Chronic Anthracycline Cardiotoxicity Research Articles

Abstract P3111: Can ACE Inhibitors Provide Similar Long-lasting Cardioprotection Against Chronic Anthracycline Cardiotoxicity As An Approved Drug Dexrazoxane On A Well-established Animal Model?

Background: ACE inhibitors (ACEi) have been reported cardioprotective in a secondary prevention of anthracycline (ANT) cardiotoxicity in high-risk patients. However, it remains to be determined whether they can also prevent the onset of ANT-induced cardiac damage and provide long-lasting cardioprotection in primary settings similarly as approved drug dexrazoxane (DEX). Objectives: The aim of this study was to assess whether ACEis can prevent TOP2B-mediated DNA damage induced by ANTs in the heart as a very upstream event, and thus provide long-lasting cardioprotection against chronic ANT cardiotoxicity. Methods: Chronic cardiotoxicity was induced in rabbits by daunorubicin (DAU, 3 mg/kg weekly for 10 weeks). Perindopril (PER) in two clinically relevant doses (0.05 and 0.1 mg/kg/day) was administered before and throughout the chronic DAU treatment. The cardioprotection was evaluated at the end of treatment period and after 3- and 10-week drug-free post-treatment follow-up (FU). TOP2B-depedent DNA damage signaling in the heart was determined 6 h after single dose of DAU, while TOPB interaction was studied in vitro ; the results were compared to DEX. Results: A week after completion of the chronic DAU administration, PER-co-treatment completely overcame or markedly reduced DAU-induced mortality, blood congestion and systolic dysfunction (LVFS 41.5% vs. 34.3% in the DAU group, p<0.05), increase of troponin T in plasma and histopathological changes in the heart. However, most of these parameters were significantly deteriorated during 3-week drug-free FU. Further worsening of the left ventricular systolic function and cardiac morphological damage occurred in the 10-week FU which led to a heart failure-related mortality in the PER co-treated group. DEX showed very effective protection against DAU cardiotoxicity both at the end of chronic treatment and after the 10-week FU. In contrast to DEX, the PER co-treatment did not affect TOP2B activity in vitro and did not prevent DAU-induced acute p53-mediated DNA damage signaling in the heart. Conclusions: Unlike approved drug DEX, the ACEi treatment provided only temporary control of ANT cardiotoxicity development which may be associated with the lack of the effects on ANT-induced and TOP2B-mediated DNA damage response in the heart.

Abstract P3112: Pharmacological Inhibition Of ATM Sensitizes Rabbit Hearts For Development Of Chronic Anthracycline Cardiotoxicity And Heart Failure

Introduction: Anthracycline (ANT) cardiotoxicity is still a serious complication of cancer chemotherapy. While it has been originally explained by direct oxidative damage to the heart, recently topoisomerase II beta (TOP2B)-dependent DNA damage to cardiomyocytes has been implicated. However, the specific role of DNA damage response (DDR) signaling downstream of TOP2B in the development of chronic ANT cardiotoxicity remains unclear. Hypothesis: Pharmacological inhibition of ATM will confirm the involvement of the ATM pathway in DDR signaling in the heart after ANT exposure and determine whether this signaling leads to the development of ANT cardiotoxicity or the opposite is true. Methods: A well-established rabbit model of chronic ANT cardiotoxicity (daunorubicin/DAU/3 mg/kg, weekly for ten weeks) was employed. The highly selective ATM inhibitor AZD0156, which is currently in clinical evaluation elsewhere, was administered at 0.5 mg/kg before each DAU dose. The results were compared with the group receiving AZD0156 alone and the controls receiving saline or vehicle for AZD0156. In another set of animals, the acute DDR in the heart was studied 6 hours after a single administration of the same drugs. Results: AZD0156 effectively prevented acute DAU-induced increase of p53 levels and up-regulation of p53 target genes (p21 and many others) in the left ventricular myocardium. Chronic co-treatment of AZD0156 with DAU markedly increased the incidence of DAU-induced blood congestion (hydrothorax 80 % vs. 40 % in the DAU-alone group), end-stage heart failure, and heart failure-related mortality (60 % vs. 20 % in the DAU-alone group). Before the observed deaths, plasma levels of cardiac troponin T increased steeply, while left ventricular fractional shortening (LVFS) determined by echocardiography declined. The last measured LVFS values in the AZD0156+DAU group were significantly lower than in the DAU-alone group. AZD0156 alone was well tolerated and had no significant impact on any studied parameter. Conclusion: ANT-induced DDR signaling in the heart appears to be ATM-dependent, and pharmacological inhibition of ATM sensitizes rabbit hearts to ANT-induced chronic cardiotoxicity and heart failure.

Primary prevention of chronic anthracycline cardiotoxicity with ACE inhibitor is temporarily effective in rabbits, but benefits wane in post-treatment follow-up.

Angiotensin-converting enzyme inhibitors (ACEis) have been used to treat anthracycline (ANT)-induced cardiac dysfunction, and they appear beneficial for secondary prevention in high-risk patients. However, it remains unclear whether they truly prevent ANT-induced cardiac damage and provide long-lasting cardioprotection. The present study aimed to examine the cardioprotective effects of perindopril on chronic ANT cardiotoxicity in a rabbit model previously validated with the cardioprotective agent dexrazoxane (DEX) with focus on post-treatment follow-up (FU). Chronic cardiotoxicity was induced by daunorubicin (DAU; 3 mg/kg/week for 10 weeks). Perindopril (0.05 mg/kg/day) was administered before and throughout chronic DAU treatment. After the completion of treatment, significant benefits were observed in perindopril co-treated animals, particularly full prevention of DAU-induced mortality and prevention or significant reductions in cardiac dysfunction, plasma cardiac troponin T (cTnT) levels, morphological damage, and most of the myocardial molecular alterations. However, these benefits significantly waned during 3 weeks of drug-free FU, which was not salvageable by administering a higher perindopril dose. In the longer (10-week) FU period, further worsening of left ventricular function and morphological damage occurred together with heart failure (HF)-related mortality. Continued perindopril treatment in the FU period did not reverse this trend but prevented HF-related mortality and reduced the severity of the progression of cardiac damage. These findings contrasted with the robust long-lasting protection observed previously for DEX in the same model. Hence, in the present study, perindopril provided only temporary control of ANT cardiotoxicity development, which may be associated with the lack of effects on ANT-induced and topoisomerase II β (TOP2B)-dependent DNA damage responses in the heart.

Prodrug of ICRF-193 provides promising protective effects against chronic anthracycline cardiotoxicity in a rabbit model in vivo.

The anthracycline (ANT) anticancer drugs such as doxorubicin or daunorubicin (DAU) can cause serious myocardial injury and chronic cardiac dysfunction in cancer survivors. A bisdioxopiperazine agent dexrazoxane (DEX) has been developed as a cardioprotective drug to prevent these adverse events, but it is uncertain whether it is the best representative of the class. The present study used a rabbit model of chronic ANT cardiotoxicity to examine another bisdioxopiperazine compound called GK-667 (meso-(butane-2,3-diylbis(2,6-dioxopiperazine-4,1-diyl))bis(methylene)-bis(2-aminoacetate) hydrochloride), a water-soluble prodrug of ICRF-193 (meso-4,4'-(butan-2,3-diyl)bis(piperazine-2,6-dione)), as a potential cardioprotectant. The cardiotoxicity was induced by DAU (3 mg/kg, intravenously, weekly, 10 weeks), and GK-667 (1 or 5 mg/kg, intravenously) was administered before each DAU dose. The treatment with GK-667 was well tolerated and provided full protection against DAU-induced mortality and left ventricular (LV) dysfunction (determined by echocardiography and LV catheterization). Markers of cardiac damage/dysfunction revealed minor cardiac damage in the group co-treated with GK-667 in the lower dose, whereas almost full protection was achieved with the higher dose. This was associated with similar prevention of DAU-induced dysregulation of redox and calcium homeostasis proteins. GK-667 dose-dependently prevented tumor suppressor p53 (p53)-mediated DNA damage response in the LV myocardium not only in the chronic experiment but also after single DAU administration. These effects appear essential for cardioprotection, presumably because of the topoisomerase IIβ (TOP2B) inhibition provided by its active metabolite ICRF-193. In addition, GK-667 administration did not alter the plasma pharmacokinetics of DAU and its main metabolite daunorubicinol (DAUol) in rabbits in vivo. Hence, GK-667 merits further investigation as a promising drug candidate for cardioprotection against chronic ANT cardiotoxicity.

Investigation of Structure-Activity Relationships of Dexrazoxane Analogs Reveals Topoisomerase IIβ Interaction as a Prerequisite for Effective Protection against Anthracycline Cardiotoxicity.

Bisdioxopiperazine agent dexrazoxane (ICRF-187) has been the only effective and approved drug for prevention of chronic anthracycline cardiotoxicity. However, the structure-activity relationships (SARs) of its cardioprotective effects remain obscure owing to limited investigation of its derivatives/analogs and uncertainties about its mechanism of action. To fill these knowledge gaps, we tested the hypothesis that dexrazoxane derivatives exert cardioprotection via metal chelation and/or modulation of topoisomerase IIβ (Top2B) activity in chronic anthracycline cardiotoxicity. Dexrazoxane was alkylated in positions that should not interfere with the metal-chelating mechanism of cardioprotective action; that is, on dioxopiperazine imides or directly on the dioxopiperazine ring. The protective effects of these agents were assessed in vitro in neonatal cardiomyocytes. All studied modifications of dexrazoxane molecule, including simple methylation, were found to abolish the cardioprotective effects. Because this challenged the prevailing mechanistic concept and previously reported data, the two closest derivatives [(±)-4,4'-(propane-1,2-diyl)bis(1-methylpiperazine-2,6-dione) and 4-(2-(3,5-dioxopiperazin-1-yl)ethyl)-3-methylpiperazine-2,6-dione] were thoroughly scrutinized in vivo using a rabbit model of chronic anthracycline cardiotoxicity. In contrast to dexrazoxane, both compounds failed to protect the heart, as demonstrated by mortality, cardiac dysfunction, and myocardial damage parameters, although the pharmacokinetics and metal-chelating properties of their metabolites were comparable to those of dexrazoxane. The loss of cardiac protection was shown to correlate with their abated potential to inhibit and deplete Top2B both in vitro and in vivo. These findings suggest a very tight SAR between bisdioxopiperazine derivatives and their cardioprotective effects and support Top2B as a pivotal upstream druggable target for effective cardioprotection against anthracycline cardiotoxicity. SIGNIFICANCE STATEMENT: This study has revealed the previously unexpected tight structure-activity relationships of cardioprotective effects in derivatives of dexrazoxane, which is the only drug approved for the prevention of cardiomyopathy and heart failure induced by anthracycline anticancer drugs. The data presented in this study also strongly argue against the importance of metal-chelating mechanisms for the induction of this effect and support the viability of topoisomerase IIβ as an upstream druggable target for effective and clinically translatable cardioprotection.

Are cardioprotective effects of NO-releasing drug molsidomine translatable to chronic anthracycline cardiotoxicity settings?

Chronic anthracycline (ANT) cardiotoxicity is a serious complication of cancer chemotherapy. Molsidomine, a NO-releasing drug, has been found cardioprotective in different models of I/R injury and recently in acute high-dose ANT cardiotoxicity. Hence, we examined whether its cardioprotective effects are translatable to chronic ANT cardiotoxicity settings without induction of nitrosative stress and interference with antiproliferative action of ANTs. The effects of molsidomine (0.025 and 0.5mg/kg, i.v.) were studied on the well-established model of chronic ANT cardiotoxicity in rabbits (daunorubicin/DAU/3mg/kg/week for 10 weeks). Molsidomine was unable to significantly attenuate mortality, development of heart failure and morphological damage induced by DAU. Molsidomine did not alter DAU-induced myocardial lipoperoxidation, MnSOD down-regulation, up-regulation of HO-1, IL-6, and molecular markers of cardiac remodeling. Although molsidomine increased 3-nitrotyrosine in the myocardium, this event had no impact on cardiotoxicity development. Using H9c2 myoblasts and isolated cardiomyocytes, it was found that SIN-1 (an active metabolite of molsidomine) induces significant protection against ANT toxicity, but only at high concentrations. In leukemic HL-60 cells, SIN-1 initially augmented ANT cytotoxicity (in low and clinically achievable concentrations), but it protected these cells against ANT in the high concentrations. UHPLC-MS/MS investigation demonstrated that the loss of ANT cytotoxicity after co-incubation of the cells in vitro with high concentrations of SIN-1 is caused by unexpected chemical depletion of DAU molecule. The present study demonstrates that cardioprotective effects of molsidomine are not translatable to clinically relevant chronic form of ANT cardiotoxicity. The augmentation of antineoplastic effects of ANT in low (nM) concentrations may deserve further study.

Testosterone Antagonizes Doxorubicin-Induced Senescence of Cardiomyocytes.

BackgroundChronic cardiotoxicity is less common in male than in female patients receiving doxorubicin and other anthracyclines at puberty and adolescence. We hypothesized that this sex difference might be secondary to distinct activities of sex hormones on cardiomyocyte senescence, which is thought to be central to the development of long‐term anthracycline cardiomyopathy.Methods and ResultsH9c2 cells and neonatal mouse cardiomyocytes were exposed to doxorubicin with or without prior incubation with testosterone or 17β‐estradiol, the main androgen and estrogen, respectively. Testosterone, but not 17β‐estradiol, counteracted doxorubicin‐elicited senescence. Downregulation of telomere binding factor 2, which has been pinpointed previously as being pivotal to doxorubicin‐induced senescence, was also prevented by testosterone, as were p53 phosphorylation and accumulation. Pretreatment with the androgen receptor antagonist flutamide, the phosphatidylinositol 3 kinase inhibitor LY294002, and the nitric oxide synthase inhibitor L‐NG‐nitroarginine methyl ester abrogated the reduction in senescence and the normalization of telomere binding factor 2 levels attained by testosterone. Consistently, testosterone enhanced the phosphorylation of AKT and nitric oxide synthase 3. In H9c2 cells, doxorubicin‐stimulated senescence was still observed up to 21 days after treatment and increased further when cells were rechallenged with doxorubicin 14 days after the first exposure to mimic the schedule of anthracycline‐containing chemotherapy. Remarkably, these effects were also inhibited by testosterone.ConclusionsTestosterone protects cardiomyocytes against senescence caused by doxorubicin at least in part by modulating telomere binding factor 2 via a pathway involving the androgen receptor, phosphatidylinositol 3 kinase, AKT, and nitric oxide synthase 3. This is a potential mechanism by which pubescent and adolescent boys are less prone to chronic anthracycline cardiotoxicity than girls.

Cardioprotective effects of inorganic nitrate/nitrite in chronic anthracycline cardiotoxicity: Comparison with dexrazoxane

Dexrazoxane (DEX) is a clinically available cardioprotectant that reduces the toxicity induced by anthracycline (ANT) anticancer drugs; however, DEX is seldom used and its action is poorly understood. Inorganic nitrate/nitrite has shown promising results in myocardial ischemia–reperfusion injury and recently in acute high-dose ANT cardiotoxicity. However, the utility of this approach for overcoming clinically more relevant chronic forms of cardiotoxicity remains elusive. Hence, in this study, the protective potential of inorganic nitrate and nitrite against chronic ANT cardiotoxicity was investigated, and the results were compared to those using DEX. Chronic cardiotoxicity was induced in rabbits with daunorubicin (DAU). Sodium nitrate (1g/L) was administered daily in drinking water, while sodium nitrite (0.15 or 5mg/kg) or DEX (60mg/kg) was administered parenterally before each DAU dose. Although oral nitrate induced a marked increase in plasma NOx, it showed no improvement in DAU-induced mortality, myocardial damage or heart failure. Instead, the higher nitrite dose reduced the incidence of end-stage cardiotoxicity, prevented related premature deaths and significantly ameliorated several molecular and cellular perturbations induced by DAU, particularly those concerning mitochondria. The latter result was also confirmed in vitro. Nevertheless, inorganic nitrite failed to prevent DAU-induced cardiac dysfunction and molecular remodeling in vivo and failed to overcome the cytotoxicity of DAU to cardiomyocytes in vitro. In contrast, DEX completely prevented all of the investigated molecular, cellular and functional perturbations that were induced by DAU. Our data suggest that the difference in cardioprotective efficacy between DEX and inorganic nitrite may be related to their different abilities to address a recently proposed upstream target for ANT in the heart — topoisomerase IIβ.

Experimental determination of diagnostic window of cardiac troponins in the development of chronic anthracycline cardiotoxicity and estimation of its predictive value

BackgroundCardiac troponins (cTns) seem to be more sensitive for the detection of anthracycline cardiotoxicity than the currently recommended method of monitoring LV systolic function. However, the optimal timing of blood sampling remains unknown. Hence, the aims of the present study were to determine the precise diagnostic window for cTns during the development of chronic anthracycline cardiotoxicity and to evaluate their predictive value. MethodsCardiotoxicity was induced in rabbits with daunorubicin (3mg/kg, weekly, for 8weeks). Blood samples were collected 2–168h after the 1st, 5th and 8th drug administrations, and concentrations of cTns were determined using highly sensitive assays: hs cTnT (Roche) and hs cTnI (Abbott). ResultsThe plasma levels of cTns progressively increased with the rising number of chemotherapy cycles. While only a mild non-significant increase in both cTn levels occurred after the first daunorubicin dose, a significant rise was observed after the 5th and 8th administrations. Two hours after these administrations, a significant increase occurred with a peak between 4–6h and a decline until 24h. Discrete cTn release continued even after cessation of the therapy. While greater variability of cTn levels was observed around the peak concentrations, the values did not correspond well with the severity of LV systolic dysfunction. Unlike AMI in cardiotoxicity, cTn elevations may be better associated with cumulative dose and concentrations at steady state than cmax. ConclusionsTo the best of our knowledge, this is the first study to precisely describe the diagnostic window and predictive value of cTns in anthracycline cardiotoxicity.

STUDY OF MOLECULAR MECHANISMS INVOLVED IN CARDIOPROTECTIVE ACTION OF DEXRAZOXANE AGAINST ANTHRACYCLINE CARDIOTOXICITY IN RABBITS

So far dexrazoxane (DEX) is the only drug approved for prevention of chronic anthracycline (ANT) cardiotoxicity. However, molecular mechanisms responsible for its cardioprotective effects remain unclear. This report addresses traditional as well as alternative mechanisms of its cardioprotective action against chronic ANT cardiotoxicity. Daunorubicin (DAU, 3 mg/kg/week for 10 weeks) was used to induced cardiotoxicity in rabbits and DEX (60 mg/kg) was administered prior each DAU dose. LV myocardium was analyzed for oxidative stress, mitochondrial damage, changes in mtDNA and mtDNA/nDNA ratio, and perturbations in mitochondrial proteins expression. DEX ability to interact with iron was addressed in H9c2 cardiomyoblasts. In addition, topoisomerase-2β (TOP2b) expression was studied after DEX exposure in vitro and in vivo. DEX completely prevented DAU-induced heart damage as well as mitochondrial damage. This protection was not directly based on protection from oxidative damage of myocardium or common deletion in mtDNA. Instead, DEX was able to prevent DAU-induced significant decrease in expression of mitochondrial biogenesis regulators (e.g. TFAM) and OXPHOS subunits encoded by both nDNA and mtDNA. Noteworthy, in vitro experiments showed inability of DEX to mobilize iron from cells. Finally, DEX exposure decreased TOP2b protein levels which can correspond with recent data showing that ANT cardiotoxicity may beTOP2b-mediated. The present data suggest that DEX cardioprotective effects need not be based on iron chelation and prevention of oxidative stress or mtDNA deletions. Instead, DEX-induced depletion of TOP2b may be important for cardioprotection and merit further study. Supported by GACR 13–15008S and PRVOUK P37/05.

CAN INORGANIC NITRATE/NITRITE EFFECTIVELY OVERCOME CHRONIC ANTHRACYCLINE CARDIOTOXICITY IN RABBITS?

Inorganic nitrate/nitrite have been shown cardioprotective against ischemia-reperfusion injury and recently also against acute high-dose anthracycline (ANT) cardiotoxicity. However, translatability of the latter findings to clinically more relevant chronic ANT...

Molecular remodeling of left and right ventricular myocardium in chronic anthracycline cardiotoxicity and post-treatment follow up.

Chronic anthracycline cardiotoxicity is a serious clinical issue with well characterized functional and histopathological hallmarks. However, molecular determinants of the toxic damage and associated myocardial remodeling remain to be established. Furthermore, details on the different propensity of the left and right ventricle (LV and RV, respectively) to the cardiotoxicity development are unknown. Hence, the aim of the investigation was to study molecular changes associated with remodeling of the LV and RV in chronic anthracycline cardiotoxicity and post-treatment follow up. The cardiotoxicity was induced in rabbits with daunorubicin (3 mg/kg/week for 10 weeks) and animals were sacrificed either at the end of the treatment or after an additional 10 weeks. Daunorubicin induced severe and irreversible cardiotoxicity associated with LV dysfunction and typical morphological alterations, whereas the myocardium of the RV showed only mild changes. Both ventricles also showed different expression of ANP after daunorubicin treatment. Daunorubicin impaired the expression of several sarcomeric proteins in the LV, which was not the case of the RV. In particular, a significant drop was found in titin and thick filament proteins at both mRNA and protein level and this might be connected with persistent LV down-regulation of GATA-4. In addition, the LV was more affected by treatment-induced perturbations in calcium handling proteins. LV cardiomyocytes showed marked up-regulation of desmin after the treatment and vimentin was mainly induced in LV fibroblasts, whereas only weaker changes were observed in the RV. Remodeling of extracellular matrix was almost exclusively found in the LV with particular induction of collagen I and IV. Hence, the present study describes profound molecular remodeling of myocytes, non-myocyte cells and extracellular matrix in response to chronic anthracycline treatment with marked asymmetry between LV and RV.

Early and delayed cardioprotective intervention with dexrazoxane each show different potential for prevention of chronic anthracycline cardiotoxicity in rabbits

Despite incomplete understanding to its mechanism of action, dexrazoxane (DEX) is still the only clearly effective cardioprotectant against chronic anthracycline (ANT) cardiotoxicity. However, its clinical use is currently restricted to patients exceeding significant ANT cumulative dose (300mg/m2), although each ANT cycle may induce certain potentially irreversible myocardial damage. Therefore, the aim of this study was to compare early and delayed DEX intervention against chronic ANT cardiotoxicity and study the molecular events involved. The cardiotoxicity was induced in rabbits with daunorubicin (DAU; 3mg/kg/week for 10 weeks); DEX (60mg/kg) was administered either before the 1st or 7th DAU dose (i.e. after ≈300mg/m2 cumulative dose). While both DEX administration schedules prevented DAU-induced premature deaths and severe congestive heart failure, only the early intervention completely prevented the left ventricular dysfunction, myocardial morphological changes and mitochondrial damage. Further molecular analyses did not support the assumption that DEX cardioprotection is based and directly proportional to protection from DAU-induced oxidative damage and/or deletions in mtDNA. Nevertheless, DAU induced significant up-regulation of heme oxygenase 1 pathway while heme synthesis was inversely regulated and both changes were schedule-of-administration preventable by DEX. Early and delayed DEX interventions also differed in ability to prevent DAU-induced down-regulation of expression of mitochondrial proteins encoded by both nuclear and mitochondrial genome. Hence, the present functional, morphological as well as the molecular data highlights the enormous cardioprotective effects of DEX and provides novel insights into the molecular events involved. Furthermore, the data suggests that currently recommended delayed intervention may not be able to take advantage of the full cardioprotective potential of the drug.

CMR shows that anthracycline cardiotoxicity is common in women treated for early breast cancer and associated with undiagnosed hypertension; but cannot be reliably detected using late-gadolinium enhancement imaging

Background A growing number of patients with cancer are at risk from chronic anthracycline cardiotoxicity (cAC) as a result of improving cancer prognosis. Although susceptibility is cumulative dose-related, it is also idiosyncratic. Furthermore, at present there is no way to reliably identify those at risk. The common practice of serially measuring LV ejection fraction (LVEF) only identifies cardiotoxicity after significant damage has been incurred. We hypothesised that risk of cAC could be determined from patient and treatment factors, known at baseline, together with assessment of the cardiac response to the 1st dose of anthracycline. Here we report the prevalence of cAC detected using CMR, together with the associations with baseline BP and anthracycline dose. Methods Women due to receive anthracycline-based chemotherapy for early breast cancer were recruited. Those with known cardiovascular disease were excluded. CMR was performed on Siemens 1.5T scanners before chemotherapy and at follow-up (>1 year after the final anthracycline cycle, and >3 months after Trastuzumab). LVEF was measured from cine images by a single operator (PK) blind to clinical and temporal data, using CMRtools. Chronic AC (cAC) was defined as a fall in absolute LVEF ≥5%. Results 164 subjects completed the study 18.5 [15.1-23.7] months after finishing treatment. 99% received epirubicin (400 [300-450] mg/m2). The mean fall in LVEF was 2.2% (p 20% of patients. Declines in resting LVEF are relatively late in the pathological process of cAC and therefore likely to reflect increased risk of heart failure as a ‘late-effect’ of cancer treatment. Our data suggest that undiagnosed hypertension was common; diagnosing and treating it may offer an opportunity to reduce cAC. A fall in LVEF ≥5% detected by CMR may be a better end-point for monitoring cardiotoxicity in oncology trials than those currently used. Although fibrosis is a hallmark of cAC based on biopsy

The breast cancer, early disease: toxicity from therapy with epirubicin regimens - cardiac assessment and risk evaluation (BETTER-CARE) study: CMR with early gadolinium relative enhancement, but not high-sensitivity troponin T, predicts the risk of chronic anthracycline cardiotoxicity

The breast cancer, early disease: toxicity from therapy with epirubicin regimens cardiac assessment and risk evaluation (BETTER-CARE) study: CMR with early gadolinium relative enhancement, but not high-sensitivity troponin T, predicts the risk of chronic anthracycline cardiotoxicity Paul Kotwinski, Gillian Smith, Julie Sanders, Louise Ma, Jackie Cooper, Michael Thomas, Michael (Monty) G Mythen, Alison Jones, Hugh E Montgomery, Dudley J Pennell

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

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. 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. 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. 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.

Chronic Anthracycline Cardiotoxicity: Molecular and Functional Analysis with Focus on Nuclear Factor Erythroid 2-Related Factor 2 and Mitochondrial Biogenesis Pathways

Anthracycline anticancer drugs (e.g., doxorubicin or daunorubicin) can induce chronic cardiotoxicity and heart failure (HF), both of which are believed to be based on oxidative injury and mitochondrial damage. In this study, molecular and functional changes induced by chronic anthracycline treatment with progression into HF in post-treatment follow-up were analyzed with special emphasis on nuclear factor erythroid 2-related factor 2 (Nrf2) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) pathways. Chronic cardiotoxicity was induced in rabbits with daunorubicin (3 mg/kg, weekly for 10 weeks), and the animals were followed for another 10 weeks. Echocardiography revealed a significant drop in left ventricular (LV) systolic function during the treatment with marked progression to LV dilation and congestive HF in the follow-up. Although daunorubicin-induced LV lipoperoxidation was found, it was only loosely associated with cardiac performance. Furthermore, although LV oxidized glutathione content was increased, the oxidized-to-reduced glutathione ratio itself remained unchanged. Neither Nrf2, the master regulator of antioxidant response, nor the majority of its target genes showed up-regulation in the study. However, down-regulation of manganese superoxide dismutase and NAD(P)H dehydrogenase [quinone] 1 were observed together with heme oxygenase 1 up-regulation. Although marked perturbations in mitochondrial functions were found, no induction of PGC1α-controlled mitochondrial biogenesis pathway was revealed. Instead, especially in the post-treatment period, an impaired regulation of this pathway was observed along with down-regulation of the expression of mitochondrial genes. These results imply that global oxidative stress need not be a factor responsible for the development of anthracycline-induced HF, whereas suppression of mitochondrial biogenesis might be involved.

018 The breast cancer, early disease: toxicity from therapy with epirubicin regimens ¨ c cardiac assessment and risk evaluation (better-care), cardiovascular magnetic resonance (CMR) sub-study: cycle 1 changes predict late anthracycline cardiotoxicity

IntroductionA growing number of patients are at risk from chronic anthracycline cardiotoxicity (cAC) as a result of improving prognosis of cancer. This is true even at low, adjuvant doses. In...

Abstract 5675: Potential use of proteosome pathway inhibitor (bortezomib) in combination with anthracyclines to treat multiple myeloma and pancreatic cancer

Abstract Anthracyclines are widely used to treat cancers, but may also cause a cumulative dose-related cardiotoxicity. One possible mechanism of cardiotoxicity relates to effects on the cardiomyocyte proteasomal/ubiquitin system (UPS), the major protein recycling system in the cell. The goal of the research is to determine the impact of anthracyclines on the UPS and modulate cardiotoxicity by using other drugs in combination. Rats were treated chronically with a clinically relevant dose of daunorubicin (DNR) or the vehicle (controls) over 9 weeks. Another group received DNR pretreated with ICRF (dexrazoxane; a known protectant against anthracycline cardiotoxicity). The hearts were harvested one week later and analyzed. Isometric atrial preparations from rats treated with DNR showed decreased contractility compared to those pretreated with ICRF or with DNR vehicle only. Ubiquitin ligase atrogin-1 has been associated with muscle atrophy and cancer cachexia. In western blot analysis of common E3 ligases in left ventricle samples from rats treated with DNR, Atrogin-1 showed a significant reduction (P<0.05) compared to animals pretreated with ICRF or DNR vehicle. This suggests that chronic anthracycline cardiotoxicity is accompanied by ubiquitin function. Bortezomib, a proteasomal inhibitor, is approved for treatment of multiple myeloma (MM) and is being investigated for treatment of pancreatic cancer with other drugs. To understand the antineoplastic interaction of a proteosome inhibitor (bortezomib) with an anthracycline (doxorubicin), we performed dose-response assays using MM and pancreatic cancer cell lines. Our studies indicate that, compared to bortezomib alone, 0.05 µM of doxorubicin in combination with bortezomib, enhanced cytotoxicity of bortezomib in the two cell lines. Thus, bortezomib and anthracycline combination therapy may provide enhanced tumoricidal activity for MM and pancreatic cancer compared to bortezomib alone. It is important to understand the mechanisms of the effect of bortezomib and anthracyclines on ubiquitin-proteasome pathway. (Supported by a St. Luke's Health System Mountain States Tumor and Medical Research Institute grant) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5675. doi:1538-7445.AM2012-5675

Proteomic insights into chronic anthracycline cardiotoxicity

Chronic anthracycline cardiotoxicity is a feared complication of cancer chemotherapy. However, despite several decades of primarily hypothesis-driven research, the molecular basis of this phenomenon remains poorly understood. The aim of this study was to obtain integrative molecular insights into chronic anthracycline cardiotoxicity and the resulting heart failure. Cardiotoxicity was induced in rabbits (daunorubicin 3 mg/kg, weekly, 10 weeks) and changes in the left ventricular proteome were analyzed by 2D-DIGE. The protein spots with significant changes (p < 0.01, > 1.5-fold) were identified using MALDI-TOF/TOF. Key data were corroborated by immunohistochemistry, qRT-PCR and enzyme activity determination and compared with functional, morphological and biochemical data. The most important alterations were found in mitochondria — especially in proteins crucial for oxidative phosphorylation, energy channeling, antioxidant defense and mitochondrial stress. Furthermore, the intermediate filament desmin, which interacts with mitochondria, was determined to be distinctly up-regulated and disorganized in its expression pattern. Interestingly, the latter changes reflected the intensity of toxic damage in whole hearts as well as in individual cells. In addition, a marked drop in myosin light chain isoforms, activation of proteolytic machinery (including the proteasome system), increased abundance of chaperones and proteins involved in chaperone-mediated autophagy, membrane repair as well as apoptosis were found. In addition, dramatic changes in proteins of basement membrane and extracellular matrix were documented. In conclusion, for the first time, the complex proteomic signature of chronic anthracycline cardiotoxicity was revealed which enhances our understanding of the basis for this phenomenon and it may enhance efforts in targeting its reduction.