Cardiovascular toxicity with cancer chemotherapy

Cardiovascular Complications of Pan-Cancer Therapies: The Need for Cardio-Oncology

It is more likely that a long-term survivor will have both cardiovascular disease and cancer on account of the progress in cancer therapy. Cardiotoxicity is a well-recognized and highly concerning adverse effect of cancer therapies. This side effect can manifest in a proportion of cancer patients and may lead to the discontinuation of potentially life-saving anticancer treatment regimens. Consequently, this discontinuation may adversely affect the patient's survival prognosis. There are various underlying mechanisms by which each anticancer treatment affects the cardiovascular system. Similarly, the incidence of cardiovascular events varies with different protocols for malignant tumors. In the future, comprehensive cardiovascular risk assessment and clinical monitoring should be considered for cancer treatments. Baseline cardiovascular evaluation risk should be emphasized prior to initiating clinical therapy in patients. Additionally, we highlight that there is a need for cardio-oncology to avoid or prevent cardiovascular side effects. Cardio-oncology service is based on identifying cardiotoxicity, developing strategies to reduce these toxicities, and minimizing long-term cardiotoxic effects.

Breast Cancer and the Cardiovascular Disease: A Narrative Review

Breast cancer is the most common malignancy affecting females worldwide and is also among the top causes of all cancer-related deaths. Cardiovascular disease (CVD) is known to have the highest rate of mortality in women. There are several risk factors for both CVD and breast cancer that overlap, such as diet, smoking, and obesity, and also the current breast cancer treatment has a significant detrimental effect on cardiovascular health in general. Patients with exposure to potentially cardiotoxic treatments, including anthracyclines, trastuzumab, and radiation therapy, are more likely to develop CVD than non-cancer controls. Early detection and treatment may reduce the risk of the development of cardiac morbidity and mortality and would increase the number of breast cancer survivors. This article provides a comprehensive overview of breast cancer, identifies shared risk factors among breast cancer and CVD, and the cardiotoxic effects of therapy. It also reviews possible prevention and treatment of CVD in breast cancer patients and reviews literature about chemoprevention of cardiac disease in the setting of breast cancer treatment.

The role of iron in doxorubicin-induced cardiotoxicity: recent advances and implication for drug delivery

As an anthracycline antibiotic, doxorubicin (DOX) is one of the most potent and widely used chemotherapeutic agents for treating various types of tumors. Unfortunately, the clinical application of this drug results in severe side effects, particularly dose-dependent cardiotoxicity. There are multiple mechanisms involved with the cardiotoxicity caused by DOX, among which intracellular iron homeostasis plays an essential role based on a recent discovery. In this mini-review, we summarize the clinical features and symptoms of DOX-dependent cardiotoxicity, discuss the correlation between iron and cardiotoxicity, and highlight the involvement of iron-dependent ferroptotic cell death therein. Recent advances in this topic will aid the development of novel DOX delivery systems with reduced adverse effects, and expand the clinical application of anthracycline.

Parameritannin A-2 from Urceola huaitingii enhances doxorubicin-induced mitochondria-dependent apoptosis by inhibiting the PI3K/Akt, ERK1/2 and p38 pathways in gastric cancer cells

Parameritannin A-2 (PA-2) is a natural product extracted from the stems of the plant Urceola huaitingii. Our previous studies have shown that PA-2 exhibits significant synergistic anticancer effects with doxorubicin (DOX) in HGC27 gastric cancer cell lines. Here we report that our isobolographic analysis confirms the synergistic cytotoxic effects of PA-2 and DOX in HGC27 cells. Flow cytometry and immunoblotting indicate that PA-2 enhances DOX-mediated apoptosis. Importantly, PA-2 enhances the intracellular accumulation of DOX in HGC27 cells. The combination of DOX and PA-2 remarkably increases the release of cytochrome C and the activation of caspase-3 and caspase-9, compared with DOX treatment alone. Moreover, PA-2 attenuates the DOX-induced activation of Akt, ERK1/2 and p38 signaling pathways, providing a molecular mechanism for the synergistic effects of DOX and PA-2 in the induction of apoptosis. In conclusion, our studies demonstrate that PA-2 and DOX synergistically induce mitochondria-dependent apoptosis as PA-2 inhibits the PI3K/Akt, ERK1/2 and p38 pathways in HGC27 cells. These findings suggest that the combination treatment with PA-2 and DOX may represent a potent therapy for gastric cancer.

Intratumoral Delivery of Doxorubicin on Folate-Conjugated Graphene Oxide by In-Situ Forming Thermo-Sensitive Hydrogel for Breast Cancer Therapy

By taking advantage of the pH-sensitive drug release property of graphene oxide (GO) after intracellular uptake, we prepared folic acid (FA)-conjugated GO (GOFA) for targeted delivery of the chemotherapeutic drug doxorubicin (DOX). GOFA-DOX was further encapsulated in an injectable in-situ forming thermo-sensitive hyaluronic acid-chitosan-g-poly(N-isopropylacrylamide) (HACPN) hydrogel for intratumoral delivery of DOX. As the degradation time of HACPN could be extended up to 3 weeks, intratumoral delivery of GOFA-DOX/HACPN could provide controlled and targeted delivery of DOX through slow degradation HACPN and subsequent cellular uptake of released GOFA-DOX by tumor cells through interactions of GOFA with folate receptors on the tumor cell's surface. GOFA nano-carrier and HACPN hydrogel were first characterized for the physico-chemical properties. The drug loading experiments indicated the best preparation condition of GOFA-DOX was by reacting 0.1 mg GOFA with 2 mg DOX. GOFA-DOX showed pH-responsive drug release with ~5 times more DOX released at pH 5.5 than at pH 7.4 while only limited DOX was released from GOFA-DOX/HACPN at pH 7.4. Intracellular uptake of GOFA by endocytosis and release of DOX from GOFA-DOX in vitro could be confirmed from transmission electron microscopic and confocal laser scanning microscopic analysis with MCF-7 breast cancer cells. The targeting effect of FA was revealed when intracellular uptake of GOFA was blocked by excess FA. This resulted in enhanced in vitro cytotoxicity as revealed from the lower half maximal inhibitory concentration (IC50) value of GOFA-DOX (7.3 μg/mL) compared with that of DOX (32.5 μg/mL) and GO-DOX (10 μg/mL). The flow cytometry analysis indicated higher apoptosis rates for cells treated with GOFA-DOX (30%) compared with DOX (8%) and GO-DOX (11%). Animal studies were carried out with subcutaneously implanted MCF-7 cells in BALB/c nude mice and subject to intratumoral administration of drugs. The relative tumor volumes of control (saline) and GOFA-DOX/HACPN groups at day 21 were 2.17 and 1.79 times that at day 0 with no significant difference. In comparison, the relative tumor volumes of treatment groups at the same time were significantly different at 1.02, 0.67 and 0.48 times for DOX, GOFA-DOX and GOFA-DOX/HACPN groups, respectively. The anti-tumor efficacy was also supported by images from an in vivo imaging system (IVIS) using MCF-7 cells transfected with luciferase (MCF-7/Luc). Furthermore, tissue biopsy examination and blood analysis indicated that intratumoral delivery of DOX using GOFA-DOX/HACPN did not elicit acute toxicity. Taken together, GOFA-DOX/HACPN could be deemed as a safe and efficient intratumoral drug delivery system for breast cancer therapy.

Current pharmacological developments in 2,3,4',5-tetrahydroxystilbene 2-O-β-D-glucoside (TSG)

2,3,4',5-tetrahydroxystilbene 2-O-β-D-glucoside (TSG), a resveratrol analog with glucoside, is purified from a traditional Chinese herbal medicine polygonum multiflorum. It has been extensively studied in last decade and known to exert strong anti-inflammatory, anti-oxidative, anti-apoptotic, and free radical scavenging activities, and therefore has been listed as a potential agent for disease therapies. Recent studies extend well-beyond effects of TSG on the injury of neurons, cardiomyocytes and endothelial cells, and report important functions of TSG in a lot of pathophysiological conditions. For example, TSG has been shown to prevent the production of pro-inflammatory cytokines in microglia and macrophages in vitro, and ameliorate pro-inflammatory responses in animal models with neurodegeneration, atherosclerosis, and rat paw or ear oedema. TSG can prevent the proliferation of vascular smooth cells, gastrointestinal dysfunctions, platelet aggregation, osteoblastic injury, diabetic nephropathy and melanogenesis. TSG is also indicated to facilitate long-term potentiation and learning and memory in both normal and pathological conditions. These effects to some extent enrich the understanding about the role of TSG in disease prevention and therapy. However, to date, we still have no outlined knowledges about the pharmacological effects of TSG, though the role of TSG in aging and Alzheimer's disease has been reviewed in recent years. Here, we summarize the current pharmacological developments of TSG as well as its possible mechanisms in disease prevention and therapy, aiming to push the understanding about the protective role of TSG as well as its preclinical assessment of novel applications.

A novel injectable phospholipid gel co-loaded with doxorubicin and bromotetrandrine for resistant breast cancer treatment by intratumoral injection

Systemically administered anticancer treatments were greatly limited by extensive side effects mainly due to nonspecific distributions in vivo, and multidrug resistance in various tumors. A phospholipids-based in situ-forming gel platform has been developed for the concurrent delivery of doxorubicin (DOX) and bromotetrandrin (W198). Phospholipid gel containing DOX and W198 remained in a solution (sol) state before injection and underwent rapid gelation after injection in vivo. The release of DOX and W198 from phospholipid gel (PG) was sustained in vitro for over 20 days (d). DOX and W198 from PG achieved prolonged release for over two weeks in rats via subcutaneous injection. Compared with repeated injections of free drug, eliminated cardiac toxicity and less bone marrow inhibition were observed for DOX and W198-loaded PG (DOX/W198-PG) in normal rats via subcutaneous injection. Also, a single intratumoral injection of DOX/W198-PG in the resistant MCF-7/Adr xenograft-bearing mice showed much better antitumor efficacy compared to other treatment groups. In sum, DOX/W198-PG was well demonstrated to achieve sustained drug release both in vitro and in vivo with eliminated toxicity and improved antitumor efficacy by reversing the multidrug resistance in breast cancers.

The Crossroads of Geriatric Cardiology and Cardio-Oncology

Cancer and cardiovascular disease (CVD) are two major causes of mortality in older adults. With improved survival and outcomes from cancer and CVD, the role of the geriatrician is evolving. Geriatricians provide key skills to facilitate patient-centered and value-based care in the growing older population of cancer patients (and survivors). Cancer treatment in older adults is particularly injurious with respect to complications stemming from cancer therapy and as well as to CVD related to cancer therapy in the context of physiologic aging. To best meet their natural potential as caregiving leaders, geriatricians must hone skills and insights pertaining to oncologic and cardiovascular care, insights that can inform and enhance key management expertise. In this paper, we will review common chemotherapy and radiation-induced cardiovascular complications, screening recommendations, and advance the concept of a geriatric, cardiology, and oncology collaboration. We assert that geriatricians are well suited to a leadership role in the care of older cardio-oncology patients and in the education of primary care physicians and subspecialists on geriatric principles.

Key Structural Features of Azanaphthoquinone Annelated Pyrrole Derivative as Anticancer Agents Based on the Rational Drug Design Approaches

Azanaphthoquinone annelated pyrrole derivatives have been developed and synthesized with a continuous attempt to develop novel DNA intercalating agents as anti-cancer compounds with lower organ toxicity. With the remarkable antiproliferative activity of synthesized azanaphthoquinone annelated pyrrole derivatives, a structurally novel scaffold of these compounds is appropriated for further development of novel anti-cancer agents. Therefore, in the present study, 3D QSAR study (CoMSIA) was applied on 28 azanaphthoquinone annelated pyrrole derivatives to evaluate the structural requirement of these compounds. The resulting CoMSIA model is satisfied with r(2) of 0.99 and q(2) of 0.65. The interpretation of CoMSIA contours reveals the significant importance of steric, electrostatic, hydrophobic and hydrogen acceptor descriptors on the activities of azanaphthoquinone annelated pyrrole derivatives. Remarkably, the structural requirement of six substituent positions on the azanaphthoquinone annelated pyrrole scaffold was elucidated here. This result is the useful concept for design of new and more active azanaphthoquinone annelated pyrrole derivatives. Moreover, MD simulations using AMBER program were performed to model the binding of azanaphthoquinone annelated pyrrole derivatives in the intercalation site of the DNA duplex. Based on MD simulations, the information in terms of ligand-DNA interaction, complex structure and binding free energy was provided in this work. Therefore, the integrated results are informative for further modification of azanaphthoquinone annelated pyrrole scaffold leading to gain novel azanaphthoquinone annelated pyrrole derivatives possessing better antiproliferative activity.

Severe cardiotoxicity associated with ixabepilone use in metastatic breast cancer

OBJECTIVE

To report a case of cardiogenic shock and fulminant heart failure associated with a single dose of ixabepilone.

CASE SUMMARY

A 32-year-old woman presented to the emergency department (ED) with abdominal pain and difficulty breathing within 1 hour after receiving a partial dose of ixabepilone (26 mg/m(2)) at an oncologist's office. She had breast cancer, with metastases to the bone and liver and evidence of early liver failure. While in the ED, she developed acute respiratory failure requiring intubation. Bedside ultrasound imaging showed free abdominal fluid. Computed tomography (CT) scans showed evidence of right-sided heart failure and abdominal fluid consistent with ascites but no evidence of pulmonary embolism. After the CT scan, the patient experienced pulseless electrical activity cardiac arrest. All attempts at resuscitation were unsuccessful.

DISCUSSION

Ixabepilone is a novel drug for treatment of advanced breast cancer. The most commonly reported adverse effects are peripheral neuropathies and hematologic issues such as neutropenia. To our knowledge, this is the first detailed report of a severe adverse cardiac event associated with ixabepilone use. Many other chemotherapeutic agents have cardiotoxic effects. An objective causality assessment, using the Naranjo probability scale, revealed that an adverse drug event was probable.

CONCLUSIONS

Clinicians should maintain broad differential diagnoses that include adverse reactions to drugs relatively new to the market. Ixabepilone may have cardiotoxic effects that necessitate further study, particularly when the drug is administered after cardiotoxic chemotherapy.

Zinc supplementation augments in vivo antitumor effect of chemotherapy by restoring p53 function

Activated p53 is necessary for tumor suppression. Homeodomain-interacting protein kinase-2 (HIPK2) is a positive regulator of functional p53. HIPK2 modulates wild-type p53 activity toward proapoptotic transcription and tumor suppression by the phosphorylation of serine 46. Knock-down of HIPK2 interferes with tumor suppression and sensitivity to chemotherapy. Combined administration of adriamycin and zinc restores activity of misfolded p53 and enables the induction of its proapoptotic and tumor suppressor functions in vitro and in vivo. We therefore looked for a cancer model where HIPK2 expression is low. MMTV-neu transgenic mice overexpressing HER2/neu, develop mammary tumors at puberty with a long latency, showing very low expression of HIPK2. Here we show that whereas these tumors are resistant to adriamycin treatment, a combination of adriamycin and zinc suppresses tumor growth in vivo in these mice, an effect evidenced by the histological features of the mammary tumors. The combined treatment of adriamycin and zinc also restores wild-type p53 conformation and induces proapoptotic transcription activity. These findings may open up new possibilities for the treatment of human cancers via the combination of zinc with chemotherapeutic agents, for a selected group of patients expressing low levels of HIPK2, with an intact p53. In addition, HIPK2 may serve as a new biomarker for tumor aggressiveness.

Synthesis and antiproliferative activity of new cytotoxic azanaphthoquinone pyrrolo-annelated derivatives: Part II

A series of 6-azanaphthoquinone pyrrolo-annelated derivatives carrying different basic side chains have been synthesized. The antiproliferative activities of all compounds were evaluated on at least four different cell lines with Mitoxantrone as reference compound. Cytotoxic effects and DNA intercalation behavior were investigated.

Chemotherapy induced cardiomyopathy: pathogenesis, monitoring and management

The survival rate of cancer patients has greatly increased over the last 20 years. However, to achieve this result, a considerable price has been paid in terms of the side effects associated with the intensive anticancer treatment. The most common adverse effect is cardiotoxicity which may compromise the clinical effectiveness of chemotherapy, affecting the patient's survival and quality of life independently of the oncological prognosis. There are 2 types of cardiac toxicities, type I which is more serious and result in permanent damage to the myocardium and type II which is usually reversible. Chemotherapies varies in their incidence of inducing cardiomyopathy, and the onset which may occur acutely (during or shortly after treatment), sub-acutely (within days or weeks after completion of chemotherapy) or chronically (weeks to months after drug administration). Cardiac events associated with chemotherapy may consist of mild blood pressure changes, thrombosis, Electrocardiographic (ECG) changes, arrhythmias, myocarditis, pericarditis, myocardial infarction, cardiomyopathy, cardiac failure (left ventricular failure), and congestive heart failure (CHF). The risk for such effects depends upon: cumulative dose, rate of drug administration, mediastinal radiation, advanced age, younger age, female gender, pre-existing heart disease and hypertension. Serial measurements of LVEF and fractional shortening are the most common indices monitored to assess left ventricular systolic function and cardiotoxicity. This can be achieved by 2-dimensional, M-mode and color Doppler echocardiographic examination; also Cardiac troponins as a biological marker for myocardial damage can be used for monitoring in patients received anthracyclines. Angiotensin-converting enzyme (ACE) inhibitors (ACEIs) have been shown to slow the progression of left ventricular dysfunction in several different clinical settings, including anthracycline-induced cardiomyopathy. Carvedilol and probably with anti-oxidants like Probucol and vitamin E benefits also.

Decreased oxygen transfer capacity of erythrocytes as a cause of 5-fluorouracil related ischemia

Various mechanisms have been proposed to account for chemotherapy related ischemia, but none of them can explain the available clinical data. In order to explore the possibility that the decreased ability of erythrocytes to deliver oxygen to the heart could be responsible for cardiotoxicity, we have performed an ex vivo and in vivo study of the effects of cisplatin/5-FU on erythrocytes, using a variety of biophysical techniques. Combining EPR and microscopy it was concluded that both cardiotoxic 5-FU and non-cardiotoxic cisplatin have similar effects on the erythrocyte membrane, thus eliminating those changes as a potential source of cardiotoxicity. On the contrary, 31P-NMR and polarography showed that the effects of these cytostatics on the intracellular milieu differ significantly. 5-FU provoked a pronounced decrease of the O2 level in blood and affected the metabolism of phosphate compounds, while cisplatin had no such effects. When combined these two drugs showed synergistic effects, which matches the higher frequency of cardiotoxicity of the combination relative to the sole application of 5-FU. Preliminary results acquired on blood of patients receiving cisplatin/5-FU therapy verified observations obtained ex vivo. These results open a possibility of applying NMR in preclinical trials of new drugs in order to predict their ischemic potential.

Aqueous fish extract increases survival in the mouse model of cytostatic toxicity

Background

Treatment of cancer patients with anthracycline antibiotic doxorubicin (DOX) may be complicated by development of acute and chronic congestive heart failure (CHF), malignant arrhythmias and death. The aim of this study was to test whether an aqueous low molecular weight (LMW) extract from cod muscle decreases acute mortality in the mouse model of acute CHF caused by DOX.

Methods

A LMW fraction (<500 Da) of the aqueous phase of cod light muscle (AOX) was used for treatment of male BALB/c mice (~25 g, n = 70). The animals were divided into four groups, DOX + AOX (n = 20), DOX + saline (NaCl) (n = 30), NaCl + AOX (n = 10) and NaCl only (n = 10). Echocardiography was performed in the separate subgroups (DOX treated n = 6 and controls n = 6) to verify the presence and the grade of acute CHF. The cod extract was delivered by subcutaneously implanted osmotic minipumps over the period of 2 weeks. High-dose injection of DOX was administered to randomly selected animals. The animals received single intraperitoneal injection of DOX (25 mg/kg) and were followed over two weeks for mortality.

Results

Mortality rate was 68% lower (p < 0.05) in the mice treated with the extract. The analyses of cod extract have shown strong antioxidative effect in vitro.

Conclusion

The aqueous LMW cod muscles extract decreases mortality in the mouse model of DOX induced acute CHF. This effect may be mediated by cardioprotection through antioxidative mechanisms.

Cardiomyocyte count in rat myocardium under the effect of antitumor agents cyclophosphamide and triterpenoids

Structural reorganization of the myocardium in response to antitumor agents (cyclophosphamide, betulonic acid and its amide) was studied. Cardiotoxic effects of these chemicals manifested in cardiomyocyte contracture and lytic injuries and by significant hemodynamic disorders. The most pronounced lytic and necrobiotic changes in cardiomyocytes were detected after injection of cyclophosphamide followed by betulonic amide; this led to a more pronounced decrease in heart weight as a result of a decrease in total cardiomyocyte count. Antitumor drugs differently changed the ratio of mono- to binuclear cardiomyocytes, which differ by their regeneratory and compensatory adaptive potential.

Synthesis and biological evaluation of novel cytotoxic azanaphthoquinone annelated pyrrolo oximes

Two series of azanaphthoquinone annelated pyrrolo oximes have been synthesized. The antiproliferative activities of 10 compounds were evaluated on at least four different cell lines. One series of pyrrolo derivatives showed high cytotoxic activity. The effects on cell cycle and caspase activity were investigated. Compounds 9a and 9b showed an accumulation of cells in G2/M phase. Substantial and dose-dependent caspase activity was found after treatment of cells with 9a and 9b. This indicates an apoptosis inducing property of these compounds.

Anthracycline-induced cardiotoxicity: course, pathophysiology, prevention and management

Although effective anti-neoplastic agents, anthracyclines are limited by their well recognized and pervasive cardiotoxic effects. The incidence of late progressive cardiovascular disease in long-term survivors of cancer is established and may contribute to heart failure and death. To maximize the benefits of these drugs, a high-risk population has been identified and new strategies have been investigated to minimize toxic effects, including limiting the cumulative dose, controlling the rate of administration and using liposomal preparations and novel anthracycline analogues. Dexrazoxane also shows promise as a cardioprotectant during treatment. This paper reviews these strategies, as well as medications used to manage anthracycline-induced cardiotoxicity, and functional and biochemical means of monitoring cardiotoxicity, including echocardiography, radionuclide scans and biomarker analysis. The treatment of adult cancer survivors who have had anthracycline-related cardiotoxicity has not been systematically studied. Empirically, anthracycline-associated cardiac dysfunction is treated very similarly to other forms of heart failure. These treatments include avoiding additional cardiotoxic regimens, controlling hypertension, lifestyle changes, medications and heart transplantation.

Evaluation of relative DNA binding affinities of anthrapyrazoles by electrospray ionization mass spectrometry

Binding interactions of a new series of anthrapyrazoles (APs) with DNA were evaluated by electrospray ionization mass spectrometry (ESI-MS). Relative binding affinities were estimated from the ESI-MS data based on the fraction of bound DNA for DNA/anthrapyrazole mixtures, and they show a correlation to the shift in melting point of the DNA measured from a previous study. Minimal sequence specificity was observed for the series of anthrapyrazoles. Upon collisionally activated dissociation of the duplex/anthrapyrazole complexes, typically ejection of the ligand was the dominant pathway for most of the complexes. However, for complexes containing AP2 or mitoxantrone, strand separation with the ligand remaining on one of the single strands was observed, indicative of a different binding mode or stronger binding.

Anthracycline cardiotoxicity in long-term survivors of childhood cancer

Anthracycline chemotherapy is a widely-used and effective treatment for a wide spectrum of childhood cancers. Its use is limited by associated progressive and clinically significant cardiotoxic effects. Onset can be acute, early, or late. While acute onset is rare, long-term survivors have significantly elevated rates of cardiac morbidity and mortality. Major complications include cardiomyopathy, coronary artery disease, and atherosclerosis. Means of prevention and treatment continue to be explored including limiting cumulative anthracycline dose, controlling the rate of administration, and using liposomal preparations and novel anthracycline analogues. Dexrazoxane prior to anthracycline chemotherapy has been shown to significantly lower rates of elevated serum cardiac troponin levels, a marker of myocyte injury, indicating a cardioprotective effect. Pilot studies indicate that exercise interventions may also be beneficial in long-term survivors with cardiac damage. Support and study of this population to decrease the morbidity and morality associated with anthracycline-induced cardiotoxicity is indicated in a time sensitive fashion.

Heart failure induced by non-cardiac drugs

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

Protectors against doxorubicin-induced cardiotoxicity: Flavonoids

Doxorubicin is a widely used anthracycline anticancer agent. Its use may cause cardiomyopathy: in fact, the development of cumulative dose-related cardiotoxicity forms the major limitation of clinical doxorubicin use. We therefore searched for protective agents that combine iron-chelating and oxygen radical-scavenging properties. Moreover, any novel protector should not interfere with the cytostatic activity of doxorubicin. After extensive in vitro screening we found that flavonoids could serve this purpose. In particular 7-monohydroxyethylrutoside almost completely protected against the negative inotropic action of doxorubicin in the electrically paced mouse left atrium model. In vivo it gave full protection at 500 mg/kg intraperitoneally against the doxorubicin-induced ST-interval lengthening in the ECG. Moreover, this protector did not influence the antitumor effect of doxorubicin either in vitro using the human ovarian cell lines A2780 and OVCAR-3 and the human breast cancer cell line MCF-7 or in vivo in A2780 and OVCAR-3 subcutaneous xenografts in nude mice. Comparison of various iron chelators suggest that iron, in contrast to the general assumption, might not play a crucial role in the oxidative stress-induced toxicity of doxorubicin. Moreover, incubation of vascular endothelial cells with doxorubicin produced overexpression of adhesion molecules, which could be inhibited by 7-monohydroxyethylrutoside. From a study in human volunteers, we conclude that an intravenous dose of 1500 mg/m(2) of 7-monohydroxyethylrutoside is feasible and is safe to be investigated as protection against doxorubicin-induced cardiotoxicity.

Cytoprotective role of DL-α-Lipoic acid in cyclophosphamide induced myocardial toxicity

Cyclophosphamide (CP), a potent antitumor drug is known to cause severe cardiotoxicity. The present study is aimed at evaluating the cardioprotective role of lipoic acid in CP induced toxicity. Male albino rats of Wistar strain were divided into four groups and treated as follows: Group I served as control, Group II received a single dose of CP (200 mg/kg b.wt., i.p.), Group III received lipoic acid (25 mg/kg b.wt., orally) for 10 days, Group IV received CP immediately followed by lipoic acid for 10 days. In CP administered rats, the activities of tissue marker enzymes (creatine phosphokinase, lactate dehydrogenase, aspartate transaminase and alanine transaminase) were significantly (p<0.001) reduced, ATPases suffered loss in enzyme activity and thiols were depleted. Histopathological observations were also in agreement with the above abnormal changes. Lipoic acid effectively reverted these abnormal biochemical changes and minimized the histopathological lesions in heart. These observations highlight the protective role of lipoic acid in CP induced cardiac injury.

A comparison of the benefits of mitoxantrone and other recent therapeutic approaches in multiple sclerosis

The approval by the FDA of four immunomodulators (three IFNs and glatiramer acetate) and one immunosuppressant (mitoxantrone; Novantrone) for the treatment of multiple sclerosis is definitely the most important progress in this field since the first description of the disease > 150 years ago. However, both types of immunotherapies raise specific problems. Immunomodulators benefit patients in the relapsing-remitting phase, or patients in the secondary-progressive phase showing clinical and/or radiological signs of active inflammatory processes. Their benefit is modest, but seems to persist with long-term administration, as their tolerance is acceptable. Mitoxantrone is a rescue therapy reserved to patients with an aggressive, rapidly progressive form of the disease. This immunosuppressant is effective on inflammatory processes and pathomechanisms responsible for disability progression. Unfortunately, its cardiotoxicity and potential leukaemogenicity prevent an administration beyond 2 or 3 years. Thus, there is a need to improve on the efficacy of immunomodulators and to reduce the toxicity of immunosuppressants. Combination therapies with immunomodulators and antioxidants or with neuroprotective drugs against excitotoxicity or Na + /Ca 2+ channellopathy are currently being investigated. With regard to immunosuppressants, the development of monoclonal antibodies with fully human protein sequences and the synthesis of a new molecule as effective as mitoxantrone but with a much lower toxicity (pixantrone) seem promising to halt or even to prevent disability progression.

Antitumor AZA-anthrapyrazoles: biophysical and biochemical studies on 8- and 9-aza regioisomers

Aza-bioisosteres of anthrapyrazoles (Aza-APs) bearing the C-N substitution at position 9 are powerful anticancer agents now in clinical trials. In contrast, their 8-substituted regioisomers are practically devoid of chemotherapeutic effects. To understand the molecular basis for a dramatically different response by otherwise very similar compounds, we performed a detailed investigation on the physico-chemical properties of several aza-APs belonging to the two families, on their DNA-binding affinity and specificity as well as on their capacity to impair the activity of the two isoforms of human Topoisomerase II (top2alpha and top2beta). Our results indicate that molecular size and shape, electronic distribution, redox properties, lipophilicity and protonation equilibria are essentially the same when comparing 9- with 8-substituted congeners. Although no major difference could be picked up when comparing the DNA binding properties of corresponding members of the 8- and 9-aza families, interestingly the affinity and specificity for the nucleic acid is modulated by the nature of the side-arms linked to the aza-AP scaffold, suggesting structural motifs that may determine DNA sequence recognition by the studied drug. Topoisomerase II poisoning activity was much higher for 9-aza derivatives than 8-aza analogues as shown by a cleavage assay with purified recombinant top2 isoforms. The difference appears to account for the divergent anticancer potential exhibited by different aza-AP regioisomers and suggests a specific molecular recognition of the cleavage complex by the studied drugs.

Cardiac effects of adjuvant therapy for early breast cancer

Adjuvant chemotherapy is an established standard of care for most patients diagnosed with early breast cancer, and its popularity is gaining worldwide. The systemic armamentarium presently includes anthracyclines and taxanes, alkylating agents, fluoropyrimidines, and antimetabolites; in the future, it may include platinum compounds and the recombinant humanized anti-HER2 monoclonal antibody, trastuzumab, as well. Anti-estrogens continue to play an important role in the adjuvant setting for hormone-sensitive primary breast cancer. Adjuvant radiotherapy is common in the setting of early-stage disease as breast conservation gains popularity, and radiation is often employed in the postmastectomy setting as well. As treatment guidelines continue to evolve with newer data, the relative benefits of treatment in many situations continues to grow. Refinement of the optimal identification of patients at risk for local and distant relapse is a continued challenge facing the treating clinician. Parallel to this effort, and of equal importance, is the ability to shield patients that will gain little, if any, benefit from treatment and to identify those who may be at greater risk to suffer from potential toxicities. Until these factors are better defined, the recognition by clinicians of long-term side effects associated with adjuvant therapy is obligatory. Acute toxicities from treatment are often reversible, but late onset adverse effects of therapy can increase morbidity and mortality in long-term survivors, and continue to be of concern. One of the most serious side effects of adjuvant therapy of early breast cancer is cardiac toxicity. This article will provide an overview of the cardiac effects of adjuvant therapy in the treatment of early breast cancer.

Acute arrhythmogenicity of first-dose chemotherapeutic agents in children

BACKGROUND

Chemotherapeutic agents have been reported to cause severe arrhythmias and sudden death in the first 24 hr after administration. In this prospective study, we determined the magnitude of acute arrhythmogenicity of those agents in children.

PROCEDURE

Thirty-three patients with diverse malignancies (leukemia n = 16, Wilms tumor n = 3, brain tumor n = 3, lymphoma n = 3, others n = 8) were studied with Holter monitors 24 hr before, during, and in the first 24 hr following the first-dose therapy.

RESULTS

Two patients experienced conduction disturbances (phases of 2nd degree sinuatrial and atrioventricular blocks) during a 4-hr period corresponding to a 30 mg/m(2) daunorubicin infusion. Eight patients experienced supraventricular extrasystole (SE), ventricular extrasystole (VE), and/or short salvos of supraventricular (SVT) and/or ventricular tachycardia (VT). Six had leukemia (therapy: daunorubicin + vincristine), one had a lymphoma (therapy: vincristine + cyclophosphamide), and the last one a brain tumor (therapy: carboplatin + procarbazine). Three patients with leukemia had pretreatment arrhythmias (1 VT, 2 SVT). One of them and the five other patients had arrhythmias during and after the first-dose therapy (2 VE, 2 SVT, 1 SVT + VE, 1 VE + SE + SVT). No patient had life-threatening arrhythmias and no prognostic value of those disturbances could be demonstrated.

CONCLUSIONS

Conduction disturbances and arrhythmias are common in cancer children at the beginning of the therapy, but no acute or long-term adverse consequences are related to their appearance.

Chemotherapy-induced cardiotoxicity: current practice and prospects of prophylaxis

Cardiotoxicity is a potential side effect of few chemotherapeutic agents. The anthracycline class of cytotoxic antibiotics are the most famous, but other chemotherapeutic agents can also cause serious cardiotoxicity and are not so well recognised. Examples include cyclophosphamide, ifosfamide, mitomycin and fluorouracil. Prediction and hence prophylaxis has always been a difficult task. Ideal monitoring techniques, upon which efficient prophylaxis depends, are yet to be determined. Current prophylaxis relies upon early detection of systolic and/or diastolic dysfunction. While somewhat useful, in some cases by the time defects are detected progression of chemotherapy-induced cardiomyopathy is beyond prevention. Prophylaxis would be much more efficient if a biochemical marker of myocardiocyte damage could be reliably used to stop further chemotherapy at the correct time before irreversible progressive 'macroscopic' damage becomes evident upon imaging. Work is currently progressing to identify the role of markers such as troponins and natriuretic peptides in this regard.

Cardiotoxicity of chemotherapeutic agents: incidence, treatment and prevention

Cytostatic antibiotics of the anthracycline class are the best known of the chemotherapeutic agents that cause cardiotoxicity. Alkylating agents such as cyclophosphamide, ifosfamide, cisplatin, carmustine, busulfan, chlormethine and mitomycin have also been associated with cardiotoxicity. Other agents that may induce a cardiac event include paclitaxel, etoposide, teniposide, the vinca alkaloids, fluorouracil, cytarabine, amsacrine, cladribine, asparaginase, tretinoin and pentostatin. Cardiotoxicity is rare with some agents, but may occur in >20% of patients treated with doxorubicin, daunorubicin or fluorouracil. Cardiac events may include mild blood pressure changes, thrombosis, electrocardiographic changes, arrhythmias, myocarditis, pericarditis, myocardial infarction, cardiomyopathy, cardiac failure (left ventricular failure) and congestive heart failure. These may occur during or shortly after treatment, within days or weeks after treatment, or may not be apparent until months, and sometimes years, after completion of chemotherapy. A number of risk factors may predispose a patient to cardiotoxicity. These are: cumulative dose (anthracyclines, mitomycin); total dose administered during a day or a course (cyclophosphamide, ifosfamide, carmustine, fluorouracil, cytarabine); rate of administration (anthracyclines, fluorouracil); schedule of administration (anthracyclines); mediastinal radiation; age; female gender; concurrent administration of cardiotoxic agents; prior anthracycline chemotherapy; history of or pre-existing cardiovascular disorders; and electrolyte imbalances such as hypokalaemia and hypomagnesaemia. The potential for cardiotoxicity should be recognised before therapy is initiated. Patients should be screened for risk factors, and an attempt to modify them should be made. Monitoring for cardiac events and their treatment will usually depend on the signs and symptoms anticipated and exhibited. Patients may be asymptomatic, with the only manifestation being electrocardiographic changes. Continuous cardiac monitoring, baseline and regular electrocardiographic and echocardiographic studies, radionuclide angiography and measurement of serum electrolytes and cardiac enzymes may be considered in patients with risk factors or those with a history of cardiotoxicity. Treatment of most cardiac events induced by chemotherapy is symptomatic. Agents that can be used prophylactically are few, although dexrazoxane, a cardioprotective agent specific for anthracycline chemotherapy, has been approved by the US Food and Drug Administration. Cardiotoxicity can be prevented by screening and modifying risk factors, aggressively monitoring for signs and symptoms as chemotherapy is administered, and continuing follow-up after completion of a course or the entire treatment. Prompt measures such as discontinuation or modification of chemotherapy or use of appropriate drug therapy should be initiated on the basis of changes in monitoring parameters before the patient exhibits signs and symptoms of cardiotoxicity.

Chelation therapy in cardiovascular disease: ethylenediaminetetraacetic acid, deferoxamine, and dexrazoxane

This review was conducted to assess whether there is sufficient evidence for the clinical use of chelation therapy in cardiovascular disease based on original articles and abstracts published in the last 30 years, with emphasis placed on the most recent placebo-controlled studies. Articles postulating the mechanisms of chelation also were included. The majority of the literature focused on three chelators in particular, ethylenediaminetetraacetic acid (EDTA), deferoxamine, and dexrazoxane (ICRF-187). Historically, much has been written on the beneficial effects of EDTA. However, there are few controlled studies, and the mechanism of action of EDTA is poorly understood. Although studies of deferoxamine are more recent, most of the research is limited to animals and ex vivo models. Recently, dexrazoxane was approved, but only for parenteral use for reducing the incidence and severity of cardiomyopathy associated with doxorubicin administration in women with metastatic breast cancer. Given these limitations, it is concluded that more controlled studies are required to determine the efficacy of chelation therapy in cardiovascular disease before it can be used broadly in the clinical setting.