Effects of verapamil on anthracycline-induced cardiomyopathy: preliminary results of a prospective multicenter trial

Intermittent Hypoxic Preconditioning Plays a Cardioprotective Role in Doxorubicin-Induced Cardiomyopathy

Intermittent hypoxic preconditioning (IHP) is a well-established cardioprotective intervention in models of ischemia/reperfusion injury. Nevertheless, the significance of IHP in different cardiac pathologies remains elusive. In order to investigate the role of IHP and its effects on calcium-dependent signalization in HF, we employed a model of cardiomyopathy induced by doxorubicin (Dox), a widely used drug from the class of cardiotoxic antineoplastics, which was i.p. injected to Wistar rats (4 applications of 4 mg/kg/week). IHP-treated group was exposed to IHP for 2 weeks prior to Dox administration. IHP ameliorated Dox-induced reduction in cardiac output. Western blot analysis revealed increased expression of sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA2a) while the expression of hypoxia inducible factor (HIF)-1-α, which is a crucial regulator of hypoxia-inducible genes, was not changed. Animals administered with Dox had further decreased expression of TRPV1 and TRPV4 (transient receptor potential, vanilloid subtype) ion channels along with suppressed Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) activation. In summary, IHP-mediated improvement in cardiac output in the model of Dox-induced cardiomyopathy is likely a result of increased SERCA2a expression which could implicate IHP as a potential protective intervention in Dox cardiomyopathy, however, further analysis of observed effects is still required.

Subclinical Cardiac Dysfunction in Childhood Cancer Survivors on 10-Years Follow-Up Correlates With Cumulative Anthracycline Dose and Is Best Detected by Cardiopulmonary Exercise Testing, Circulating Serum Biomarker, Speckle Tracking Echocardiography, and Tissue Doppler Imaging

Background: Survivors of childhood cancer are at risk for anthracycline- and/or radiotherapy-induced cardiotoxicity. Aims: The aim of this study was to assess clinical, laboratory, and imaging parameters of subclinical cardiovascular disease in childhood cancer survivors. Methods: Patients underwent cardiopulmonary exercise test (CPET), laboratory testing, transthoracic echocardiography (TTE) with tissue doppler imaging (TDI) and speckle tracking. A subset of patients also underwent cardiovascular magnetic resonance imaging (CMR). Findings were correlated to cumulative anthracycline and exposure to mediastinal irradiation during cancer treatment. In a subgroup analysis, TTE and CMR findings were compared to data from 40 gender- and age-matched patients with childhood onset hypertrophic cardiomyopathy (HCM). Results: Cardiac evaluation was performed in 79 patients (43 males) at 11.2 ± 4.5 years after cancer treatment. Oncologic diagnosis at a median age of 12.0 years was Hodgkin lymphoma in 20, sarcoma in 17, acute leukemia in 24, relapse leukemia in 10, and others in 8 patients. Cumulative anthracycline dose exceeded 300 mg/m² in 28 patients. Twenty six patients also received mediastinal irradiation. Decreased peak respiratory oxygen uptake in % predicted on CPET, increased levels of N-terminal pro-brain natriuretic peptide (NTproBNP), increased global longitudinal strain on TTE speckle tracking, and diastolic dysfunction on TDI were the most prominent findings on detailed cardiology follow-up. In contrast to HCM patients, childhood cancer survivors did not show left ventricular hypertrophy (LVPWd z-score median 0.9 vs. 2.8, p < 0.001), hyperdynamic systolic function on TTE (Ejection fraction 62 ± 7 vs. 72 ± 12%, p = 0.001), or fibrotic myocardial changes on CMR (Late gadolinium positive 0/13 vs. 13/36, p = 0.001; extracellular volume fraction 22 ± 2 vs. 28 ± 3, p < 0.001) at time of follow-up. There was no correlation between chest radiation exposure and abnormal cardiac findings. Cumulative anthracycline dose was the only significant independent predictor on multivariate analysis for any cardiovascular abnormality on follow-up (p = 0.036). Conclusion: Increasing cumulative anthracycline dose during cancer treatment correlates with subclinical cardiac dysfunction in childhood cancer survivors best detected by elevated cardiac serum biomarkers, decreased exercise capacity on CPET, and abnormalities on echocardiographic speckle tracking and TDI.

Anthracycline Chemotherapy and Cardiotoxicity

Anthracycline chemotherapy maintains a prominent role in treating many forms of cancer. Cardiotoxic side effects limit their dosing and improved cancer outcomes expose the cancer survivor to increased cardiovascular morbidity and mortality. The basic mechanisms of cardiotoxicity may involve direct pathways for reactive oxygen species generation and topoisomerase 2 as well as other indirect pathways. Cardioprotective treatments are few and those that have been examined include renin angiotensin system blockade, beta blockers, or the iron chelator dexrazoxane. New treatments exploiting the ErbB or other novel pro-survival pathways, such as conditioning, are on the cardioprotection horizon. Even in the forthcoming era of targeted cancer therapies, the substantial proportion of today's anthracycline-treated cancer patients may become tomorrow's cardiac patient.

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.

Managing chemotherapy-related cardiotoxicity in survivors of childhood cancers

In the US, children diagnosed with cancer are living longer, but not without consequences from the same drugs that cured their cancer. In these patients, cardiovascular disease is the leading cause of non-cancer-related morbidity and mortality. Although this review focuses on anthracycline-related cardiomyopathy in childhood cancer survivors, the global lifetime risk of other cardiovascular diseases such as atherosclerosis, arrhythmias and intracardiac conduction abnormalities, hypertension, and stroke also are increased. Besides anthracyclines, newer molecularly targeted agents, such as vascular endothelial growth factor receptor and tyrosine kinase inhibitors, also have been associated with acute hypertension, cardiomyopathy, and increased risk of ischemic cardiac events and arrhythmias, and are summarized here. This review also covers other risk factors for chemotherapy-related cardiotoxicity (including both modifiable and non-modifiable factors), monitoring strategies (including both blood and imaging-based biomarkers) during and following cancer treatment, and discusses the management of cardiotoxicity (including prevention strategies such as cardioprotection by use of dexrazoxane).

The role of antioxidants in the era of cardio‑oncology

Although most chemotherapeutic drugs have the potential to exert cardiotoxicity, these drugs have been chosen for use in cancer treatment because survival and curability benefits outweigh the risk of these complications. Anthracyclines, for example, are a powerful class of chemotherapeutic agents; however, their use is restricted by dose-related cardiotoxicity. Experimental evidence strongly supports the role of reactive oxygen species in this process, suggesting that antioxidants may be effective in protecting the heart from toxicity. Clinical use of antioxidants to protect the heart during anthracycline chemotherapy has been controversial due to the potential for reduced cytotoxic efficacy toward cancer cells. Results from randomized clinical trials addressing whether antioxidants either reduce the incidence of clinical heart failure among patients undergoing anthracycline-based chemotherapy or reduce the response rates to anthracycline-based chemotherapy have been unclear. While anthracyclines are by far the most well-studied antitumor agents with cardiotoxic properties, evidence now shows that reactive oxygen species may play roles in cardiotoxicity induced by other chemotherapeutic agents such as cyclophosphamide, cisplatin, 5-fluorouracil, and trastuzumab. Thus, in the new era of combination therapy and long-term survival of cancer patients, the use of antioxidants to support cancer therapy should be revisited.

Cardioprotective interventions for cancer patients receiving anthracyclines

BACKGROUND

Anthracyclines are among the most effective chemotherapeutic agents in the treatment of numerous malignancies. Unfortunately, their use is limited by a dose-dependent cardiotoxicity. In an effort to prevent this cardiotoxicity, different cardioprotective agents have been studied.

OBJECTIVES

The objective of this review was to assess the efficacy of different cardioprotective agents in preventing heart damage in cancer patients treated with anthracyclines.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 10), MEDLINE (1966 to November 2010) and EMBASE (1980 to November 2010) databases. In addition, we handsearched reference lists, conference proceedings of the International Society of Paediatric Oncology (SIOP) and American Society of Clinical Oncology (ASCO) meetings (1998 to 2010) and ongoing trials registers.

SELECTION CRITERIA

Randomised controlled trials (RCTs) in which any cardioprotective agent was compared to no additional therapy or placebo in cancer patients (children and adults) receiving anthracyclines.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed the study selection, risk of bias assessment and data extraction including adverse effects.

MAIN RESULTS

We identified RCTs for the eight cardioprotective agents N-acetylcysteine, phenethylamines, coenzyme Q10, a combination of vitamins E and C and N-acetylcysteine, L-carnitine, carvedilol, amifostine and dexrazoxane (mostly for adults with advanced breast cancer). All studies had methodological limitations and for the first seven agents there were too few studies to allow pooling of results. None of the individual studies showed a cardioprotective effect. The 10 included studies on dexrazoxane enrolled 1619 patients. The meta-analysis for dexrazoxane showed a statistically significant benefit in favour of dexrazoxane for the occurrence of heart failure (risk ratio (RR) 0.29, 95% CI 0.20 to 0.41). No evidence was found for a difference in response rate or survival between the dexrazoxane and control groups. The results for adverse effects were ambiguous. No significant difference in the occurrence of secondary malignancies was identified.

AUTHORS' CONCLUSIONS

No definitive conclusions can be made about the efficacy of cardioprotective agents for which pooling of results was impossible. Dexrazoxane prevents heart damage and no evidence for a difference in response rate or survival between the dexrazoxane and control groups was identified. The evidence available did not allow us to reach any definite conclusions about adverse effects. We conclude that if the risk of cardiac damage is expected to be high, it might be justified to use dexrazoxane in patients with cancer treated with anthracyclines. However, clinicians should weigh the cardioprotective effect of dexrazoxane against the possible risk of adverse effects for each individual patient.

Cardioprotective interventions for cancer patients receiving anthracyclines

BACKGROUND

Anthracyclines are among the most effective chemotherapeutic agents in the treatment of numerous malignancies. Unfortunately, their use is limited by a dose-dependent cardiotoxicity. In an effort to prevent this cardiotoxicity, different cardioprotective agents have been studied.

OBJECTIVES

The objective of this review was to assess the efficacy of different cardioprotective agents in preventing heart damage in cancer patients treated with anthracyclines.

SEARCH STRATEGY

We searched the databases of the Cochrane Central Register of Controlled Trials (CENTRAL, Issue 2, 2007), MEDLINE (1966 to April 2007) and EMBASE (1980 to April 2007). In addition, we handsearched reference lists and conference proceedings of the SIOP and ASCO meetings (1998 to 2006).

SELECTION CRITERIA

Randomised controlled trials (RCTs) in which any cardioprotective agent was compared to no additional or placebo therapy in cancer patients (children and adults) receiving anthracyclines.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

We identified RCTs for seven cardioprotective agents: N-acetylcysteine, phenetylamines, coenzyme Q10, combination of vitamins E and C and N-acetylcysteine, L-carnitine, carvedilol and dexrazoxane (mostly adults with advanced breast cancer). All studies had methodological limitations. For the first six agents, there were too few studies to allow pooling of results. None of the individual studies showed a cardioprotective effect. The nine included studies of dexrazoxane enrolled 1403 patients. The meta-analysis of dexrazoxane showed a statistically significant benefit in favour of dexrazoxane for the occurrence of heart failure (Relative Risk (RR) 0.29, 95% CI 0.20 to 0.41). No evidence was found for a difference in response rate or survival between the dexrazoxane and control group. Only for one adverse effect (abnormal white blood cell count at nadir) a difference in favour of the control group was identified.

AUTHORS' CONCLUSIONS

For cardioprotective agents for which pooling was impossible, no definitive conclusions can be made about their efficacy. Dexrazoxane prevents heart damage and no evidence for a difference in response rate or survival between the dexrazoxane and control group was identified. Only for an abnormal white blood cell count at nadir a clearly significant difference in favour of the control group was identified. We conclude that if the risk of cardiac damage is expected to be high, it might be justified to use dexrazoxane in patients with cancer treated with anthracyclines. However, for each individual patient clinicians should weigh the cardioprotective effect of dexrazoxane against the possible risk of adverse effects.

Cardioprotective interventions for cancer patients receiving anthracyclines

BACKGROUND

Anthracyclines are among the most effective chemotherapeutic agents in the treatment of numerous malignancies. Unfortunately, their use is limited by a dose-dependent cardiotoxicity. In an effort to prevent this cardiotoxicity, different cardioprotective agents have been studied.

OBJECTIVES

The objective of this review was to assess the efficacy of different cardioprotective agents in preventing heart damage in cancer patients treated with anthracyclines.

SEARCH STRATEGY

We searched the databases of CENTRAL (The Cochrane Library, Issue 3, 2002), MEDLINE (1966 to August 2002) and EMBASE (1980 to August 2002). In addition, we handsearched reference lists and conference proceedings of the International Society for Paediatric Oncology (SIOP) and the American Society of Clinical Oncology (ASCO) (1998 to 2002).

SELECTION CRITERIA

Randomised controlled trials (RCTs) in which any cardioprotective agent was compared to no additional or placebo therapy in cancer patients (children and adults) receiving anthracyclines.

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

We identified RCTs for 5 cardioprotective agents: N-acetylcysteine (1 study; 54 patients), phenetylamines (2 studies; 100 patients), coenzyme Q10 (1 study; 20 patients), combination of vitamin E, vitamin C and N-acetylcysteine (1 study; 14 patients) and dexrazoxane (6 studies; 1013 patients). All studies had methodological limitations. Due to the insufficient number of studies, for the first four mentioned cardioprotective agents pooling of the results was impossible. None of the individual studies showed a cardioprotective effect. The meta-analysis of the dexrazoxane-studies showed a statistically significant benefit in favour of dexrazoxane for the occurrence of heart failure (Relative Risk (RR) = 0.28, 95% Confidence Interval (CI) 0.18 to 0.42, P < 0.00001). No statistically significant difference in response rate between the dexrazoxane and control group was found (RR = 0.88, 95% CI 0.77 to 1.01, P = 0.06), but there was some suggestion that patients treated with dexrazoxane might have a lower anti-tumour response rate. Our meta-analysis of survival showed no significant difference between the dexrazoxane and control group. For adverse effects pooling was impossible. However, no important differences in the occurrence of side effects were found. The majority of the patients included in this meta-analysis were adults with advanced breast cancer.

AUTHORS' CONCLUSIONS

For cardioprotective agents for which pooling was impossible no high quality evidence was available and therefore, no definitive conclusions can be made about their efficacy. Dexrazoxane prevents heart damage, however there was some suggestion that patients treated with dexrazoxane might have a lower anti-tumour response rate. There was no significant difference in survival between the dexrazoxane and control group. We conclude that if the risk of cardiac damage is expected to be high, it might be justified to use dexrazoxane in patients with cancer treated with anthracyclines. However, for each individual patient clinicians should weigh the cardioprotective effect of dexrazoxane against the possible risk of a lower response rate.