Genotyping the risk of anthracycline-induced cardiotoxicity

Revisiting treatment-related cardiotoxicity in patients with malignant lymphoma-a review and prospects for the future

Treatment of malignant lymphoma has for years been represented by many cardiotoxic agents especially anthracyclines, cyclophosphamide, and thoracic irradiation. Although they are in clinical practice for decades, the precise mechanism of cardiotoxicity and effective prevention is still part of the research. At this article we discuss most routinely used anti-cancer drugs in chemotherapeutic regiments for malignant lymphoma with the focus on novel insight on molecular mechanisms of cardiotoxicity. Understanding toxicity at molecular levels may unveil possible targets of cardioprotective supportive therapy or optimization of current therapeutic protocols. Additionally, we review novel specific targeted therapy and its challenges in cardio-oncology.

SIRT1 activation and its effect on intercalated disc proteins as a way to reduce doxorubicin cardiotoxicity

According to the World Health Organization, the neoplasm is one of the main reasons for morbidity and mortality worldwide. At the same time, application of cytostatic drugs like an independent type of cancer treatment and in combination with surgical methods, is often associated with the development of cardiovascular complications both in the early and in the delayed period of treatment. Doxorubicin (DOX) is the most commonly used cytotoxic anthracycline antibiotic. DOX can cause both acute and delayed side effects. The problem is still not solved, as evidenced by the continued activity of researchers in terms of developing approaches for the prevention and treatment of cardiovascular complications. It is known, the heart muscle consists of cardiomyocytes connected by intercalated discs (ID), which ensure the structural, electrical, metabolic unity of the heart. Various defects in the ID proteins can lead to the development of cardiovascular diseases of various etiologies, including DOX-induced cardiomyopathy. The search for ways to influence the functioning of ID proteins of the cardiac muscle can become the basis for the creation of new therapeutic approaches to the treatment and prevention of cardiac pathologies. SIRT1 may be an interesting cardioprotective variant due to its wide functional significance. SIRT1 activation triggers nuclear transcription programs that increase the efficiency of cellular, mitochondrial metabolism, increases resistance to oxidative stress, and promotes cell survival. It can be assumed that SIRT1 can not only provide a protective effect at the cardiomyocytes level, leading to an improvement in mitochondrial and metabolic functions, reducing the effects of oxidative stress and inflammatory processes, but also have a protective effect on the functioning of IDs structures of the cardiac muscle.

Venetoclax Induces Cardiotoxicity through Modulation of Oxidative-Stress-Mediated Cardiac Inflammation and Apoptosis via NF-κB and BCL-2 Pathway

Cardiovascular damage induced by anticancer therapy has become the main health problem after tumor elimination. Venetoclax (VTX) is a promising novel agent that has been proven to have a high efficacy in multiple hematological diseases, especially acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL). Considering its mechanism of action, the possibility that VTX may cause cardiotoxicity cannot be ruled out. Therefore, this study was designed to investigate the toxic effect of VTX on the heart. Male Sprague-Dawley rats were randomly divided into three groups: control, low-dose VTX (50 mg/kg via oral gavage), and high-dose VTX (100 mg/kg via oral gavage). After 21 days, blood and tissue samples were collected for histopathological, biochemical, gene, and protein analyses. We demonstrated that VTX treatment resulted in cardiac damages as evidenced by major changes in histopathology and markedly elevated cardiac enzymes and hypertrophic genes markers. Moreover, we observed a drastic increase in oxidative stress, as well as inflammatory and apoptotic markers, with a remarkable decline in the levels of Bcl-2. To the best of our knowledge, this study is the first to report the cardiotoxic effect of VTX. Further experiments and future studies are strongly needed to comprehensively understand the cardiotoxic effect of VTX.

Genetic basis of anthracyclines cardiotoxicity: Literature review

The purpose of this review was to systematize data on molecular genetic markers of increased risk of cardiotoxic effects, as well as to search for risk and protective variants of candidate genes. Today, the therapy of malignant neoplasms is based on the use of anthracyclines – drugs of the cytostatic mechanism of action. Along with their effectiveness, these drugs can have a cardiotoxic effect on cardiomyocytes by increasing the amount of reactive oxygen species and disrupting mitochondrial biogenesis. Pathological disorders lead to an increased risk of myocardial dysfunction and a number of other cardiovascular pathologies in patients receiving chemotherapy using anthracyclines. The cardiotoxic effect of anthracyclines leads to cardiomyopathy, heart failure, myocardial infarction, and thrombosis. Early detection of cardiotoxic damage leads to reducing the negative effects of these drugs due to changes in chemotherapy tactics. It is known that the risk of cardiotoxic myocardial damage is genetically determined and controlled by more than 80 genes. In this review, the description of basic molecules such as ATP-binding cassette transporters and solute carrier family (SLC transporters), carbonyl reductase, molecules of antioxidant defense, xenobiotic and iron metabolism was performed. In addition, a special attention is paid to the study of epigenetic and post-translational regulation. The available data are characterized by some inconsistency that may be explained by the ethnic differences of the studied populations. Thus, a more detailed research of various ethnic groups, gene-gene interactions between potential candidate genes and epigenetic regulation is necessary. Thus, understanding the contribution of genetic polymorphism to the development of cardiotoxicity will help to assess the individual risks of cardiovascular pathology in patients with various types of cancer, as well as reduce the risk of myocardial damage by developing individual preventive measures and correcting chemotherapy.

Nicotinamide Riboside for the Prevention and Treatment of Doxorubicin Cardiomyopathy. Opportunities and Prospects

Despite the progress in the development of new anticancer strategies, cancer is rapidly spreading around the world and remains one of the most common diseases. For more than 40 years, doxorubicin has been widely used in the treatment of solid and hematological tumors. At the same time, the problem of its cardiotoxicity remains unresolved, despite the high efficiency of this drug. Symptomatic therapy is used as a treatment for side-effects of doxorubicin or pathological conditions that have already appeared in their background. To date, there are no treatment methods for doxorubicin cardiomyopathy as such. A drug such as nicotinamide riboside can play an important role in solving this problem. Nicotinamide riboside is a pyridine nucleoside similar to vitamin B3 that acts as a precursor to NAD⁺. There is no published research on nicotinamide riboside effects on cardiomyopathy, despite the abundance of works devoted to the mechanisms of its effects in various pathologies. The review analyzes information about the effects of nicotinamide riboside on various experimental models of pathologies, its role in the synthesis of NAD⁺, and also considers the possibility and prospects of its use for the prevention of doxorubicin cardiomyopathy.

SULT genetic polymorphisms: physiological, pharmacological and clinical implications

INTRODUCTION

Cytosolic sulfotransferases (SULTs)-mediated sulfation is critically involved in the metabolism of key endogenous compounds, such as catecholamines and thyroid/steroid hormones, as well as a variety of drugs and other xenobiotics. Studies performed in the past three decades have yielded a good understanding about the enzymology of the SULTs and their structural biology, phylogenetic relationships, tissue/organ-specific/developmental expression, as well as the regulation of the SULT gene expression. An emerging area is related to the functional impact of the SULT genetic polymorphisms.

AREAS COVERED

The current review aims to summarize our current knowledge about the above-mentioned aspects of the SULT research. An emphasis is on the information concerning the effects of the polymorphisms of the SULT genes on the functional activity of the SULT allozymes and the associated physiological, pharmacological, and clinical implications.

EXPERT OPINION

Elucidation of how SULT SNPs may influence the drug-sulfating activity of SULT allozymes will help understand the differential drug metabolism and eventually aid in formulating personalized drug regimens. Moreover, the information concerning the differential sulfating activities of SULT allozymes toward endogenous compounds may allow for the development of strategies for mitigating anomalies in the metabolism of these endogenous compounds in individuals with certain SULT genotypes.

Role of Oxidative Stress in the Mechanisms of Anthracycline-Induced Cardiotoxicity: Effects of Preventive Strategies

Anthracycline-induced cardiotoxicity (AIC) persists as a significant cause of morbidity and mortality in cancer survivors. Although many protective strategies have been evaluated, cardiotoxicity remains an ongoing threat. The mechanisms of AIC remain unclear; however, several pathways have been proposed, suggesting a multifactorial origin. When the central role of topoisomerase 2β in the pathophysiology of AIC was described some years ago, the classical reactive oxygen species (ROS) hypothesis shifted to a secondary position. However, new insights have reemphasized the importance of the role of oxidative stress-mediated signaling as a common pathway and a critical modulator of the different mechanisms involved in AIC. A better understanding of the mechanisms of cardiotoxicity is crucial for the development of treatment strategies. It has been suggested that the available therapeutic interventions for AIC could act on the modulation of oxidative balance, leading to a reduction in oxidative stress injury. These indirect antioxidant effects make them an option for the primary prevention of AIC. In this review, our objective is to provide an update of the accumulated knowledge on the role of oxidative stress in AIC and the modulation of the redox balance by potential preventive strategies.

Possible Susceptibility Genes for Intervention against Chemotherapy-Induced Cardiotoxicity

Recent therapeutic advances have significantly improved the short- and long-term survival rates in patients with heart disease and cancer. Survival in cancer patients may, however, be accompanied by disadvantages, namely, increased rates of cardiovascular events. Chemotherapy-related cardiac dysfunction is an important side effect of anticancer therapy. While advances in cancer treatment have increased patient survival, treatments are associated with cardiovascular complications, including heart failure (HF), arrhythmias, cardiac ischemia, valve disease, pericarditis, and fibrosis of the pericardium and myocardium. The molecular mechanisms of cardiotoxicity caused by cancer treatment have not yet been elucidated, and they may be both varied and complex. By identifying the functional genetic variations responsible for this toxicity, we may be able to improve our understanding of the potential mechanisms and pathways of treatment, paving the way for the development of new therapies to target these toxicities. Data from studies on genetic defects and pharmacological interventions have suggested that many molecules, primarily those regulating oxidative stress, inflammation, autophagy, apoptosis, and metabolism, contribute to the pathogenesis of cardiotoxicity induced by cancer treatment. Here, we review the progress of genetic research in illuminating the molecular mechanisms of cancer treatment-mediated cardiotoxicity and provide insights for the research and development of new therapies to treat or even prevent cardiotoxicity in patients undergoing cancer treatment. The current evidence is not clear about the role of pharmacogenomic screening of susceptible genes. Further studies need to done in chemotherapy-induced cardiotoxicity.

Pathophysiological mechanisms of cardiotoxicity in chemotherapeutic agents

Certain success has been achieved in the treatment of cancer due to the development of various effective chemotherapeutic drugs. However, an increase in their effectiveness (aggressiveness) was associated with a growth of undesirable effects on the entire human body, in particular, on the cardiovascular system. The damage to the cardiovascular system from chemotherapy in many cases is more significant than from the underlying disease. In recent years, a new direction of medicine has been formed - cardio-oncology. The major groups of cardiotoxic chemotherapeutic agents are anthracyclines, inhibitors of epidermal growth factor receptor type 2 (anti-HER2), antimetabolites, microtubule inhibitors, proteasome inhibitors, platinum-based chemotherapeutic drugs, and angiogenesis inhibitors (inhibitors of vascular endothelial growth factor). This review discusses principal pathophysiological mechanisms of the cardiotoxicity of these chemotherapeutic drugs.

Impact of NADPH oxidase functional polymorphisms in acute myeloid leukemia induction chemotherapy

Efficacy and toxicity of anthracycline treatment in acute myeloid leukemia (AML) is mediated by reactive oxygen species (ROS). NADPH oxidase is the major endogenous source of ROS and a key mediator of oxidative cardiac damage. The impact of NADPH oxidase polymorphisms (CYBA:rs4673, NCF4:rs1883112, RAC2:rs13058338) was evaluated in 225 adult de novo AML patients. Variant alleles of NCF4 and RAC2 were related to higher complete remission (P=0.035, P=0.016), and CYBA homozygous variant showed lower overall survival with recessive model (P=0.045). Anthracycline-induced cardiotoxicity was associated to NCF4 homozygous variant (P=0.012) and CYBA heterozygous genotype (P=0.027). Novel associations were found between variant allele of CYBA and lower lung and gastrointestinal toxicities, and a protective effect in nephrotoxicity and RAC2 homozygous variant. Moreover, RAC2 homozygous variant was related to delayed thrombocytopenia recovery. This study supports the interest of NADPH oxidase polymorphisms regarding efficacy and toxicity of AML induction therapy, in a coherent integrated manner.

Cardio-oncology: conflicting priorities of anticancer treatment and cardiovascular outcome

BACKGROUND

This article about the emerging field of cardio-oncology highlights typical side effects of oncological therapies in the cardiovascular system, cardiovascular complications of malignancies itself, and potential preventive or therapeutic modalities.

METHODS

We performed a selective literature search in PubMed until September 2016.

RESULTS

Cardiovascular events in cancer patients can be frequently attributed to oncological therapies or to the underlying malignancy itself. Furthermore, many patients with cancer have pre-existing cardiovascular diseases that can be aggravated by the malignancy or its therapy. Cardiovascular abnormalities in oncological patients comprise a broad spectrum from alterations in electrophysiological, laboratory or imaging tests to the occurrence of thromboembolic, ischemic or rhythmological events and the impairment of left ventricular function or manifest heart failure.

DISCUSSION

A close interdisciplinary collaboration between oncologists and cardiologists/angiologists as well as an increased awareness of potential cardiovascular complications could improve clinical care of cancer patients and provides a basis for an improved understanding of underlying mechanisms of cardiovascular morbidity.

Genome-wide association and pathway analysis of left ventricular function after anthracycline exposure in adults

BACKGROUND

Anthracyclines are important chemotherapeutic agents, but their use is limited by cardiotoxicity. Candidate gene and genome-wide studies have identified putative risk loci for overt cardiotoxicity and heart failure, but there has been no comprehensive assessment of genomic variation influencing the intermediate phenotype of anthracycline-related changes in left ventricular (LV) function. The purpose of this study was to identify genetic factors influencing changes in LV function after anthracycline chemotherapy.

METHODS

We conducted a genome-wide association study (GWAS) of change in LV function after anthracycline exposure in 385 patients identified from BioVU, a resource linking DNA samples to de-identified electronic medical record data. Variants with P values less than 1×10 were independently tested for replication in a cohort of 181 anthracycline-exposed patients from a prospective clinical trial. Pathway analysis was performed to assess combined effects of multiple genetic variants.

RESULTS

Both cohorts were middle-aged adults of predominantly European descent. Among 11 candidate loci identified in discovery GWAS, one single nucleotide polymorphism near PR domain containing 2, with ZNF domain (PRDM2), rs7542939, had a combined P value of 6.5×10 in meta-analysis. Eighteen Kyoto Encyclopedia of Gene and Genomes pathways showed strong enrichment for variants associated with the primary outcome. Identified pathways related to DNA repair, cellular metabolism, and cardiac remodeling.

CONCLUSION

Using genome-wide association we identified a novel candidate susceptibility locus near PRDM2. Variation in genes belonging to pathways related to DNA repair, metabolism, and cardiac remodeling may influence changes in LV function after anthracycline exposure.

Mechanisms and Genetic Susceptibility of Chemotherapy-Induced Cardiotoxicity in Patients With Breast Cancer

BACKGROUND

Cardiotoxicity remains an important adverse reaction of chemotherapy used in the treatment of breast cancer, leading to increased morbidity and mortality.

DATA SOURCES

Anthracyclines, taxanes, and trastuzumab are the most commonly used cytotoxic drugs for the treatment of breast cancer. Cardiotoxicity may vary from asymptomatic forms to irreducible heart failure and death.

AREAS OF UNCERTAINTY

Susceptibility for the occurrence of chemotherapy-induced cardiotoxicity and treatment resistance is multifactorial, with interindividual variability, determined by the interaction between genetic and phenotypic factors. Implementation of pharmacogenomic findings into clinical practice might be useful, to predict cardiotoxicity and to allow appropriate therapeutic measures.

RESULTS AND CONCLUSIONS

This review will summarize the cellular mechanisms of chemotherapy-induced cardiotoxicity in breast cancer patients and will discuss the role of the genetic susceptibility for cardiac dysfunction.

Cancer drug related cardiotoxicity during breast cancer treatment

INTRODUCTION

Breast cancer (BC) is the most common cancer in women. Although therapeutic armamentarium like chemotherapy, endocrine and target agents have increased survival, cardiovascular side effects have been observed. A comprehensive risk assessment, early detection and management of cardiac adverse events is therefore needed.

AREAS COVERED

In this review we focus on cardiotoxicity data deriving from Phase III randomized trials, systematic reviews and meta-analysis in BC patients. We provide insight into advances that have been made in the molecular mechanisms, clinical presentation and management of such adverse event.

EXPERT OPINION

Despite the large number of data from Phase III trials about cardiac events incidence, there are poor evidences for detection, monitoring and management of cardiotoxicity during BC treatment. Future cardiotoxicity-oriented clinical cancer research can help to predict the risk of cardiac adverse events and improve patients' outcome. Multidisciplinary approach as well as integration of blood biomarkers with imaging will be desirable.

Cardio-Oncology: An Update on Cardiotoxicity of Cancer-Related Treatment

Through the success of basic and disease-specific research, cancer survivors are one of the largest growing subsets of individuals accessing the healthcare system. Interestingly, cardiovascular disease is the second leading cause of morbidity and mortality in cancer survivors after recurrent malignancy. This recognition has helped stimulate a collaboration between oncology and cardiology practitioners and researchers, and the portmanteau cardio-oncology (also known as onco-cardiology) can now be found in many medical centers. This collaboration promises new insights into how cancer therapies impact cardiovascular homeostasis and long-term effects on cancer survivors. In this review, we will discuss the most recent views on the cardiotoxicity related to various classes of chemotherapy agents and radiation. We will also discuss broadly the current strategies for treating and preventing cardiovascular effects of cancer therapy.

Cardiac Outcomes in Survivors of Pediatric and Adult Cancers

More than 80% of children and 60% of adults with cancer will become long-term survivors, emphasizing the importance of late effects of cancer therapy. Cardiotoxicity due to chemotherapy and radiation is a frequent cause of serious morbidity and premature mortality in survivors. Anthracyclines, a core component of many treatment regimens, have been implicated as a principal cause of irreversible cardiomyopathy. Approximately 60% of anthracycline-treated children will develop echocardiographic evidence of cardiac dysfunction, and 10% of those treated with high-dose anthracyclines will develop congestive heart failure within the 20 years after therapy. Adults treated with trastuzumab are at risk of a cardiomyopathy that is usually reversible. As many as 12% of adults treated with trastuzumab and 20% of those who have also received an anthracycline will develop cardiotoxicity within 5 years. Risk factors for cardiomyopathy include patient (eg, age, sex, genetic predisposition) and treatment characteristics (eg, cumulative anthracycline dose). Radiotherapy to a field involving the heart increases the risk of cardiomyopathy, coronary artery disease, valvular dysfunction, arrhythmias, and pericardial disease. Surveillance guidelines are available to guide long-term cardiac follow-up of childhood cancer survivors, but not for survivors of adult cancers; however, periodic follow-up to detect cardiac dysfunction may be reasonable. Modifiable cardiac risk factors such as hypertension, smoking, and dyslipidemia interact with cancer therapies to increase the risk of cardiac disease, emphasizing the importance of risk-factor control. Coordination of care between oncologists and cardiologists would optimize care for those individuals at high risk of cardiotoxicity who would benefit from appropriate surveillance and treatment strategies.

The Crossroads of Geriatric Cardiology and Cardio-Oncology

Cancer and cardiovascular disease (CVD) are two major causes of mortality in older adults. With improved survival and outcomes from cancer and CVD, the role of the geriatrician is evolving. Geriatricians provide key skills to facilitate patient-centered and value-based care in the growing older population of cancer patients (and survivors). Cancer treatment in older adults is particularly injurious with respect to complications stemming from cancer therapy and as well as to CVD related to cancer therapy in the context of physiologic aging. To best meet their natural potential as caregiving leaders, geriatricians must hone skills and insights pertaining to oncologic and cardiovascular care, insights that can inform and enhance key management expertise. In this paper, we will review common chemotherapy and radiation-induced cardiovascular complications, screening recommendations, and advance the concept of a geriatric, cardiology, and oncology collaboration. We assert that geriatricians are well suited to a leadership role in the care of older cardio-oncology patients and in the education of primary care physicians and subspecialists on geriatric principles.

Role of DNA Methylation on the Expression of the Anthracycline Metabolizing Enzyme AKR7A2 in Human Heart

The intracardiac synthesis of anthracycline alcohol metabolites by aldo-keto reductases (AKRs) contributes to the pathogenesis of anthracycline-related cardiotoxicity. AKR7A2 is the most abundant anthracycline reductase in hearts from donors with and without Down syndrome (DS), and its expression varies between individuals (≈tenfold). We investigated whether DNA methylation impacts AKR7A2 expression in hearts from donors with (n = 11) and without DS (n = 30). Linear models were used to test for associations between methylation status and cardiac AKR7A2 expression. In hearts from donors without DS, DNA methylation status at CpG site -865 correlated with AKR7A2 mRNA (Pearson's regression coefficient, r = -0.4051, P = 0.0264) and AKR7A2 protein expression (r = -0.5818, P = 0.0071). In heart tissue from donors with DS, DNA methylation status at CpG site -232 correlated with AKR7A2 protein expression (r = 0.8659, P = 0.0025). Multiple linear regression modeling revealed that methylation at several CpG sites is associated with the synthesis of cardiotoxic daunorubicinol. AKR7A2 methylation status in lymphoblastoid cell lines from donors with and without DS was examined to explore potential parallelisms between cardiac tissue and lymphoid cells. These results suggest that DNA methylation impacts AKR7A2 expression and the synthesis of cardiotoxic daunorubicinol.

Prevention and Treatment of Cardiac Dysfunction in Breast Cancer Survivors

As recurrence free survival following a breast cancer diagnosis continues to improve, cardiovascular morbidity and mortality will assume greater importance in the breast cancer survivorship research agenda particularly for women receiving potentially cardiotoxic therapy. Development of (1) tools to readily identify pre-diagnostic risk factors for cardiac dysfunction, (2) well-tolerated prophylactic treatments to reduce the risk of cardiac injury, and (3) sensitive and affordable monitoring techniques which can identify subclinical toxicity prior to a drop in left ventricular ejection fraction are or should be focus areas of cardio-oncology research. Since weight as well as cardiorespiratory fitness generally decline after a breast cancer diagnosis, behavioral approaches which can improve energy balance and fitness are important to optimize cardiovascular health in all breast cancer survivors not just those undergoing cardiotoxic therapy. These goals are likely best achieved by partnerships between cardiologists, oncologists and internists such as those initiated with the formation of the International CardiOncology Society (ICOS) and the NCI Community Cardiotoxicity Task Force.

Current Views on Anthracycline Cardiotoxicity in Childhood Cancer Survivors

Owing to their high efficacy, anthracycline antibiotics are included in numerous chemotherapeutic regimens used-often in combination with radiation therapy and/or surgery-in treatment of solid tumours and blood malignancies, both in children and adults. However, the efficacy of modern cancer treatments, owing to which the population of cancer survivors has been on the rise in recent years, may be limited by the risk of serious complications involving multiple organs and systems, including the cardiovascular system. Being an important side effect of anthracyclines, cardiotoxicity may limit the efficacy of cancer therapies in the acute phase (i.e. during the treatment) and induce the long-term sequelae, observed years after treatment completion in childhood cancer survivors. It is very important to understand the cardiotoxicity-associated mechanisms and to determine its risk factors in order to develop and/or improve the effective countermeasures. Based on published data, the paper provides an outline of current views on anthracycline cardiotoxicity and discusses such aspects as molecular mechanisms of cardiotoxicity and its clinical manifestations as well as the new preventive strategies and diagnostic techniques used for the assessment of cardiovascular abnormalities. The widespread awareness of cancer treatment-related cardiotoxicity among the healthcare professionals may significantly improve the quality of life of the childhood cancer survivors.

Cardiotoxicity and cardioprotection in childhood cancer

Children diagnosed with cancer are now living longer as a result of advances in treatment. However, some commonly used anticancer drugs, although effective in curing cancer, can also cause adverse late effects. The cardiotoxic effects of anthracycline chemotherapy, such as doxorubicin, and radiation can cause persistent and progressive cardiovascular damage, emphasizing a need for effective prevention and treatment to reduce or avoid cardiotoxicity. Examples of risk factors for cardiotoxicity in children include higher anthracycline cumulative dose, higher dose of radiation, younger age at diagnosis, female sex, trisomy 21 and black race. However, not all who are exposed to toxic treatments experience cardiotoxicity, suggesting the possibility of a genetic predisposition. Cardioprotective strategies under investigation include the use of dexrazoxane, which provides short- and long-term cardioprotection in children treated with doxorubicin without interfering with oncological efficacy, the use of less toxic anthracycline derivatives and nutritional supplements. Evidence-based monitoring and screening are needed to identify early signs of cardiotoxicity that have been validated as surrogates of subsequent clinically significant cardiovascular disease before the occurrence of cardiac damage, in patients who may be at higher risk.

Long-term follow-up for cardiovascular disease after chemotherapy and/or radiotherapy for breast cancer in an unselected population

PURPOSE

Whereas earlier research focused on specific patient groups, this study assessed the risk of cardiovascular disease (CVD) in an unselected population curatively treated for breast cancer (BC), compared with an age-matched random sample of controls.

METHODS

Risks were determined in BC survivors and controls. CVD was divided into three categories: congestive heart failure, vascular cardiac diseases, and "other" cardiac diseases. Hazard ratios (HRs) and 95% confidence intervals (95% CI) adjusted for age, CVD, and CVD risk factors at baseline were determined by Cox regression analyses.

RESULTS

All 561 survivors of BC experienced surgery of whom 229 received (neo)adjuvant radiotherapy, 145 received chemotherapy (with or without radiotherapy), and 187 received no adjuvant therapy. During follow-up (median 9; range 5-57 years), CVD occurred in 176/561 (31%) survivors and in 398/1,635 (24%) controls. After radiotherapy, no increased risks of congestive heart failure (HR 0.5; 95% CI 0.2-1.8), vascular cardiac diseases (HR 1.1; 95% CI 0.7-1.7), or other cardiac diseases (HR 1.3; 95% CI 0.8-2.3) were found compared with controls. Similar results were found after chemotherapy for congestive heart failure (HR 1.8; 95% CI 0.6-5.8), vascular cardiac diseases (HR 1.1; 95% CI 0.5-2.3), and other cardiac diseases (HR 1.2; 95% CI 0.3-5.5).

CONCLUSIONS

In an unselected population of BC survivors, no significant increased risk of CVD after radiotherapy and/or chemotherapy was found compared with controls. However, the HRs after chemotherapy were in-line with previous studies. Future studies should include more detailed information on treatment and more specific outcome measures.

Correlation of aldo-ketoreductase (AKR) 1C3 genetic variant with doxorubicin pharmacodynamics in Asian breast cancer patients

AIMS

Aldo-ketoreductases have been implicated in the metabolism of doxorubicin. We sought to assess the influence of AKR1C3 genetic variants on doxorubicin metabolism.

METHODS

We sequenced AKR1C3 exon 5 and genotyped seven functional single nucleotide polymorphisms in CBR3, ABCB1 and SLC22A16 involved in doxorubicin pharmacology in 151 Asian breast cancer patients treated with doxorubicin-containing chemotherapy, and correlated these genotypes with doxorubicin pharmacokinetics and pharmacodynamics.

RESULTS

Two previously reported AKR1C3 intronic variants, IVS4-212 C>G and IVS4+218 G>A, were detected. The AKR1C3 IVS4-212 GG genotype was associated with significantly lower cycle 1 day 15 leucocyte (mean leucocytes 2.49 ± 1.57 × 10(9) vs. 3.85 ± 3.42 × 10(9) l(-1) , P = 0.007) and neutrophil counts (mean neutrophils 0.70 ± 1.01 × 10(9) vs. 1.56 ± 2.80 × 10(9) l(-1) , P = 0.008) and significant improvement of progression-free survival [PFS, mean PFS 49.0 (95% confidence interval 42.2-55.8) vs. 31.0 (95% confidence interval 20.7-41.2) months, P = 0.017] and overall survival [OS; mean OS 64.4 (95% confidence interval 58.3-70.5) vs. 46.3 (95% confidence interval 35.1-57.5) months, P = 0.006] compared with those carrying at least one C allele. There was no significant association between AKR1C3 IVS4-212 C>G and doxorubicin pharmacokinetics. Of the other seven single nucleotide polymorphisms genotyped, CBR3 G11A correlated with doxorubicinol area under the concentration-time curve and OS, ABCB1 G2677T/A correlated with doxorubicin clearance and platelet toxicity, while ABCB1 IVS26+59 T>G correlated with OS. The AKR1C3 IVS4-212 C<G genotype remained significantly correlated with both PFS and OS on multivariate analysis with clinical prognosticators.

CONCLUSIONS

The AKR1C3 IVS4-212 GG genotype was associated with greater haematological toxicity and longer progression-free survival and overall survival after doxorubicin-based therapy, suggesting potential interaction of this variant with doxorubicin metabolism.

Genetic susceptibility to anthracycline-related congestive heart failure in survivors of haematopoietic cell transplantation

Haematopoietic cell transplantation (HCT) survivors are at increased risk for developing congestive heart failure (CHF), primarily due to pre-HCT exposure to anthracyclines. We examined the association between the development of CHF after HCT and polymorphisms in 16 candidate genes involved in anthracycline metabolism, iron homeostasis, anti-oxidant defence, and myocardial remodelling. A nested case-control study design was used. Cases (post-HCT CHF) were identified from 2950 patients who underwent HCT between 1988 and 2007 at City of Hope and had survived ≥1 year. This cohort formed the sampling frame for selecting controls (without CHF) matched on: age, race/ethnicity, cumulative anthracycline exposure, stem cell source (allogeneic, autologous), and length of follow-up. Seventy-seven cases with pre-HCT germline DNA and 178 controls were genotyped. Multivariate analysis revealed that the odds of CHF was higher in females [Odds Ratio (OR) = 2·9, P < 0·01], individuals with pre-HCT chest radiation (OR = 4·7, P = 0·05), hypertension (OR = 2·9, P = 0·01), and with variants of genes coding for the NAD(P)H-oxidase subunit RAC2 (rs13058338, 7508T→A; OR = 2·8, P < 0·01), HFE (rs1799945, 63C→G; OR = 2·5, P = 0·05) or the doxorubicin efflux transporter ABCC2 (rs8187710, 1515G→A; OR = 4·3, P < 0·01). A combined (clinical and genetic) CHF predictive model performed better [area under the curve (AUC), 0·79] than the genetic (AUC = 0·67) or the clinical (AUC = 0·69) models alone.

Imaging of early modification in cardiomyopathy: the doxorubicin-induced model

Doxorubicin chemotherapy is effective and widely used to treat acute lymphoblastic leukemia. However, its effectiveness is hampered by a wide spectrum of dose-dependent cardiotoxicity including both morphological and functional changes, affecting primarily the myocardium. Non-invasive imaging techniques are used for the diagnosis and monitoring of these cardiotoxic effects. The purpose of this review is to summarize and compare the most common imaging techniques used in early detection and therapeutic monitoring of doxorubicin-induced cardiotoxicity and the suggested mechanisms of such side effects. Imaging techniques using echocardiography including conventional 2D and 3D echocardiography along with MRI sequences including Tagging, Cine, and quantitative MRI in detecting early myocardial damage are also reviewed. As there is a multitude of reported indices and imaging methods to assess particular functional alterations, we limit this review to the most relevant techniques based on their clinical application and their potential to early detection of doxorubicin-induced cardiotoxic effects.

The relationship between changes in functional cardiac parameters following anthracycline therapy and carbonyl reductase 3 and glutathione S transferase Pi polymorphisms

The aim of this prospective clinical study is to evaluate the relationship between changes in functional cardiac parameters following anthracycline therapy and carbonyl reductase 3 (CBR3p.V244M) and glutathione S transferase Pi (GSTP1p.I105V) polymorphisms. Seventy patients with normal cardiac function and no history of cardiac disease scheduled to undergo anthracycline chemotherapy were included in the study. The patients' cardiac function was evaluated by gated blood pool scintigraphy and echocardiography before and after chemotherapy, as well as 1 year following therapy. Gene polymorphisms were genotyped in 70 patients using TaqMan probes, validated by DNA sequencing. A deteriorating trend was observed in both systolic and diastolic parameters from GG to AA in CBR3p.V244M polymorphism. Patients with G-allele carriers of GSTP1p.I105V polymorphism were common (60%), with significantly decreased PFR compared to patiens with AA genotype. Variants of CBR3 and GSTP1 enzymes may be associated with changes in short-term functional cardiac parameters.

Oxidative stress, redox signaling, and metal chelation in anthracycline cardiotoxicity and pharmacological cardioprotection

SIGNIFICANCE

Anthracyclines (doxorubicin, daunorubicin, or epirubicin) rank among the most effective anticancer drugs, but their clinical usefulness is hampered by the risk of cardiotoxicity. The most feared are the chronic forms of cardiotoxicity, characterized by irreversible cardiac damage and congestive heart failure. Although the pathogenesis of anthracycline cardiotoxicity seems to be complex, the pivotal role has been traditionally attributed to the iron-mediated formation of reactive oxygen species (ROS). In clinics, the bisdioxopiperazine agent dexrazoxane (ICRF-187) reduces the risk of anthracycline cardiotoxicity without a significant effect on response to chemotherapy. The prevailing concept describes dexrazoxane as a prodrug undergoing bioactivation to an iron-chelating agent ADR-925, which may inhibit anthracycline-induced ROS formation and oxidative damage to cardiomyocytes.

RECENT ADVANCES

A considerable body of evidence points to mitochondria as the key targets for anthracycline cardiotoxicity, and therefore it could be also crucial for effective cardioprotection. Numerous antioxidants and several iron chelators have been tested in vitro and in vivo with variable outcomes. None of these compounds have matched or even surpassed the effectiveness of dexrazoxane in chronic anthracycline cardiotoxicity settings, despite being stronger chelators and/or antioxidants.

CRITICAL ISSUES

The interpretation of many findings is complicated by the heterogeneity of experimental models and frequent employment of acute high-dose treatments with limited translatability to clinical practice.

FUTURE DIRECTIONS

Dexrazoxane may be the key to the enigma of anthracycline cardiotoxicity, and therefore it warrants further investigation, including the search for alternative/complementary modes of cardioprotective action beyond simple iron chelation.

Cardiac side effects of anticancer treatments: new mechanistic insights

Damage to heart cells leading to heart failure is a known complication of well-established cancer therapies including anthracycline antibiotics and radiation therapy, and the cardiovascular complications of these therapies has been controlled in large part through dose limitations and modifications of delivery methods. Recent research into the cellular and molecular mechanisms for the cardiovascular effects of these therapies may lead to other cardioprotective strategies that improve effectiveness of cancer treatments. Newer cancer therapies that have been developed based upon specifically targeting oncogene signaling also have been associated with heart failure. Rapid development of a detailed understanding of how these agents cause cardiac dysfunction promises to improve outcomes in cancer patients, as well as stimulate concepts of cardiovascular homeostasis that will likely accelerate development of cardiovascular therapies.

Unexpected doxorubicin-mediated cardiotoxicity in sisters: possible role of polymorphisms in histamine n-methyl transferase

The anthracycline anticancer agent doxorubicin has long been recognized to induce a dose-limiting cardiotoxicity and may be associated with genes relevant to doxorubicin disposition. Recent reports suggest a role for a number of single nucleotide polymorphisms in anthracycline cardiotoxicity in children. We describe two adult sisters with anthracycline cardiotoxicity that developed after a relatively low dose of doxorubicin. One sister carried the variant genotype for histamine N-ethyl transferase (HNMT, rs17583889) while the other was heterozygous, suggesting a similar role for these genotypes in adults with anthracycline cardiotoxicity. Although this requires further study, these genotypes may be important in the clinical dosing, or use of the liposomal formulation of doxorubicin.

Late cardiac effects of cancer treatment

Cardiac toxicities from cancer therapy can become evident many years after treatment, and these late cardiac effects can have a profound impact on cancer survivors. There are a myriad of potential cardiovascular complications from cancer therapy, but these can be grouped into three main categories. First, vascular conditions including atherosclerosis, thrombosis, and hypertension predominate. Second, cardiac structural problems, especially valvular degeneration, can have a dramatic impact long term. Lastly, and most importantly, cardiac dysfunction and heart failure are potentially common late cardiac effects and can certainly be prevented or detected early during active cancer therapy to result in optimal outcomes. Future research on late cardiac effects in cancer survivors needs to include advanced cardiac imaging techniques, novel cardiac biomarkers, and genetic determinants of response to cancer treatment.

Mitochondrionopathy phenotype in doxorubicin-treated Wistar rats depends on treatment protocol and is cardiac-specific

Although doxorubicin (DOX) is a very effective antineoplastic agent, its clinical use is limited by a dose-dependent, persistent and cumulative cardiotoxicity, whose mechanism remains to be elucidated. Previous works in animal models have failed to use a multi-organ approach to demonstrate that DOX-associated toxicity is selective to the cardiac tissue. In this context, the present work aims to investigate in vivo DOX cardiac, hepatic and renal toxicity in the same animal model, with special relevance on alterations of mitochondrial bioenergetics. To this end, male Wistar rats were sub-chronically (7 wks, 2 mg/Kg) or acutely (20 mg/Kg) treated with DOX and sacrificed one week or 24 hours after the last injection, respectively. Alterations of mitochondrial bioenergetics showed treatment-dependent differences between tissues. No alterations were observed for cardiac mitochondria in the acute model but decreased ADP-stimulated respiration was detected in the sub-chronic treatment. In the acute treatment model, ADP-stimulated respiration was increased in liver and decreased in kidney mitochondria. Aconitase activity, a marker of oxidative stress, was decreased in renal mitochondria in the acute and in heart in the sub-chronic model. Interestingly, alterations of cardiac mitochondrial bioenergetics co-existed with an absence of echocardiograph, histopathological or ultra-structural alterations. Besides, no plasma markers of cardiac injury were found in any of the time points studied. The results confirm that alterations of mitochondrial function, which are more evident in the heart, are an early marker of DOX-induced toxicity, existing even in the absence of cardiac functional alterations.

Role of genetic susceptibility in development of treatment-related adverse outcomes in cancer survivors

Clear and unambiguous associations have been established between therapeutic exposures and specific complications. However, considerable interindividual variability is observed in the risk of developing an outcome for a given therapeutic exposure. Genetic predisposition and especially its interaction with therapeutic exposures can potentially exacerbate the toxic effect of treatment on normal tissues and organ systems, and can possibly explain the interindividual variability. This article provides a brief overview of the current knowledge about the role of genomic variation in the development of therapy-related complications. Relatively common outcomes with strong associations with therapeutic exposures, including cardiomyopathy, obesity, osteonecrosis, ototoxicity, and subsequent malignancies are discussed here. To develop a deeper understanding of the molecular underpinnings of therapy-related complications, comprehensive and near-complete collection of clinically annotated samples is critical. Methodologic issues such as study design, definition of the endpoints or phenotypes, identification of appropriate and adequately sized study population together with a reliable plan for collecting and maintaining high-quality DNA, and selection of an appropriate approach or platform for genotyping are also discussed. Understanding the etiopathogenetic pathways that lead to the morbidity is critical to developing targeted prevention and intervention strategies, optimizing risk-based health care of cancer survivors, thus minimizing chronic morbidities and improving quality of life.

National Cancer Institute-National Heart, Lung and Blood Institute/pediatric Blood and Marrow Transplant Consortium First International Consensus Conference on late effects after pediatric hematopoietic cell transplantation: long-term organ damage and dysfunction

Long-term complications after hematopoietic cell transplantation (HCT) have been studied in detail. Although virtually every organ system can be adversely affected after HCT, the underlying pathophysiology of these late effects remain incompletely understood. This article describes our current understanding of the pathophysiology of late effects involving the gastrointestinal, renal, cardiac, and pulmonary systems, and discusses post-HCT metabolic syndrome studies. Underlying diseases, pretransplantation exposures, transplantation conditioning regimens, graft-versus-host disease, and other treatments contribute to these problems. Because organ systems are interdependent, long-term complications with similar pathophysiologic mechanisms often involve multiple organ systems. Current data suggest that post-HCT organ complications result from cellular damage that leads to a cascade of complex events. The interplay between inflammatory processes and dysregulated cellular repair likely contributes to end-organ fibrosis and dysfunction. Although many long-term problems cannot be prevented, appropriate monitoring can enable detection and organ-preserving medical management at earlier stages. Current management strategies are aimed at minimizing symptoms and optimizing function. There remain significant gaps in our knowledge of the pathophysiology of therapy-related organ toxicities disease after HCT. These gaps can be addressed by closely examining disease biology and identifying those patients at greatest risk for adverse outcomes. In addition, strategies are needed for targeted disease prevention and health promotion efforts for individuals deemed at high risk because of their genetic makeup or specific exposure profile.

Anthracycline cardiotoxicity

INTRODUCTION

Anthracyclines are widely prescribed anticancer agents that cause a dose-related cardiotoxicity, often aggravated by nonanthracycline chemotherapeutics or new generation targeted drugs. Anthracycline cardiotoxicity may occur anytime in the life of cancer survivors. Understanding the molecular mechanisms and clinical correlates of cardiotoxicity is necessary to improve the therapeutic index of anthracyclines or to identify active, but less cardiotoxic analogs.

AREAS COVERED

The authors review the pharmacokinetic, pharmacodynamic and biochemical mechanisms of anthracycline cardiotoxicity and correlate them to clinical phenotypes of cardiac dysfunction. Attention is paid to bioactivation mechanisms that converted anthracyclines to reactive oxygen species (ROS) or long-lived secondary alcohol metabolites. Preclinical aspects and clinical implications of the "oxidative stress" or "secondary alcohol metabolite" hypotheses are discussed on the basis of literature that cuts across bench and evidence-based medicine. Interactions of anthracyclines with comorbidities or unfavorable lifestyle choices were identified as important cofactors of the lifetime risk of cardiotoxicity and as possible targets of preventative strategies.

EXPERT OPINION

Anthracycline cardiotoxicity is a multifactorial process that needs to be incorporated in a translational framework, where individual genetic background, comorbidities, lifestyles and other drugs play an equally important role. Fears for cardiotoxicity should not discourage from using anthracyclines in many oncologic settings. Cardioprotective strategies are available and should be used more pragmatically in routine clinical practice.

Mechanisms of anthracycline cardiotoxicity and strategies to decrease cardiac damage

Anthracyclines are common chemotherapeutic agents used to treat many different types of cancer. Unfortunately, the use of anthracyclines is limited by their cardiotoxic effects, which may become manifest as late as 20 years from initial exposure. Studies in cells and animals suggest that the mechanism of anthracycline-induced cardiotoxicity (AIC) is multifactorial. Anthracyclines induce multiple forms of cellular injury by free radical production. In addition, anthracyclines alter nucleic acid biology by intercalation into DNA and modulate intracellular signaling, leading to cell death and the disruption of homeostatic processes such as sarcomere maintenance. In an effort to decrease AIC, many strategies have been tested, but no specific therapies are universally acknowledged to prevent or treat anthracycline-induced cardiac dysfunction. Newer imaging modalities and cardiac biomarkers may be useful in improving early detection of cardiac injury and dysfunction. As long as there is no cardiac-specific therapy for AIC, evidence suggests that high-risk patients will benefit from prophylactic treatment with neurohormonal blockade by angiotensin-converting enzyme inhibitors and beta-adrenergic receptor blockers.

Adverse effects of treatment in childhood acute lymphoblastic leukemia: general overview and implications for long-term cardiac health

Survival of childhood acute lymphoblastic leukemia (ALL) is one of the greatest medical success stories of the last four decades. Unfortunately, childhood ALL survivors experience medical late effects that increase their risk of morbidity and premature death, often due to heart and vascular disease. Research has helped elucidate the mechanisms and trajectory of direct damage to the heart from treatment exposure, particularly to anthracyclines, and has also contributed knowledge on the influences of related chronic conditions, such as obesity and insulin resistance on heart health in these survivors. This article summarizes the key issues associated with early morbidity and mortality from cardiac-related disease in childhood ALL survivors and suggests directions for interventions to improve long-term outcomes.

Cardiovascular Disease

Although important advances have been made in curing childhood cancer in the last several decades, long-term survivors face considerable morbidity and mortality because of late effects from their initial anticancer therapy. By 30 years after treatment, the cumulative mortality from treatment-related medical illness actually exceeds that of mortality from cancer recurrence. Cardiovascular disease, in particular, is a leading threat to the well-being of adult survivors of childhood cancers. Unfortunately, the mechanisms of these late cardiac effects are understudied and poorly understood. This article reviews cardiotoxicity associated with 2 major anticancer regimens used in treating childhood cancer patients: anthracycline treatment and radiation therapy. The known pathophysiology and clinical cardiac risk factors that further predispose these patients to late-onset cardiac events are discussed. Basic and translational research is urgently needed to clarify pathophysiologic mechanisms of late cardiac effects and to develop therapies to improve both long-term survival and quality of life of adults cured of pediatric cancers.

Cardiovascular effects in childhood cancer survivors treated with anthracyclines

Anthracyclines are commonly used to treat childhood leukemias and lymphomas, as well as other malignancies, leading to a growing population of long-term childhood cancer survivors. However, their use is limited by cardiotoxicity, increasing survivors' vulnerability to treatment-related complications that can markedly affect their quality of life. Survivors are more likely to suffer from heart failure, coronary artery disease, and cerebrovascular accidents compared to the general population. The specific mechanisms of anthracycline cardiotoxicity are complex and remain unclear. Hence, determining the factors that may increase susceptibility to cardiotoxicity is of great importance, as is monitoring patients during and after treatment. Additionally, treatment and prevention options, such as limiting cumulative dosage, liposomal anthracyclines, and dexrazoxane, continue to be explored. Here, we review the cardiovascular complications associated with the use of anthracyclines in treating malignancies in children and discuss methods for preventing, screening, and treating such complications in childhood cancer survivors.

Late effects in the era of modern therapy for Hodgkin lymphoma

Extended-field and subtotal nodal radiation therapy (RT), developed in the 1960s, was the first reliably curative treatment for early-stage Hodgkin lymphoma (HL). However, the large volume of normal tissue irradiated resulted in significant delayed toxicity, including cardiac disease and second cancers (SCs). The 30-year cumulative incidence of heart disease among adult survivors receiving 40-45 Gy of extended-field or mantle RT is approximately 30%; the incidence of SCs is similar. Improving disease control while reducing the toxicity of treatment has been a major objective of HL trials for more than 2 decades. Contemporary involved-field RT (IFRT) reduces irradiated volumes and produces significant reductions in normal tissue dose compared with historic treatments. Recent data indicate that, compared with mantle RT, IFRT reduces the relative risk of breast cancer among young females receiving mediastinal RT by approximately 60% and also reduces cardiac dose. The recent transition to involved-node RT allows further reductions in normal tissue dose. Response-adapted therapy is being evaluated in clinical trials as a means of identifying those patients most likely to benefit from treatment reduction or intensification, enhanced screening will facilitate early intervention to reduce the clinical burden of late effects, and there is increasing interest in elucidating the genetic correlates of treatment toxicity.

Cardiovascular effects of systemic cancer treatment

Many methods of systemic anticancer treatment have detrimental effects on the cardiovascular system, thus limiting the possibility of further therapy, worsening patients' quality of life and increasing mortality. The best recognized and most clinically relevant is the cardiotoxicity of anthracyclines. Other cytotoxic drugs associated with significant risk of cardiovascular complications include alkylating agents, 5-fluorouracil and paclitaxel. Cardiovascular adverse effects are also associated with the use of targeted therapies, such as trastuzumab, bevacizumab and tyrosine kinase inhibitors, and some of the drugs used in the treatment of hematological malignancies, such as all-trans-retinoic acid and arsenic trioxide. The most serious cardiac complication of anticancer therapy is congestive heart failure, associated predominantly with the use of anthracyclines, trastuzumab and high-dose cyclophosphamide. Myocardial ischemia is mainly caused by antimetabolite and interferon alpha treatment. Other adverse effects may include hypotension, hypertension, arrhythmias and conduction disorders, edema, pericarditis and thrombo-embolic complications. The aim of this review is to summarize and critically analyze the available evidence on the cardiovascular toxicity of systemic anticancer therapies, with particular attention to the recently recognized adverse effects of targeted therapies.