Doxorubicin cardiac toxicity manifesting seven years after treatment. Case report and review

The Mechanism of Dynamic Interaction between Doxorubicin and Calf Thymus DNA at the Single-Molecule Level Based on Confocal Raman Spectroscopy

It is of great fundamental significance and practical application to understand the binding sites and dynamic process of the interaction between doxorubicin (DOX) and DNA molecules. Based on the Confocal Raman spectroscopy, the interaction between DOX and calf thymus DNA has been systemically investigated, and some meaningful findings have been found. DOX molecules can not only interact with all four bases of DNA molecules, i.e., adenine, thymine, cytosine, guanine, and phosphate, but also affect the DNA conformation. Meanwhile, the binding site of DOX and its derivatives such as daunorubicin and epirubicin is certain. Furthermore, the interaction between DOX and DNA molecules is a dynamic process since the intensities of each characteristic peaks of the base, e.g., adenine, cytosine, and phosphate, are all regularly changed with the interaction time. Finally, a dynamic mechanism model of the interaction between DOX and DNA molecules is proposed; that is, there are two kinds of interaction between DOX and DNA molecules: DOX-DNA acts to form a complex, and DOX-DOX acts to form a multimer. The two effects are competitive, as the former compresses DNA molecules, and the latter decompresses these DNA molecules. This work is helpful for accurately understanding and developing new drugs and pathways to improve and treat DOX-induced cytotoxicity and cardiotoxicity.

High Co-loading Capacity and Stimuli-Responsive Release Based on Cascade Reaction of Self-Destructive Polymer for Improved Chemo-Photodynamic Therapy

Photodynamic therapy (PDT) shows a promising synergy with chemotherapy in the therapeutic outcome of malignant cancers. The minimal invasiveness and nonsystemic toxicity are appealing advantages of PDT, but combination with chemotherapy brings in the nonselective toxicity. We designed a polymeric nanoparticle system that contains both a chemotherapeutic agent and a photosensitizer to seek improvement for chemo-photodynamic therapy. First, to address the challenge of efficient co-delivery, polymer-conjugated doxorubicin (PEG-PBC-TKDOX) was synthesized to load photosensitizer chlorin e6 (Ce6). Ce6 is retained with DOX by a π-π stacking interaction, with high loading (41.9 wt %) and the optimal nanoparticle size (50 nm). Second, light given in PDT treatment not only excites Ce6 to produce cytotoxic reactive oxygen species (ROS) but also spatiotemporally activates a cascade reaction to release the loaded drugs. Finally, we report a self-destructive polymeric carrier (PEG-PBC-TKDOX) that depolymerizes its backbone to facilitate drug release upon ROS stimulus. This is achieved by grafting the ROS-sensitive pendant thioketal to aliphatic polycarbonate. When DOX is covalently modified to this polymer via thioketal, target specificity is controlled by light, and off-target delivery toxicity is mostly avoided. An oral squamous cell carcinoma that is clinically relevant to PDT was used as the cancer model. We put forward a polymeric system with improved efficiency for chemo-photodynamic therapy and reduced off-target toxicity.

Prognostic role of troponin and natriuretic peptides as biomarkers for deterioration of left ventricular ejection fraction after chemotherapy

Cardiotoxicity due to anthracyclines, trastuzumab and other potential cardiotoxic drugs is still a problem of modern chemotherapy. For years researchers have tried to find biological markers that can predict changes in the heart. The most thoroughly tested markers are troponin and natriuretic peptides. Some studies have proven that these markers can indeed be useful. In studies which have shown the predictive role of troponin I the assessment of this marker was performed very frequently. It is not possible to carry out such serial measurements in many centers because of typical 1-day hospital stay times. The predictive role of natriuretic peptides still needs further investigation. This review considers the newest research from recent years.

Doxorubicin loaded silica nanorattles actively seek tumors with improved anti-tumor effects

Silica nanorattles (SNs) have proven to be promising vehicles for drug delivery. In order to further enhance efficacy and minimize adverse effects, active targeted delivery to tumors is necessary. In this work, SNs modified with a tumor specific targeting ligand, folic acid (FA), was used as carrier of doxorubicin (DOX) (DOX-FA-SNs). Drug loading, cytotoxicity and cellular uptake of DOX-FA-SNs in vitro in human cervical carcinoma cells (HeLa cells) were evaluated. DOX-FA-SNs showed a higher cytotoxicity in human cervical carcinoma cells (HeLa cells) than DOX loaded carboxyl (-COOH) and poly(ethylene glycol) (PEG) modified SNs (DOX-COOH-SNs and DOX-PEG-SNs, respectively). However, DOX-FA-SNs showed lower cytotoxicity in folate receptor negative normal mouse fibroblast cells (L929 cells) compared with free DOX. In vivo tumor-targeted fluorescence imaging indicated specific tumor targeting and uptake of FA-SNs in nude mice bearing subcutaneous HeLa cell-derived xenograft tumors. In vivo anti-tumor experiments demonstrated that DOX-FA-SNs (10 mg kg(-1) of DOX) significantly regressed the tumor growth and reduced toxicity compared with free DOX. These results have great significance in developing and optimizing SNs as effective intracellular delivery and specific tumor targeting vehicles.

The antioxidant phenylaminoethyl selenide reduces doxorubicin-induced cardiotoxicity in a xenograft model of human prostate cancer

Anthracyclines are potent anticancer agents, but cardiotoxicity mediated by free radical generation limits their clinical use. This study evaluated the anticancer activity of phenyl-2-aminoethyl selenide (PAESe) and its potential to reduce doxorubicin (DOX)-induced cardiotoxicity. Growth inhibitory effects of PAESe with DOX, and vincristine, clinically used anticancer agents, and tert-butylhydroperoxide (TBHP), a known oxidant, on the growth of human prostate carcinoma (PC-3) cells was determined. PAESe (≤1μm) did not alter the growth of PC-3 cells, however, concomitant use of PAESe decreased the oxidative-mediated cytotoxicity of TBHP, but had limited effect on vincristine or DOX activity. Further, PAESe decreased the formation of intracellular reactive oxygen species from TBHP and DOX. The effect of PAESe on the activity of DOX was determined using a tumor (PC-3) xenograft model in mice. PAESe did not alter DOX antitumor activity and showed evidence of direct antitumor activity relative to controls. DOX treatment decreased mice body weight significantly, whereas concomitant administration of PAESe and DOX was similar to controls. Most importantly, PAESe decreased DOX-mediated infiltration of neutrophil and macrophages into the myocardium. These data suggest PAESe had in vivo antitumor activity and in combination with DOX decreased early signs of cardiotoxicity while preserving its antitumor activity.

Chemotherapy and Cardiotoxicity in Older Breast Cancer Patients: A Population-Based Study

Purpose

Adjuvant chemotherapy, especially with anthracyclines, is known to cause acute and chronic cardiotoxicity in breast cancer patients. We studied the cardiac effects of chemotherapy in a population-based sample of breast cancer patients aged ≥ 65 years with long-term follow-up.

Patients and Methods

In the Surveillance, Epidemiology, and End Results (SEER)-Medicare database, we analyzed treatments and outcomes among women ≥ 65 years of age who were diagnosed with stage I to III breast cancer from January 1, 1992 to December 31, 1999. Propensity scores were used to control for baseline heart disease (HD) and other known predictors of chemotherapy, and Cox proportional hazards models were used to estimate the risk of cardiomyopathy (CM), congestive heart failure (CHF), and HD after chemotherapy.

Results

Of 31,748 women with stage I to III breast cancer, 5,575 (18%) received chemotherapy. Chemotherapy was associated with younger age, fewer comorbidities, hormone receptor negativity, multiple primary tumors, and advanced disease. Patients who received chemotherapy were less likely than other patients to have pre-existing HD (45% v 55%, respectively; P < .001). The hazard ratios for CM, CHF, and HD for patients treated with doxorubicin (DOX) compared with patients who received no chemotherapy were 2.48 (95% CI, 2.10 to 2.93), 1.38 (95% CI, 1.25 to 1.52), and 1.35 (95% CI, 1.26 to 1.44), respectively. The relative risk of cardiotoxicity among patients who received DOX compared with untreated patients remained elevated 5 years after diagnosis.

Conclusion

When baseline HD was taken into account, chemotherapy, especially with anthracyclines, was associated with a substantially increased risk of CM. As the number of long-term survivors grows, identifying and minimizing the late effects of treatment will become increasingly important.

N-Terminal Pro-B-Type Natriuretic Peptide after High-Dose Chemotherapy: A Marker Predictive of Cardiac Dysfunction?

Background: Chronic cardiac dysfunction may develop after administration of aggressive chemotherapy, sometimes leading to development of congestive heart failure (CHF). Recently, N-terminal pro-B-type natriuretic peptide (NT-proBNP) was implicated as a marker of CHF. In this study we evaluated the predictive role of NT-proBNP in patients treated with high-dose chemotherapy (HDC).

Methods: NT-proBNP was measured after 62 chemotherapy treatments in 52 patients affected by aggressive malignancies. Blood samples were drawn before the start of HDC, at the end of HDC administration, and 12, 24, 36, and 72 h thereafter. In these patients, echocardiograms were performed regularly during a 1-year follow-up.

Results: Seventeen patients (33%) had persistently increased NT-proBNP, 19 patients (36%) had only transient increases (concentrations went back to baseline at 72 h), and 16 (31%) had no increases [mean (SD) values at 72 h, 1163 (936) ng/L vs 185 (101) ng/L vs 39 (19) ng/L, respectively; P &lt;0.0001]. Only patients with persistently increased NT-proBNP had a significant worsening of the left ventricular diastolic indexes from baseline to 12 months [ratio of peak early to peak late flow velocities from 1.42 (0.33) to 0.78 (0.11); P &lt;0.0001; isovolumetric relaxation time from 90 (15) to 141 (26) ms; P &lt;0.0001; E-wave deceleration time from 162 (17) to 224 (32) ms; P = 0.0004] and of the left ventricular ejection fraction [from 62.8 (3.4)% to 45.6 (11.5)%; P &lt;0.0001].

Conclusions: Persistently increased NT-proBNP early after administration of HDC is strongly associated with development of cardiac dysfunction. This finding has important implications for identifying patients at risk of developing chemotherapy-induced cardiotoxicity.

Left ventricular diastolic dysfunction induced by cyclophosphamide in blood stem cell transplantation

Cardiac complications are major limiting factors regarding the success of high-dose chemotherapy supported by blood stem cell transplantation (BSCT). The cardiotoxicity of cyclophosphamide remains obscure relative to that of anthracyclines. The aim of this study was to estimate noninvasively the cardiotoxicity of cyclophosphamide administered during the pretransplant conditioning of BSCT for patients with various hematological diseases. A total of 27 consecutive patients were divided into two groups depending on the conditioning regimen, ie, group A (n=15) which received cyclophosphamide (median dose of 120 mg/kg; range 100 to 200 mg/kg) and group B (n=12) which did not. Ultrasound cardiograms (UCG) and signal-averaged electrocardiograms (SAECG) were recorded in the two groups both preceding and following the BSCT. There were no statistical intergroup or intragroup differences in left ventricular (LV) dimensions or contractile function. Significant (P<0.01) posttransplant increases in interventricular septal wall thickness and Ap/Ep ratio were noted in group A. Moreover, the filtered QRS duration as estimated by SAECG was prolonged (P<0.05) whereas the summated LV voltage (S(V1)+R(V5)) was reduced in the posttransplant period only in group A. These results suggest that early cyclophosphamide cardiotoxicity was characterized by LV diastolic rather than systolic dysfunction. These findings may contribute to acute hemodynamic deterioration observed after cyclophosphamide-containing conditioning chemotherapy.

Myocardial injury revealed by plasma troponin I in breast cancer treated with high-dose chemotherapy

BACKGROUND

High-dose chemotherapy (HDC) has been widely utilized in high-risk breast cancer, but it may induce cardiac toxicity. Cardiac dysfunction may become evident weeks or months after HDC and, to date, no early markers of myocardial injury that are able to predict late ventricular impairment are available. We investigated the role of plasma troponin I (TnI) in this setting.

PATIENTS AND METHODS

We measured TnI plasma concentration after HDC in 211 high-risk breast cancer women (46 +/- 11 years, mean +/- SD). According to TnI value (< 0.5 or > or = 0.5 ng/ml), patients were allocated into a troponin positive (TnI+; n = 70) and a troponin negative (TnI-; n = 141) group. All patients underwent left ventricular ejection fraction (LVEF, Echo) examination during the following 12 months.

RESULTS

LVEF progressively decreased in the TnI+ group but not in the TnI- group. In TnI+ patients a close relationship between the TnI increase, as well as the number of positive TnI assays, and the maximal LVEF decrement, was found (r = -0.92, P < 0.0001 and r = -0.93, P < 0.0001, respectively).

CONCLUSIONS

In our population, the elevation of TnI soon after HDC accurately predicts the development of future LVEF depression. In this setting, TnI can be considered a sensitive and reliable marker of myocardial damage with relevant clinical and prognostic implications.

Doxorubicin affects the cardiac muscarinic system in the rat

During the study on the mechanism of doxorubicin-induced cardiotoxicity, we observed that a long incubation (4 hr) with doxorubicin reduced the maximal negative inotropic effects of a muscarinic receptor agonist, carbachol. The mechanism responsible for this doxorubicin-induced reduction of the efficacy of carbachol was examined in isolated guinea pig hearts. In isolated left atrial muscle preparations, 1 hr incubation with 100 microM doxorubicin caused a parallel right-ward shift of the concentration-response curves for carbachol, but a longer (4 hr) incubation with this agent (30, 100 or 200 microM), caused a significant reduction of the magnitude of the negative inotropic effect of carbachol in addition to the concentration-dependent parallel right-ward shift. The 4-hr incubation with these concentrations of doxorubicin also reduced the maximal negative inotropic effect of an adenosine A1 receptor agonist, R-phenylisopropyl adenosine (R-PIA), without affecting the potency of this agonist. Doxorubicin (1 to 100 microM) reduced [3H]quinuclidinyl benzilate (QNB) binding in a concentration dependent manner, but failed to alter [3HIR-PIA binding. The decrease in the magnitude of the maximal negative inotropic effect by doxorubicin was caused by changes in the muscarinic system at steps common to the transduction of muscarinic and adenosine A1 receptor mechanisms.

High-dose mitoxantrone + melphalan (MITO/L-PAM) as conditioning regimen supported by peripheral blood progenitor cell (PBPC) autograft in 113 lymphoma patients: high tolerability with reversible cardiotoxicity

Hematological and extrahematological toxicity of high-dose (hd) mitoxantrone (MITO) and melphalan (L-PAM) as conditioning regimen prior to peripheral blood progenitor cell (PBPC) autograft was evaluated in 113 lymphoma patients (87 at disease onset). Autograft was the final part of a hd-sequential (HDS) chemotherapy program, including a debulkying phase (1-2 APO +/- 2 DHAP courses) and then sequential administration of hd-cyclophosphamide, methotrexate (or Ara-C) and etoposide, at 10 to 30 day intervals. Autograft phase included: (1) hd-MITO, given at 60 mg/m2 on day -5; (2) hd-L-PAM, given at 180 mg/m2 on day -2; (3) PBPC autograft, with a median of 11 x 10(6) CD34+/kg, or 70 x 10(4) CFU-GM/kg, on day 0. A rapid hematological recovery was observed in most patients, with ANC >500/microL and Plt >20,000/microl values reached at a median of 11 and 10 days since autograft, respectively. The good hemopoietic reconstitution allowed the delivery of consolidation radiotherapy (RT) to bulky sites in 53 out of 57 candidate patients, within 1 to 3 months following autograft; five of these patients required back-up PBPC re-infusion due to severe post-RT pancytopenia. Few severe infectious complications were recorded. There was one single fatal event due to severe pancytopenia following whole abdomen RT. Cardiac toxicity was evaluated as left ventricular ejection fraction (LVEF), monitored by cardiac radionuclide scan. LVEF prior to and after autograft was significantly reduced (median values: 55% vs 46%) in 58 evaluated patients; however, a significant increase to a median value of 50% was observed in 45 patients evaluated at 1 to 3 years since autograft. At a median follow-up of 3.6 years, 92 patients are alive, with a 7-year overall survival projection and 6.7-year failure-free survival projection of 77% and 69%, respectively. We conclude that a conditioning regimen with hd-MITOIL-PAM fits well within the HDS program. It implies good tolerability and reversible cardiotoxicity and it may have contributed to the good long-term outcome observed in this series of patients.

Long-term chemotherapy-related cardiovascular morbidity

As a consequence of the successful use of chemotherapy in the treatment of curable neoplasms such as germ cell tumours and malignant lymphomas, and the increasing application of primary and adjuvant chemotherapy for various tumour types, the number of patients with a prolonged life expectancy after treatment is rising. Attention to long-term side-effects, including cardiovascular toxicity, is therefore of growing importance. In this review we evaluate the literature on long-term cardiovascular toxicity related to chemotherapy in adult patients. Two categories of patient with favourable life expectancy have been reviewed, namely patients cured of metastatic disease by chemotherapy and patients treated with adjuvant chemotherapy. In the first category, the literature on long-term cardiovascular morbidity in survivors of metastatic testicular cancer and lymphomas is discussed, while in the second category this is done for patients treated with adjuvant chemotherapy for breast and colon cancer. As well as the direct toxic effects of chemotherapy on the cardiovascular system, the indirect toxic effects such as chemotherapy-related metabolic changes that may cause cardiovascular morbidity are also discussed.

Left ventricular dysfunction predicted by early troponin I release after high-dose chemotherapy

OBJECTIVES

We investigated the role of cardiac troponin I (cTnI) in patients with aggressive malignancies treated with high-dose chemotherapy (HDC).

BACKGROUND

High dose chemotherapy is potentially limited by cardiac toxicity. Considering the fact that cardiac dysfunction may become clinically evident weeks or months after HDC, the availability of an early marker of myocardial injury, able to predict late ventricular impairment, is a current need.

METHODS

We measured, in 204 patients (45+/-10 years) affected by cancer resistant to conventional treatment, the cTnI plasma concentration after every single cycle of HDC. According to the cTnI value (< or = or >0.4 ng/ml), patients were divided into a troponin positive (cTnI+, n = 65) and a troponin negative (cTnI-, n = 139) group. All patients underwent echocardiographic examination during the following seven months.

RESULTS

In the cTnI- group, left ventricular ejection fraction (LVEF) progressively decreased after HDC, reaching a maximal reduction after three months; however, myocardial depression was transient and no longer detectable at later follow-up. By contrast, in the cTnI+ group LVEF reduction was more marked and still evident at the end of the follow-up. In cTnI+ patients, a close relationship between the short-term cTnI increment and the greatest LVEF reduction was found (r = -0.87, p<0.0001).

CONCLUSIONS

The elevation of cTnI in patients undergoing HDC for aggressive malignancies accurately predicts the development of future LVEF depression. In this setting, cTnI can be considered a sensitive and reliable marker of acute minor myocardial damage with relevant clinical and prognostic implications.

Doxorubicin-induced late cardiotoxicity: delayed impairment of Ca2+-handling mechanisms in the sarcoplasmic reticulum in the rat

Doxorubicin treatment causes delayed development of cardiotoxicity. Whether the doxorubicin-induced impairment of cardiac functions reverses or progresses with time after the cessation of the treatment was examined. The rats were injected with doxorubicin (2.5 mg/kg, i.v., once a week for 3 weeks) and sacrificed at 1 (1W), 13 (13W), or 18 (18W) weeks after the final doxorubicin administration. The time to peak of twitch contraction observed at 2-Hz stimulation was not altered in left atrial or ventricular muscle preparations isolated from 1W rats, but it was prolonged in those from 13W and 18W rats. The reduction of the magnitude of postrest contraction and the alteration of force-frequency relationships in left atrial muscle preparations in 1W rats were not significant, but were intensified in the 13W and 18W groups. Alterations in the postrest contraction and the force-frequency relationships in ventricular muscle preparations isolated from doxorubicin-treated rat hearts were weaker, but the pattern of alteration was similar to that observed in left atrial muscle preparations. Caffeine-induced contraction observed in skinned fibers that were isolated from the 1W rats was not altered, but it was reduced in the 18W rats. The Ca2+ sensitivity of contractile proteins was not altered in doxorubicin-treated rat hearts in any of the groups. The Kd values estimated from a [3H]ryanodine binding study were not altered, but the Bmax values were significantly lower in the 13W and 18W groups than those observed in control rats. These results suggest that the dysfunction of the sarcoplasmic reticulum progresses after the completion of doxorubicin treatment and contributes to the doxorubicin-induced late cardiotoxicity.Key words: doxorubicin, late cardiotoxicity, rat heart, sarcoplasmic reticulum.

Biochemical changes induced by intravitreally-injected doxorubicin in the iris-ciliary body and lens of the rabbit eye

The aim of this study was to examine the chronic effects and mode of action of doxorubicin in ocular tissues. A dose of 10 microg (17.24 nanomoles) of doxorubicin hydrochloride in 20 microl sterile saline were intravitreally injected, under local anaesthesia, in one eye of 13 rabbits and 50 microg (86.20 nanomoles) were similarly injected in one eye of 3 rabbits. The contralateral eye received 20 microl of saline only. The dose of 50 microg induced initially mild uveal inflammation which became chronic and turned into circular iritis. Both doses of the drug induced cataract of the lens and clouding of the cornea within 2-3 months. The activity of superoxide dismutase, in iris-ciliary bodies and lenses treated with either 10 or 50 microg of the compound, was significantly lower relative to that in respective control tissues. In contrast to superoxide dismutase, catalase showed an increased activity in experimental tissues relative to control. The lysosomal hydrolases acid phosphatase, N-acetyl-B-D-glucosaminidase, aryl sulphatase and acid cathepsin, all showed significantly elevated activities in iris-ciliary body tissues one year after injection with the 50 microg doxorubicin. The reduction in superoxide dismutase activity may render ocular tissues susceptible to peroxidative attack and the increased activities of lysosomal hydrolases may contribute to chronic cell injury and inflammation.

The spectrum of dilated cardiomyopathy. The Johns Hopkins experience with 1,278 patients

This report describes the evaluation of 1,278 patients referred to The Johns Hopkins Hospital with dilated cardiomyopathy. After a careful history and physical examination, selected laboratory tests, and endomyocardial biopsy, a specific diagnosis was made in 49% of cases. In 16% of cases the biopsy demonstrated a specific histologic diagnosis. Myocarditis and coronary artery disease were the most frequent specific diagnoses; 51% of patients were classified as idiopathic. Thus a rigorous and systematic search can demonstrate an underlying cause for approximately one-half of patients with unexplained cardiomyopathy. Endomyocardial biopsy plays a crucial role in this evaluation. Six cases are presented which demonstrate the utility of endomyocardial biopsy in specific clinical situations. In addition to its routine use in monitoring rejection in heart transplant recipients, endomyocardial biopsy is indicated in the evaluation of possible infiltrative cardiomyopathy, in differentiating restrictive cardiomyopathy from constrictive pericarditis, and in diagnosing and monitoring doxorubicin cardiotoxicity. The importance of diagnosing myocarditis remains controversial, and disagreement persists about the utility of immunosuppressive therapy in these patients. A combination of clinical and histologic features can divide patients with myocarditis into 4 subgroups--acute, fulminant, chronic active, and chronic persistent. This classification provides prognostic information and may identify those patients who may respond to immunosuppression, as well as those likely to have adverse outcomes from such treatment. The continued development of novel molecular techniques may allow endomyocardial biopsy to provide greater prognostic and therapeutic information in the future.

[Genetics of dilated cardiomyopathy]

Dilated cardiomyopathy (DCM) is a heart muscle disorder characterized by cardiac dilatation and impaired systolic function. In an increasing number of all DCM cases a specific etiology can be identified and in the remaining patients DCM is termed idiopathic. There is a wide variation of the clinical presentation in DCM. The majority of patients manifests classical disease, i.e. heart failure due to left (and right) ventricular systolic dysfunction. However, some cases may come to clinical attention because of supraventricular arrhythmias such as sinus node dysfunction, AV-block or atrial fibrillation. Although a multitude of etiologies may be responsible for DCM (e.g. viral, immunological, toxic), the disease is inherited as a single gene disorder in at least 20 to 35% of cases. Most genetic forms of DCM are caused by autosomal dominant gene defects. Six dominant disease loci on chromosomes 1p1-q1, 1q32, 3p22-p25, 6q23, 9q13 und 10q21-q23 have been identified but the corresponding disease genes are not yet known. X-linked DCM without skeletal muscle disease is a rare variety of adult DCM which can be caused by specific mutations in the dystrophin gene on chromosome Xp21.

Involvement of phosphorylation in doxorubicin-mediated myofibril degeneration. An immunofluorescence microscopy analysis

Loss of myofilaments has been observed in both adaptive cardiac responses (i.e., hypertrophy) as well as in chemotheraputic use of antineoplastic drugs with cardiotoxic side effects (i.e., doxorubicin). An understanding of the degenerative process is a prerequisite for determining approaches to limit the cardiomyopathic changes associated with chronic heart disease or long-term chemotheraputic treatments. However, little is known about the specific events and molecular changes that initiate the degenerative process. To study this process, neonatal rat cardiomyocytes were treated with doxorubicin, which induced rapid and widespread thin-filament degeneration as observed by fluorescence confocal microscopy. Which demonstrated deterioration of sarcomeric thin-filament structure. Changes in the spontaneous beating of cardiomyocytes corresponding with myofibrillar degeneration were apparent using differential interference contrast video microscopy. After finding induction of kinase activity by doxorubicin in cultured cardiomyocytes, the protective effects of specific inhibitors of kinase activity were assessed for their ability to inhibit doxorubicin-induced myofibrillar break-down. Doxorubicin-induced changes appeared similar to the degeneration observed after treatment with a protein kinase activator (phorbol 12-myristate 13-acetate) or a serine-threonine protein phosphatase inhibitor (okadaic acid). Collectively, these results indicate that activation of protein kinase is an important event in the initiation of myofibrillar degeneration by doxorubicin. Further analyses of myofibrillar proteins with respect to biochemical modifications will be necessary to determine if phosphorylation events transmit signal(s) to initiate degeneration.

Ventricular repolarization time indexes following anthracycline treatment

The anthracyclines, doxorubicin and daunorubicin, are antibiotics effective in the treatment of many malignancies. However, their usefulness is limited by the development of potentially fatal cardiotoxicity. Cardiac monitoring by a noninvasive test capable of identifying patients at high risk of cardiac damage, before the ejection fraction deteriorates would have clinical utility. Electrocardiograms and echocardiograms are routinely utilized for noninvasive assessment of myocardial function. However, of the ECG abnormalities described, none has been noted to be of consistent predictive value for cardiotoxicity. The aim of this study was to assess the effects of doxorubicin on ventricular repolarization time indexes, as they have been shown to be effective in the identification of electrical myocardial instability and, hence, in the identification of risk for either arrhythmia or heart failure. For this reason, electrocardiograms were compared in 35 cancer patients at the first presentation (drug-free state) and after 29.4 +/- 37.65 weeks of treatment with doxorubicin. The results of the present study showed that after only a short period of treatment with doxorubicin there was a significant increase in ventricular recovery time dispersion indexes (QTc, JT, and JTc dispersion, and their "adjusted" values). Thus, increased regional variation in ventricular repolarization could be, in the absence of a significant modification of the echocardiographic parameters, an early marker of an electropathy, due to the early cardiotoxic action of doxorubicin on myocardial cells, eventually leading to heart failure.

Dobutamine stress echocardiography in the evaluation of late anthracycline cardiotoxicity in childhood cancer survivors

Late anthracycline cardiotoxicity has been of increasing concern to pediatric oncologists. An increasing number of patients with cardiac dysfunction has been reported without a good correlation between cardiac function or symptoms and routine echocardiographic follow-up. We studied dobutamine stress echocardiography in patients who had received moderate doses of anthracyclines years before. Twenty-three patients (14 male, 9 female; 7-25 y) who completed chemotherapy with moderate doses of anthracyclines (180-380 mg/m2) more than 2 y previously underwent dobutamine stress echocardiography and were compared with a control group of 26 healthy young people (15 male, 11 female; 6-26 y) matched for age and weight. Dobutamine was administered in three periods up to a rate of 5 micro g/kg/min. Eighty-five percent of the patients showed an abnormal response to dobutamine. Both systolic and diastolic functions were affected. The systolic dysfunction was not related to diminished contractility but to an elevated systolic wall stress due to inadequate cardiac muscle thickening. The diminished wall thickening was related to the length of follow-up. Dobutamine proved to be a very sensitive method to detect clinical and subclinical cardiac dysfunction in patients post anthracycline chemotherapy and questions the concept of a safe dose.

Cardiac failure and dysrhythmias 6-19 years after anthracycline therapy: a series of 15 patients

The clinical course of late symptomatic anthracycline cardiomyopathy, and resultant changes of cardiac function, were described in 15 patients. They represented a subset of 300 patients who had cardiac evaluations to identify the prevalence of late cardiotoxicity more than 4 years after anthracycline therapy in these patients. The clinical course and all available cardiac evaluations including electrocardiography, continuous taped electrocardiography, echocardiography, radionuclide cardiac angiography, cardiac catheterization, and endomyocardial biopsy, of the 15 patients were reviewed. The patients had received 285-870 (median 540) mg/M2 of daunorubicin and/or doxorubicin 6-19 (median 12) years prior to the onset of late symptoms. Seven patients also had 2,100-4,000 cGy mediastinal radiotherapy. Five patients had required treatment for cardiac symptoms at the end of chemotherapy but 10 patients had no cardiac problems anteceding their late decompensation. Fractional shortening on echocardiogram at late decompensation was 8-20% (median 17%) and radionuclide left ventricular ejection fraction was 8-59% (median 38%). All were treated with digitalis and diuretics and 13/15 with afterload reduction, with at least transient improvement of symptoms. They were followed for 1-9 (median 3) years after late decompensation. One died of uncontrollable cardiac failure. Another underwent successful cardiac transplantation. Conduction abnormalities and dysrhythmias were present in 14/15 patients and 3 died suddenly. Two more had syncope, one requiring an automatic cardiac defibrillator. Endomyocardial biopsy or autopsy revealed hypertrophy and fibrosis in 10/10 patients. Our patients with early cardiac symptoms improved transiently but decompensated later and patients with no early symptoms developed cardiac symptoms more than 10 years after anthracycline therapy. Therefore, patients who have received anthracyclines should have continued cardiac evaluation.

Cardioprotection with ICRF-187 (Cardioxane) in patients with advanced breast cancer having cardiac risk factors for doxorubicin cardiotoxicity, treated with the FDC regimen

A study of cardioprotection with ICRF-187 (Cardioxane, Eurocetus) has been performed in 35 patients with metastatic breast cancer treated with the FDC regimen (5-fluorouracil 500 mg/m2 i.v., day 1; doxorubicin 50 mg/m2 i.v., day 1; cyclophosphamide 500 mg/m2 i.v., day 1). All patients had one or more cardiac risk factors for doxorubicin cardiotoxicity including 24 who had previously received left-chest-wall irradiation. Cardioxane was applied at a dosage of 1000 mg/m2 as a 15-min infusion in Ringer lactate solution 30 min before doxorubicin administration. Cardiological monitoring included left-ventricular ejection fraction (LVEF) determination by echocardiography before treatment and before each cycle following the cumulative doxorubicin dose of 200 mg/m2. Of the 35 patients, 34 were evaluable fore response, and the overall response rate was 19/34 (56%) with 3/34 complete responses and 16/34 partial responses. Statistical analysis of LVEF values in relation to increasing cumulative doxorubicin doses with Wilcoxon's test of equivalent pairs and Friedman's test has demonstrated that no cardiotoxicity was detected up to a cumulative doxorubicin dose of between 800 mg/m2 and 1000 mg/m2, except for 2 patients in whom a decrease of 20% in relation to the LVEF pretreatment level was demonstrated following a cumulative drug dose of 250 mg/m2. Thus Cardioxane provides an effective cardioprotection even in breast cancer patients with cardiac risk factors for doxorubicin cardiotoxicity treated with the FDC regimen.

Probucol protects against adriamycin cardiomyopathy without interfering with its antitumor effect

BACKGROUND

The usefulness of adriamycin (ADR), a potent antitumor antibiotic, is limited by the development of life-threatening cardiomyopathy and congestive heart failure. Subcellular changes leading to heart failure are suggested to be mediated by a drug-induced increase in free radicals and lipid peroxidation. In an earlier study, concurrent treatment with probucol (PROB), a lipid-lowering drug with strong antioxidant properties, was shown to offer only partial protection against ADR cardiomyopathy. The present study had two aims: to determine whether this protective effect can be improved further by extended treatment with PROB, and to determine whether PROB affects the antitumor properties of ADR.

METHODS AND RESULTS

ADR (cumulative dose, 15 mg/kg body wt) was administered in rats in six equal injections (IP) over a period of 2 weeks. Three weeks after the end treatment, cardiomyopathy and congestive heart failure were characterized by ascites, congested liver, depressed cardiac function, elevated left ventricular end-diastolic pressure, and myocardial cell damage. Myocardial glutathione peroxidase (GSHPx) activity was decreased and lipid peroxidation was increased. Administration of PROB (cumulative dose, 120 mg/kg body wt) in 12 equal injections (IP), before and concurrent with ADR, completely prevented these cardiomyopathic changes, normalized left ventricular function, lowered mortality, and eliminated ascites. Treatment with PROB was also accompanied by an increase in myocardial GSHPx and superoxide dismutase activities with a concomitant decrease in lipid peroxidation. Tumor regression in syngeneic DBA/2 mice inoculated with L5178Y-F9 lymphoma cells in the ADR+PROB group was significant and comparable to the ADR group.

CONCLUSIONS

These data show for the first time that PROB can provide complete protection against ADR cardiomyopathy without interfering with antitumor properties of the drug. This protective effect of PROB may be related to the maintenance of the antioxidant status of the heart.

Late doxorubicin-associated cardiotoxicity in children. The possible role of intercurrent viral infection

BACKGROUND

The most frequently encountered doxorubicin related cardiac toxicity is a dose-related myocardial dysfunction occurring 1-6 months after chemotherapy. Recently, late cardiotoxicity has been the focus of interest. This paper explores the possibility that acute intercurrent viral illness may trigger late cardiotoxicity.

METHODS

Thirty selected pediatric patients were followed for changes in their echocardiographically measured fractional shortening (FS) for 2-10 years after completion of their doxorubicin chemotherapy. They were divided according to the dose of doxorubicin they received (< 300 mg/m2 or > or = 300 mg/m2) and to whether the manifestations of an acute intercurrent viral illness during the observation period were documented. Eleven patients experienced such infections.

RESULTS

Changes in FS demonstrated two different responses. The usual response to doxorubicin was a gradual, dose-related fall in FS, followed by recovery; while the second response included an unexpected, late, sudden decrease in FS. Four patients in the low dose subgroup experienced an acute intercurrent viral illness, but none of these demonstrated the unexpected decrease. Of the seven patients who acquired such illness in the high dose subgroup, five demonstrated the sudden, late decrease in FS, with two of them developing severe, reversible congestive heart failure.

CONCLUSIONS

The most likely explanation for the late, sudden decrease in FS is an additional stress in patients who already have sustained subclinical cardiac damage as a result of their doxorubicin chemotherapy. An acute intercurrent viral illness may have triggered late cardiac dysfunction in some of these patients.

Anthracyclines and the heart

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Comparison of cardiac function tests after anthracycline therapy in childhood. Implications for screening

BACKGROUND

Numerous methods for evaluating cardiac function after cardiotoxic therapy have been suggested. A practical algorithm for screening a large patient population is needed.

METHODS

Seventy-three patients (median age, 15.3 years [range, 9-29 years) who received anthracyclines (median dose, 300 mg/m2 [range, 50-750 mg/m2) for a childhood malignancy underwent a battery of commonly used tests of cardiac function: (1) echocardiographic shortening fraction (ESF); (2) resting and exercise radionuclide scan (multiple gaited acquisition [MUGA]); (3) electrocardiogram (ECG); (4) 24-hour Holter monitor, and (5) questionnaire concerning exercise tolerance.

RESULTS

Patients with an abnormal resting ejection fraction on MUGA were more likely to have an abnormal ESF (P = 0.023), prolongation of the QTc interval (P = 0.014), and complaints of "difficulty" with exercise (P = 0.04). An abnormal results for a resting study was not predictive of an abnormal MUGA exercise response. There was no association between the presence of significant dysrhythmia on Holter monitor and any resting test. An algorithm was developed using a normal ESF and QTc interval, and a negative history of exercise intolerance to identify patients who need not undergo a MUGA. With the use of such an algorithm, 29 of the 73 patients would not have undergone the MUGA, only 2 of whom had an abnormal resting ejection fraction.

CONCLUSION

Patients at risk for cardiac damage after cancer therapy who have normal ESF and QTc interval results and no history of exercise intolerance are unlikely to have abnormal MUGA results. Significant dysrhythmia may be present in the absence of other abnormalities.

Doxorubicin cardiomyopathy is associated with a decrease in calcium release channel of the sarcoplasmic reticulum in a chronic rabbit model

Doxorubicin is a highly effective cancer chemotherapeutic agent that produces a dose-dependent cardiomyopathy that limits its clinical usefulness. Clinical and animal studies of morphological changes during the early stages of doxorubicin-induced cardiomyopathy have suggested that the sarcoplasmic reticulum, the intracellular membrane system responsible for myoplasmic calcium regulation in adult mammalian heart, may be the early target of doxorubicin. To detect changes in the calcium pump protein or the calcium release channel (ryanodine receptor) of the sarcoplasmic reticulum during chronic doxorubicin treatment, rabbits were treated with intravenous doxorubicin (1 mg/kg) twice weekly for 12 to 18 doses. Pair-fed controls received intravenous normal saline. The severity of cardiomyopathy was scored by light and electron microscopy of left ventricular papillary muscles. Developed tension was measured in isolated atrial strips. In subcellular fractions from heart, [3H]ryanodine binding was decreased in doxorubicin-treated rabbits (0.33 +/- 0.03 pmol/mg) compared with control rabbits (0.66 +/- 0.02 pmol/mg; P < 0.0001). The magnitude of the decrease in [3H]ryanodine binding correlated with both the severity of the cardiomyopathy graded by pathology score (light and electron microscopy) and the decrease in developed tension in isolated atrial strips. Bmax for [3H]ryanodine binding and the amount of immunoreactive ryanodine receptor by Western blot analysis using sequence-specific antibody were both decreased, consistent with a decrease in the amount of calcium release channel of sarcoplasmic reticulum in doxorubicin-treated rabbits. In contrast, there was no decrease in the amount or the activity of the calcium pump protein of the sarcoplasmic reticulum in doxorubicin-treated rabbits. Doxorubicin treatment did not decrease [3H]ryanodine binding or the amount of immunoreactive calcium release channel of sarcoplasmic reticulum in skeletal muscle. Since the sarcoplasmic reticulum regulates muscle contraction by the cyclic uptake and release of a large internal calcium pool, altered function of the calcium release channel could lead to the abnormalities of contraction and relaxation observed in the doxorubicin cardiomyopathy.

Doxorubicin-induced cardiotoxicosis. Clinical features in 32 dogs

Clinical cardiac abnormalities developed in 32 of 175 dogs that had various malignancies and were treated with doxorubicin: 31 dogs had electrocardiographic abnormalities including arrhythmias and nonspecific alterations in the R wave, ST segment, or QRS duration and 7 dogs had congestive heart failure. All seven dogs that had congestive heart failure died within 90 days. At necropsy, 13 of 32 affected dogs had noninflammatory myocardial degeneration, myocytolysis, vacuolation, and/or fibrosis and there was intramural coronary arteriosclerosis in all 13. Five dogs with lymphosarcoma were in complete clinical remission when they died of doxorubicin-induced cardiomyopathy, but the overall survival times of the lymphosarcoma subset was nevertheless longer than in previous studies. The clinical use of doxorubicin in the dog can cause cardiotoxicosis but the therapeutic benefit appears to outweigh risks in most dogs.

Dobutamine stress echocardiography: a sensitive indicator of diminished myocardial function in asymptomatic doxorubicin-treated long-term survivors of childhood cancer

Doxorubicin is an effective anticancer chemotherapeutic agent known to cause acute and chronic cardiomyopathy. To develop a more sensitive echocardiographic screening test for cardiac damage due to doxorubicin, a cohort study was performed using dobutamine infusion to differentiate asymptomatic long-term survivors of childhood cancer treated with doxorubicin from healthy control subjects. Echocardiographic data from the experimental group of 21 patients (mean age 16 +/- 5 years) treated from 1.6 to 14.3 years (median 5.3) before this study with 27 to 532 mg/m2 of doxorubicin (mean 196) were compared with echocardiographic data from 12 normal age-matched control subjects. Graded dobutamine infusions of 0.5, 2.5, 5 and 10 micrograms/kg per min were administered. Echocardiographic Doppler studies were performed before infusion and after 15 min of infusion at each rate. Dobutamine infusion at 10 micrograms/kg per min was discontinued after six studies secondary to a 50% incidence rate of adverse symptoms. The most important findings were that compared with values in control subjects, end-systolic left ventricular posterior wall dimension and percent of left ventricular posterior wall thickening in doxorubicin-treated patients were decreased at baseline study and these findings were more clearly delineated with dobutamine stimulation. End-systolic left ventricular posterior wall dimension at baseline for the doxorubicin-treated group was 11 +/- 1.9 mm versus 13.1 +/- 1.5 mm for control subjects (p less than 0.01). End-systolic left ventricular posterior wall dimension at the 5-micrograms/kg per min dobutamine infusion for the doxorubicin-treated group was 14.1 +/- 2.4 mm versus 19.3 +/- 2.6 mm for control subjects (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term sequelae of autologous bone marrow or peripheral stem cell transplantation for lymphoid malignancies

The study was made to evaluate the long-term physical and psychosocial changes after high-dose therapy and autologous bone marrow or peripheral stem transplantation for recurrent lymphoid malignancies. Patients who had undergone high dose therapy and autologous bone marrow or peripheral stem cell transplantation for recurrent lymphoid malignancies at least 1 year previously were contacted by phone interview regarding their status after the transplant. The patients' comments were confirmed by checking medical records when possible. Fifty patients who had undergone transplantation at the University of Nebraska Medical Center at least 1 year before the interview were available for interview and willing to answer questions. After transplant, many patients noticed temporary changes in their appearance, which usually returned to normal within 1 year. Few patients reported remarkable cardiovascular, gastrointestinal, or pulmonary changes after transplantation. However, up to one-third of the patients reported changes in sexual function or desire. The most common infectious problem after transplant was Herpes zoster, which occurred in 25% of the patients. Overall, the patients had a positive outlook after high-dose therapy and transplantation, with most being able to return to work and enjoy a normal life style. Ninety-six percent of the patients stated that they would be willing to undergo high-dose therapy and transplantation again under the same circumstances.

Exercise echocardiography in the detection of anthracycline cardiotoxicity

Twenty long-term survivors of childhood cancer underwent exercise echocardiography to evaluate possible late anthracycline-induced cardiac toxicity. Ten patients ages 10 to 20 years had received anthracyclines, and ten patients ages 8 to 27 years had not received anthracyclines as part of their medical regimen. Both groups had normal cardiac function at rest. Patients who had not received anthracyclines had a greater increase in M-mode shortening fraction (P less than 0.005), velocity of circumferential fiber shortening (P = 0.05), and Doppler aortic peak flow velocity (P = 0.01) than patients receiving anthracyclines. There were no significant differences in work performed, or increase in heart rate or blood pressure with exercise between the groups. These results suggest that subtle abnormalities in myocardial function exist which become apparent only after exercise in survivors of childhood cancer who have received anthracyclines and have normal resting cardiac function.

The survivors of childhood solid tumors

With the improvement in cancer therapy in recent years, the number of cancer survivors is rapidly increasing. Potential late medical and psychosocial sequelae of cancer therapy are reviewed. A practical guide for the primary health care giver is provided.