High sensitivity of radiolabelled antimyosin scintigraphy in assessing anthracycline related early myocyte damage preceding cardiac dysfunction

Nuclear medicine in the assessment and prevention of cancer therapy-related cardiotoxicity: prospects and proposal of use by the European Association of Nuclear Medicine (EANM)

Cardiotoxicity may present as (pulmonary) hypertension, acute and chronic coronary syndromes, venous thromboembolism, cardiomyopathies/heart failure, arrhythmia, valvular heart disease, peripheral arterial disease, and myocarditis. Many of these disease entities can be diagnosed by established cardiovascular diagnostic pathways. Nuclear medicine, however, has proven promising in the diagnosis of cardiomyopathies/heart failure, and peri- and myocarditis as well as arterial inflammation. This article first outlines the spectrum of cardiotoxic cancer therapies and the potential side effects. This will be complemented by the definition of cardiotoxicity using non-nuclear cardiovascular imaging (echocardiography, CMR) and biomarkers. Available nuclear imaging techniques are then presented and specific suggestions are made for their application and potential role in the diagnosis of cardiotoxicity.

Nuclear cardiology in the context of multimodality imaging to detect cardiac toxicity from cancer therapeutics: Established and emerging methods

The complexity of cancer therapies has vastly expanded in the last decade, along with type and severity of cardiac toxicities associated with these treatments. Prevention of pre-clinical cardiotoxicity may improve cardiovascular outcomes and circumvent the decision to place life-sustaining chemotherapeutic agents on hold, making the early detection of cancer therapeutic related cardiac toxicity with non-invasive imaging essential to the care of these patients. There are several established methods of cardiac imaging in the areas of nuclear cardiology, echocardiography, computed tomography, and cardiac magnetic resonance imaging that are used to assess for cardiovascular toxicity of cancer treatments, with several methods under development. The following review will provide an overview of current and emerging imaging techniques in these areas.

From Molecular Mechanisms to Clinical Management of Antineoplastic Drug-Induced Cardiovascular Toxicity: A Translational Overview

Significance: Antineoplastic therapies have significantly improved the prognosis of oncology patients. However, these treatments can bring to a higher incidence of side-effects, including the worrying cardiovascular toxicity (CTX). Recent Advances: Substantial evidence indicates multiple mechanisms of CTX, with redox mechanisms playing a key role. Recent data singled out mitochondria as key targets for antineoplastic drug-induced CTX; understanding the underlying mechanisms is, therefore, crucial for effective cardioprotection, without compromising the efficacy of anti-cancer treatments. Critical Issues: CTX can occur within a few days or many years after treatment. Type I CTX is associated with irreversible cardiac cell injury, and it is typically caused by anthracyclines and traditional chemotherapeutics. Type II CTX is generally caused by novel biologics and more targeted drugs, and it is associated with reversible myocardial dysfunction. Therefore, patients undergoing anti-cancer treatments should be closely monitored, and patients at risk of CTX should be identified before beginning treatment to reduce CTX-related morbidity. Future Directions: Genetic profiling of clinical risk factors and an integrated approach using molecular, imaging, and clinical data may allow the recognition of patients who are at a high risk of developing chemotherapy-related CTX, and it may suggest methodologies to limit damage in a wider range of patients. The involvement of redox mechanisms in cancer biology and anticancer treatments is a very active field of research. Further investigations will be necessary to uncover the hallmarks of cancer from a redox perspective and to develop more efficacious antineoplastic therapies that also spare the cardiovascular system.

Cardiovascular imaging in cardio-oncology

Cancer therapy may lead to cardiovascular complications and can promote each aspect of cardiac disease manifestation, such as vascular disease including coronary heart disease, myocardial diseases including heart failure, structural heart diseases including valvular heart diseases, and rhythm disorders. All potential complications of cancer therapy onto the cardiovascular system require imaging for diagnostic workup as well as monitoring of therapy. Transthoracic echocardiography (TTE) is the most frequently used tool for assessment of cardiac function during or after cancer therapy in daily clinical routine. With modern techniques like strain analysis, echocardiography allows to detect a variety of cardiac diseases as caused by cancer therapy even at subclinical stages. For further workup, specific imaging techniques including nuclear imaging are needed in a multimodality imaging approach to in detail characterize the underlying pathophysiology and to improve the management of the patients. Therefore, the field of imaging in cardio-oncology is rapidly growing. This review article will give an overview about existing literature regarding the role of imaging in the diagnostic evaluation and management of therapy in patient with prior or ongoing cancer therapy.

Targeted Nuclear Imaging Probes for Cardiac Amyloidosis

PURPOSE OF REVIEW

The aim of the present manuscript is to review the latest advancements of radionuclide molecular imaging in the diagnosis and prognosis of individuals with cardiac amyloidosis.

RECENT FINDINGS

^99mTechnetium labeled bone tracer scintigraphy had been known to image cardiac amyloidosis, since the 1980s; over the past decade, bone scintigraphy has been revived specifically to diagnose transthyretin cardiac amyloidosis. ¹⁸F labeled and ¹¹C labeled amyloid binding radiotracers developed for imaging Alzheimer's disease, have been repurposed since 2013, to image light chain and transthyretin cardiac amyloidosis. ^99mTechnetium bone scintigraphy for transthyretin cardiac amyloidosis, and amyloid binding targeted PET imaging for light chain and transthyretin cardiac amyloidosis, are emerging as highly accurate methods. Targeted radionuclide imaging may soon replace endomyocardial biopsy in the evaluation of patients with suspected cardiac amyloidosis. Further research is warranted on the role of targeted imaging to quantify cardiac amyloidosis and to guide therapy.

Comprehensive review on cardio-oncology: Role of multimodality imaging

Cancer and cardiovascular disease are the two leading causes of mortality worldwide. Evolving oncologic therapy, including the use of newer targeted agents, has led to an improvement in survival from childhood- and adult-onset cancers. Consequently, there has been a growing realization of cardiotoxic complications related to cancer therapy, with some complications manifesting over months to decades after completion of cancer treatment. This paper reviews cancer therapeutics-related cardiovascular toxicity and its manifestations, multimodality imaging techniques for surveillance and detection of this complication, and the current state of knowledge in this emerging field.

Update on cardiotoxicity of anti-cancer treatments

BACKGROUND AND AIMS

Anti-cancer treatments markedly improved the prognosis of patients, but unfortunately might be hampered by cardiotoxicity. Both symptomatic and asymptomatic clinical forms of heart failure have been reported, which may be reversible or irreversible. The aim of this review is to provide an overview of the antineoplastic agents associated with cardiac toxicity and of the available diagnostic techniques.

METHODS AND METHODS

This narrative review is based on material from MEDLINE and PUBMED up to November 2015. We looked at the terms antineoplastic drugs and cardiac toxicity in combination with echocardiography, troponins, cardiac magnetic resonance, and positron emission tomography.

RESULTS

Anthracyclines, monoclonal antibodies, fluoropyrimidines, taxanes, alkylating agents, vinka alkaloids were reported to induce different clinical manifestations of cardioxicity. Chest radiotherapy is also associated with various forms of cardiac damage, which are indistinguishable from those found in patients with heart disease of other aetiologies and that may even appear several years after administration. Among diagnostic techniques, echocardiography is a noninvasive, cost-effective, and widely available imaging tool. Nuclear imaging and cardiac magnetic resonance may be used but are not so widely available and are more difficult to perform. Finally, some biomarkers, such as troponins, may be used to evaluate cardiac damage, but establishing the optimal timing of troponin assessment remains unclear and defining the cut-off point for positivity is still an important goal.

CONCLUSIONS

Cardiotoxicity of anti-cancer treatments is associated with development of heart failure. Novel diagnostic tools might be relevant to early recognize irreversible forms cardiac diseases.

Doxorubicin induced heart failure: Phenotype and molecular mechanisms

Long term survival of childhood cancers is now more than 70%. Anthracyclines, including doxorubicin, are some of the most efficacious anticancer drugs available. However, its use as a chemotherapeutic agent is severely hindered by its dose-limiting toxicities. Most notably observed is cardiotoxicity, but other organ systems are also degraded by doxorubicin use. Despite the years of its use and the amount of information written about this drug, an understanding of its cellular mechanisms is not fully appreciated. The mechanisms by which doxorubicin induces cytotoxicity in target cancer cells have given insight about how the drug damages cardiomyocytes. The major mechanisms of doxorubicin actions are thought to be as an oxidant generator and as an inhibitor of topoisomerase 2. However, other signaling pathways are also invoked with significant consequences for the cardiomyocyte. Further the interaction between oxidant generation and topoisomerase function has only recently been appreciated and the consequences of this interaction are still not fully understood. The unfortunate consequences of doxorubicin within cardiomyocytes have promoted the search for new drugs and methods that can prevent or reverse the damage caused to the heart after treatment in cancer patients. Alternative protocols have lessened the impact on newly diagnosed cancer patients. However the years of doxorubicin use have generated a need for monitoring the onset of cardiotoxicity as well as understanding its potential long-term consequences. Although a fairly clear understanding of the short-term pathologic mechanisms of doxorubicin actions has been achieved, the long-term mechanisms of doxorubicin induced heart failure remain to be carefully delineated.

Recent Advances on Pathophysiology, Diagnostic and Therapeutic Insights in Cardiac Dysfunction Induced by Antineoplastic Drugs

Along with the improvement of survival after cancer, cardiotoxicity due to antineoplastic treatments has emerged as a clinically relevant problem. Potential cardiovascular toxicities due to anticancer agents include QT prolongation and arrhythmias, myocardial ischemia and infarction, hypertension and/or thromboembolism, left ventricular (LV) dysfunction, and heart failure (HF). The latter is variable in severity, may be reversible or irreversible, and can occur soon after or as a delayed consequence of anticancer treatments. In the last decade recent advances have emerged in clinical and pathophysiological aspects of LV dysfunction induced by the most widely used anticancer drugs. In particular, early, sensitive markers of cardiac dysfunction that can predict this form of cardiomyopathy before ejection fraction (EF) is reduced are becoming increasingly important, along with novel therapeutic and cardioprotective strategies, in the attempt of protecting cardiooncologic patients from the development of congestive heart failure.

Current and emerging modalities for detection of cardiotoxicity in cardio-oncology

Advancements in diagnostic tools and curative-intent therapies have improved cancer-specific survival. With prolonged survival, patients are now subject to increased aging and development of cardiovascular risk factors such that further improvements in cancer-specific mortality are at risk of being offset by increased cardiovascular mortality. Moreover, established and novel adjuvant therapies used in cancer treatment are associated with unique and varying degrees of direct as well as indirect myocardial and cardiovascular injury (i.e., cardiotoxicity). Current approaches for evaluating anticancer therapy-induced injury have limitations, particularly lack of sensitivity for early detection of subclinical cardiac and cardiovascular dysfunction. With emerging evidence suggesting early prevention and treatment can mitigate the degree of cardiotoxicity and limit interruption of life-saving cancer therapy, the importance of early detection is increasingly paramount. Newer imaging modalities, functional capacity testing and blood biomarkers have the potential to improve early detection of cardiotoxicity and reduce cardiovascular morbidity and mortality.

Noninvasive imaging of cardiovascular injury related to the treatment of cancer

The introduction of multiple treatments for cancer, including chemotherapeutic agents and radiation therapy, has significantly reduced cancer-related morbidity and mortality. However, these therapies can promote a variety of toxicities, among the most severe being the ones involving the cardiovascular system. Currently, for many surviving cancer patients, cardiovascular (CV) events represent the primary cause of morbidity and mortality. Recent data suggest that CV injury occurs early during cancer treatment, creating a substrate for subsequent cardiovascular events. Researchers have investigated the utility of noninvasive imaging strategies to detect the presence of CV injury during and after completion of cancer treatment because it starts early during cancer therapy, often preceding the development of chemotherapy or cancer therapeutics related cardiac dysfunction. In this State-of-the-Art Paper, we review the utility of current clinical and investigative CV noninvasive modalities for the identification and characterization of cancer treatment-related CV toxicity.

Cardiotoxicity of antineoplastic agents: what is the present and future role for imaging?

As antineoplastic treatment options expand at an increasing rate, both traditional and novel agents continue to be limited by their cardiotoxic effects. While functional decline becomes clinically apparent at late states of toxicity, little is known about early stages during which treatment or prevention may still be an option. Several imaging modalities,including echocardiography, multiple gated acquisition, and cardiac magnetic resonance imaging have the ability to identify cardiac effects before they produce clinical symptoms.Here we discuss the current and future role of cardiac imaging in the assessment of cardiotoxicity of antineoplastic agents. effects on cardiac tissue, resulting in myocardial cellular damage,and ultimately lead to a wide range of effects including electrophysiological abnormalities, symptomatic heart failure(HF), and even death. This represents a limiting factor in the therapy of several otherwise treatable neoplasms [2].The cardiotoxicity of antineoplastic agents raises several important questions regarding the actual prevalence of cardiac toxicity, the ability to effectively treat or prevent such effects with pharmaceutical interventions, and the availability of a means for early diagnosis. Here, we focus on the latter, specifically examining current and potential future imaging strategies to detect the cardiac effects of chemotherapeutic agents.

Cardiovascular toxicity caused by cancer treatment: strategies for early detection

Cardiovascular toxicity is one of the most devastating complications of cancer treatment and can arise during or shortly after treatment, or even several years later. Identification of the left ventricular ejection fraction (LVEF) is the most common method to screen for toxic effects on the heart; however, this approach underestimates cardiac damage and additional strategies for the monitoring of treatment-induced cardiotoxicity are being explored. Guidelines for monitoring have been formulated for several cancer treatments; however, appropriate underlying evidence is still largely absent. In this Review, we summarise conventional and contemporary methods for early detection of cardiotoxicity and designate a level of evidence for the basis of each method.

Cardiac toxicity in breast cancer survivors: review of potential cardiac problems

As breast cancer survival is increased by the diagnosis of earlier-stage disease and treatments improve, the side effects of cancer treatments, such as cardiotoxicity, remain clinically important. Although physicians have known for 30 years that anthracyclines cause acute and chronic cardiotoxicity, the cardiotoxic effects of radiation therapy, hormonal therapy (including tamoxifen and the aromatase inhibitors), and chemotherapy with taxanes and trastuzumab treatment have emerged more recently. This review examines the cardiac toxicity of adjuvant therapy, monitoring for early changes and existing guidelines for monitoring cardiac function in patients with breast cancer.

Anticancer agents and cardiotoxicity

Although rare, cardiotoxicity is a significant complication of cancer treatment. The incidence and severity of cardiotoxicity are dependent on the type of drugs used, dose and schedule employed, and age of patients, as well as the presence of coexisting cardiac diseases and previous mediastinal irradiation. Anthracyclines are among one of the most active agents in oncology, but their use is often hampered by their cumulative dose-limiting cardiotoxicity. Combination therapy with new drugs in the last decade, such as taxanes and trastuzumab, in the treatment of metastatic breast cancer has yielded impressive results but also unexpected cardiotoxicity. Existing methods of minimizing cardiotoxicity include the use of protective agents such as dexrazoxane, different preparations of anthracyclines such as liposomal formulations, and alternative scheduling techniques. Assessment of left ventricular ejection fraction (LVEF) with two-dimensional (2D)-echocardiography or radionuclide ventriculography (RNVG) remains the most pragmatic means of monitoring for cardiotoxicity. The increasing number of long-term survivors of pediatric cancers, as well as the use of trastuzumab, taxanes, and anthracyclines in adjuvant treatment of breast cancer, means that more than ever, cardiotoxicity will remain an important issue for clinicians.

First preclinical evaluation of mono-[123I]iodohypericin as a necrosis-avid tracer agent

PURPOSE

We have labelled hypericin, a polyphenolic polycyclic quinone found in St. John's wort (Hypericum perforatum), with( 123)I and evaluated mono-[(123)I]iodohypericin (MIH) as a potential necrosis-avid diagnostic tracer agent.

METHODS

MIH was prepared by an electrophilic radioiodination method. The new tracer agent was evaluated in animal models of liver infarction in the rat and heart infarction in the rabbit using single-photon emission computed tomography (SPECT), triphenyltetrazolium chloride (TTC) histochemical staining, serial sectional autoradiography and microscopy, and radioactivity counting techniques.

RESULTS

Using in vivo SPECT imaging, hepatic and cardiac infarctions were persistently visualised as well-defined hot spots over 48 h. Preferential uptake of the tracer agent in necrotic tissue was confirmed by perfect match of images from post-mortem TTC staining, autoradiography (ARX) and histology. Radioactivity concentration in infarcted tissues was over 10 times (liver; 3.51% ID/g in necrotic tissue vs 0.38% ID/g in normal tissue at 60 h p.i.) and over 6 times (myocardium; 0.36% ID/g in necrotic tissue vs 0.054% ID/g in normal tissue; ratios up to 18 for selected parts on ARX images) higher than in normal tissues.

CONCLUSION

The results suggest that hypericin derivatives may serve as powerful necrosis-avid diagnostic agents for assessment of tissue viability.

The prevention and management of cardiovascular complications of chemotherapy in patients with cancer

Cardiac toxicity of chemotherapeutic agents is a rapidly evolving area of increasing significance because of the increasing pool of long-term cancer survivors. The spectrum of cardiotoxicity with chemotherapeutic agents includes hypertension, QTc prolongation, acute cardiomyopathy, and bradyarrhythmias. The most common issue to arise has been cardiomyopathy with anthracyclines. Preventative strategies that have met with some success have included the use of less cardiotoxic analogs such as epirubicin and liposomal anthracycline preparations. The cardioprotectant agent dexrazoxane reduces cardiomyopathy but there are significant toxicity issues. Therefore, the main strategy for preventing cardiotoxicity remains careful monitoring with radionuclide angiography or echocardiography. The role of investigational markers of myocardial injury, such as troponin T or brain natriuretic peptide, remains of great interest. Management is according to conventional management of congestive heart failure. Trastuzumab is an antibody therapy directed against the human epidermal growth factor receptor-2 (HER2) receptor, which increases survival in patients with metastatic breast cancer and is under evaluation in the adjuvant setting. It also causes a decrease in left ventricular ejection fraction (LVEF) in a minority of patients. Incidence is increased if trastuzumab is given in conjunction with paclitaxel or anthracyclines. It differs from anthracycline cardiotoxicity in that it is not cumulative dose-dependent and often improves after withdrawal of treatment. Re-treatment with trastuzumab is often possible. Novel agents under development offer a different spectrum of toxicity to existing anticancer drugs and it appears likely that cardiovascular toxicity will be an important issue for many of these drugs, particularly those that target the tumor vasculature.

Monitoring Cardiac Function in Patients Receiving Doxorubicin

Despite its well-known cardiotoxicity, doxorubicin continues to be an effective and widely used antineoplastic agent. Many efforts have focused on understanding the mechanism of doxorubicin-induced cardiotoxicity and on preventing it completely. Currently protective agents, eg, liposomal doxorubicin formulation, which results in less myocardial uptake, and the use of dexrazoxane, an intracellular iron chelator reducing the formation of radical complexes, have shown evidence of reducing incidences of cardiotoxicity at high dose of doxorubicin. However, they have not been able to completely eliminate cardiotoxicity. Therefore, it is crucial that careful monitoring to identify those patients who are at risk of developing unpredictable and sometimes-irreversible cardiac dysfunction is conducted while allowing other patients who respond to doxorubicin-containing therapy to receive their maximal therapeutic dose. Serial measurement of left ventricular ejection fraction by radionuclide angiocardiography remains a useful and widely adopted modality in monitoring patients that are receiving doxorubicin. Efforts are continuing on finding a more sensitive and reliable predictor of eventual clinical cardiac dysfunction.

Cardiac safety of liposomal anthracyclines

Conventional anthracyclines are active against many tumor types, but cardiotoxicity related to the cumulative dose may limit their use; this is particularly problematic for patients with risk factors for increased toxicity, for those who have received any anthracycline in the past, or for those who are to receive other cardiotoxic agents. Preclinical studies determined that encapsulating conventional anthracyclines in liposomes reduced the incidence and severity of cumulative dose-related cardiomyopathy while preserving antitumor activity. In controlled clinical trials, the risk of cardiotoxicity was significantly lower when nonpegylated liposomal doxorubicin (Myocet [NPLD]) was substituted for conventional doxorubicin, but the risk was not significantly different when NPLD was used in place of conventional epirubicin. Direct comparisons to conventional doxorubicin therapy showed comparable efficacy but significantly lower risk of cardiotoxicity with pegylated liposomal doxorubicin (Doxil/Caelyx [PLD]) therapy. Retrospective and prospective trials have not identified a maximum "cardiac safe" dose of PLD, despite use of cumulative doses exceeding 2,000 mg/m2 in some patients. Liposomal daunorubicin (DaunoXome [DNX]) may be associated with a lower risk of cardiotoxicity than conventional anthracyclines, but comparative trials are not available. With respect to combination chemotherapy, early results of clinical trials suggest that combining trastuzumab or a taxane with NPLD or PLD instead of a conventional anthracycline significantly reduces cardiotoxicity risk without reducing chemotherapeutic efficacy. Further results are eagerly awaited from ongoing controlled trials of cardiac safety with long-term liposomal anthracycline therapy, either alone or in combination with other potentially cardiotoxic agents.

In vitro selection of a peptide with high selectivity for cardiomyocytes in vivo

One approach to targeted therapies for cardiovascular disease relies on isolating ligands that enhance the tissue-specific uptake of genes or drugs by heart cells. To obtain heart-targeting ligands, phage display biopanning was used to isolate a 20-mer peptide that binds to isolated primary cardiomyocytes. The isolated phage, PCM.1, displays the peptide WLSEAGPVVTVRALRGTGSW, and binds these cells 180 times better than a control phage from the library. Furthermore, phage displaying this peptide preferentially bind to cardiomyocytes when compared with a panel of other cell types. A BLAST search revealed that this peptide contains a 12 amino acid segment with sequence identity to a peptide in tenascin-X, an extracellular matrix protein. Synthetic peptides containing the complete 20-mer or a 12-mer tenascin peptide partially blocked phage binding to the cardiomyocytes. We developed a quantitative real-time PCR assay to assess uptake of this phage by tissues in vivo. Using this assay, preferential localization of the PCM.1 phage in heart was observed compared to the uptake of this phage by other tissues or other phage by heart. Furthermore, PCM.1 phage was associated with cardiomyocytes isolated from mice treated with a phage in vivo. These results demonstrate the utility of biopanning on isolated cells for identifying specific binding peptides that can target a tissue in vivo.

Non-invasive in vivo imaging of myocardial apoptosis and necrosis

Myocardial necrosis plays an important role in the pathogenesis of various cardiovascular disorders and can result from different myocardial insults. Its non-invasive identification and localisation therefore may help in the diagnosis of these disorders, as well as in prognosis and assessment of treatment response. Apoptosis, or programmed cell death, is important in the spectrum of myocardial damage since it is gradually becoming more apparent that cell death may begin as apoptosis and not as necrosis. First attempts to directly visualise the area of myocardial necrosis were based on recognition of myocardial infarction with "hot spot imaging agents" in patients with chest pain. Since then, the study of myocardial necrosis with gamma imaging agents has gone beyond the detection of myocardial infarction, and attempts have been made to diagnose other cardiovascular disorders associated with cardiac cell death such as heart transplant rejection, myocarditis, cardiotoxicity and cardiomyopathies. Traditionally, two hot spot imaging agents have been used for the detection of myocardial necrosis, (99m)Tc-pyrophosphate and (111)In-antimyosin. In addition, preliminary studies have demonstrated promising results with (99m)Tc-glucarate. Recently, (99m)Tc-annexin V has been successfully used for non-invasive gamma imaging of apoptosis after acute myocardial infarction, acute myocardial ischaemia, acute cardiac allograft rejection and malignant intracardiac tumours. This review article focusses on the characteristics of these different myocardial necrotic and apoptotic markers and compares their role in the assessment of myocardial damage.