Doxorubicin cardiotoxicity: response of left ventricular ejection fraction to exercise and incidence of regional wall motion abnormalities

Anthracyclines and regional myocardial damage in breast cancer patients. A multicentre study from the Working Group on Drug Cardiotoxicity and Cardioprotection, Italian Society of Cardiology (SIC)

AIMS

In breast cancer (BC) patients treated with anthracyclines-based therapies, we aim at assessing whether adjuvant drugs impact cardiac function differently and whether their cardiotoxicity has a regional pattern.

METHODS AND RESULTS

In a multicentre study, 146 BC patients (56 ± 11 years) were prospectively enrolled and divided into three groups according to the received treatments: AC/EC-Group (doxorubicin or epirubicin + cyclophosphamide), AC/EC/Tax-Group (AC/EC + taxanes), FEC/Tax-Group (fluorouracil + EC + taxanes). Fifty-six patients of the total cohort also received trastuzumab. Left ventricular ejection fraction (LVEF) and global longitudinal strain (GLS) were calculated before starting chemotherapy (T0), at 3 months (T3), at 6 (T6), and 12 months (T12). A ≥10% drop of EF, while remaining within the normal range, was reached at T6 in 25.3% of patients from the whole cohort with an early decrease only in FEC/Tax-Group (P = 0.04). A ≥15% GLS reduction was observed in many more (61.6%) patients. GLS decreased early both in the whole population (P < 0.001) and in the subgroups. The FEC-Tax Group showed the worst GLS at T6. Trastuzumab further worsened GLS at T12 (P = 0.031). A significant reduction of GLS was observed in all LV segments and was more relevant in the anterior septum and apex.

CONCLUSIONS

The decrease of GLS is more precocious and pronounced in BC patients who received FEC + taxanes. Cardiac function further worsens after 6 months of adjuvant trastuzumab. All LV segments are damaged, with the anterior septum and the apex showing the greatest impairments.

Exercise Training Preserves Myocardial Strain and Improves Exercise Tolerance in Doxorubicin-Induced Cardiotoxicity

Doxorubicin causes cardiotoxicity and exercise intolerance. Pre-conditioning exercise training seems to prevent doxorubicin-induced cardiac damage. However, the effectiveness of the cardioprotective effects of exercise training concomitantly with doxorubicin treatment remains largely unknown. To determine whether low-to-moderate intensity aerobic exercise training during doxorubicin treatment would prevent cardiotoxicity and exercise intolerance, we performed exercise training concomitantly with chronic doxorubicin treatment in mice. Ventricular structure and function were accessed by echocardiography, exercise tolerance by maximal exercise test, and cardiac biology by histological and molecular techniques. Doxorubicin-induced cardiotoxicity, evidenced by impaired ventricular function, cardiac atrophy, and fibrosis. Exercise training did not preserve left ventricular ejection fraction or reduced fibrosis. However, exercise training preserved myocardial circumferential strain alleviated cardiac atrophy and restored cardiomyocyte cross-sectional area. On the other hand, exercise training exacerbated doxorubicin-induced body wasting without affecting survival. Finally, exercise training blunted doxorubicin-induced exercise intolerance. Exercise training performed during doxorubicin-based chemotherapy can be a valuable approach to attenuate cardiotoxicity.

Two-dimensional strain echocardiography for detection of cardiotoxicity in breast cancer patients undergoing chemotherapy

Introduction: Two-dimensional (2D) strain echocardiography has emerged as a novel method for early diagnosis of myocardial dysfunction in patients receiving anthracycline chemotherapy. Certain myocardial segments might be more vulnerable for development of dysfunction.

Methods: Sixty-three patients with breast cancer who were deemed amenable for anthracycline chemotherapy were prospectively studied from March 2013 to March 2015 in University Hospital settings. Global left ventricular (LV) ejection fraction (EF), fractional shortening and the strain over 17 segments of the LV were examined using 2-dimensional transthoracic echocardiography (TTE) before and after chemotherapy. More than 15% reduction in longitudinal peak systolic strain (LPSS) was considered significant.

Results: The mean age of patients was 47 ± 10 years. LVEF was 59.7 ± 6.5% at baseline. Significant reduction of global LPSS was detected in 13% of patients. A significant LPSS reduction occurred in 32.4% of 1071 segments examined following chemotherapy. LPSS significantly decreased in 28% of apical segments, 31% of mid segments and 37% of basal segments. LPSS reduction occurred more frequently over the basal segments than all other segments (P = 0.031).

Conclusion: Segmental pattern appears to exist in LPSS reduction following anthracycline therapy. As significant segmental decreases can be seen in the setting of unchanged global LPSS, segmental evaluation of LPSS might be a more accurate way for assessment of myocardial function.

Cardiac imaging approaches to evaluate drug-induced myocardial dysfunction

The ability to make informed benefit-risk assessments for potentially cardiotoxic new compounds is of considerable interest and importance at the public health, drug development, and individual patient levels. Cardiac imaging approaches in the evaluation of drug-induced myocardial dysfunction will likely play an increasing role. However, the optimal choice of myocardial imaging modality and the recommended frequency of monitoring are undefined. These decisions are complicated by the array of imaging techniques, which have varying sensitivities, specificities, availabilities, local expertise, safety, and costs, and by the variable time-course of tissue damage, functional myocardial depression, or recovery of function. This White Paper summarizes scientific discussions of members of the Cardiac Safety Research Consortium on the main factors to consider when selecting nonclinical and clinical cardiac function imaging techniques in drug development. We focus on 3 commonly used imaging modalities in the evaluation of cardiac function: echocardiography, magnetic resonance imaging, and radionuclide (nuclear) imaging and highlight areas for future research.

Carbonyl reductase 1 as a novel target of (-)-epigallocatechin gallate against hepatocellular carcinoma

Human carbonyl reductase 1 (CBR1) converts the antitumor drug and anthracycline daunorubicin (DNR) into the alcohol metabolite daunorubicinol (DNROL) with significantly reduced antitumor activity and cardiotoxicity, and this limits the clinical use of DNR. Inhibition of CBR1 can thus increase the efficacy and decrease the toxicity of DNR. Here we report that (-)-epigallocatechin gallate (EGCG) from green tea is a promising inhibitor of CBR1. EGCG directly interacts with CBR1 and acts as a noncompetitive inhibitor with respect to the cofactor reduced nicotinamide adenine dinucleotide phosphate and the substrate isatin. The inhibition is dependent on the pH, and the gallate moiety of EGCG is required for activity. Molecular modeling has revealed that EGCG occupies the active site of CBR1. Furthermore, EGCG specifically enhanced the antitumor activity of DNR against hepatocellular carcinoma SMMC7721 cells expressing high levels of CBR1 and corresponding xenografts. We also demonstrated that EGCG could overcome the resistance to DNR by Hep3B cells stably expressing CBR1 but not by RNA interference of CBR1-HepG2 cells. The level of the metabolite DNROL was negatively correlated with that of EGCG in the cell extracts. Finally, EGCG decreased the cardiotoxicity of DNR in a human carcinoma xenograft model with both SMMC7721 and Hep3B cells in mice.

CONCLUSION

These results strongly suggest that EGCG can inhibit CBR1 activity and enhance the effectiveness and decrease the cardiotoxicity of the anticancer drug DNR. These findings also indicate that a combination of EGCG and DNR might represent a novel approach for hepatocellular carcinoma therapy or chemoprevention.

Effects of Adriamycin on heart mitochondrial function in rested and exercised rats

The effect of Adriamycin (ADM) administration on heart mitochondria was investigated in rats at rest and after an acute bout of maximal exercise. ADM was given intravenously at a dosage of 8 mg/kg body weight 24 and 1 hr before rats were decapitated. Respiratory functions of the isolated heart mitochondria were measured polarographically with both site 1 (pyruvate-malate and 2-oxoglutarate) and site 2 (succinate) substrates. State 4 (basal) respiration was increased using all substrates in ADM-treated rat hearts compared with non-drug control hearts. The mitochondrial respiratory control index was decreased with ADM, but the reduction was due to an increase in state 4 rather than a decrease of state 3 (ADP-stimulated) respiration. ADM administration abolished an exercise-induced elevation of state 3 respiration using all substrates. There was no significant myocardial oxidative damage of dysfunction as evaluated by lipid peroxidation and antioxidant enzyme activity. Addition of exogenous free radicals to the respiratory medium using hypoxanthine and xanthine oxidase resulted in significant deterioration of mitochondrial function in all parameters measured, but no drug- or exercise-specific patterns of damage were revealed. It is concluded that the current dose of ADM (20% of the established cumulative toxic dose) administered within 24 hr can interfere with normal heart mitochondrial function both at rest and during heavy exercise, but does not elicit overwhelming oxidative damage to the myocardium.