Current Views on Anthracycline Cardiotoxicity in Childhood Cancer Survivors

Anthracycline-induced hypertension in pediatric cancer survivors: unveiling the long-term cardiovascular risks

BACKGROUND

Long-term cardiovascular complications are common among pediatric cancer survivors, and anthracycline-induced hypertension has become an essential reason for concern. Compared to non-cancer controls, survivors have a higher prevalence of hypertension, and as they age, their incidence rises, offering significant dangers to cardiovascular health.

MAIN BODY

Research demonstrates that exposure to anthracyclines is a major factor in the development of hypertension in children who have survived cancer. Research emphasizes the frequency and risk factors of anthracycline-induced hypertension, highlighting the significance of routine measurement and management of blood pressure. Furthermore, cardiovascular toxicities, such as hypertension, after anthracycline-based therapy are a crucial be concerned, especially for young adults and adolescents. Childhood cancer survivors deal with a variety of cardiovascular diseases, such as coronary artery disease and cardiomyopathy, which are made worse by high blood pressure. In order to prevent long-term complications, it is essential to screen for and monitor for anthracycline-induced hypertension. Echocardiography and cardiac biomarkers serve as essential tools for early detection and treatment. In order to lower cardiovascular risks in pediatric cancer survivors, comprehensive management strategies must include lifestyle and medication interventions in addition to survivor-centered care programs.

SHORT CONCLUSION

Proactive screening, monitoring, and management measures are necessary for juvenile cancer survivors due to the substantial issue of anthracycline-induced hypertension in their long-term care. To properly include these strategies into survivor-ship programs, oncologists, cardiologists, and primary care physicians need to collaborate together. The quality of life for pediatric cancer survivors can be enhanced by reducing the cardiovascular risks linked to anthracycline therapy and promoting survivor-centered care and research.

A Comprehensive Review of Cancer Drug-Induced Cardiotoxicity in Blood Cancer Patients: Current Perspectives and Therapeutic Strategies

OPINION STATEMENT

Cardiotoxicity has emerged as a serious outcome catalyzed by various therapeutic targets in the field of cancer treatment, which includes chemotherapy, radiation, and targeted therapies. The growing significance of cancer drug-induced cardiotoxicity (CDIC) and radiation-induced cardiotoxicity (CRIC) necessitates immediate attention. This article intricately unveils how cancer treatments cause cardiotoxicity, which is exacerbated by patient-specific risks. In particular, drugs like anthracyclines, alkylating agents, and tyrosine kinase inhibitors pose a risk, along with factors such as hypertension and diabetes. Mechanistic insights into oxidative stress and topoisomerase-II-B inhibition are crucial, while cardiac biomarkers show early damage. Timely intervention and prompt treatment, especially with specific agents like dexrazoxane and beta-blockers, are pivotal in the proactive management of CDIC.

Re-Exploring the Anthracycline Chemical Space for Better Anti-Cancer Compounds

The anthracycline anti-cancer drugs are intensely used in the clinic to treat a wide variety of cancers. They generate DNA double strand breaks, but recently the induction of chromatin damage was introduced as another major determinant of anti-cancer activity. The combination of these two events results in their reported side effects. While our knowledge on the structure-activity relationship of anthracyclines has improved, many structural variations remain poorly explored. Therefore, we here report on the preparation of a diverse set of anthracyclines with variations within the sugar moiety, amine alkylation pattern, saccharide chain and aglycone. We assessed the cytotoxicity in vitro in relevant human cancer cell lines, and the capacity to induce DNA- and chromatin damage. This coherent set of data allowed us to deduce a few guidelines on anthracycline design, as well as discover novel, highly potent anthracyclines that may be better tolerated by patients.

Assessment of Cardiovascular Function in Childhood Leukemia Survivors: The Role of the Right Heart

Childhood acute lymphoblastic leukemia (ALL) survivors who underwent chemotherapy with anthracyclines have an increased cardiovascular risk. The aim of the study was to evaluate left and right cardiac chamber performances and vascular endothelial function in childhood ALL survivors. Fifty-four ALL survivors and 37 healthy controls were enrolled. All patients underwent auxological evaluation, blood pressure measurements, biochemical parameters of endothelial dysfunction, flow-mediated dilatation (FMD) of the brachial artery, mean common carotid intima-media thickness (c-IMT), antero-posterior diameter of the infra-renal abdominal aorta (APAO), and echocardiographic assessment. The ALL subjects had significantly lower FMD (p = 0.0041), higher left (p = 0.0057) and right (p = 0.0021) echocardiographic/Doppler Tei index (the non-invasive index for combined systolic and diastolic ventricular function) as compared to controls. Tricuspid annular plane excursion (TAPSE) was 16.9 ± 1.2 mm vs. 24.5 ± 3.7 mm, p < 0.0001. Cumulative anthracycline doses were related to TAPSE (p < 0.001). The ALL survivors treated with anthracyclines demonstrated systo/diastolic alterations of the right ventricle and reduced endothelial function compared with healthy controls. The early recognition of subclinical cardiac and vascular impairment during follow up is of utmost importance for the cardiologist to implement strategies preventing overt cardiovascular disease considering the growing number of young adults cured after childhood ALL.

The Therapeutic Potential of Carnosine as an Antidote against Drug-Induced Cardiotoxicity and Neurotoxicity: Focus on Nrf2 Pathway

Different drug classes such as antineoplastic drugs (anthracyclines, cyclophosphamide, 5-fluorouracil, taxanes, tyrosine kinase inhibitors), antiretroviral drugs, antipsychotic, and immunosuppressant drugs are known to induce cardiotoxic and neurotoxic effects. Recent studies have demonstrated that the impairment of the nuclear factor erythroid 2–related factor 2 (Nrf2) pathway is a primary event in the pathophysiology of drug-induced cardiotoxicity and neurotoxicity. The Nrf2 pathway regulates the expression of different genes whose products are involved in antioxidant and inflammatory responses and the detoxification of toxic species. Cardiotoxic drugs, such as the anthracycline doxorubicin, or neurotoxic drugs, such as paclitaxel, suppress or impair the Nrf2 pathway, whereas the rescue of this pathway counteracts both the oxidative stress and inflammation that are related to drug-induced cardiotoxicity and neurotoxicity. Therefore Nrf2 represents a novel pharmacological target to develop new antidotes in the field of clinical toxicology. Interestingly, carnosine (β-alanyl-l-histidine), an endogenous dipeptide that is characterized by strong antioxidant, anti-inflammatory, and neuroprotective properties is able to rescue/activate the Nrf2 pathway, as demonstrated by different preclinical studies and preliminary clinical evidence. Starting from these new data, in the present review, we examined the evidence on the therapeutic potential of carnosine as an endogenous antidote that is able to rescue the Nrf2 pathway and then counteract drug-induced cardiotoxicity and neurotoxicity.

Approaches for monitoring and treating cardiomyopathy among cancer survivors following anthracycline or thoracic radiation treatment

Background

Anthracycline chemotherapy and thoracic radiation therapy (RT) are known causes of cardiomyopathy among cancer survivors, however, management guidelines for this population are lacking. In this study we describe our single institution management approach for cancer survivors with low left ventricular ejection fraction (LVEF) secondary to cancer treatment.

Methods

We conducted a retrospective descriptive study of childhood and young adult (CAYA) cancer survivors in the Adult Long-Term Follow-Up Clinic at Memorial Sloan Kettering Cancer Center enrolled between November 2005 and July 2019. Those included were treated with anthracycline and/or thoracic RT as a part of their cancer therapy and had recorded a LVEF of < 55% on at least one post-treatment echocardiogram. Details regarding survivor characteristics, screening, and management were abstracted. Differences in management approaches among survivors with LVEF of 50–54.9%, 40–49.9%, and < 40% were described. Qualitative management approaches were abstracted as well.

Results

Among 668 CAYA survivors in the initial cohort, 80 were identified who had received anthracycline and/or thoracic RT and had a LVEF of < 55%. Median age at cancer diagnosis was 16.1 years, median time from cancer diagnosis was 25.8 years, and 55% of survivors were female. Cardiology referrals, nuclear stress tests, multi-gated acquisition scans, angiograms, echocardiograms, treatment with angiotensin converting enzyme inhibitors or receptor blockers, beta-blockers, diuretics, aldosterone antagonists, aspirin, and insertion of pacemaker or implantable cardioverter-defibrillators differed by LVEF category. Documentation suggested uncertainty regarding management of survivors with borderline low-LVEF, with low-LVEF that improved on follow-up, and with subsequent cancers requiring additional treatment.

Conclusions

The management of CAYA cancer survivors with low-LVEF largely followed guidelines designed for the general population, however, uncertainty remains for issues specific to cancer survivors. Cardiomyopathy management guidelines that address issues specific to cancer survivors are needed.

Heart failure in childhood cancer survivors-a systematic review protocol

BACKGROUND

Over the past decades, the survival rate for childhood cancer has greatly improved. However, the risk of late cardiac complications after cancer treatment remains high. Previous studies have shown that the risk for heart failure among childhood cancer survivors is significantly higher than that observed in varying control populations. The aim of this systematic review is to identify, critically appraise, and synthesize existing population-based studies reporting on the frequency of heart failure, both the incidence and prevalence, that may develop after treatment for childhood cancer.

METHOD

The following databases will be searched from their inception date until May 17, 2021: MEDLINE, Embase, Scopus, CINAHL, CAB International, AMED, Global Health, PsycINFO, Web of Science, and Google Scholar. Population-based studies reporting on the incidence and/or prevalence of heart failure after the treatment of any type of childhood cancer will be included. The screening of articles, data extraction, and quality assessment will be performed independently by two reviewers. The quality and risk of bias in the included studies will be assessed by using the Effective Public Health Practice Project tool. A narrative synthesis of the extracted data will be carried out, and for studies that are sufficiently homogenous, a meta-analysis using random-effects models will be performed.

DISCUSSION

This systematic review will provide a clearer picture of the epidemiology of heart failure after the treatment of childhood cancer. The collected data will be of value for future childhood cancer treatment protocols and will offer guidance for posttreatment cardiac surveillance among survivors.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42021247622 . Registered on April 28, 2021. This protocol follows the structure of the recommendation of the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P).

The Value of Left Atrial Volume Changes in Predicting Cardiotoxicity in Patients Undergoing Anthracycline Chemotherapy

In order to study the value of left atrial volume three-dimensional echocardiography in predicting cardiotoxicity in patients with multiple myeloma undergoing anthracycline chemotherapy, a total of 53 patients with multiple myeloma who are treated in the Department of Hematology of our hospital from January 2018 to December 2020 are selected as the research object, and all patients underwent three cycles (T1-T3) of chemotherapy. Before and after each cycle of chemotherapy, the patients are examined with 3D ultrasound and serology detection. These patients are divided into the cardiotoxicity group and noncardiotoxicity group. The serological indexes and three-dimensional echocardiographic parameters between two groups are compared. Multivariate logistic regression is used to determine the independent risk factors of cardiotoxicity in patients undergoing chemotherapy. And ROC curves are performed to evaluate the diagnostic value of related indicators in predicting cardiotoxicity. A total of 53 patients with multiple myeloma are included in this study. Serological indexes (T3 cTnI and T3 Pro-BNP), T2 LAVmin, T3 LAVmin, T2 LAVprep, and T3 LAVprep in the cardiotoxicity group are significantly higher than those in the noncardiotoxicity group. Multivariate logistic regression further found that T3 cTnI, T3 Pro-BNP, T2 LAVmin, T3 LAVmin, T2 LAVprep, T3 LAVprep could be used to predict the occurrence of cardiotoxicity (P < 0.05). The results of ROC curves showed that T3 LAVmin had the most diagnostic efficiency of cardiotoxicity (AUC = 0.938; sensitivity 75.72%; specificity 93.82%). Detection of changes in left atrial volume using three-dimensional ultrasound could be used as strong predictors of cardiotoxicity caused by anthracycline chemotherapy drugs in patients with multiple myeloma.

Cardiotoxicidad por antraciclinas en supervivientes de cáncer durante la infancia

Introducción: a nivel mundial, cada año cerca de 300.000 niños entre 0 y 19 años son diagnosticados con cáncer. El porcentaje de supervivientes va en aumento, llegando a 80 % en países desarrollados y 60 % en América Latina. Sin embargo, la expectativa y la calidad de vida de estas personas pueden verse comprometidas ante el desarrollo de cardiotoxicidad, un efecto adverso asociado al uso de algunos agentes antineoplásicos, como los antracíclicos.Objetivo: resaltar los aspectos clínicos relevantes para la prevención, detección oportuna, tratamiento y seguimiento de la cardiotoxicidad secundaria a la administración de antraciclinas durante la infancia.Síntesis de contenido: reflexión teórica que presenta consideraciones clínicas relevantes para guiar las acciones de enfermería y del equipo multidisciplinario en la atención y el cuidado de la salud cardiovascular de los supervivientes de cáncer a cualquier edad. Es importante destacar que en población pediátrica la única estrategia efectiva de prevención primaria para cardiotoxicidad por antraciclinas es la administración de dexrazoxano, mientras que la prevención secundaria debe incluir detección oportuna, control y  seguimiento de las alteraciones de la función cardíaca y de los factores de riesgo cardiovascular. Por su parte, la prevención terciaria se centra en el control de la enfermedad y el manejo farmacológico. Conclusiones: no existe un  tratamiento estándar para la cardiotoxicidad inducida por quimioterapia o radioterapia, siendo el objetivo principal de este tipo de tratamientos prevenir o retrasar la remodelación del ventrículo izquierdo. Todos los supervivientes requieren seguimiento vitalicio y búsqueda activa de signos de cardiotoxicidad, siendo fundamental la acción conjunta de diferentes profesionales y la consolidación de los servicios de cardio-oncología.

Anthracycline Treatment and Left Atrial Function in Children: A Real-Time 3-Dimensional Echocardiographic Study

Anthracycline (AC) therapy is associated with left ventricular (LV) dysfunction. Left atrial (LA) size and function are used to assess LV diastolic function in heart failure in adults. Data on LA size and function following AC therapy in children is limited. We hypothesized that LA size and function will be abnormal in children following AC chemotherapy. This retrospective review included patients who received AC for pediatric cancers. Controls had normal echocardiograms performed for evaluation of chest pain, murmur, or syncope. Real-time three-dimensional echocardiography was performed to evaluate LA reservoir, conduit, and booster pump function parameters. In addition to LA volume data, LV shortening fraction, spectral and tissue Doppler variables assessing diastolic function as well as myocardial performance index was obtained. Groups with and without AC therapy were compared by student t-test and chi-square test. We evaluated 136 patients, 55 (40.4%) had received AC. There was no significant difference between the groups in LV shortening fraction, diastolic as well as global function indices. LA reservoir and conduit function parameters were significantly lower in AC group compared to controls. The booster function parameters showed variable results. It is intriguing that AC-treated children have smaller LA reservoir and abnormal booster function. We speculate that these findings may reflect early changes in LA compliance associated with AC exposure. Assessment of LA volumes and function as prognostic markers of AC-induced cardiotoxicity in children is warranted.

The utility of strain imaging in the cardiac surveillance of bone marrow transplant patients

OBJECTIVE

To evaluate the utility of two-dimensional multiplanar speckle tracking strain to assess for cardiotoxicity post allogenic bone marrow transplantation (BMT) for haematological conditions.

METHODS

Cross-sectional study of 120 consecutive patients post-BMT (80 pretreated with anthracyclines (BMT+AC), 40 BMT alone) recruited from a late effects haematology clinic, compared with 80 healthy controls, as part of a long-term cardiotoxicity surveillance study (mean duration from BMT to transthoracic echocardiogram 6±6 years). Left ventricular global longitudinal strain (LV GLS), global circumferential strain (LV GCS) and right ventricular free wall strain (RV FWS) were compared with traditionl parameters of function including LV ejection fraction (LVEF) and RV fractional area change.

RESULTS

LV GLS (-17.7±3.0% vs -20.2±1.9%), LV GCS (-14.7±3.5% vs -20.4±2.1%) and RV FWS (-22.6±4.7% vs -28.0±3.8%) were all significantly (p=0.001) reduced in BMT+AC versus controls, while only LV GCS (-15.9±3.5% vs -20.4±2.1%) and RV FWS (-23.9±3.5% vs -28.0±3.8%) were significantly (p=0.001) reduced in BMT group versus controls. Even in patients with LVEF >53%, ~75% of patients in both BMT groups demonstrated a reduction in GCS.

CONCLUSION

Multiplanar strain identifies a greater number of BMT patients with subclinical LV dysfunction rather than by GLS alone, and should be evaluated as part of post-BMT patient surveillence. Reduction in GCS is possibly due to effects of preconditioning, and is not fully explained by AC exposure.

Risk Factors of Daunorubicine Induced Early Cardiotoxicity in Childhood Acute Lymphoblastic Leukemia: A Retrospective Study

Background:

Daunorubicine, a type of anthracycline, is a drug commonly used in cancer chemotherapy that increases survival rate but consequently compromises with cardiovascular outcomes in some patients. Thus, preventing the early progression of cardiotoxicity is important to improve the treatment outcome in childhood acute lymhoblastic leukemia (ALL).

Objective:

The present study aimed to identify the risk factors in anthracycline-induced early cardiotoxicity in childhood ALL.

Methods:

This retrospective study was conducted by observing ALL-diagnosed children from 2014 to 2019 in Dr. Soetomo General Hospital. There were 49 patients who met the inclusion criteria and were treated with chemotherapy using Indonesian Childhood ALL Protocol 2013. Echocardiography was performed by pediatric cardiologists to compare before and at any given time after anthracycline therapy. Early cardiotoxicity was defined as a decline of left ventricle ejection fraction (LVEF) greater than 10% with a final LVEF < 53% during the first year of anthracycline administration. Risk factors such as sex, age, risk stratification group, and cumulative dose were identified by using multiple logistic regression. Diagnostic performance of cumulative anthracycline dose was evaluated by receiver operating characteristic (ROC) curve.

Results:

Early anthracycline-induced cardiotoxicity was observed in 5 out of 49 patients. The median cumulative dose of anthracycline was 143.69±72.68 mg/m². Thirty-three patients experienced a decreasing LVEF. The factors associated with early cardiomyopathy were age of ≥ 4 years (PR= 1.128; 95% CI: 1.015-1.254; p= 0.001), high risk group (PR= 1.135; 95% CI: 1.016-1.269; p= 0.001), and cumulative dose of ≥120 mg / m² (CI= 1.161; 95% CI:1.019-1.332).

Conclusion:

Age of ≥ 4 years, risk group, and cumulative dose of ≥120 mg/m² are significant risk factors for early cardiomyopathy in childhood ALL.

Clear cell sarcoma of the kidney in Austrian children: Long-term survival after relapse

INTRODUCTION

Clear cell sarcoma of the kidney (CCSK) is a rare malignant childhood renal tumour. Recently, the central nervous system (CNS) was found to be the most frequent site of relapse associated with a poor outcome. Optimal treatment strategies are scarce.

PATIENTS AND METHODS

Retrospective data analysis of all Austrian children with CCSK. They were enrolled in the Austrian-Hungarian Wilms Tumour Study (AHWTS) 1989, the SIOP93-01 or the SIOP2001 study between 1990 and 2019. Demographic, diagnostic, treatment-related variables and survival data were analysed.

RESULTS

We identified 12 children with CCSK (M = 7, F = 5; median age 1.6 years). All had localised disease (stage I: 2; stage II: 2; stage III: 8) at diagnosis, and a first complete remission (CR1) was achieved in 12/12. Six patients are in an ongoing CR1 (median follow-up 10 years). Six other patients had a relapse (local 1; brain 5) a median time of 2.4 years from diagnosis. Two patients died of the disease 4 months and 2.8 years after first relapse. Four of five patients with CNS relapse are in CR2 with a median follow-up time of 9.3 years after relapse diagnosis. Relapse treatment included a combination of chemotherapy, radiation and surgery. Two children received high-dose chemotherapy followed by autologous stem cell rescue, and one child received intrathecal mafosphamide. Long-term side effects after treatment were impaired tubular renal function (n = 4), cardiomyopathy (n = 1) and growth disorders (n = 1).

CONCLUSIONS

In this series, the brain was the most common site of relapse. Long-term survival after recurrence was achievable with intensive multimodal therapy.

Anthracycline-related acute cardiotoxicity in a very young Omani patient with acute myeloid leukaemia

Anthracycline-related cardiomyopathy is of concern in children treated for acute myeloid leukemia (AML). Risk is dose-dependent, increasing with higher doses. We aim to highlight the risk of early-onset cardiotoxicity with low-cumulative anthracycline dose in a young Omani boy with AML. We conclude in the presence of other known risk factors for cardiac dysfunction, there is probably no risk-free anthracycline dose.

Doxorubicin and Aclarubicin: Shuffling Anthracycline Glycans for Improved Anticancer Agents

Anthracycline anticancer drugs doxorubicin and aclarubicin have been used in the clinic for several decades to treat various cancers. Although closely related structures, their molecular mode of action diverges, which is reflected in their biological activity profile. For a better understanding of the structure-function relationship of these drugs, we synthesized ten doxorubicin/aclarubicin hybrids varying in three distinct features: aglycon, glycan, and amine substitution pattern. We continued to evaluate their capacity to induce DNA breaks, histone eviction, and relocated topoisomerase IIα in living cells. Furthermore, we assessed their cytotoxicity in various human tumor cell lines. Our findings underscore that histone eviction alone, rather than DNA breaks, contributes strongly to the overall cytotoxicity of anthracyclines, and structures containing N,N-dimethylamine at the reducing sugar prove that are more cytotoxic than their nonmethylated counterparts. This structural information will support further development of novel anthracycline variants with improved anticancer activity.

Uncoupling DNA damage from chromatin damage to detoxify doxorubicin

The anthracycline doxorubicin (Doxo) and its analogs daunorubicin (Daun), epirubicin (Epi), and idarubicin (Ida) have been cornerstones of anticancer therapy for nearly five decades. However, their clinical application is limited by severe side effects, especially dose-dependent irreversible cardiotoxicity. Other detrimental side effects of anthracyclines include therapy-related malignancies and infertility. It is unclear whether these side effects are coupled to the chemotherapeutic efficacy. Doxo, Daun, Epi, and Ida execute two cellular activities: DNA damage, causing double-strand breaks (DSBs) following poisoning of topoisomerase II (Topo II), and chromatin damage, mediated through histone eviction at selected sites in the genome. Here we report that anthracycline-induced cardiotoxicity requires the combination of both cellular activities. Topo II poisons with either one of the activities fail to induce cardiotoxicity in mice and human cardiac microtissues, as observed for aclarubicin (Acla) and etoposide (Etop). Further, we show that Doxo can be detoxified by chemically separating these two activities. Anthracycline variants that induce chromatin damage without causing DSBs maintain similar anticancer potency in cell lines, mice, and human acute myeloid leukemia patients, implying that chromatin damage constitutes a major cytotoxic mechanism of anthracyclines. With these anthracyclines abstained from cardiotoxicity and therapy-related tumors, we thus uncoupled the side effects from anticancer efficacy. These results suggest that anthracycline variants acting primarily via chromatin damage may allow prolonged treatment of cancer patients and will improve the quality of life of cancer survivors.

PET Radiopharmaceuticals for Imaging Chemotherapy-Induced Cardiotoxicity

Purpose of Review

Currently, cardiotoxicity is monitored through echocardiography or multigated acquisition scanning and is defined as 10% or higher LVEF reduction. The latter stage may represent irreversible myocardium injury and limits modification of therapeutic paradigms at earliest stages. To stratify patients for anthracycline-related heart failure, highly sensitive and molecularly specific probes capable of interrogating cardiac damage at the subcellular levels have been sought.

Recent Findings

PET tracers may provide noninvasive assessment of earliest changes within myocardium. These tracers are at nascent stages of development and belong primarily to (a) mitochondrial potential-targeted and (b) general ROS (reactive oxygen species)-targeted radiotracers. Given that electrochemical gradient changes at the mitochondrial membrane represent an upstream, and earliest event before triggering the production of the ROS and caspase activity in a biochemical cascade, the former category might offer interrogation of cardiotoxicity at earliest stages exemplified by PET imaging, using ¹⁸F-Mitophos and ⁶⁸Ga-Galmydar in rodent models.

Summary

Both categories of radiotracers may provide tools for monitoring chemotherapy-induced cardiotoxicity and interrogating therapeutic efficacy of cardio-protectants.

Uncoupling DNA damage from chromatin damage to detoxify doxorubicin

The anthracycline doxorubicin (Doxo) and its analogs daunorubicin (Daun), epirubicin (Epi), and idarubicin (Ida) have been cornerstones of anticancer therapy for nearly five decades. However, their clinical application is limited by severe side effects, especially dose-dependent irreversible cardiotoxicity. Other detrimental side effects of anthracyclines include therapy-related malignancies and infertility. It is unclear whether these side effects are coupled to the chemotherapeutic efficacy. Doxo, Daun, Epi, and Ida execute two cellular activities: DNA damage, causing double-strand breaks (DSBs) following poisoning of topoisomerase II (Topo II), and chromatin damage, mediated through histone eviction at selected sites in the genome. Here we report that anthracycline-induced cardiotoxicity requires the combination of both cellular activities. Topo II poisons with either one of the activities fail to induce cardiotoxicity in mice and human cardiac microtissues, as observed for aclarubicin (Acla) and etoposide (Etop). Further, we show that Doxo can be detoxified by chemically separating these two activities. Anthracycline variants that induce chromatin damage without causing DSBs maintain similar anticancer potency in cell lines, mice, and human acute myeloid leukemia patients, implying that chromatin damage constitutes a major cytotoxic mechanism of anthracyclines. With these anthracyclines abstained from cardiotoxicity and therapy-related tumors, we thus uncoupled the side effects from anticancer efficacy. These results suggest that anthracycline variants acting primarily via chromatin damage may allow prolonged treatment of cancer patients and will improve the quality of life of cancer survivors.

Critical Illness and Cardiac Dysfunction in Anthracycline-Exposed Pediatric Oncology Patients

OBJECTIVES

To determine if the presence of cardiac dysfunction in anthracycline-exposed pediatric oncology patients is associated with an increased frequency of PICU admission or mortality.

DESIGN

Retrospective parallel cohort study.

SETTING

PICU at an academic freestanding children's hospital.

SUBJECTS

Children with oncologic diagnoses who received anthracyclines between January 2006 and December 2014 and were admitted to the hospital within 1 year of completion of therapy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Charts of 734 patients were reviewed and 545 were included in analysis. Anthracycline-exposed pediatric oncology patients with cardiac dysfunction were more likely to be admitted to the PICU than those without cardiac dysfunction (87% vs 37% rate of PICU admission). PICU admission was also associated with identified infection and higher cumulative anthracycline dose. Once admitted to the PICU, those anthracycline-exposed patients with cardiac dysfunction had significantly higher mortality (26% vs 6%) and longer length of stay (7 vs 2 d) than children without cardiac dysfunction. Patients with cardiac dysfunction were more likely to require mechanical ventilation (59% vs 18%), required more vasoactive medications for longer, and were more likely to develop fluid overload. Death within 1 year of ICU admission was associated with higher cumulative anthracycline dose.

CONCLUSIONS

Children with cancer who received anthracyclines, especially at higher doses, and who develop cardiac dysfunction are at higher risk of critical illness, have higher rates of multiple organ dysfunction and higher rates of mortality than anthracycline-exposed patients without cardiac dysfunction.

Occurrence of Treatment-Related Cardiotoxicity and Its Impact on Outcomes Among Children Treated in the AAML0531 Clinical Trial: A Report From the Children's Oncology Group

PURPOSE

Late cardiotoxicity after pediatric acute myeloid leukemia therapy causes substantial morbidity and mortality. The impact of early-onset cardiotoxicity on treatment outcomes is less well understood. Thus, we evaluated the risk factors for incident early cardiotoxicity and the impacts of cardiotoxicity on event-free survival (EFS) and overall survival (OS).

METHODS

Cardiotoxicity was ascertained through adverse event monitoring over the course of follow-up among 1,022 pediatric patients with acute myeloid leukemia treated in the Children's Oncology Group trial AAML0531. It was defined as grade 2 or higher left ventricular systolic dysfunction on the basis of Common Terminology Criteria for Adverse Events (version 3) definitions.

RESULTS

Approximately 12% of patients experienced cardiotoxicity over a 5-year follow-up, with more than 70% of incident events occurring during on-protocol therapy. Documented cardiotoxicity during on-protocol therapy was significantly associated with subsequent off-protocol toxicity. Overall, the incidence was higher among noninfants and black patients, and in the setting of a bloodstream infection. Both EFS (hazard ratio [HR], 1.6; 95% CI, 1.2 to 2.1; P = .004) and OS (HR, 1.6; 95% CI, 1.2 to 2.2, P = .005) were significantly worse in patients with documented cardiotoxicity. Impacts on EFS were equivalent whether the incident cardiotoxicity event occurred in the absence (HR, 1.6; 95% CI, 1.1 to 2.2; P = .017) or presence of infection (HR, 1.6; 95% CI, 1.0 to 2.7; P = .069) compared with patients without documented cardiotoxicity. However, the reduction in OS was more pronounced for cardiotoxicity not associated with infection (HR, 1.7; 95% CI, 1.2 to 2.5; P = .004) than for infection-associated cardiotoxicity (HR, 1.3; 95% CI, 0.7 to 2.4; P = .387).

CONCLUSION

Early treatment-related cardiotoxicity may be associated with decreased EFS and OS. Cardioprotective strategies are urgently needed to improve relapse risk and both short- and long-term mortality outcomes.

Cardio-toxicity in childhood cancer survivors "Cure is not enough"

The number of pediatric cancer survivors is growing, and they are getting older. Therapy-induced cardiotoxicity therefore is debated as an ongoing problem. Recognition of the side effects in the use of anthracyclines and radiation as well as the patients' clinical condition and comorbidities leads back as far as the beginning of systematic cancer treatment in children in the 1980s. Since, numerous case reports, meta-analyses and retrospective surveys were published worldwide. However, randomized clinical trials with standardized protocols yet fail to be designed. This article gives an overview of the recent reports and emphasizes on the heterogeneity of the different approaches. A standardized work-up which may identify the patient at risk-including the patient's history and condition, individual genetic dispositions, dosage and method of drug application, consideration of co-medication, radiation therapy and dose, standardized imaging methods-is the main proposition of our report. The fusion of already established sources, e.g., data of different registries or study centers, might help to create preventive strategies for and a better understanding of patients with therapy induced cardiomyopathy.

Identification of a novel microRNA profile in pediatric patients with cancer treated with anthracycline chemotherapy

Anthracycline chemotherapy (AC) is associated with decline in left ventricular ejection fraction (LVEF), yet the mechanisms remain unclear. Although changes in microRNAs (miRs) have been identified in adult cardiovascular disease, miR profiles in pediatric patients with AC have not been well studied. The goal of this study was to examine miR profiles (unbiased array) in pediatric patients with AC compared with age-matched referent normal patients. We hypothesize that pediatric patients with AC will express a unique miR profile at the initiation and completion of therapy and will be related to LVEF. Serum was collected in pediatric patients (10–22 yr, n = 12) with newly diagnosed malignancy requiring AC within 24–48 h after the initiation of therapy (30–60 mg/m2) and ~1 yr after completing therapy. A custom microarray of 84 miRs associated with cardiovascular disease was used (quantitative RT-PCR) and indexed to referent normal profiles (13–17 yr, n = 17). LVEF was computed by cardiac MRI. LVEF fell from AC initiation at ~1 yr after AC completion (64.28 ± 1.78% vs. 57.53 ± 0.95%, respectively, P = 0.004). Of the 84 miRs profiled, significant shifts in 17 miRs occurred relative to referent normal ( P ≤ 0.05). Moreover, the functional domain of miRs associated with myocardial differentiation and development fell over threefold at the completion of AC ( P ≤ 0.05). Moreover, eight miRs were significantly downregulated after AC completion in those patients with the greatest decline in LVEF (≥10%, P < 0.05). This study demonstrates, for the first time, that changes in miR expression occur in pediatric patients with AC. These findings suggest that miRs are a potential strategy for the early identification of patients with AC susceptible to left ventricular dysfunction.

NEW & NOTEWORTHY Although anthracycline chemotherapy (AC) is effective for a number of pediatric cancers, an all too often consequence of AC is the development of left ventricular failure. The present study identified that specific shifts in the pattern of microRNAs, which regulate myocardial growth, function, and viability, occurred during and after AC in pediatric patients, whereby the magnitude of this shift was associated with the degree of left ventricular failure.

Perturbation of microRNA signalling by doxorubicin in spermatogonial, Leydig and Sertoli cell lines in vitro

We have previously shown that in addition to its widely recognised cardiotoxicity, the chemotherapeutic doxorubicin (DOX) is able to induce transcriptional, microRNA (miRNA) and DNA methylation changes in the mouse testis. These changes perturb pathways involved in stress/cell death and survival and testicular function and lead to germ cell loss and reproductive organ damage. Here, we further investigated the differential miRNA expression induced by DOX in mouse spermatogonial (GC1), Leydig (TM3) and Sertoli (TM4) cell lines in vitro. We began by performing cell cycle analysis of the three mouse testicular cell lines to evaluate their sensitivity to DOX and thus select suitable doses for miRNA profiling. In keeping with our in vivo data, the spermatogonial cell line was the most sensitive, and the Sertoli cell line the most resistant to DOX-induced cell cycle arrest. We then further demonstrated that each cell line has a distinct miRNA profile, which is perturbed upon treatment with DOX. Pathway analysis identified changes in the miRNA-mediated regulation of specialised signalling at germ-Sertoli and Sertoli-Sertoli cell junctions following treatment with DOX. Amongst the most significant disease categories associated with DOX-induced miRNA expression were organismal injury and abnormalities, and reproductive system disease. This suggests that miRNAs play significant roles in both normal testicular function and DOX-induced testicular toxicity. Comparison of our in vitro and in vivo data highlights that in vitro cell models can provide valuable mechanistic information, which may also help facilitate the development of biomarkers of testicular toxicity and high-throughput in vitro screening methods to identify potential testicular toxicants.

Dynamic Myocardial Response to Exercise in Childhood Cancer Survivors Treated with Anthracyclines

BACKGROUND

Anthracycline cardiotoxicity can cause significant long-term morbidity in childhood cancer survivors (CCS), but many CCS do not manifest clinical symptoms until adulthood. The aims of this study were to characterize the dynamic myocardial response to exercise of CCS at long-term follow-up by combining semisupine bicycle exercise stress echocardiography with myocardial imaging techniques and to establish whether semisupine bicycle exercise stress echocardiography could identify CCS with abnormal exercise response.

METHODS

This was a single-center prospective cross-sectional study. One hundred CCS and 51 control subjects underwent semisupine bicycle exercise stress echocardiography. Color Doppler tissue imaging peak systolic (s') and diastolic (e') velocities, myocardial acceleration during isovolumic contraction, and longitudinal strain were measured at rest and at incremental heart rates in the left ventricular (LV) lateral wall, basal septum, and right ventricle. The relationship with increasing heart rate was evaluated for each parameter by plotting the values against heart rate at each stage of exercise. Kernel density estimate was used to establish the normality of the individual CCS exercise responses.

RESULTS

At rest, no significant differences were found for LV lateral wall, right ventricular (RV), and basal septal systolic and diastolic velocities between CCS and control subjects. Only septal e' was lower in CCS. LV longitudinal strain was similar between groups, while RV longitudinal strain was lower in CCS. At peak exercise, LV lateral wall, RV, and septal s' were not different between groups, while e' were significantly lower in CCS. LV lateral wall and septal isovolumic acceleration were also reduced in CCS. LV longitudinal strain was different between groups, while RV longitudinal strain was similar. The dynamic response of Doppler tissue imaging velocities, isovolumic acceleration, and strain was similar between CCS and control subjects. Kernel density estimate analysis confirmed that most CCS responses were within the normal range.

CONCLUSIONS

At 10-year follow-up, anthracycline-treated CCS with normal baseline ejection fractions have LV and RV systolic and diastolic myocardial exercise response comparable with that of control subjects. Minor differences were observed between CCS and control subjects at rest and at peak exercise, but the dynamic response is within the normal range.

Cardiotoxicity of anthracycline (ANT) treatment in children with malignant tumors

OBJECTIVE

To investigate the cardiotoxicity indexes in children with malignant tumors after the administration of anthracycline (ANT) chemotherapy.

MATERIALS AND METHODS

Data from 131 children with malignant tumors who were treated using ANT chemotherapy at our hospital from January 2011 to December 2015 were collected to analyze the serologic indexes (such as N-terminal pro-brain natriuretic peptide [NT-proBNP] and isoenzyme of creatine kinase [CK-MB]) and changes in corrected QT interval(QT-c) and left ventricular ejection fraction (LVEF) before and after treatment with different ANT cumulative doses.

RESULTS

General clinical data revealed that 2 of the 131 children developed clinical cardiotoxicity. The ANT cumulative dose range was 12-697 mg/m². All patients were divided into three groups according to the ANT cumulative dose: group 1 (<100 mg/m²), 2 (≥100 and <200 mg/m²), and 3 (≥200 mg/m²). Although NT-proBNP and LVEF among the three groups differed significantly after chemotherapy (p = 0.022 and 0.035, respectively), no significance was noted for CK-MB and QT-c among the three groups after chemotherapy (p = 0.190 and p = 0.084, respectively). Multiple linear regression analysis revealed that the ANT cumulative dose had the most significant impact on NT-proBNP (standardized coefficient 0.423, p = 0). Pearson correlation analysis revealed that ANT cumulative dose was positively correlated with NT-proBNP post-treatment (correlation coefficient 0.423), but LVEF was negatively correlated with NT-proBNP after chemotherapy (correlation coefficient -0.542).

CONCLUSIONS

NT-proBNP showed significant changes when the ANT dose was >200 mg/m². Post-treatment serum NT-proBNP was linearly correlated with ANT cumulative dose, hence strictly controlling the ANT cumulative dose and monitoring serum NT-proBNP may have certain clinical significance in predicting cardiotoxicity.

Anthracyclines suppress pheochromocytoma cell characteristics, including metastasis, through inhibition of the hypoxia signaling pathway

Pheochromocytomas (PHEOs) and paragangliomas (PGLs) are rare, neuroendocrine tumors derived from adrenal or extra-adrenal chromaffin cells, respectively. Metastases are discovered in 3-36% of patients at the time of diagnosis. Currently, only suboptimal treatment options exist. Therefore, new therapeutic compounds targeting metastatic PHEOs/PGLs are urgently needed. Here, we investigated if anthracyclines were able to suppress the progression of metastatic PHEO. We explored their effects on experimental mouse PHEO tumor cells using in vitro and in vivo models, and demonstrated that anthracyclines, particularly idarubicin (IDA), suppressed hypoxia signaling by preventing the binding of hypoxia-inducible factor 1 and 2 (HIF-1 and HIF-2) to the hypoxia response element (HRE) sites on DNA. This resulted in reduced transcriptional activation of HIF target genes, including erythropoietin (EPO), phosphoglycerate kinase 1 (PGK1), endothelin 1 (EDN1), glucose transporter 1 (GLUT1), lactate dehydrogenase A (LDHA), and vascular endothelial growth factor (VEGFA), which consequently inhibited the growth of metastatic PHEO. Additionally, IDA downregulated hypoxia signaling by interfering with the transcriptional activation of HIF1A and HIF2A. Furthermore, our animal model demonstrated the dose-dependent suppressive effect of IDA on metastatic PHEO growth in vivo. Our results indicate that anthracyclines are prospective candidates for inclusion in metastatic PHEO/PGL therapy, especially in patients with gene mutations involved in the hypoxia signaling pathway.

Pharmacogenetics of anthracyclines

Anthracyclines constitute a fundamental part of the chemotherapy regimens utilized to treat a number of different malignancies both in pediatric and adult patients. These drugs are one of the most efficacious anticancer agents ever invented. On the other hand, anthracyclines are cardiotoxic. Childhood cancer survivors treated with anthracyclines often undergo cardiac complications which are influenced by genetic variations of the patients. The scientific literature comprises numerous investigations in the subject of the pharmacogenetics of anthracyclines. In this review, we provide a comprehensive overview of this research topic. Genetic variants are proposed targets in the personalized treatment in order to individualize dosing and therefore reduce side effects.