Does anthracycline administration by infusion in children affect late cardiotoxicity?

Lithocholic bile acid induces apoptosis in human nephroblastoma cells: a non-selective treatment option

Lithocholic bile acid (LCA) has been reported to selectively kill cancer cells within many tumor cell lines including neuroblastoma or glioblastoma. Wilms’ tumor shares similarities with neuro- and glioblastoma. Hence, the aim of the study was to evaluate the effects of LCA on nephroblastoma. To test the effects of LCA, nephroblastoma cell line WT CLS1 was used. SK NEP1 was tested as well. It was originally classified as a nephroblastoma cell line but was meanwhile reclassified as an ewing sarcoma cell line. As control cell lines HEK 293 from embryonic kidney and RC 124 from adult kidney tissue as well as podocytes were used. The effects were evaluated using proliferation assay, caspase activity assay, FACS and Western blot. LCA showed a dose and time-dependent selective effect inducing apoptosis in nephroblastoma cells. However, these effects were not limited to the nephroblastoma cell line but also affected control kidney cell lines and the sarcoma cells; only podocytes are significantly less affected by LCA (at dosages < 200 µm). There were no significant differences regarding the TGR5 receptor expression. The study showed that LCA has a strong, yet unselective effect on all used in vitro cell-lines, sparing the highly differentiated podocytes in lower concentrations. Further studies are needed to verify our results before dismissing LCA as an anti-cancer drug.

Thioredoxin Decreases Anthracycline Cardiotoxicity, But Sensitizes Cancer Cell Apoptosis

Cardiotoxicity is a major limitation for anthracycline chemotherapy although anthracyclines are potent antitumor agents. The precise mechanism underlying clinical heart failure due to anthracycline treatment is not fully understood, but is believed to be due, in part, to lipid peroxidation and the generation of free radicals by anthracycline-iron complexes. Thioredoxin (Trx) is a small redox-active antioxidant protein with potent disulfide reductase properties. Here, we present evidence that cancer cells overexpressing Trx undergo enhanced apoptosis in response to daunomycin. In contrast, cells overexpressing redox-inactive mutant Trx were not effectively killed. However, rat embryonic cardiomyocytes (H9c2 cells) overexpressing Trx were protected against daunomycin-mediated apoptosis, but H9c2 cells with decreased levels of active Trx showed enhanced apoptosis in response to daunomycin. We further demonstrate that increased level of Trx is specifically effective in anthracycline toxicity, but not with other topoisomerase II inhibitors such as etoposide. Collectively these data demonstrate that whereas high levels of Trx protect cardiomyocytes against anthracycline toxicity, it potentiates toxicity of anthracyclines in cancer cells.

Anthracycline and Peripartum Cardiomyopathies

Anthracycline-associated cardiomyopathy and peripartum cardiomyopathy are nonischemic cardiomyopathies that often afflict previously healthy young patients; both diseases have been well described since at least the 1970s and both occur in the settings of predictable stressors (ie, cancer treatment and pregnancy). Despite this, the precise mechanisms and the ability to reliably predict who exactly will go on to develop cardiomyopathy and heart failure in the face of anthracycline exposure or childbirth have proven elusive. For both cardiomyopathies, recent advances in basic and molecular sciences have illuminated the complex balance between cardiomyocyte and endothelial homeostasis via 3 broad pathways: reactive oxidative stress, interference in apoptosis/growth/metabolism, and angiogenic imbalance. These advances have already shown potential for specific, disease-altering therapies, and as our mechanistic knowledge continues to evolve, further clinical successes are expected to follow.

Anthracycline‑Induced Cardiac Toxicity: A Clinical Review

Anthracyclines (ATCs) have a great efficacy against many types of cancer and is currently considered a cornerstone in the treatment of numerous pediatric and adult hematological and solid tumors. Great advances have been achieved after the entry of ATC group into the cancer treatment in the early 1960s, and the overall survival ratio has increased from 30% to near 70%. Due to their significant role and great value in cancer therapy, which is persistent to date, ATCs are listed in the World Health Organization model list of essential medicines. The clinical use of ATC such as doxorubicin and daunorubicin can be viewed as a sort of double-edged sword. On the one hand, ATCs play an undisputed key role in the treatment of many neoplastic diseases; on the other hand, the administration of ATC is associated with the risk of severe adverse effects. The most common side effect of the ATC group is cardiotoxicity (CTX), which may limit its use and increases mortality and morbidity rates. The clinical use of ATC is limited by unique maximum total cumulative dose (approximately 350 mg/m2) limiting CTX. ATC CTX is cumulative dose-dependent and is in most of the occasions irreversible. Lowering the cumulative dose has been proved to be useful in minimize the risk of heart failure (HF), but, yet, there is a growing concern that HF might occur following doses that were thought to be safe. The average incidence of HF is around 5% at a cumulative dose of 400 mg/m2 that becomes higher above 500 mg/m2, albeit with substantial individual variation. The newer generations ATC medications such as epirubicin, idarubicin, and mitoxantrone were thought to be safer; however, subsequent clinical studies showed more or less similar toxicity profiles. The use of cardioprotective agents (e.g., dexrazoxane and amifostine) has been associated with improved safety range; however, questions are looming on their effect on ATC antitumor effects. An overwhelming amount of clinical evidence suggests that ATCs are too good to be old. Yet, they would look much better if they caused less harm to the heart when administered as either single agents or in combination with otherwise promising new drugs. In this review article, we present a comprehensive account on the ATC and provide up to date data on their clinical use and toxicity profile. In addition, we provide a contemporary approach on the early detection, diagnosis, and treatment of ATC CTX.

Cardiovascular disease in survivors of childhood cancer

PURPOSE OF REVIEW

We review the cardiotoxic chemotherapeutic agents, the clinical and subclinical presentations and progression of their cardiotoxicity, and the management of the subsequent cardiovascular disease in survivors of childhood cancer. We discuss various preventive measures, especially the cardioprotectant, dexrazoxane, whose use with anthracycline chemotherapy, including doxorubicin, is based on strong evidence. Most treatment recommendations for this unique population are based on expert opinion, not on empirical evidence.

RECENT FINDINGS

As patients with childhood cancers live longer, morbidity from the cardiac side effects of chemotherapy is increasing. Treatment-related cardiac damage is irreversible and often progressive. It is imperative that such damage be prevented with strategies such as limiting the cumulative anthracycline dose, the use of anthracycline structural analogues and the use of cardioprotective agents.

SUMMARY

A deeper understanding of the mechanisms of their cardiotoxicity reveals that there is no 'safe' dose of anthracyclines. However, certain risk factors, such as higher lifetime anthracycline cumulative doses, higher anthracycline dose rates, female sex, longer follow-up, younger age at anthracycline treatment and cardiac irradiation, are associated with more severe cardiotoxicity. We advocate the use of dexrazoxane to limit the cardiotoxic effects of anthracycline chemotherapy.

Chemotherapy-related cardiac dysfunction: grey area in type I and type II classification

PURPOSE OF REVIEW

The main aim of this review is to address and challenge an old nomenclature of reversible versus irreversible chemotherapy-induced cardiomyopathy.

RECENT FINDINGS

Chemotherapy-related cardiac dysfunction (CRCD) has been often characterized as type I or type II. Type I CRCD (e.g., anthracycline) represents a group of chemotherapeutic agents that has often been correlated with irreversible cardiac dysfunction. Conversely, type II CRCD (e.g., trastuzumab) represents a group of anticancer agents that has been considered as reversible. Recent evidence suggests that this nomenclature may not hold true, thus affecting clinical prognosis as well as timely management. It is prudent to address this concern so that physicians are armed with appropriate information, thus providing our oncological patients with informed care. The purpose is to highlight the grey area in this dichotomous classification.

SUMMARY

Type I CRCD can be reversible if cardioprotective medications are administered in a timely manner. Conversely, a small proportion of type II CRCD may develop irreversible dysfunction and therefore, will require a long-term follow-up. Therefore, every case should be dealt on an individual basis and an appropriate prognosis should be given to patients based on the clinical evidence on hand.

Cardiovascular Complications of Cancer Therapy: Best Practices in Diagnosis, Prevention, and Management: Part 1

Modern cancer therapy has successfully cured many cancers and converted a terminal illness into a chronic disease. Because cancer patients often have coexisting heart diseases, expert advice from cardiologists will improve clinical outcome. In addition, cancer therapy can also cause myocardial damage, induce endothelial dysfunction, and alter cardiac conduction. Thus, it is important for practicing cardiologists to be knowledgeable about the diagnosis, prevention, and management of the cardiovascular complications of cancer therapy. In this first part of a 2-part review, we will review cancer therapy-induced cardiomyopathy and ischemia. This review is based on a MEDLINE search of published data, published clinical guidelines, and best practices in major cancer centers. With the number of cancer survivors expanding quickly, the time has come for cardiologists to work closely with cancer specialists to prevent and treat cancer therapy-induced cardiovascular complications.

Cardiotoxicity from anthracycline and cardioprotection in paediatric cancer patients

Notwithstanding the steady progress in survival rates of children and adolescents suffering from cancer, the benefits associated with chemotherapy do not come without risks involving multiple organs and systems, including the cardiovascular apparatus. Anthracyclines-often administered in combination with radiation therapy and/or surgery-are the most used chemotherapeutic compounds in order to treat tumours and blood malignancies even in paediatric age. Being an important side-effect of anthracyclines, carduitoxicity may limit their efficacy during the treatment and induce long-term sequelae, observed even many years after therapy completion. The purpose of this review was to perform an overview about all the possible strategies to prevent and/or limit the anthracyclines adverse side-effects for the cardiovascular system in childhood cancer survivors.

Recommendations for genetic testing to reduce the incidence of anthracycline-induced cardiotoxicity

AIMS

Anthracycline-induced cardiotoxicity (ACT) occurs in 57% of treated patients and remains an important limitation of anthracycline-based chemotherapy. In various genetic association studies, potential genetic risk markers for ACT have been identified. Therefore, we developed evidence-based clinical practice recommendations for pharmacogenomic testing to further individualize therapy based on ACT risk.

METHODS

We followed a standard guideline development process, including a systematic literature search, evidence synthesis and critical appraisal, and the development of clinical practice recommendations with an international expert group.

RESULTS

RARG rs2229774, SLC28A3 rs7853758 and UGT1A6 rs17863783 variants currently have the strongest and the most consistent evidence for association with ACT. Genetic variants in ABCC1, ABCC2, ABCC5, ABCB1, ABCB4, CBR3, RAC2, NCF4, CYBA, GSTP1, CAT, SULT2B1, POR, HAS3, SLC22A7, SCL22A17, HFE and NOS3 have also been associated with ACT, but require additional validation. We recommend pharmacogenomic testing for the RARG rs2229774 (S427L), SLC28A3 rs7853758 (L461L) and UGT1A6*4 rs17863783 (V209V) variants in childhood cancer patients with an indication for doxorubicin or daunorubicin therapy (Level B - moderate). Based on an overall risk stratification, taking into account genetic and clinical risk factors, we recommend a number of management options including increased frequency of echocardiogram monitoring, follow-up, as well as therapeutic options within the current standard of clinical practice.

CONCLUSIONS

Existing evidence demonstrates that genetic factors have the potential to improve the discrimination between individuals at higher and lower risk of ACT. Genetic testing may therefore support both patient care decisions and evidence development for an improved prevention of ACT.

Different dosage schedules for reducing cardiotoxicity in people with cancer receiving anthracycline chemotherapy

BACKGROUND

This review update has been managed by both the Childhood Cancer and Cochrane Gynaecological, Neuro-oncology and Orphan Cancer Groups.The use of anthracycline chemotherapy is limited by the occurrence of cardiotoxicity. To prevent this cardiotoxicity, different anthracycline dosage schedules have been studied.

OBJECTIVES

To determine the occurrence of cardiotoxicity with the use of different anthracycline dosage schedules (that is peak doses and infusion durations) in people with cancer.

SEARCH METHODS

We searched the databases of the Cochrane Register of Controlled Trials (CENTRAL) (the Cochrane Library, Issue 11, 2015), MEDLINE (1966 to December 2015), and EMBASE (1980 to December 2015). We also searched reference lists of relevant articles, conference proceedings, experts in the field, and ongoing trials databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in which different anthracycline dosage schedules were compared in people with cancer (children and adults).

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, the 'Risk of bias' assessment, and data extraction. We performed analyses according to the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We identified 11 studies: 7 evaluated different infusion durations (803 participants), and 4 evaluated different peak doses (5280 participants). Seven studies were RCTs addressing different anthracycline infusion durations; we identified long-term follow-up data for one of the trials in this update. The meta-analysis showed a statistically significant lower rate of clinical heart failure with an infusion duration of six hours or longer as compared to a shorter infusion duration (risk ratio (RR) 0.27; 95% confidence interval 0.09 to 0.81; 5 studies; 557 participants). The majority of participants included in these studies were adults with different solid tumours. For different anthracycline peak doses, we identified two RCTs addressing a doxorubicin peak dose of less than 60 mg/m(2) versus 60 mg/m(2) or more, one RCT addressing a liposomal doxorubicin peak dose of 25 mg/m(2) versus 50 mg/m(2), and one RCT addressing an epirubicin peak dose of 83 mg/m(2) versus 110 mg/m(2). A significant difference in the occurrence of clinical heart failure was identified in none of the studies. The participants included in these studies were adults with different solid tumours. High or unclear 'Risk of bias' issues were present in all studies.

AUTHORS' CONCLUSIONS

An anthracycline infusion duration of six hours or longer reduces the risk of clinical heart failure, and it seems to reduce the risk of subclinical cardiac damage. Since there is only a small amount of data for children and data obtained in adults cannot be extrapolated to children, different anthracycline infusion durations should be evaluated further in children.We identified no significant difference in the occurrence of clinical heart failure in participants treated with a doxorubicin peak dose of less than 60 mg/m(2) or 60 mg/m(2) or more. Only one RCT was available for the other identified peak doses, so we can make no definitive conclusions about the occurrence of cardiotoxicity. More high-quality research is needed, both in children and adults and in leukaemias and solid tumours.

Cardiac complications in childhood cancer survivors treated with anthracyclines

Cardiovascular complications are among the leading causes of morbidity and mortality among survivors of childhood cancer, after cancer relapse and secondary malignancies. Although advances in cancer treatment have improved the 5-year survival rates, the same treatments, such as anthracyclines, that cure cancer also increase the risk for adverse cardiovascular effects. Anthracycline-related cardiotoxicity in survivors of childhood cancer is progressive and can take years to develop, initially presenting as sub-clinical cardiac abnormalities that, if left undetected or untreated, can lead to heart failure, myocardial infarction, or other clinical cardiac dysfunction. A higher cumulative dose of anthracycline is associated with cardiotoxicity in children; however, sub-clinical cardiac abnormalities are evident at lower doses with longer follow-up, suggesting that there is no "safe" dose of anthracycline. Other risk factors include female sex, younger age at diagnosis, black race, trisomy 21, longer time since treatment, and the presence of pre-existing cardiovascular disease and co-morbidities. Cardioprotective strategies during treatment are limited in children. Enalapril provides only temporary cardioprotection, whereas continuous anthracycline infusion extends none. On the other hand, dexrazoxane successfully prevents or reduces anthracycline-related cardiotoxicity in children with cancer, without increased risks for recurrence of primary or second malignancies or reductions in anti-tumour efficacy. With more childhood cancer survivors now reaching adulthood, it is vital to understand the adverse effects of cancer treatment on the cardiovascular system and their long-term consequences to identify and establish optimal prevention and management strategies that balance oncologic efficacy with long-term safety.

Cardiovascular disease in adult survivors of childhood cancer

Treatment advances have increased survival in children with cancer, but subclinical, progressive, irreversible, and sometimes fatal treatment-related cardiovascular effects may appear years later. Cardio-oncologists have identified promising preventive and treatment strategies. Dexrazoxane provides long-term cardioprotection from doxorubicin-associated cardiotoxicity without compromising the efficacy of anticancer treatment. Continuous infusion of doxorubicin is as effective as bolus administration in leukemia treatment, but no evidence has indicated that it provides long-term cardioprotection; continuous infusions should be eliminated from pediatric cancer treatment. Angiotensin-converting enzyme inhibitors can delay the progression of subclinical and clinical cardiotoxicity. All survivors, regardless of whether they were treated with anthracyclines or radiation, should be monitored for systemic inflammation and the risk of premature cardiovascular disease. Echocardiographic screening must be supplemented with screening for biomarkers of cardiotoxicity and perhaps by identification of genetic susceptibilities to cardiovascular diseases; optimal strategies need to be identified. The health burden related to cancer treatment will increase as this population expands and ages.

Balancing cure and long-term risks in acute lymphoblastic leukemia

Cure rates for children and adolescents with acute lymphoblastic leukemia (ALL) have improved dramatically over the last few decades. With this success has come increasing recognition of the adverse late effects of treatment. The significant long-term sequelae in the earliest cohort of long-term survivors treated in the 1970s and 1980s are well documented. To reduce the incidence of these late effects, the majority of pediatric patients treated on more contemporary regimens receive less intensive treatment than did those treated 30-40 years ago. However, current therapies are not risk free; children treated with contemporary regimens remain at risk for developing long-term toxicities, including cardiac dysfunction, osteonecrosis, neurocognitive impairment, and second malignant neoplasms. One of the great challenges facing clinical investigators today is to identify interventions that will reduce the frequency and severity of long-term toxicities without adversely affecting cure rates. The use of dexrazoxane as a cardioprotectant (to prevent anthracycline-associated cardiotoxicity) and alternate-week dosing of dexamethasone (to reduce the risk of osteonecrosis) are examples of 2 such successful strategies. This article provides an overview of the long-term toxicities associated with current therapies and reviews results of clinical trials designed to minimize the burden of cure in long-term survivors.

Treatment-related cardiotoxicity in survivors of childhood cancer

Treatment advances and higher participation rates in clinical trials have rapidly increased the number of survivors of childhood cancer. However, chemotherapy and radiation treatments are cardiotoxic and can cause cardiomyopathy, conduction defects, myocardial infarction, hypertension, stroke, pulmonary oedema, dyspnoea and exercise intolerance later in life. These cardiotoxic effects are often progressive and irreversible, emphasizing a need for effective prevention and treatment to reduce or avoid cardiotoxicity. Medical interventions, such as angiotensin-converting enzyme inhibitors, β-blockers, and growth hormone therapy, might be used to treat cardiotoxicity in childhood cancer survivors. Preventative strategies should include the use of dexrazoxane, which provides cardioprotection without reducing the oncological efficacy of doxorubicin chemotherapy; less-toxic anthracycline derivatives and the use of antioxidant nutritional supplements might also be beneficial. Continuous-infusion doxorubicin provides no benefit over bolus infusion in children. Identifying patient-related (for example, obesity and hypertension) and drug-related (for example, cumulative dose) risk factors for cardiotoxicity could help tailor treatments to individual patients. However, all survivors of childhood cancer are at increased risk of cardiotoxicity, suggesting that survivor screening recommendations for assessment of global risk of premature cardiovascular disease should apply to all survivors. Optimal, evidence-based monitoring strategies and multiagent preventative treatments still need to be identified.

Anthracycline induced cardiac toxicity in pediatric Ewing sarcoma: a longitudinal study

BACKGROUND

Reports on incidence and factors associated with anthracycline cardiotoxicity in patients with Ewing sarcoma vary and few studies evaluate effect over time. Longitudinal trends in cardiac function and prognostic value of % decline in ejection fraction (EF) during therapy have not been previously described in Ewing sarcoma.

PROCEDURE

A retrospective review of patients age <17 years, diagnosed with Ewing sarcoma during 1978-2006, treated at British Columbia Children's Hospital with anthracycline chemotherapy was undertaken. Echocardiograms performed pre-treatment, worst function during treatment, on therapy completion; worst function during surveillance and the most recent echocardiogram were reviewed. Cardiac toxicity was graded using Common Terminology Criteria for Adverse Events v 3.0 and 4.0.

RESULTS

Among 71 eligible patients, median age at diagnosis 11.1 years, median cumulative dose of anthracycline was 365 mg/m2 . There were 397 echocardiograms with 153 (39%) abnormal. There were 21/71 patients with EF < 50%, 11 with EF < 40% and five cardiac deaths including 2/3 patients post-cardiac transplant. The median time to worst cardiac function was 51 months. Post-therapy completion 16/71 patients with progressive decline in cardiac function were noted. No patient with 10-15% decline in EF during therapy developed cardiotoxicity. Younger age (P = 0.004) and low BMI (P = 0.034) as continuous variables with anthracycline administration by IV push (P = 0.03) were risk factors for cardiotoxicity on univariate analysis but not significant within logistic regression models.

CONCLUSIONS

The high incidence of cardiotoxicity associated with higher administered anthracycline dose, young age, bolus infusion, and EF decline warrants evaluation in a larger cohort.

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.

Continuous Versus Bolus Infusion of Doxorubicin in Children With ALL: Long-term Cardiac Outcomes

BACKGROUND AND OBJECTIVES

Doxorubicin, effective against many malignancies, is limited by cardiotoxicity. Continuous-infusion doxorubicin, compared with bolus-infusion, reduces early cardiotoxicity in adults. Its effectiveness in reducing late cardiotoxicity in children remains uncertain. We determined continuous-infusion doxorubicin cardioprotective efficacy in long-term survivors of childhood acute lymphoblastic leukemia (ALL).

METHODS

The Dana-Farber Cancer Institute ALL Consortium Protocol 91-01 enrolled pediatric patients between 1991 and 1995. Newly diagnosed high-risk patients were randomly assigned to receive a total of 360 mg/m(2) of doxorubicin in 30 mg/m(2) doses every 3 weeks, by either continuous (over 48 hours) or bolus-infusion (within 15 minutes). Echocardiograms at baseline, during, and after doxorubicin therapy were blindly remeasured centrally. Primary outcomes were late left ventricular (LV) structure and function.

RESULTS

A total of 102 children were randomized to each treatment group. We analyzed 484 serial echocardiograms from 92 patients (n = 49 continuous; n = 43 bolus) with ≥1 echocardiogram ≥3 years after assignment. Both groups had similar demographics and normal baseline LV characteristics. Cardiac follow-up after randomization (median, 8 years) showed changes from baseline within the randomized groups (depressed systolic function, systolic dilation, reduced wall thickness, and reduced mass) at 3, 6, and 8 years; there were no statistically significant differences between randomized groups. Ten-year ALL event-free survival rates did not differ between the 2 groups (continuous-infusion, 83% versus bolus-infusion, 78%; P = .24).

CONCLUSIONS

In survivors of childhood high-risk ALL, continuous-infusion doxorubicin, compared with bolus-infusion, provided no long-term cardioprotection or improvement in ALL event-free survival, hence provided no benefit over bolus-infusion.

Modifications to induction therapy decrease risk of early death in infants with acute lymphoblastic leukemia treated on Children's Oncology Group P9407

BACKGROUND

Infants (<366 days of age) with acute lymphoblastic leukemia (ALL) have a poor prognosis. Most treatment failures occur within 6-9 months of diagnosis, primarily from relapse.

PROCEDURE

The Children's Oncology Group P9407 study was designed to test if early intensified treatment would improve outcome for infants with ALL. Due to a significant number of early deaths (< 90 days from enrollment), Induction therapy was amended three times. Cohorts 1 + 2 (n = 68), received identical Induction therapy except for reduced daunorubicin dose in Cohort 2. Cohort 3 (n = 141) received prednisone (40 mg/m(2)/day) instead of dexamethasone (10 mg/m(2)/day) and short infusion daunorubicin (30 minutes) instead of continuous infusion (48 hours), as well as additional supportive care measures throughout therapy.

RESULTS

Early deaths occurred in 17/68 (25%) infants in Cohorts 1 + 2 and 8/141 (5.7%) infants in Cohort 3 (P < 0.0001). Among infants ≤90 days of age at diagnosis, early death occurred in 10/17 (58.8%) in Cohorts 1 + 2 and 4/27 (14.8%) in Cohort 3 (P = 0.006). Among infants >90 days of age at diagnosis, early death occurred in 7/51 (13.7%) in Cohorts 1 + 2 and 4/114 (3.5%) in Cohort 3 (P = 0.036). Bacterial, viral, and fungal infections were more common in Cohorts 1 + 2 versus Cohort 3.

CONCLUSIONS

Early morbidity and mortality for infants with ALL were reduced by substitution of prednisone (40 mg/m(2)/day) for dexamethasone (10 mg/m(2)/day), the delivery of daunorubicin over 30 minutes instead of a continuous infusion for 48 hours, and the provision of more specific supportive care measures.

Strategies to prevent anthracycline-related congestive heart failure in survivors of childhood cancer

Cardiovascular complications are a leading cause of therapy-related morbidity and mortality in long-term survivors of childhood malignancy. In fact, childhood cancer survivors are at a 15-fold risk of developing CHF compared to age-matched controls. There is a strong dose-dependent association between anthracycline exposure and risk of CHF, and the incidence increases with longer followup. Outcome following diagnosis of CHF is generally poor, with overall survival less than 50% at 5 years. The growing number of childhood cancer survivors makes it imperative that strategies be developed to prevent symptomatic heart disease in this vulnerable population. We present here an overview of the current state of knowledge regarding primary, secondary, and tertiary prevention strategies for childhood cancer survivors at high risk for CHF, drawing on lessons learned from prevention studies in nononcology populations as well as from the more limited experience in cancer survivors.

Cardiotoxicity in childhood cancer survivors: strategies for prevention and management

Advances in cancer treatment have greatly improved survival rates of children with cancer. However, these same chemotherapeutic or radiologic treatments may result in long-term health consequences. Anthracyclines, chemotherapeutic drugs commonly used to treat children with cancer, are known to be cardiotoxic, but the mechanism by which they induce cardiac damage is still not fully understood. A higher cumulative anthracycline dose and a younger age of diagnosis are only a few of the many risk factors that identify the children at increased risk of developing cardiotoxicity. While cardiotoxicity can develop at anytime, starting from treatment initiation and well into adulthood, identifying the best cardioprotective measures to minimize the long-term damage caused by anthracyclines in children is imperative. Dexrazoxane is the only known agent to date, that is associated with less cardiac dysfunction, without reducing the oncologic efficacy of the anthracycline doxorubicin in children. Given the serious long-term health consequences of cancer treatments on survivors of childhood cancers, it is essential to investigate new approaches to improving the safety of cancer treatments.

Prevalence and predictors of anthracycline cardiotoxicity in children treated for acute myeloid leukaemia: retrospective cohort study in a single centre in the United Kingdom

BACKGROUND

Anthracycline cardiomyopathy is of concern in children treated for acute myeloid leukaemia (AML), but there are few data on the incidence and natural history of cardiotoxicity after AML treatment in the United Kingdom, where regimens have included high anthracycline exposure.

PROCEDURE

Prevalence and predictors of cardiotoxicity were retrospectively reviewed in 124 children treated on the MRC AML 10 and AML 12 trials in a single, large centre from November 1987 to September 2004. Subclinical cardiotoxicity was defined as a shortening fraction of less than 28% and clinical cardiomyopathy as evidence of heart failure, and both were classified as late cardiotoxicity 1 year after completing first line therapy.

RESULTS

Cumulative survival was 61% at 10 years. The prevalence of early and late cardiotoxicity was 13.7% (95%-CI: 8.2-22.0%) and 17.4% (95%-CI: 10.9-26.8%), respectively. Early cardiotoxicity was a strong predictor (OR = 9.18; 95%-CI: 2.10-40.11; P < 0.005) and children who received salvage therapy following relapse showed a trend towards increased late cardiotoxicity (OR = 3.53; 95%-CI: 0.86-14.48; P < 0.08). Subclinical cardiotoxicity resolved spontaneously in all but one case, but clinical cardiomyopathy always required continuing therapy. Two children died of cardiomyopathy and six remained on medical therapy.

CONCLUSIONS

Anthracycline cardiotoxicity remains a major concern for survivors of childhood AML and correlates with early cardiotoxicity and treatment intensity. Long-term follow-up is required to fully determine the outcome for children with subclinical cardiotoxicity.

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.

Dexrazoxane as a cardioprotectant in children receiving anthracyclines

Anthracyclines play a critical role in the treatment of a variety of childhood cancers. However, the cumulative cardiotoxic effects of anthracyclines limit the use of these agents in many treatment regimens. Dexrazoxane is a cardioprotectant that significantly reduces the incidence of adverse cardiac events in women with advanced breast cancer treated with doxorubicin-containing regimens. Clinical evidence for the efficacy of dexrazoxane as a cardioprotectant in children, especially from randomized clinical trials, is limited, but the available data support a short-term cardioprotective effect. Long-term follow-up in children treated with dexrazoxane has not been reported. Dexrazoxane's impact on the antitumor effect and toxicity profile of the anthracyclines and the role of dexrazoxane in the development of secondary malignant neoplasms in patients who received dexrazoxane are reviewed. Based on the available data, dexrazoxane appears to be a safe and effective cardioprotectant in children, and it does not appear to alter overall survival times in children with cancer. Continued follow-up from previous trials is needed to determine the long-term effect of dexrazoxane on cardiac outcomes and quality of life.

Cardiac functions evaluated with tissue Doppler imaging in childhood cancers treated with anthracyclines

AIM

The aim of this study was to assess the cardiac functions using conventional echocardiography and tissue Doppler imaging in childhood cancers treated with anthracyclines.

METHODS

The study group was selected from the patients admitted to the pediatric oncology department for a treatment protocol that included doxorubicin. Body surface area was calculated and complete 2-dimensional, M-mode, pulse wave Doppler and pulse wave tissue Doppler echocardiographic examinations were performed just before the first treatment and at least 6 months after the last treatment.

RESULTS

This study included 20 patients (12 males and 8 females). Mean cumulative antracycline dose was 189 +/- 102.90 mg/m(2). There were no significant differences between the pre- and post-treatment groups regarding systolic and diastolic blood pressures, heart rates, left ventricular ejection fraction and fractional shortening, right and left ventricular conventional and tissue Doppler diastolic parameters (E and A waves, E/A ratio, E' and A' waves, E'/A' ratio), but there were significant differences between the pre- and post-treatment groups regarding body surface area, right and left ventricular myocardial performance index observed by conventional pulse wave and pulse wave tissue Doppler methods.

CONCLUSION

Tissue Doppler imaging provided additional information on cardiac functions. While systolic and diastolic functions were in normal range, myocardial performance index observed by tissue Doppler method was impaired in children who were treated with anthracyclines.

Survivorship: childhood cancer survivors

Late effects of therapy for childhood cancer are frequent and serious. Fortunately, many late effects are also modifiable. Proactive and anticipatory risk-based care can reduce the frequency and severity of treatment-related morbidity. The primary care clinician should be an integral component in risk-based care of survivors. Continued communication between the "late effects" staff at the cancer center and the primary care clinician is essential for optimum care of this high-risk population.

Different dosage schedules for reducing cardiotoxicity in cancer patients receiving anthracycline chemotherapy

BACKGROUND

The use of anthracycline chemotherapy is limited by the occurrence of cardiotoxicity. To prevent this cardiotoxicity, different anthracycline dosage schedules have been studied.

OBJECTIVES

To determine the occurrence of cardiotoxicity with the use of different anthracycline dosage schedules (i.e. peak doses and infusion durations) in cancer patients.

SEARCH STRATEGY

We searched the databases of The Cochrane Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 4, 2008), MEDLINE (1966 to November 2008) and EMBASE (1980 to November 2008). Also, we searched reference lists of relevant articles, conference proceedings and ongoing trials databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in which different anthracycline dosage schedules were compared in cancer patients (children and adults).

DATA COLLECTION AND ANALYSIS

Two authors independently performed the study selection, the risk of bias assessment and the data-extraction.

MAIN RESULTS

We identified seven RCTs addressing different anthracycline infusion durations. The meta-analysis showed a statistically significant lower rate of clinical heart failure with an infusion duration of 6 hours or longer as compared to a shorter infusion duration (relative risk (RR) = 0.27; 95% confidence interval (CI) 0.09 to 0.81; 5 studies; 557 patients). The majority of patients included in these studies were adults with different solid tumours. For different anthracycline peak doses we identified two RCTs addressing a doxorubicin peak dose of less than 60 mg/m(2) versus 60 mg/m(2) or more, one RCT addressing a liposomal doxorubicin peak dose of 25 mg/m(2) versus 50 mg/m(2) and one RCT addressing an epirubicin peak dose of 83 mg/m(2) versus 110 mg/m(2). In none of the studies a significant difference in the occurrence of clinical heart failure was identified. All patients included in these studies were adults with different solid tumours.

AUTHORS' CONCLUSIONS

An anthracycline infusion duration of six hours or longer reduces the risk of clinical heart failure and it seems to reduce the risk of subclinical cardiac damage. Since there is only a small amount of data for children and data obtained in adults cannot be extrapolated to children, different anthracycline infusion durations should be evaluated further in children.No significant difference in the occurrence of clinical heart failure was identified in patients treated with a doxorubicin peak dose of less than 60 mg/m(2) or 60 mg/m(2) or more. For the other identified peak doses only one RCT was available, so no definitive conclusions can be made about the occurrence of cardiotoxicity. More high quality research is needed, both in children and adults and in leukaemias and solid tumours.

Anthracycline-induced cardiotoxicity: overview of studies examining the roles of oxidative stress and free cellular iron

The risk of cardiotoxicity is the most serious drawback to the clinical usefulness of anthracycline antineoplastic antibiotics, which include doxorubicin (adriamycin), daunorubicin or epirubicin. Nevertheless, these compounds remain among the most widely used anticancer drugs. The molecular pathogenesis of anthracycline cardiotoxicity remains highly controversial, although the oxidative stress-based hypothesis involving intramyocardial production of reactive oxygen species (ROS) has gained the widest acceptance. Anthracyclines may promote the formation of ROS through redox cycling of their aglycones as well as their anthracycline-iron complexes. This proposed mechanism has become particularly popular in light of the high cardioprotective efficacy of dexrazoxane (ICRF-187). The mechanism of action of this drug has been attributed to its hydrolytic transformation into the iron-chelating metabolite ADR-925, which may act by displacing iron from anthracycline-iron complexes or by chelating free or loosely bound cellular iron, thus preventing site-specific iron-catalyzed ROS damage. However, during the last decade, calls for the critical reassessment of this "ROS and iron" hypothesis have emerged. Numerous antioxidants, although efficient in cellular or acute animal experiments, have failed to alleviate anthracycline cardiotoxicity in clinically relevant chronic animal models or clinical trials. In addition, studies with chelators that are stronger and more selective for iron than ADR-925 have also yielded negative or, at best, mixed outcomes. Hence, several lines of evidence suggest that mechanisms other than the traditionally emphasized "ROS and iron" hypothesis are involved in anthracycline-induced cardiotoxicity and that these alternative mechanisms may be better bases for designing approaches to achieve efficient and safe cardioprotection.

Anthracycline cardiotoxicity in childhood

Over the last 40 years, a significant advance has been made in the treatment of childhood and adult cancers. However, the increase of the survival rate points out medium- and long-term adverse effects that constitute a serious limitation for the quality of life in adults survived from a childhood cancer. Cardiovascular disease is an important cause of morbidity and mortality in adults treated with chemo- and radiotherapy for childhood cancers. Although some antitumor treatments are potentially cardiotoxic, anthracycline therapy and radiotherapy are mostly responsible for long-term cardiac damage. Anthracycline toxicity is generally limited to the myocardium, while radiation can cause injury to all components of the heart. The purpose of this review is to discuss the mechanisms of action of anthracyclines, their cardiotoxicity, the feasibility of screening, and the prevention of cardiac damage after treatment in childhood.

Monitoring for cardiovascular disease in survivors of childhood cancer: report from the Cardiovascular Disease Task Force of the Children's Oncology Group

Curative therapy for childhood cancer has improved significantly in the last 2 decades such that, at present, approximately 80% of all children with cancer are likely to survive > or = 5 years after diagnosis. Prevention, early diagnosis, and treatment of long-term sequelae of therapy have become increasingly more significant as survival rates continue to improve. Cardiovascular disease is a well-recognized cause of increased late morbidity and mortality among survivors of childhood cancer. The Children's Oncology Group Late Effects Committee and Nursing Discipline and Patient Advocacy Committee have recently developed guidelines for follow-up of long-term survivors of pediatric cancer. A multidisciplinary task force critically reviewed the existing literature to evaluate the evidence for the cardiovascular screening recommended by the Children's Oncology Group guidelines. In this review we outline the clinical manifestations of late cardiovascular toxicities, suggest modalities and frequency of monitoring, and address some of the controversial and unresolved issues regarding cardiovascular disease in childhood cancer survivors.

Exercise echocardiography reveals subclinical cardiac dysfunction in young adult survivors of childhood acute lymphoblastic leukemia

OBJECTIVE

Anthracyclines (AC) have contributed significantly to increased survival rate in acute lymphoblastic leukemia (ALL), although the use of these drugs is limited due to cardiotoxicity. The aim was to evaluate heart muscle function in asymptomatic adult survivors of ALL treated in early childhood in relation to the combined effects of AC and other potential cardiotoxic factors.

PROCEDURE

Twenty-three young adult ALL survivors who had all received treatment with median 120 (120-400) mg AC/m(2) before the onset of puberty were examined median 21 years after remission and compared with 12 healthy controls. Basal echocardiography including two-dimensional (2D) M-mode and Doppler examination was performed, followed by a maximal exercise stress test and stress echocardiography immediately after stress test and after 5 min recovery.

RESULTS

We found significant differences in systolic function between patients and controls at maximal exercise despite absence of reported symptoms from the patients. The most marked difference was in ejection fraction at stress 59.5% (32.6-81.1) and 77.3% (66.2-85.3), respectively (P < 0.00006). Ten out of 23 patients reduced their ejection fraction at stress compared with at rest; this was not found in any of the controls. Cardiovascular risk factors such as GH deficiency and a high proportion of trunk fat did not have an impact on cardiac function.

CONCLUSIONS

With very long follow up in a homogenous cohort of ALL survivors, we found subclinical cardiac dysfunction with exercise stress echocardiography even after low doses of AC.

Noninvasive Evaluation of Late Anthracycline Cardiac Toxicity in Childhood Cancer Survivors

Purpose

Childhood cancer survivors treated with anthracyclines and cardiac radiation are at risk for late-onset cardiotoxicity. The purpose of this study was to delineate the relationship between clinical factors and abnormalities of noninvasive cardiac testing (NICT).

Patients and Methods

Participants were recruited from a long-term follow-up clinic. Study measures comprised physical examination, laboratory evaluation, echocardiogram, and ECG. Mean fractional shortening (FS) and afterload were compared for survivors who did (at risk [AR]) and did not (no risk [NR]) receive potentially cardiotoxic modalities, and with values expected for comparable age- and sex-matched controls.

Results

The 278 study participants (mean age, 18.1 years; median age, 16.8 years; range, 7.5 to 39.7 years) included 223 survivors AR for cardiotoxicity after treatment with anthracyclines (median dose ± standard deviation [SD], 202 ± 109 mg/m2) and/or cardiac radiation. Mean FS (± SD) was lower for AR (0.33 ± 0.06) compared with NR survivors (0.36 ± 0.05; P = .004) and normative controls (0.36 ± 0.04; P < .001). Mean afterload (± SD) was higher for AR (58 ± 21 g/cm2) compared with NR survivors (46 ± 15 g/cm2; P < .001) and normative controls (48 ± 13 g/cm2; P < .001). The distribution of FS and afterload among NR survivors did not differ from that of controls. After adjustment for age group at diagnosis and time since completion of therapy, anthracycline dose predicted decline in distribution of FS (P < .001) and increase in distribution of afterload (P < .001). Treatment with anthracycline doses ≥ 100 mg/m2 increased the risk of abnormal NICT; survivors who received ≥ 270 mg/m2 had a 4.5-fold excess risk of abnormal NICT (95% CI, 2.1 to 9.6) compared with controls.

Conclusion

Childhood cancer survivors treated with anthracycline doses ≥ 270 mg/m2 are at greatest risk for abnormalities of FS and afterload.

Clinical and cost-effectiveness of cardioprotection against the toxic effects of anthracyclines given to children with cancer: a systematic review

This review systematically assessed the evidence on the clinical and cost-effectiveness of cardioprotection against the toxic effects of anthracyclines given to children with cancer. We searched eight electronic databases, including Medline and the Cochrane Library, from inception to January 2006 for systematic reviews and randomised controlled trials that reported death, heart failure, arrhythmias or measures of cardiac performance associated with cardioprotective technologies compared with standard treatment in children treated for cancer with anthracyclines. Economic evaluations were also sought. Inclusion criteria, data extraction and quality assessment were undertaken by standard methodology. Four randomised controlled trials met the inclusion criteria of the review; each had methodological limitations. No economic evaluations were identified. Studies were combined through narrative synthesis. One trial found that continuous infusion of doxorubicin did not offer any cardioprotection over rapid infusion. One suggested that continuous infusion of daunorubicin provoked less cardiotoxicity than rapid infusion. One concluded that dexrazoxane reduces cardiac injury during doxorubicin therapy and one reported a protective effect of coenzyme Q₁₀ on cardiac function during anthracycline therapy. The evidence on the effectiveness of cardioprotective technologies in children is limited in quality and quantity thus making conclusions difficult. This is surprising given the importance of anthracycline use in children with cancer. Further long-term research, which includes relevant outcome measures, is needed to determine whether technologies influence the development of cardiac damage without limiting the antitumour efficacy of anthracyclines.

Heart failure induced by non-cardiac drugs

Although heart failure is predominantly caused by cardiovascular conditions such as hypertension, coronary heart disease and valvular heart disease, it can also be an adverse reaction induced by drug therapy. In addition, some drugs have the propensity to adversely affect haemodynamic mechanisms in patients with an already existing heart condition. In this article, non-cardiac drugs known to be associated with the development or worsening of heart failure are reviewed. Moreover, drugs that may adversely affect the heart as a pump without causing symptoms or signs of heart failure are also included. The drugs discussed include anticancer agents such as anthracyclines, mitoxantrone, cyclophosphamide, fluorouracil, capecitabine and trastuzumab; immunomodulating drugs such as interferon-alpha-2, interleukin-2, infliximab and etanercept; antidiabetic drugs such as rosiglitazone, pioglitazone and troglitazone; antimigraine drugs such as ergotamine and methysergide; appetite suppressants such as fenfulramine, dexfenfluramine and phentermine; tricyclic antidepressants; antipsychotic drugs such as clozapine; antiparkinsonian drugs such as pergolide and cabergoline; glucocorticoids; and antifungal drugs such as itraconazole and amphotericin B. NSAIDs, including selective cyclo-oxygenase (COX)-2 inhibitors, are included as a result of their ability to cause heart disease, particularly in patients with an already existing cardiorenal dysfunction. Two drug groups are of particular concern. Anthracyclines and their derivatives may cause cardiomyopathy in a disturbingly high number of exposed individuals, who may develop symptoms of insidious onset several years after drug therapy. The risk seems to encompass all exposed individuals, but data suggest that children are particularly vulnerable. Thus, a high degree of awareness towards this particular problem is warranted in cancer survivors subjected to anthracycline-based chemotherapy. A second group of problematic drugs are the NSAIDs, including the selective COX-2 inhibitors. These drugs may cause renal dysfunction and elevated blood pressure, which in turn may precipitate heart failure in vulnerable individuals. Although NSAID-related cardiotoxicity is relatively rare and most commonly seen in elderly individuals with concomitant disease, the widespread long-term use of these drugs in risk groups is potentially hazardous. Pending comprehensive safety analyses, the use of NSAIDs in high-risk patients should be discouraged. In addition, there is an urgent need to resolve the safety issues related to the use of COX-2 inhibitors. As numerous drugs from various drug classes may precipitate or worsen heart failure, a detailed history of drug exposure in patients with signs or symptoms of heart failure is mandatory.

Different dosage schedules for reducing cardiotoxicity in cancer patients receiving anthracycline chemotherapy

BACKGROUND

The use of anthracycline chemotherapy is limited by the occurrence of cardiotoxicity. In an effort to prevent this cardiotoxicity, different anthracycline dosage schedules (i.e. peak doses and infusion durations) have been studied.

OBJECTIVES

The primary objective was to determine the occurrence of cardiotoxicity with the use of different anthracycline dosage schedules in cancer patients.

SEARCH STRATEGY

We searched the databases of The Cochrane Register of Controlled Trials (CENTRAL), (The Cochrane Library, Issue 2, 2004), MEDLINE (1966 to June 2004) and EMBASE (1980 to June 2004). In addition, we searched reference lists of relevant articles, conference proceedings and ongoing trials databases.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in which different anthracycline dosage schedules were compared in cancer patients (children and adults).

DATA COLLECTION AND ANALYSIS

Two authors independently performed the study selection, quality assessment and data-extraction including adverse effects.

MAIN RESULTS

We identified six RCTs of varying quality addressing different anthracycline infusion durations (625 patients). The meta-analysis showed a statistically significant lower rate of clinical heart failure with an infusion duration of 6 hours or longer as compared to a shorter infusion duration, i.e. maximal duration of 1 hour (RR = 0.27; 95% confidence interval (CI) 0.09 to 0.81; 5 studies; 557 patients). In individual studies the infusion duration of 6 hours or longer also seemed to reduce the risk of subclinical cardiac damage. No statistically significant difference in response rate was found (RR = 0.83; 95% CI 0.45 to 1.54; 2 studies; 292 patients). No statistically significant difference in overall survival was found (HR = 1,42; 95% CI 0.61 to 3.30; 2 studies; 322 patients), but there was unexplained heterogeneity (I(2)=75%). No conclusions can be made regarding adverse effects. It should be emphasised that the majority of patients included in these studies were adults with different solid tumours. Children with leukaemia could not be included in the performed meta-analyses, but they were included in the descriptive results of non-pooled studies. No RCTs addressing different anthracycline peak doses with the same cumulative anthracycline dose in both treatment groups were identified.

AUTHORS' CONCLUSIONS

An anthracycline infusion duration of six hours or longer reduces the risk of clinical heart failure, and it seems to reduce the risk of subclinical cardiac damage. There is no evidence which suggests a difference in response rate and survival between both treatment groups. Since there is only a small amount of data for children and also because data obtained in adults cannot be extrapolated to children, different anthracycline infusion durations should be evaluated further in children. For different anthracycline peak doses no high quality evidence was available and therefore, no definitive conclusions can be made about the occurrence of cardiotoxicity in patients treated with different anthracycline peak doses.

Anthracycline cardiotoxicity

The use of anthracyclines is limited by dose-dependent cardiotoxicity. Three forms of anthracycline cardiotoxicity are described; an immediate pericarditis-myocarditis syndrome, an early onset chronic progressive CHF developing during or shortly after therapy and late-onset cardiotoxicity presenting years following treatment. A number of risk factors have been reported, including; cumulative dose, administration schedule, mediastinal radiotherapy, old and young age, concurrent cardiovascular disease, combination therapy, gender, ethnicity and chromosomal abnormalities. Evaluation of left ventricular ejection fraction has been widely adopted as a means of monitoring and assessing anthracycline-induced cardiotoxicity. Biochemical markers and other techniques, such as endomyocardial biopsy, metaiodobenzylguanidine and indium-111-antimyosin scintigraphy are not routinely used. Methods employed to prevent cardiotoxicity include cumulative dose limitation, alteration of administration schedule, anthracycline analogues, liposomal formulations and the cardioprotective agent, dexrazoxane. With the growing number of paediatric malignancy survivors and the increasing use of anthracyclines in the adjuvant treatment of breast cancer, the cardiotoxicity associated with these agents will remain a formidable issue for physicians. Further work is required to identify patients at increased risk of cardiotoxicity and to develop novel methods of protecting and treating this adverse effect.

Exposure to anthracyclines during childhood causes cardiac injury

The use of anthracyclines in the treatment of acute lymphoblastic leukemia is limited by associated cardiotoxic effects, which can result in cardiomyopathy and congestive heart failure, and may be irreversible. Anthracycline-induced cardiotoxicity in long-term survivors of childhood cancer is characterized by reduced left ventricular wall thickness and mass, which is indicative of decreased cardiac muscle and depressed left ventricular contractility which is indicative of unhealthy heart muscle. Risk factors for anthracycline-induced cardiotoxicity include high cumulative anthracycline doses, high anthracycline dose intensity, and radiotherapy. Radiotherapy in patients with cancer treated with anthracyclines can exacerbate anthracycline-induced cardiac tissue damage. Several studies have shown that cardiomyopathy disease progression can be delayed in adults by using angiotensin-converting enzyme inhibitors such as enalapril. Studies in long-term survivors of pediatric cancer showed that enalapril has significant benefits in preventing cardiac functional deterioration on a short-term basis, but this is not sustained. Anthracycline-associated cardiotoxic effects can be combatted by preventing cardiac injury during chemotherapy administration. There is evidence that dexrazoxane significantly reduces the cardiotoxicity associated with anthracyclines such as daunorubicin, doxorubicin, and epirubicin in adult patients with a wide range of tumor types. A study of the efficacy of dexrazoxane in reducing doxorubicin-induced cardiotoxicity in children and adolescents with high-risk acute lymphoblastic leukemia, showed that significantly fewer dexrazoxane-treated patients (21%) had elevated serum cardiac troponin (a biomarker of acute myocardial injury) levels than patients treated with chemotherapy alone (50%; P <.001). Dexrazoxane was also shown to have no effect on the event-free survival rate at 2.5 years, emphasizing that it does not detrimentally affect the efficacy of anthracycline therapy.

A phase I study of intravenous liposomal daunorubicin (DaunoXome) in paediatric patients with relapsed or resistant solid tumours

Anthracyclines are widely used in paediatric oncology, but their use is limited by the risk of cumulative cardiac toxicity. Encapsulating anthracyclines in liposomes may reduce cardiac toxicity and possibly increase drug availability to tumours. A phase I study in paediatric patients was designed to establish the dose limiting toxicity (DLT) and maximum tolerated dose (MTD) after a single course of liposomal daunorubicin, ‘DaunoXome’, as a 1 h infusion on day 1 of a 21 day cycle. Patients were stratified into two groups according to prior treatment: Group A (conventional) and group B (heavily pretreated patients). Dose limiting toxicity was expected to be haematological, and a two-step escalation was planned, with and without G-CSF support. Pharmacokinetic studies were carried out in parallel. In all, 48 patients aged from 1 to 18 years were treated. Dose limiting toxicity was neutropenia for both groups. Maximum tolerated dose was defined as 155 mg m⁻² for Group A and 100 mg m⁻² for Group B. The second phase with G-CSF was interrupted because of evidence of cumulative cardiac toxicity. Cardiac toxicity was reported in a total of 15 patients in this study. DaunoXome shares the early cardiotoxicity of conventional anthracyclines in paediatric oncology. This study has successfully defined a haematological MTD for DaunoXome, but the significance of this is limited given the concerns of delayed cardiac toxicity. The importance of longer-term follow-up in patients enrolled into phase I studies has been underestimated previously, and may lead to an under-recognition of important adverse events.