Induced Cardiomyopathy in a Zebrafish Heart-Failure Model

Doxorubicin is a highly effective chemotherapy agent used to treat many common malignancies. However, its use is limited by cardiotoxicity, and cumulative doses exponentially increase the risk of heart failure. To identify novel heart failure treatment targets, a zebrafish model of doxorubicin-induced cardiomyopathy was previously established for small-molecule screening. Using this model, several small molecules that prevent doxorubicin-induced cardiotoxicity both in zebrafish and in mouse models have previously been identified. In this study, exploration of doxorubicin cardiotoxicity is expanded by screening 2271 small molecules from a proprietary, target-annotated tool compound collection. It is found that 120 small molecules can prevent doxorubicin-induced cardiotoxicity, including 7 highly effective compounds. Of these, all seven exhibited inhibitory activity towards cytochrome P450 family 1 (CYP1). These results are consistent with previous findings, in which visnagin, a CYP1 inhibitor, also prevents doxorubicin-induced cardiotoxicity. Importantly, genetic mutation of cyp1a protected zebrafish against doxorubicin-induced cardiotoxicity phenotypes. Together, these results provide strong evidence that CYP1 is an important contributor to doxorubicin-induced cardiotoxicity and highlight the CYP1 pathway as a candidate therapeutic target for clinical cardioprotection.

A small-molecule allosteric inhibitor of BAX protects against doxorubicin-induced cardiomyopathy

Doxorubicin remains an essential component of many cancer regimens, but its use is limited by lethal cardiomyopathy, which has been difficult to target, owing to pleiotropic mechanisms leading to apoptotic and necrotic cardiac cell death. Here we show that BAX is rate-limiting in doxorubicin-induced cardiomyopathy and identify a small-molecule BAX inhibitor that blocks both apoptosis and necrosis to prevent this syndrome. By allosterically inhibiting BAX conformational activation, this compound blocks BAX translocation to mitochondria, thereby abrogating both forms of cell death. When co-administered with doxorubicin, this BAX inhibitor prevents cardiomyopathy in zebrafish and mice. Notably, cardioprotection does not compromise the efficacy of doxorubicin in reducing leukemia or breast cancer burden in vivo, primarily due to increased priming of mitochondrial death mechanisms and higher BAX levels in cancer cells. This study identifies BAX as an actionable target for doxorubicin-induced cardiomyopathy and provides a prototype small-molecule therapeutic.

Abstract P5-14-06: Statins to mitigate cardiotoxicity in breast cancer patients treated with anthracyclines and/or trastuzumab: A systematic review and meta-analysis

Background: Due to advances in treatment and early detection, nearly 90% of women with breast cancer are living at least 5 years following their diagnosis. Yet, there is a risk for cardiotoxicity as a result of cancer treatments such as anthracyclines and/or trastuzumab. Recent evidence has demonstrated the potential for statins to mitigate the risk of cardiotoxicity. This systematic review and meta-analysis was aimed to address the research question of: Does statin use lower the risk of cardiotoxicity among breast cancer patients who receive treatment with anthracyclines and/or trastuzumab? Methods: A systematic review of the literature was conducted using the databases PubMed, Embase, Web of Science, ClinicalTrials.gov, and Cochrane Central. Two reviewers independently performed study selection and data extraction. Five studies were identified, of which only one was a prospective randomized controlled trial; all examined statin use among breast cancer patients treated with anthracyclines and/or trastuzumab; four studies examined the primary outcome of cardiotoxicity defined as 1) incidence of heart failure or 2) having a reduction in left ventricular ejection fraction of &gt;10% from baseline to an absolute value of &lt;50%; and three studies included the secondary outcome of mean change in left ventricular ejection fraction from baseline (before statin use) to the time of collected outcome. Pooled relative risks and weighted mean differences using study-specific estimates were calculated, and a random-effects model using inverse variance weighting was applied. Results: Data were available on 890 patients (two studies also included gastric cancer, leukemia, and lymphoma), all treated with anthracyclines and/or trastuzumab. For the primary outcome of cardiotoxicity, there was a decreased risk of cardiotoxicity in patients treated with statins versus control (6.85% vs 13.89%, relative risk of 0.49 (95% CI 0.31 to 0.79), p = 0.003). For the secondary outcome, there was a smaller decline in left ventricular ejection fraction from baseline among statin users compared to controls with risk difference of 5.35% (95% CI 2.48 to 8.21), p &lt; 0.001. Sensitivity analyses in studies restricted to breast cancer patients showed consistent results. Conclusions: Statins are associated with decreased overall risk of cardiotoxicity and mitigate changes in left ventricular ejection fraction among cancer patients treated with anthracyclines and/or trastuzumab. While small sample sizes and retrospective design for most studies are a limitation of this meta-analyses and further research is warranted, statin use is a potential solution to mitigate cardiotoxicity from breast cancer treatment.

Citation Format: Jacqueline B Vo, Arielle Abovich, Mary Obasi, Yawen Gao, Anju Nohria, Aarti Asnani, Ann H Partridge. Statins to mitigate cardiotoxicity in breast cancer patients treated with anthracyclines and/or trastuzumab: A systematic review and meta-analysis [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P5-14-06.

Fluoropyrimidine-Associated Cardiotoxicity: A Retrospective Case-Control Study

BACKGROUND

The fluoropyrimidines, 5-fluorouracil (5-FU) and capecitabine, are commonly used chemotherapeutic agents that have been associated with coronary vasospasm.

METHODS

In this retrospective case-control study, we identified patients at our institution who received 5-FU or capecitabine in 2018. We compared characteristics of patients who experienced cardiotoxicity with controls. We described phenotypes and outcomes of cardiotoxic cases.

RESULTS

We identified 177 patients who received fluoropyrimidines. After adjudication, 4.5% of the cohort met the criteria for cardiovascular toxicity. Coronary artery disease was more common among cases than controls (38% vs. 7%, p < .05). There was also a trend toward increased prevalence of cardiovascular risk factors in cases compared with controls. Most cardiotoxic cases had chest pain, although a minority of cases presented with nonischemic cardiomyopathy.

CONCLUSION

Cardiotoxicity phenotypes associated with fluoropyrimidine use are not limited to coronary vasospasm. Cardiac risk factors and ischemic heart disease were highly prevalent among patients with cardiotoxicity.

Fluoropyrimidine-Associated Cardiotoxicity

Fluoropyrimidines are chemotherapeutic agents that confer great benefit to many patients with solid tumors, but their use is often limited by cardiotoxicity. The incidence and precise mechanisms of cardiotoxicity remain uncertain. Clinical presentations of fluoropyrimidine toxicity are varied and include chest pain, myocardial infarction, acute cardiomyopathy, arrhythmia, cardiogenic shock, and sudden cardiac death. Proposed mechanisms include coronary vasospasm, coronary endothelial dysfunction, direct myocardial toxicity, myocarditis, and Takotsubo cardiomyopathy. Therapeutic and prophylactic interventions primarily target coronary vasospasm as the underlying cause. Prospective studies are needed to develop evidence-based approaches to cardioprotection in patients receiving fluoropyrimidines.

A novel network-based approach for discovering dynamic metabolic biomarkers in cardiovascular disease

Metabolic biomarkers may play an important role in the diagnosis, prognostication and assessment of response to pharmacological therapy in complex diseases. The process of discovering new metabolic biomarkers is a non-trivial task which involves a number of bioanalytical processing steps coupled with a computational approach for the search, prioritization and verification of new biomarker candidates. Kinetic analysis provides an additional dimension of complexity in time-series data, allowing for a more precise interpretation of biomarker dynamics in terms of molecular interaction and pathway modulation. A novel network-based computational strategy for the discovery of putative dynamic biomarker candidates is presented, enabling the identification and verification of unexpected metabolic signatures in complex diseases such as myocardial infarction. The novelty of the proposed method lies in combining metabolic time-series data into a superimposed graph representation, highlighting the strength of the underlying kinetic interaction of preselected analytes. Using this approach, we were able to confirm known metabolic signatures and also identify new candidates such as carnosine and glycocholic acid, and pathways that have been previously associated with cardiovascular or related diseases. This computational strategy may serve as a complementary tool for the discovery of dynamic metabolic or proteomic biomarkers in the field of clinical medicine.

Cardiotoxicities associated with immune checkpoint inhibitors

This review provides an overview of clinical manifestations, diagnostic approaches, and management strategies for cardiotoxicities associated with the use of immune checkpoint inhibitors (ICI). ICI therapy represents a novel treatment modality for advanced-stage malignancies, including melanoma, metastatic renal cell cancer, and non-small cell lung cancers. ICIs have been shown to provide significant mortality benefit and are generally well-tolerated. The major adverse effects associated with ICIs are immune-mediated toxicities, which can affect multiple different organ systems. Immune-mediated cardiotoxicity is quickly gaining recognition as a rare but devastating consequence of ICI therapy. ICI-associated cardiotoxicity can manifest in a variety of ways, including fulminant lymphocytic myocarditis, supraventricular and ventricular arrhythmias, pericardial disease, and even Takotsubo-like cardiomyopathy. While not entirely clear, the primary mechanism of injury has been hypothesized to involve hyperactivation and infiltration of cytotoxic T-cells into cardiovascular tissue. The diagnosis is typically made using cardiac biomarkers and imaging, in conjunction with endomyocardial biopsy when necessary. Treatment options remain limited and generally focus on immunosuppression.

Chest Pain During Chemotherapy: A Case of Severe Myocardial Bridging

A cancer patient presented with acute chest pain at rest 40 hours after IV fluorouracil infusion. Angiography showed evidence of myocardial bridging.

Highly potent visnagin derivatives inhibit Cyp1 and prevent doxorubicin cardiotoxicity

Anthracyclines such as doxorubicin are highly effective chemotherapy agents used to treat many common malignancies. However, their use is limited by cardiotoxicity. We previously identified visnagin as protecting against doxorubicin toxicity in cardiac but not tumor cells. In this study, we sought to develop more potent visnagin analogs in order to use these analogs as tools to clarify the mechanisms of visnagin-mediated cardioprotection. Structure-activity relationship studies were performed in a zebrafish model of doxorubicin cardiomyopathy. Movement of the 5-carbonyl to the 7 position and addition of short ester side chains led to development of visnagin analogs with 1,000-fold increased potency in zebrafish and 250-fold increased potency in mice. Using proteomics, we discovered that doxorubicin caused robust induction of Cytochrome P450 family 1 (CYP1) that was mitigated by visnagin and its potent analog 23. Treatment with structurally divergent CYP1 inhibitors, as well as knockdown of CYP1A, prevented doxorubicin cardiomyopathy in zebrafish. The identification of potent cardioprotective agents may facilitate the development of new therapeutic strategies for patients receiving cardiotoxic chemotherapy. Moreover, these studies support the idea that CYP1 is an important contributor to doxorubicin cardiotoxicity and suggest that modulation of this pathway could be beneficial in the clinical setting.

Management of atrial fibrillation in patients taking targeted cancer therapies

Atrial fibrillation (AF) is frequently observed in patients being treated for cancer and can lead to increased morbidity and mortality in this population. With the use of newer, targeted cancer therapies, several drug-drug interactions have emerged that complicate the use of antiarrhythmic drugs (AADs) in patients with active malignancy. Moreover, specific targeted therapies such as ibrutinib may contribute directly to the development of AF. The decision to pursue systemic anticoagulation can be challenging in patients with malignancy due to a number of factors, including the need for frequent procedures, the presence of malignancy-related risk factors for bleeding, and limited data regarding the safety of the novel oral anticoagulants (NOACs) in cancer patients. This review describes the challenges associated with AF management in patients with cancer and highlights a number of important drug-drug interactions that can impact patient management.

Cardiac Toxicity of Cancer Chemotherapy

With the aging of the population, the number of patients diagnosed with cancer has grown significantly over the past few decades. In parallel, survival rates have improved due to the increased efficacy and tolerability of cancer treatments. As such, the acute and long-term toxicities of cancer therapies have become increasingly prominent as contributors to morbidity and mortality in cancer survivors. Cardiac toxicity can occur with a broad range of cancer treatments, from conventional cytotoxic agents to newer targeted and immune-based therapies. Common manifestations of chemotherapy-associated cardiotoxicity include asymptomatic left ventricular dysfunction, congestive heart failure, myocardial ischemia, myocarditis, QT prolongation, and arrhythmia. In this review, we will describe antitumor agents that have commonly been associated with an increased risk of cardiac toxicity, with an emphasis on clinical manifestations, underlying mechanisms, and cardioprotective strategies that can be implemented in this setting.