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Citation: Alexandraki, A.;
Papageorgiou, E.; Zacharia, M.;
Keramida, K.; Papakonstantinou, A.;
Cipolla, C.M.; Tsekoura, D.; Naka, K.;
Mazzocco, K.; Mauri, D.; et al. New
Insights in the Era of Clinical
Biomarkers as Potential Predictors of
Systemic Therapy-Induced
Cardiotoxicity in Women with Breast
Cancer: A Systematic Review.
Cancers 2023,15, 3290. https://
doi.org/10.3390/cancers15133290
Academic Editor: Samuel C. Mok
Received: 10 May 2023
Revised: 9 June 2023
Accepted: 19 June 2023
Published: 22 June 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
cancers
Systematic Review
New Insights in the Era of Clinical Biomarkers as Potential
Predictors of Systemic Therapy-Induced Cardiotoxicity in
Women with Breast Cancer: A Systematic Review
Alexia Alexandraki 1, * , Elisavet Papageorgiou 1, Marina Zacharia 1, Kalliopi Keramida 2,3,
Andri Papakonstantinou 4,5 , Carlo M. Cipolla 6, Dorothea Tsekoura 7, Katerina Naka 8, Ketti Mazzocco 9,10 ,
Davide Mauri 11, Manolis Tsiknakis 12,13 , Georgios C. Manikis 13 , Kostas Marias 12,13 , Yiola Marcou 14,
Eleni Kakouri 14, Ifigenia Konstantinou 14 , Maria Daniel 15, Myria Galazi 14 , Effrosyni Kampouroglou 7,
Domen Ribnikar 16, Cameron Brown 17 , Georgia Karanasiou 18 , Athos Antoniades 19 , Dimitrios Fotiadis 20 ,
Gerasimos Filippatos 21 and Anastasia Constantinidou 14, 22, *
1A.G. Leventis Clinical Trials Unit, Bank of Cyprus Oncology Centre, 32 Acropoleos Avenue,
Nicosia 2006, Cyprus; elisavet.papageorgiou@bococ.org.cy (E.P.); marina.zacharia@bococ.org.cy (M.Z.)
2
2nd Department of Cardiology, Attikon University Hospital, National and Kapodistrian University of Athens,
12462 Athens, Greece; keramidakalliopi@hotmail.com
3Cardiology Department, General Anti-Cancer Oncological Hospital, Agios Savvas, 11522 Athens, Greece
4Department of Oncology-Pathology, Karolinska Institute, 17176 Stockholm, Sweden;
andri.papakonstantinou@ki.se
5Department for Breast, Endocrine Tumours and Sarcoma, Karolinska University Hospital,
17176 Stockholm, Sweden
6Cardioncology and Second Opinion Division, European Institute of Oncology (IEO), IRCCS, Via Ripamonti
435, 20141 Milan, Italy; carlo.cipolla@ieo.it
72nd Department of Surgery, Aretaieio University Hospital, National and Kapodistrian University of Athens,
76 Vas. Sofias Av., 11528 Athens, Greece; dtsekoura@med.uoa.gr (D.T.); effkamp@uoa.gr (E.K.)
82nd Cardiology Department, University of Ioannina Medical School, 45110 Ioannina, Greece; anaka@uoi.gr
9Applied Research Division for Cognitive and Psychological Science, European Institute of
Oncology IRCCS, 20139 Milan, Italy; ketti.mazzocco@ieo.it
10 Department of Oncology and Hemato-Oncology, University of Milan, 20122 Milan, Italy
11 Department of Medical Oncology, University of Ioannina, 45110 Ioannina, Greece; dmauri@uoi.gr
12 Department of Electrical and Computer Engineering, Hellenic Mediterranean University, 71410 Heraklion,
Greece; tsiknaki@ics.forth.gr (M.T.); kmarias@ics.forth.gr (K.M.)
13
Computational BioMedicine Laboratory (CBML), Institute of Computer Science, Foundation for Research and
Technology Hellas (FORTH), 70013 Heraklion, Greece; gmanikis@ics.forth.gr
14 Department of Medical Oncology, Bank of Cyprus Oncology Centre, 32 Acropoleos Avenue,
Nicosia 2006, Cyprus; yiola.marcou@bococ.org.cy (Y.M.); eleni.kakouri@bococ.org.cy (E.K.);
ifigenia.konstantinou@bococ.org.cy (I.K.); myria.galazi@bococ.org.cy (M.G.)
15 Department of Radiation Oncology, Bank of Cyprus Oncology Centre, 32 Acropoleos Avenue,
Nicosia 2006, Cyprus; maria.daniel@bococ.org.cy
16 Division of Medical Oncology, Institute of Oncology Ljubljana, Faculty of Medicine, University of Ljubljana,
Zaloska Cesta 2, 1000 Ljubljana, Slovenia; dribnikar@onko-i.si
17 Translational Medicine, Stremble Ventures Ltd., 59 Christaki Kranou, Limassol 4042, Cyprus;
cameron.brown@stremble.com
18 Biomedical Research Institute, Foundation for Research and Technology, Hellas, 45500 Ioannina, Greece;
g.karanasiou@gmail.com
19 Research and Development, Stremble Ventures Ltd., 59 Christaki Kranou, Limassol 4042, Cyprus;
athos.antoniades@stremble.com
20 Unit of Medical Technology and Intelligent Information Systems, Department of Materials Science and
Engineering, University of Ioannina, 45110 Ioannina, Greece; fotiadis@uoi.gr
21
Cardio-Oncology Clinic, Heart Failure Unit, Department of Cardiology, National and Kapodistrian University
of Athens Medical School, Athens University Hospital Attikon, 11527 Athens, Greece; gfilippatos@med.uoa.gr
22 School of Medicine, University of Cyprus, Panepistimiou 1, Aglantzia, Nicosia 2408, Cyprus
*Correspondence: alexia.alexandraki@bococ.org.cy (A.A.); constantinidou.anastasia@ucy.ac.cy (A.C.)
Simple Summary:
Cancer therapy-related cardiac dysfunction (CTRCD) has been an urgent medical
issue in patients that receive breast cancer therapies including anthracycline-based chemotherapies
and/or targeted anti-HER2 therapies such as trastuzumab. Traditional biomarkers used as standard
Cancers 2023,15, 3290. https://doi.org/10.3390/cancers15133290 https://www.mdpi.com/journal/cancers
Cancers 2023,15, 3290 2 of 53
of care may be useful indicators of cardiac damage but their use to predict the onset of CTRCD lacks
reliability. Ongoing clinical studies aim to explore new insights into the use of traditional biomarkers
and investigate the promising role of novel biomarkers as reliable indicators and/or predictors of
CTRCD. Patients with breast cancer could benefit from an alternative cardiac risk stratification plan
that has the potential to predict the onset of CTRCD and/or detect CTRCD at early stages. The aim of
this systematic review is to provide an overview of the human studies, which explore novel insights
into traditional biomarkers and/or novel biomarkers that can be used for the early detection and/or
prediction of CTRCD in breast cancer patients undergoing cardiotoxic-cancer therapies.
Abstract:
Cardiotoxicity induced by breast cancer therapies is a potentially serious complication
associated with the use of various breast cancer therapies. Prediction and better management of
cardiotoxicity in patients receiving chemotherapy is of critical importance. However, the management
of cancer therapy-related cardiac dysfunction (CTRCD) lacks clinical evidence and is based on limited
clinical studies. Aim: To provide an overview of existing and potentially novel biomarkers that
possess a promising predictive value for the early and late onset of CTRCD in the clinical setting.
Methods: A systematic review of published studies searching for promising biomarkers for the
prediction of CTRCD in patients with breast cancer was undertaken according to PRISMA guidelines.
A search strategy was performed using PubMed, Google Scholar, and Scopus for the period 2013–2023.
All subjects were >18 years old, diagnosed with breast cancer, and received breast cancer therapies.
Results: The most promising biomarkers that can be used for the development of an alternative risk
cardiac stratification plan for the prediction and/or early detection of CTRCD in patients with breast
cancer were identified. Conclusions: We highlighted the new insights associated with the use of
currently available biomarkers as a standard of care for the management of CTRCD and identified
potentially novel clinical biomarkers that could be further investigated as promising predictors
of CTRCD.
Keywords:
chemotherapy-induced cardiotoxicity; cancer therapy-induced cardiac dysfunction;
clinical biomarkers; breast cancer; LVEF; BNP; troponins
1. Introduction
Despite therapeutic advancements in breast cancer, the use of certain types of breast
cancer therapies can be associated with cardiac toxicity, a serious medical concern in oncol-
ogy. The definition of cardiotoxicity due to anti-cancer treatment was previously provided
in the 2016 European Society of Cardiology (ESC) Position publication and referred to
any cardiovascular (CV) complication, which may include myocardial dysfunction and
congestive heart failure (CHF), pericardial, valvular, or coronary artery diseases [
1
]. This
definition was further refined in the most recent ESC guidelines in cardio-oncology by
Lyon et al., 2022 [
2
]. Myocardial damage and HF due to chemotherapy have been asso-
ciated with high rates of morbidity and mortality [
3
–
5
] and have attracted attention as a
chemotherapy-associated CV complication. Anthracycline-based therapies and targeted
therapies have been the most well-documented therapeutic compounds to be associated
with CV toxicity [6–12].
Two categories of cancer therapy-related cardiac dysfunction (CTRCD) have been
previously proposed depending on the effects of the chemotherapeutic agents on the
pathophysiological and structural constant of the myocardium [
13
]. These include type
I CTRCD, defined as permanent cardiotoxicity, typically induced by anthracyclines and
distinctly characterized by cardiomyocyte injury, and type II CTRCD, which is considered
reversible and mostly associated with the use of targeted therapy including the recombinant
humanized monoclonal anti-HER2 antibody named trastuzumab [
14
]. However, this
classification is currently debatable as a substantial recovery of cardiac function following
anthracycline-induced cardiotoxicity can be achieved upon early diagnosis and prompt
Cancers 2023,15, 3290 3 of 53
treatment [
7
,
15
]. In parallel, evidence suggests that type II CTRCD, which was proposed
to be reversible, can persist for many years and may lead to irreversible cardiomyocyte
apoptosis [16,17].
To improve the management of CTRCD, the ESC has published Clinical Practice
Guidelines, which involve assessment of the left ventricular ejection fraction (LVEF), natri-
uretic peptides [e.g., brain natriuretic peptide (BNP)], and troponin-I determination [
1
,
18
].
Baseline risk stratification proformas have been recently proposed by the ESC in collab-
oration with the Cardio-Oncology Study Group, for patient stratification into severity
groups based on the risk for CV complications prior to treatment [
19
]. Troponins, BNP and
LVEF have been suggested as risk factors to be collected as part of the baseline proformas.
The proposed risk stratification tool is expected to improve personalized approaches and
mitigate the risk of cancer therapies-induced CV toxicity [
19
]. However, the management
of CTRCD lacks clinical evidence, and therefore clinical practice is based on limited clinical
studies. Prediction and better management of cardiotoxicity in patients receiving cytotoxic
therapies are of critical importance. Reliable biomarkers that could predict cardiotoxicity
and/or early onset of CTRCD are not currently available in the clinical setting.
It is clear that an ideal single biomarker for the prediction and/or detection of CTRCD
cannot effectively assess and/or predict CTRCD [
20
]. While cardiac troponins and/or
natriuretic peptides may be useful indicators of cardiomyocyte injury, their predictive
capacity for the onset of cardiotoxicity still lacks reliability [
18
]. In addition, despite the fact
that LVEF can be used as a strong indicator of cardiac dysfunction, it lacks sensitivity for
early detection of subclinical cardiac impairment, which can otherwise be reversed upon
prompt treatment [
9
,
21
,
22
]. Importantly, studies have shown that CHF, particularly in
elderly individuals, can be associated with a normal LVEF [
23
]. Predictive biomarkers for
the early and late onset of CTRCD are urgently needed to mitigate the risks associated with
cardiac complications. Several clinical trials are currently ongoing, aiming to advance the
diagnostic, monitoring, and predictive strategies of CTRCD in patients with breast cancer.
Promising novel biomarkers related to cardiac function, inflammation, endothelial dysfunc-
tion, myocardial ischemia, and oxidative stress are currently under
investigation [17,24–27]
.
This review aims to highlight the new insights into the use of existing and/or potentially
promising novel serum and imaging biomarkers to be used as predictors and/or indicators
of early CTRCD in patients with breast cancer. The time course of the assessment of such
biomarkers will be also investigated.
2. Materials and Methods
2.1. Search Strategies
The systematic review was conducted based on the PRISMA 2020 Checklist [
28
]. The
literature search was performed using the following electronic databases: Pubmed, Google
Scholar, and Scopus with the aim to identify new insights on the potential of using existing
clinical and/or novel biomarkers as predictive and/or diagnostic indicators of CTRCD
in patients with breast cancer. In addition, the reference lists of relevant articles were
searched. Studies published between 2013–2023 were included in the review. Restrictions
on the search included studies written in English language, gender, and human studies.
There were no restrictions on the geographics. The search strategy was conducted using
the following keywords: (cardiotoxicity) OR (induced cardiotoxicity) OR (chemotherapy-
induced cardiotoxicity) OR (therapy-induced cardiotoxicity) OR (breast cancer therapy-
induced cardiotoxicity) AND (breast cancer) OR (breast carcinomas) AND (biomarkers)
OR (clinical biomarkers) OR (circulating) OR (predict*). This search resulted in a total of
2229 results
for the period of interest (2013–2023) from the three databases searched. The
search strategy developed was peer-reviewed by an experienced information specialist
using the Peer Review of Electronic Search Strategies (PRESS) checklist [29].
A second search was also conducted using an extensive list of keywords specific to
emerging cardiac biomarkers for the detection of CTRCD. The keywords are the following:
(novel biomarkers) OR (inflammatory) OR (endothelial) OR (oxidative stress) OR (fibrosis)
Cancers 2023,15, 3290 4 of 53
OR (angiogenesis) OR (interleukin 16) OR (interleukin 1) OR (galectin-3) OR (N-terminal
pro-B-type natriuretic peptide) OR (B-type natriuretic peptide) OR (C-reactive protein) OR
(troponin) OR (high-sensitivity cardiac troponin) OR (hs-cTn) OR (hs-cTnI) OR (microRNA)
OR (miRNAs) OR (PIGF) OR (placenta growth factor) OR (ST2) OR (growth differentiation
factor 15) OR (GDF-15) OR (myeloperoxidase) OR (MPO) OR (contractility) OR (cardiac
injury biomarkers) OR (biomarkers) OR (clinical biomarkers) OR (glycogen phosphorylase
BB) OR (GPBB) OR (left ventricular diastolic dysfunction) OR (left ventricular ejection
fraction) OR (LVEF) OR (left ventricular global longitudinal strain) OR (GLS) OR (myo-
globin) OR (heart-type fatty acid-binding protein) OR (lipopolysaccharide-binding protein)
OR (myocardial cell apoptosis) OR (arginine) OR (oxide metabolite) OR (fms-like tyrosine
kinase receptor) OR (sFlt-1) OR (thrombin–antithrombin complex) AND (cardiotoxicity) OR
(chemotherapy-induced cardiotoxicity) OR (induced cardiotoxicity) OR (therapy-induced
cardiotoxicity) OR (cardiomyopathy) OR (heart failure) OR (cardiac dysfunction) AND
(breast cancer) OR (breast carcinomas) AND (biomarkers) OR (clinical biomarkers) OR
(circulating) OR (predict*). This search resulted in a total of 1391 papers. Combining
the search results using the two keyword lists, a total of 3620 papers were obtained, of
which 1880 papers were duplicates. The duplicates were removed using the Endnote
reference management software. A total of 259 were excluded during the prescreening
stage based on the relevance of the title. A total of 633 papers were selected for screening,
of which
279 papers
were excluded based on the relevance of the abstract. The remaining
354 papers were assessed based on the eligibility criteria and 157 papers were excluded
for the reasons mentioned in Figure 1. A total of 197 papers were included in this review
(Figure 1).
Two reviewers
(A.A. and A.C.) conducted the screening process independently
and identified the relevant studies that meet the eligibility criteria. Any discrepancies were
resolved by discussion.
2.2. Study Population
The study eligibility criteria were set up based on the participants, intervention,
comparator, and outcomes (PICO) elements of the review question. The eligible studies
meet the following inclusion criteria: (1) female patients aged >18 years old that have been
diagnosed with breast cancer at any disease stage, (2) received breast cancer therapies,
(3) performed
cardiac examination at the baseline. Exclusion criteria included: patients that
received cardiotoxic therapy for the treatment of secondary malignant neoplasm. Outcome
measures: cardiac examination performed to determine changes in cardiac function at the
baseline and at follow-ups. The association of existing and/or novel biomarkers in the
prediction and/or detection of CTRCD was evaluated.
2.3. Selection Criteria
Randomized controlled trials (RCTs), other clinical trials, cohort studies, and post
hoc analyses were included in the review. Literature reviews, conference abstracts, and
posters/abstracts were excluded. Preclinical reports/animal studies were not included as
they were beyond the scope of this review. Quality assessment of the clinical trials was
conducted by two reviewers independently according to the CASP randomized controlled
trial standard checklist. Risk-of-bias assessment was performed using the Robvis tool [
30
].
Five domains were assessed including: bias arising from the randomization process; bias
due to deviations from intended intervention; bias due to missing outcome data; bias in
measurement of the outcome; bias in selection of the reported result. Studies were excluded
when the outcomes of interest were not measured, or a particular outcome was explicitly
not included in the measurement. Studies with no definition of cardiotoxicity and no
treatment with breast cancer therapies were excluded from the review.
Cancers 2023,15, 3290 5 of 53
Cancers 2023, 15, x FOR PEER REVIEW 5 of 56
Figure 1. PRISMA 2020 flow diagram for the systematic review [28].
2.2. Study Population
The study eligibility criteria were set up based on the participants, intervention, com-
parator, and outcomes (PICO) elements of the review question. The eligible studies meet
the following inclusion criteria: (1) female patients aged >18 years old that have been di-
agnosed with breast cancer at any disease stage, (2) received breast cancer therapies, (3)
performed cardiac examination at the baseline. Exclusion criteria included: patients that
received cardiotoxic therapy for the treatment of secondary malignant neoplasm. Out-
come measures: cardiac examination performed to determine changes in cardiac function
at the baseline and at follow-ups. The association of existing and/or novel biomarkers in
the prediction and/or detection of CTRCD was evaluated.
Figure 1. PRISMA 2020 flow diagram for the systematic review [28].
2.4. Data Extraction
Data extraction was performed by two reviewers (A.A. and A.C.) independently using
an electronic custom-built structural data collection form. Details on the methodology,
study design (e.g., multicenter study) characteristics of the control and intervention groups,
outcome measures (e.g., LVEF measurements, circulating biomarkers, time points assessed),
and follow-up duration were extracted.
2.5. Data Synthesis
The data synthesis approach was decided based on the selected clinical studies. The
outcome measures, similarities (if any) in the study design, and the data available in each
study were considered for the synthesis method. Patients with CV diseases and/or elevated
Cancers 2023,15, 3290 6 of 53
cardiac biomarkers (if measured) at the baseline as well as patients with metastatic breast
cancer at the baseline were treated as subgroups if an adequate number of trials were
available. According to the clinical studies selected, the following data synthesis was
applied: summarizing effect estimates, providing statistical outcomes (e.g., pvalues), and
confidence intervals when available. In the case where synthesis was considered to be
inappropriate, a structured reporting of effects was applied, and the most relevant and
trustworthy studies were prioritized. A graphical abstract was also created (BioRender).
3. Results
Anthracyclines (e.g., doxorubicin, epirubicin) and targeted therapies such as trastuzumab
have been the most documented therapeutic compounds to be associated with CV toxic-
ity [
6
–
12
]. However, other breast cancer therapies that can affect the CV system include
alkylating agents (e.g., cyclophosphamide), VEGF inhibitors (e.g., bevacizumab), tyrosine
kinase inhibitors (e.g., lapatinib, neratinib), antimicrotubular agents (e.g., paclitaxel, doc-
etaxel), antimetabolites (e.g., fluorouracil, capecitabine) and hormone therapies including
cyclin-dependent kinases (CDK) 4/6 inhibitors (e.g., palbociclib, ribociclib, abemaciclib) [
16
].
Aromatase inhibitors (e.g., anastrozole, letrozole) have not been associated with induced CV
death, but an association with angina and hypertension has been identified. In addition,
venous thromboembolism has been linked with the use of tamoxifen, a blocker of estrogen
receptor [
31
,
32
]. Radiation therapy can increase the risk of cardiac dysfunction in patients
with breast cancer [
33
]; however, radiation-induced cardiotoxicity is beyond the scope of this
review. This review aims to provide new insights into the use of existing and/or potentially
novel blood and imaging biomarkers to predict the incidence of cardiotoxicity in patients
with breast cancer during cardiotoxic therapies. The time course of the assessment of the
biomarkers during treatment was also reported.
3.1. Cancer Therapy and Cardiotoxicity
3.1.1. Chemotherapy
Anthracycline-induced cardiotoxicity (AIC) was shown to be cumulative dose-related
and is categorized into three distinct groups according to the most recent classification: the
acute onset, which occurs following a single dose/course and symptoms appear 14 days
after treatment completion, which is usually reversible; the early onset of chronic cardiotox-
icity, which occurs within one year and can progressively lead to CHF; and the late-onset
of chronic cardiotoxicity, which progresses for years after completion of treatment (median
of 7 years post-treatment) and resembles chronic cardiac failure [
1
,
34
]. Acute onset of AIC
is a rare event and is observed in approximately 5% of patients. It manifests with elec-
trocardiographic (ECG) changes in 20–30% of the patients, supraventricular arrhythmias,
acute myocarditis with cardiomyocyte injury, acute CHF, and/or pericarditis. Despite the
extensive research on the mechanism through which anthracyclines lead to cardiotoxicity,
the exact molecular pathogenesis of AIC remains elusive. The acute onset of cardiotox-
icity can be characterized by reduced cardiac mass via p53-dependent inhibition of the
mammalian target of rapamycin (mTOR) signaling [
35
], induction of oxidative stress [
36
],
and topoisomerase inhibition resulting in double-strand breaks [
37
]. However, novel AIC
pathways are continuously emerging [37,38].
For example, in the case of doxorubicin, studies demonstrated doxorubicin-induced
ferroptosis, which involves the iron-dependent formation of lipid peroxides [
39
], induction
of cell death via necroptosis [
40
] and/or induction of pyroptosis through upregulation of the
terminal differentiation-induced non-coding RNA (TINCR) followed by activation of the
NLR family pyrin domain containing 3 (NLRP3)-caspase 1 pathway [
38
,
41
,
42
]. In addition,
preclinical evidence suggests that the induction of death receptors associated apoptosis by
anthracycline agents (daunorubicin, idarubicin, and epirubicin) as demonstrated in human
induced pluripotent stem cells-derived cardiomyocytes (iPS-CMs) is a potentially critical
mechanism that may underly the cardiotoxic potential of these agents [42].
Cancers 2023,15, 3290 7 of 53
Other cardiotoxic breast cancer therapy includes DNA alkylating agents (e.g., cy-
clophosphamide). Specifically, cyclophosphamide can induce hemorrhagic myocarditis,
particularly at high doses, even though lower doses of cyclophosphamide have been
associated with CHF and/or pericardial effusion. The cardiotoxic incidences of cyclophos-
phamide have been attributed to its metabolites, which have been suggested to promote
oxidative stress resulting in endothelial capillary damage, hemorrhage, edema, and throm-
bosis [
43
,
44
]. Combination regimen schemes composing taxanes (e.g., docetaxel, paclitaxel),
anthracycline, and cyclophosphamide were associated with a higher risk of cardiotoxic-
ity [
45
,
46
]. However, large-scale high-quality clinical studies are needed to further assess
the cardiotoxic outcomes of breast cancer combination treatment regimens [45].
3.1.2. Targeted Therapy
The human epidermal growth factor receptor 2 (HER2) is a transmembrane glyco-
protein [
47
,
48
], shown to be overexpressed in 15–20% of breast cancers and conferring
worse prognosis [
49
–
56
]. Trastuzumab, a humanized monoclonal antibody, is the most
frequently used HER-2 targeted therapy for the treatment of HER2+ breast cancer contribut-
ing to markedly improved survival rates [
57
–
59
]. Other HER2-targeted drugs used for
breast cancer include pertuzumab and the most recent agents, tucatinib and trastuzumab
deruxtecan [57–59].
Despite the therapeutic impact of HER2-targeted therapy [
60
–
62
], unexpected car-
diotoxicity can interfere with their efficacy [
63
]. Zhang et al., 2022 [
64
], have demonstrated
that trastuzumab or trastuzumab in combination with pertuzumab, resulted in decreased
LVEF by at least 10% in 15.9% of the patients (67 out of 420) with the incidence of 14.3%
and 17.9%, respectively. Contrary to AIC, trastuzumab-induced cardiotoxicity manifests
as an asymptomatic drop in the LVEF followed by infrequent CHF and in rare cases
cardiac death [
65
–
67
]. The risk of cardiac dysfunction increases in patients that receive
anthracyclines plus cyclophosphamide followed by trastuzumab (27%) [67].
Trastuzumab-related cardiotoxicity can be reversible upon discontinuation of treat-
ment [
5
], which may, however, be associated with tumor recurrence and worse overall
survival [
68
,
69
]. Evidence also supports that the recovered LVEF measurements in patients
treated with trastuzumab for 12 months (48.53%), never reached the baseline LVEF levels
at 30 months after treatment completion [
70
]. Calvillo-Argüelles et al., 2020 [
5
], revealed
that 43% of patients (10 out of 23) of HER2+ metastatic breast cancer patients, had their
treatment with trastuzumab interrupted. However, only 30% of patients had a cardiological
examination while 17% received cardioprotective therapy suggesting a potential gap in
cardiac care. Even though the mechanism by which trastuzumab exhibits its cardiotoxic
effect is unclear, it is thought to be associated with the direct target of the HER2/neu, which
is also expressed on cardiomyocytes and was shown to possess a cardioprotective role.
Preclinical studies demonstrated that ErbB2 knockout mice (ErbB2-CKO) showed poor
survival and dilated cardiomyopathy whilst cardiomyocytes derived from ErbB2-CKO
mice had increased susceptibility to the fatal cell damage induced by anthracyclines [
71
].
It is worth mentioning that not all anti-HER2 therapies exhibit similar cardiotoxic poten-
tial. For example, pertuzumab and lapatinib have much less severe cardiotoxicity profiles
compared to trastuzumab [72,73].
3.2. Traditional Biomarkers
3.2.1. Troponins
Cardiac troponins are regulatory protein complexes in the skeletal and cardiac muscle,
responsible for cardiac muscle contractions. Cardiac troponin T (cTnT), cardiac troponin
I (cTnI), and troponin C are the three subunits of troponins, exclusively found in the
myocardial tissue. Systemic troponin release upon cardiomyocyte necrosis is indicative
of myocardial infarctions [
74
,
75
]. Consequently, troponins are established diagnostic
biomarkers for the detection of acute and chronic myocardial damage [
75
,
76
]. Cardiac
troponins are considered to be amongst the cornerstones of cardiotoxicity monitoring in
Cancers 2023,15, 3290 8 of 53
patients treated with cardiotoxic therapies [
77
–
80
]. Previous studies revealed troponins as
predictive biomarkers of trastuzumab-induced cardiotoxicity in breast cancer patients [
80
].
However, analytical sensitivity can differ between cTnI and cTnT by 10-fold, and cTn values
may vary between different assay generations and instruments [
81
,
82
]. In addition, the time
course for the detection of induced troponin elevation in response to cardiotoxic anti-cancer
treatment is variable and not clearly understood compared to the changes mediated by
conventional CV events [
83
]. Clinical studies have investigated the utility of troponins in
predicting and/or detecting CTRCD in breast cancer patients.
Shafi et al., 2017 [
84
], showed that the elevation of cTnI (p< 0.001) detected after one
cycle of anthracycline-based chemotherapy was a frequent event in patients experiencing
cardiotoxicity (6 out of 82 patients, 7%). cTnI proved a strong independent predictor of the
incidence of cardiotoxicity (95% CI (0.003546–0.2535), p< 0.001]) and the failure of LVEF
recovery (95% CI (0.002484 to 1.680)). Cardiotoxicity was defined as a drop in LVEF of
≤
10% from baseline or a decline in LVEF < 50% and measured before treatment and every
3 months during the first year of treatment with anthracyclines. A total of 10 cardiac events
(LVEF reduction, CHF, acute coronary syndrome, arrhythmias) occurred during the study,
9 of which were associated with high levels of cTnI 9 (p< 0.001). Limitations of this study
include the small sample size, the inability to assess delayed cardiotoxicity due to the short
follow-up, and the recruitment of patients from a single cancer center.
Another study [
10
], revealed similar results showing that elevated baseline levels
of cTnI (>40 ng/L) in 13.6% (56 of 412) and cTnT (>14 ng/L) in 24.8% of (101 of 407)
HER2+ breast cancer patients were associated with a significantly higher risk of LVEF
decline (hazard ratio (HR) of 4.52, 95% CI (2.45–8.35), p< 0.001 and 3.57; 95% CI (1.95–6.55),
p< 0.001 in the univariate model, respectively) in response to trastuzumab treatment.
For 31 patients, an increase in cTnI (n = 6) and cTnT (n = 25) occurred during treatment.
Primary cardiotoxicity was defined as the clinical manifestation of CHF New York Heart
Association (NYHA) class III or IV and LVEF drop by at least 10% from baseline or decline
of LVEF < 50%. The secondary cardiac endpoint was defined as an asymptomatic or mildly
symptomatic decline in LVEF.
The predictive value of high sensitivity TnT (hscTnT) was highlighted by Blaes et al.,
2015 [
85
], showing that patients with elevated levels of hscTnT (2.7 pg/mL, p= 0.07) at
baseline were at higher risk of LVEF decline (n = 12, median LVEF = 54%) compared to
the patients with no changes in LVEF (n = 6, median LVEF = 64%, 0.1 pg/mL), suggesting
its utility as a predictive biomarker of anthracycline-induced cardiotoxicity. This is in
contrast to the cTnI and cTnT, which were undetectable at baseline. A Spearman correlation
revealed a trend towards greater reduction in LVEF in patients with increased levels of
hscTnT levels at baseline (
−
0.54, 95% CI (
−
0.80 to
−
0.08), p= 0.02) and creatine kinase-MB
(CK-MB) (
−
0.49, 95% CI (
−
0.77 to
−
0.01) p= 0.04). However, the study included a small
sample size, which was not sufficient to allow for the detection of potentially asymptomatic
drops of LVEF.
A progressive increase in hscTnT was noted in a prospective study of 72 breast
cancer patients in response to anthracycline chemotherapy reaching maximum levels
(from baseline 4.6
±
2.1 ng/L to 15.7
±
7.4 ng/L) at 96
±
13 after treatment initiation [
86
].
Interestingly, levels of hscTnT were slightly increased in patients that did not experience
cardiotoxicity (4.8
±
2.1 vs. 3.1
±
0.2; p= 0.006) and therefore no statistically significant
differences between patients with cardiotoxicity (n = 7) versus patient without (n = 65) were
observed either at baseline or during treatment. The authors also showed that hscTnT (odds
ratio (OR) = 0.923, 95% CI (0.780–1.042), p= 0.27) could not predict CTRCD in these patients.
In particular, higher levels of hscTnT were noted in 62.5% of the patients even though
cardiotoxicity was noted only in 9.7% of the patients. It was also shown that troponin
levels were linearly correlated with age (p< 0.001, R
2
= 0.16) suggesting that age should be
also considered when assessing hscTnT levels. Limitations of this study include the fact
that the patients were relatively young, had a mean age of 52.0
±
9.8 years old, and hence
data cannot be extrapolated to older patients. In addition, a limited number of patients
Cancers 2023,15, 3290 9 of 53
experienced cardiotoxicity and patients were recruited from a single center suggesting the
need for additional larger cohort studies.
In another study of 134 female breast cancer patients, treated with doxorubicin (DOX)
and epirubicin, a six-fold increase in hscTnI was noted in breast cancer patients (61%) after
treatment (38.8
±
26.7 vs. 7.0
±
4.1 ng/mL, p< 0.0001) compared to baseline. However,
there was a poor agreement between changes in troponin and cardiotoxicity (Kappa
−
0.017,
p= 0.67) and no association with changes in LVEF or GLS (R
2
= 0.03 and 0.04, respec-
tively) [
87
]. Cardiotoxicity was defined as previously described by the European Society of
Medical Oncology (ESMO) [
88
]. Limitations of the study included the small sample size
and single-center patient recruitment, which limit the extrapolation of the findings.
In contrast, Pillai et al., 2022 [
89
], showed significantly increased levels of cTnI at
6 months
and cTnT at 3 and 6 months of trastuzumab treatment (with or without per-
tuzumab) in combination with paclitaxel or docetaxel (with or without carboplatin) in
HER2-positive breast cancer patients (n = 17, p< 0.05) compared to the healthy controls
(n = 17). However, the findings need to be validated by larger cohort studies and for a
longer follow-up period. It is worth noting that a combination with taxanes, which may
also contribute to cardiotoxicity, may interfere with trastuzumab-induced cardiotoxicity.
All studies retrieved through this review in relation to the role of troponins in pre-
dicting and/or detecting CTRCD in breast cancer patients [10,83–87,89–119] are shown in
Table S1.
3.2.2. Natriuretic Peptides (NPs)
Natriuretic peptides (brain natriuretic peptide (BNP) and N-terminal part of the
pro-peptide of BNP (NT-proBNP)) are cardiac hormonal excretions from ventricular car-
diomyocytes [
120
,
121
]. Several studies reported that increased levels of BNP or NT-proBNP
in the serum are an indicator of CHF [
120
,
121
]. Clinical studies have investigated the corre-
lation of BNP and NT-proBNP with breast cancer therapy-induced CV events resulting in
inconsistent results.
A prospective study of 136 HER2+ breast cancer patients showed patients experiencing
trastuzumab-induced cardiotoxicity had lower baseline LVEF (n = 6, LVEF
57.08 ±1.36%
)
compared to the control (n = 125, LVEF 61.42
±
0.26%) in response to trastuzumab treat-
ment [
122
]. In addition to reduced baseline LVEF, patients who experienced CTRCD had
a three-fold increase in NT-proBNP (from 198.8
±
64.0 pg/mL to 678.7
±
132.4 pg/mL;
p< 0.05
) compared to the control showed a reduction at month 6 (from 131.2
±
20.9 pg/mL
to 86.7
±
8.8 pg/mL; p< 0.05). Six out of a total of one-hundred and thirty-six patients (4.4%)
experienced CTRCD at 6 or 12 months of trastuzumab treatment. The authors proposed
that assessing changes in NT-proBNP could potentially replace echocardiographic examina-
tion during the one year of trastuzumab therapy. The authors calculated the
δ
NT-proBNP
which is defined as the average difference between the baseline NT-proBNP to 6 months
and from baseline to 12 months [
122
]. They suggested 75.8 pg/mL as the cut-off value
for
δ
NT-proBNP to identify patients for echocardiographic assessment. In addition, the
authors highlighted that
δ
NT-proBNP is more suitable since absolute NT-proBNP values at
baseline differ between healthy individuals.
In line with a previous prospective study are the results of a retrospective observational
study of a total of 66 HER2+ breast cancer patients showing high levels of NT-proBNP
(OR = 22.0, 95% CI (5.7–85.4); p< 0.0001) in patients who experienced cardiotoxicity
during trastuzumab therapy (18 out of 66 patients, 27.3%) with a strong association with
diabetes mellitus (OR = 5.9, 95% CI [1.2–28.5]; p= 0.028) as revealed by a binary logistic
regression analysis [
123
]. A significant elevation of NT-proBNP was noted at 3, 6, and
12 months of trastuzumab treatment compared to baseline. In addition, a significant
association between LVEF and NT-proBNP was noted in women
≥
50 years old compared to
women < 50 years old
. Cardiotoxicity was defined as previously described in the herceptin
adjuvant (HERA) trial [
4
] and involved LVEF decrease with the development of CHF
or LVEF
decline ≥10%
resulting in an asymptomatic drop in LVEF < 50%. It must be
Cancers 2023,15, 3290 10 of 53
highlighted that the baseline levels of NT-proBNP were not available in this study, which
did not allow for assessing the predictive role of baseline NT-proBNP in patients who
developed CTRCD during trastuzumab treatment. A small number of participants were
included in this study, resulting in a small size of subgroups of 18 patients treated with
anthracyclines and 3 patients treated with taxanes (docetaxel or paclitaxel) whilst 8 patients
were affected by diabetes, which, however, showed significant association with CTRCD.
Bouwer et al., 2019 [
124
], detected higher levels of NT-proBNP in patients who ex-
perienced CTRCD (16.8 pmol/L; p= 0.031) during trastuzumab treatment compared to
patients with no cardiotoxicity (10.1 pmol/L). An increase in NT-proBNP at any time point
during follow-up was associated with a decline in LVEF (95% CI (
−
2.2%, –6.7%); p< 0.001).
In addition, patients who developed CTRCD had statistically higher baseline NT-proBNP
levels (+10.2 pmol/L) compared to those without (+ 2.5 pmol/L) and it was related to the
occurrence of CTRCD during follow-up (HR = 1.04, 95% CI (1.02–1.07; p= 0.003). Despite
the significant results showing the potential of using NT-proBNP to identify patients with
a higher risk of CTRCD, the authors concluded that the NT-proBNP is not a surrogate
diagnostic tool for the detection of the early onset of CTRCD due to the fact that there was
no gradual and/or sudden increase in the levels of NT-proBNP prior to the development of
CTRCD. In the study by Alves et al., 2021 [
125
], elevated levels of NT-proBNP by 2.1-fold
were detected in patients with cardiotoxicity (116.55
±
107.66 pg/mL) at 7 days after the last
infusion with doxorubicin compared to the baseline (54.51
±
28.58 pg/mL; p< 0.05). The
variability of results observed in the studies might be attributed to the different therapeutic
regimens, the sample size, the time points assessed, the definition of cardiotoxicity used
in each study, and/or the different assays used to detect NT-proBNP as supported by
Bouwer et al., 2019 [124].
Matos et al., 2016 [
126
], included a total of 92 breast cancer patients of which 20.6%
had a drop in LVEF
≥
10% and paradoxically had significantly higher LVEF (
70.7 ±4.4%
,
p= 0.0002) at baseline compared to the patients with no LVEF decline (64.8
±
5.5%). All pa-
tients were pre-treated with anthracyclines prior to trastuzumab treatment, and
82 patients
(89.1%) received taxanes. In this study, baseline NT-proBNP was not significantly asso-
ciated with trastuzumab-related LVEF reduction and remained within the normal range
(
<300 pg/mL
) during the follow-up time points (4, 8, and 12 months during trastuzumab).
In contrast, Lu et al., 2019 [
127
], in 149 breast cancer patients, showed significantly
increased levels of BNP in patients with cardiotoxicity during anthracycline treatment com-
pared to the non-cardiotoxicity group and it was an independent predictor of anthracycline-
related cardiac dysfunction (p= 0.047). An increase in BNP was noted after each treatment
course. The baseline serum BNP levels did not predict the onset of cardiotoxicity in pa-
tients. Cardiotoxicity was defined as a drop in LVEF < 55, a reduction in LVEF
≥
10%,
and an increase in LVDs
≥
7 mm from baseline. Despite the significant results, the study
included a small sample size, which may have resulted in a limited number of patients
with cardiotoxicity. It is worth noting that other risk factors including diabetes were
not considered.
Kouloubinis et al., 2015 [
128
], demonstrated a significant drop in LVEF (p< 0.001) in
metastatic breast cancer patients (n = 26) after treatment with epirubicin and paclitaxel
associated with elevated levels of NT-proBNP (158.0
±
8.4 vs. 283.3
±
27.2 pre- and
post-treatment, respectively, p< 0.001) and sFas (308.8
±
65.1 vs. 517.8
±
91.0 pre- and
post-treatment, respectively, p< 0.001) as well as with a decrease in sFasL (86.6
±
12.6 vs.
47.9
±
8.4 pre- and post-treatment, respectively, p= 0.010) post-treatment. Congestive HF
was noted in two of the metastatic patients (7.6%) at 12 and 14 months post-treatment.
The authors have introduced the apoptotic markers sFas, sFasL, and the cardiac-specific
marker NT-proBNP as promising markers for the early detection of CTRCD in breast
cancer patients. However, larger prospective studies are needed to further validate their
clinical utility.
Cancers 2023,15, 3290 11 of 53
The studies focusing on the role of natriuretic peptides (NPs) in predicting and/or detecting
CTRCD in breast cancer patients [
86
,
87
,
90
–
92
,
96
–
101
,
103
,
105
,
106
,
109
,
113
,
114
,
117
–
119
,
122
–
145
],
as identified in the review, are shown in Table S1.
3.2.3. Left Ventricular Ejection Fraction (LVEF) and Strain Changes
The role of left ventricular ejection fraction (LVEF) as a biomarker of diagnosis and predic-
tion of CTRCD has been presented in a number of studies (Table S1). Further to studiesdemon-
strating the role of LVEF in assessing and/or predicting CTRCD [
118
,
146
], Stoodley et al.,
2013 [
147
], revealed a significant reduction in global systolic strain (GSS) (myocardial imag-
ing) in HER2-negative breast cancer patients promptly after (
−19.0 ±2.3% to −17.5 ±2.3%
;
p< 0.001
) and at 6 months of anthracycline therapy
−
8.2
±
2.2%; p= 0.01). On the contrary,
no changes were noted in the LVEF at either time point. Even though global systolic strain
stabilized by month 12 in most patients, 16% of the patients (n = 8) who received higher doses
of anthracyclines and had greater myocardial systolic dysfunction at month 6 (
≤−
17.2%)
continued to have reduced global systolic strain.
A recent publication in the Journal of the American Heart Association [
148
], measured
changes in LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), global
circumferential strain (GCS) and LVEF at baseline and at 3 and 24 months after treatment
initiation in a prospective cohort study of 95 patients diagnosed with breast cancer
(n = 29
),
soft tissue sarcoma (n = 5) or lymphoma (n = 37). Patients received anthracyclines (
n = 48
),
trastuzumab (n = 2), taxanes (n = 28), cyclophosphamide (n = 49), other chemotherapy
(
n = 45
), and immunotherapy (n = 23). Cardiac toxicity was defined as a drop in LVEF by
>5% or LVEF by < 50% from baseline to 24 months. A decline in LVEF was noted during
the 24 months (from 62
±
7% to 58
±
9%; p< 0.0001), with 42% of patients showing an
LVEF drop by >5% at 24 months. The authors identified predictive factors at baseline or
at 3 months of treatment for a persistent 2-year decline of LVEF > 5%. These included an
increase in LVESV (>3 mL; p= 0.033) or a drop in LVEDV by >10% with a mild change
in LVESV (p= 0.001), or a GCS increase by >10% with an increase in LVESV > 3 mL or
increased GCS by >10% with a mild change in LVESV (<3 mL) with a drop in LVEDV by
> 10 mL. It is worth mentioning that all logistic regression models remained significant
after accounting for the CV risk factors, chemotherapy regimens received, demographics,
sex, age, body mass index, administration of cardioactive substances, and cancer types
(p= 0.001 to p= 0.037). A reduction in LVEF of >5% was characterized by the authors as
a subclinical decline in LVEF and further studies are required to address the long-term
effects in patients that receive cardiotoxic therapies. It is important to note that one of the
limitations of the study is that a total of 24 patients did not manage to complete the 2-year
follow-up monitoring, which may have introduced bias in the analysis of the results. It was
noted that the cancer type was a contributing factor to the discontinuation of the patient
participation (p= 0.0004); however, breast cancer patients (88%) had a higher likelihood to
complete the study compared to the patients with sarcoma or lymphoma. In addition, the
small sample size did not allow for the detection of a larger decline in LVEF that would
lead to CHF.
In another study by Bulten et al., 2015 [
149
], evaluating
123
I-met
α
iodobenzylguanidine
(
123
I-mIBG) scintigraphy and potential association with conventional ECHO parameters,
showed that global radial strain (GRS) demonstrated the strongest association with delayed
heart/mediastinum (H/M) ratio (Pearson’s r 0.36; p= 0.01), in patients after 1 year of
treatment with anthracycline (docetaxel, doxorubicin, and cyclophosphamide).
A prospective study by Tahir et al., 2021 [
150
], with a total of 66 breast cancer patients
(53
±
13 years), showed that amongst the total of 39 patients, who received epirubicin-
based chemotherapy, 20% (n = 8), developed therapy-related cardiac dysfunction. Increased
myocardial T1 relaxation time predicted the onset of cardiac dysfunction after therapy
completion (follow-up 1) with an area under the curve (AUC) of 0.712 (95% CI (0.587–08.16);
p= 0.005
), 100% sensitivity but lower specificity of 44% (31–58%). A combination of ele-
vated T1 and reduced LVEF
≤
60% after treatment completion resulted in high sensitivity
Cancers 2023,15, 3290 12 of 53
of 78% (44–95%), improved specificity of 84% (72–92%), and AUC of 0.810 (0.695–0.896).
Cancer therapy-related cardiac dysfunction was defined as a decline in LVEF
≥
10% re-
sulting in LVEF < 55% or GLS change by >15% at the second follow-up (13
±
2 months
after treatment). Similarly to the other studies, a small sample size is a limitation and
so the largest cohort studies are needed to better define the role of the cardiac magnetic
resonance imaging (CMR) parameters in the prediction of therapy-induced cardiac dys-
function. Wang et al., 2020 [
151
], conducted a prospective study to assess the utility of a
relatively new technology in monitoring cardiac function, called three-dimensional speckle
tracking imaging (3D-STI), which is a combination of two-dimensional speckle tracking
imaging (2D-STI) and real-time three-dimensional echocardiogram (RT-3DE). The study
included a total of 64 breast cancer patients and showed that right ventricular global longi-
tudinal strain (RVGLS) and right ventricular global area strain (RVGAS) were significantly
reduced after chemotherapy (
−
26.10%
±
2.33% and
−
35.78%
±
5.60%) compared to the
baseline (
p< 0.05
) in the patients that received pirarubicin chemotherapy with dexrazox-
ane (
−
28.60%
±
2.57% and
−
38.66%
±
5.73%). Dexrazoxane is an anti-neoplastic agent
that can be used to reduce the risk of anthracycline-related CHF and LVEF impairment
via inhibiting topoisomerase 2
β
[
152
]. The 3D-STI examination showed that RVGLS and
RVGAS were significantly (p< 0.05) higher in the patients treated with chemotherapy plus
dexrazoxane (
−26.10% ±2.33%
and
−
35.78%
±
5.60%, respectively), versus the control
group, that did not receive dexrazoxane (
−
24.59%
±
2.36% and
−
32.77%
±
6.23%, respec-
tively). Overall, this study highlights that monitoring the functional changes in the right
ventricular myocardium during chemotherapy in post-operative breast cancer patients us-
ing 3D-STI can provide an early and accurate indication of potential chemotherapy-induced
cardiac dysfunction.
A study assessing an extended panel of pro-inflammatory biomarkers in breast cancer
survivors revealed that LVEF was lower in patients that received chemotherapy at least
5 years
ago (57.5% (55.0–60.0%); p< 0.001), compared to the healthy individuals that
have not been diagnosed with breast cancer (59.0% (57.0–62.0%) [
153
]. Lower LVEF was
significantly associated with higher levels of pro-inflammatory genes. This may suggest
that breast cancer survivors treated with chemotherapy may experience a potentially
prolonged and persistent pro-inflammatory state [153].
According to the 2022 ESC Guidelines [
2
], in addition to the measurement of cardiac
serum biomarkers and echocardiography, cardiac imaging techniques such as cardiac mag-
netic resonance (CMR) allow for the early detection of CTRCD [
154
]. Cardiac imaging should
be performed for any patient with symptoms of cardiac dysfunction following cardiotoxic
cancer therapy. Myocardial injury as indicated by cardiac magnetic resonance imaging (cMRI)
in patients was found to be correlated with elevated concentrations in cTnI, however, small
myocardial infarcts (<1 g) are undetectable [
74
]. Multimodal imaging using stress echocar-
diography, chest computed tomography (CT), positron emission tomography (PET) imaging,
and stress CMR are suggested as excellent imaging tools for the diagnosis of ischemic inci-
dences in patients treated with cardiotoxic cancer therapies [
155
]. GLS and three-dimensional
(3D)-LVEF (transthoracic echocardiography (TTE)) are recommended for the diagnosis of
asymptomatic CTRCD [
155
,
156
]. In particular, GLS assessment can indicate the presence or
absence of asymptomatic myocardial injury in patients with physiologically low levels of
LVEF [
157
]. In addition, the predictive capacity of tissue velocity imaging (TVI) and STI in LV
dysfunction was demonstrated in breast cancer patients treated with epirubicin [
158
]. Overall,
the contribution of troponins, NT-proBNP or BNP, and LVEF and associated parameters in
detecting and monitoring CTRCD is undoubtable, but additional studies are required in order
to define their exact roles to predict CTRCD. The studies focusing on the role of LVEF, strain
changes, and other imaging biomarkers in predicting and/or detecting CTRCD in breast can-
cer
patients [84,91,94,95,99,108,109,113,118,119,130–133,137,139,141,142,146–151,153,158–220],
as identified in the review, are shown in Table S1.
Cancers 2023,15, 3290 13 of 53
3.3. Emerging Biomarkers
3.3.1. Genetic Susceptibility to CTRCD
SNPs in HER2/neu
Several studies have identified genetic variants as risk factors associated with higher
incidences of cardiotoxicity induced by breast cancer therapeutic regimens involving
trastuzumab or anthracyclines [
221
–
225
]. Such genetic variations possess a predictive value
indicating the patients are susceptible to CTRCD. Single nucleotide polymorphisms (SNPs)
are common genetic variations, that have the potential to affect response to treatment and
influence therapy-induced cardiotoxicity. A recent search on the Exome Variant Server
(https://evs.gs.washington.edu/EVS/ (accessed on 16 March 2023) reveals a total of
67 missense
SNPs in the ERBB2 gene; however, their role in the therapeutic efficacy and
response in patients with HER2 breast cancer remains to be elucidated.
To date, the best-documented polymorphism is at the amino acid position 655 of
the HER2/neu (HER2 lle655Val), which results in the nucleobase change in adenine to
guanine (HER2 codon 655 A>G), which in turn changes the translation of the amino acid
isoleucine to valine (Ile/Val). Five prospective studies [
221
,
222
,
226
–
228
] and one retrospec-
tive study [
229
] have investigated the association of HER2 codon 655 AG polymorphism
with trastuzumab-induced cardiotoxicity leading to contradictory results (Table S2).
Four out of the six studies highlight the significant correlation of the HER2 codon 655 AG
polymorphism with cardiotoxicity induced by trastuzumab-based
therapies [221,227–229]
.
Tan et al., 2020 [
221
] showed that the incidence of cardiotoxicity in response to epiru-
bicin/cyclophosphamide followed by docetaxel and trastuzumab was higher in patients
that harbor the HER2 codon 655 AG genotype (24 out of 91 patients, 26.4%) compared to
the patients with HER2 codon 655 AA genotype (64 out of 91 patients, 70.3%) (p= 0.017).
Cardiotoxicity was defined as a reduction in LVEF by at least 10% from the baseline result-
ing in LVEF < 53 and/or manifestation of CHF, fatal arrhythmia, or acute coronary artery
syndrome. The minority of the patients in this study (3 out of 91, 3.3%) had the HER2 codon
655 GG genotype, which was associated with a higher incidence of cardiotoxicity com-
pared to the HER2 codon 655 AG genotype but without statistical significance (p= 0.496),
probably due to the small sample size. Univariate logistic regression analysis showed that
the HER2 codon 655 AG (OR = 3.117, p= 0.008), baseline cTnI (OR = 1.030, p< 0.001),
and baseline NT-proBNP levels (OR = 1.015, p= 0.010) were correlated with cardiotoxicity.
However, no clear association is provided between each cardiotoxic parameter used to
define cardiotoxicity. This is except, for LVEF, which was similar in patients with or without
the HER2 codon 655 AG polymorphism, suggesting no correlation.
On the contrary, Roca et al., 2013 [
227
], revealed that patients with HER2 codon 655
AG experienced significantly increased CV complications; that is LVEF < 50%, compared to
the patients with the homozygous allele (HER2 codon 655 AA) (69% and 31%, respectively;
95% CI (1.11–13.8), p= 0.025) in response to trastuzumab therapeutic regimen.
The minority of the patients harbored the HER2 codon 655 GG genotype (5 out of 132,
4%) with no association observed with cardiac toxicity (LVEF decrease > 15%, LVEF < 50%),
potentially due to the small sample size and low frequency of this patient population, as
supported by the authors. A strong association of the HER2 codon 655 AG with cardiotoxi-
city was also noted by Gómez Peña et al., 2015 [
228
], compared to the homozygous allele
(95% CI (1.20–12.57), p= 0.024) in HER2 breast cancer patients treated with trastuzumab.
An even more significant association was observed when menopausal status and use of
anthracyclines at baseline were considered (95% (
CI 1.43–18.36
),
p= 0.012
). Cardiotoxicity
was defined as either a decrease in the LVEF by 15% resulting in LVEF < 50%, LVEF decline
by less than 45%, LVEF reduction by 15% from baseline, or manifestation of CHF. However,
no clear association of the AG polymorphism is provided for each of the specific features
used to define cardiac toxicity (e.g., decline in LVEF) in this study. The proposed association
of HER2 codon 655 AG polymorphism with cardiotoxicity is in line with the result of a
meta-analysis conducted by the authors in order to increase the sample size and statistical
power. The meta-analysis involved three previously published studies, two of which are in-
Cancers 2023,15, 3290 14 of 53
cluded in this review [
227
,
229
] and one conducted in 2007 [
230
]. The meta-analysis showed
a significant association of the HER2 codon 655 AG polymorphism with cardiotoxicity as
opposed to the homozygous allele (OR = 5.35, 95% CI (2.55–11.73), p< 0.0001) whilst the
HER2 codon 655 GG polymorphism had no correlation with cardiotoxicity [228].
The retrospective polymorphism sub-study [
229
], was conducted including 73 patients
of which 52 patients had the homozygous allele, HER2 codon 655 AA (71%), 18 patients
had the heterozygous allele, HER2 codon 655 AG (25%) and 3 patients had the HER2 codon
655 GG (4%). A higher risk to develop cardiac toxicity was noted in 33% of the patients
with the HER2 codon 655 AG compared to the 8% of the patients with the HER2 codon 655
AA (OR = 5.87, 95% CI [1.33–25.82], p= 0.02). Similarly to the other studies, patients with
the HER2 codon 655 GG did not experience cardiac toxicity, which was defined as LVEF
decreasing by at least 10% with LVEF < 50% or any decrease resulting in LVEF < 45%.
Overall, a common limitation of the four studies is the small sample size, which did
not allow for powerful statistical analysis. Hence, larger cohorts are required in order to
validate the association of HER2 codon 655 AG and/or HER2 codon 655 GG polymorphisms
with cardiotoxicity induced by trastuzumab-directed therapies in breast cancer patients.
Despite the fact that the association of HER2 codon 655 AG with cardiotoxicity is supported
by the aforementioned studies, no evidence is provided about the molecular mechanisms
through which HER2 codon 655 AG is correlated with the induction of CTRCD.
Stanton et al., 2015 [
222
], recruited a total of 140 patients in a single-center prospective
study of which 29 cases developed cardiotoxicity. Cardiotoxicity was defined as the clinical
manifestation of CHF, or a decline in LVEF of 15% resulting in interruption of trastuzumab
treatment, LVEF < 55%, or LVEF decline by 10%. In this study, two polymorphisms
among a total of 11 SNPs examined, showed to have variation within the ethnically mixed
population. The two SNPs included the HER2 codon 655 AG and HER2 codon 1170 CG
(Pro1170Ala). In this study, no association of the AG polymorphism with cardiotoxicity
was noted (p= 0.96); however, this was accompanied by no available statistical data nor
correlation analysis with each of the features used to define cardiotoxicity. In contrast, 35%
of the patients that develop cardiotoxicity (10 out of 29 patients, p= 0.04) harbor the HER2
codon 1170 CC as opposed to the 17.1% of the patients with HER2 codon 1170 CG in the
non-cardiotoxic control group (19 out of 111).
A larger cohort of a three-fold greater number of patients (n = 800) [
226
], compared to
the three aforementioned prospective studies combined (n = 300) [
221
,
227
,
228
], revealed
no association of either polymorphism, HER2 codon 655 AG and HER2 codon 1170 CC,
with cardiotoxicity (p> 0.05). This was noted based on both linear and logistic regression
models and using the definition of cardiotoxicity as per the previously published studies
including the more stringent definition of Gómez Peña et al., 2015 [
228
]. For the lack of
data reproducibility, the authors excluded the reason for genotyping errors, as multiple
probes were tested, and allele frequencies were in agreement with published studies. It
was supported that the lack of data replication is due to the small sample size of the
previously published studies, which demonstrated the association of these variants with
cardiotoxicity. In parallel, the authors managed to replicate previously published data on
the association of genetic variants in the ABCB1 (p= 0.018) and CBR3 genes (p= 0.004) with
chemotherapy-induced cardiotoxicity using doxorubicin.
In conclusion, further studies with a higher number of participants are required in
order to validate the role of SNPs mentioned above and achieve adequate statistical power.
Other SNPs
Other studies have investigated the association of other variants with CTRCD includ-
ing the SNP, rs28714259, which was identified using a genome-wide association study
(GWAS) and shown to be associated with CHF (p= 0.041, OR = 1.9) and decreased in
LVEF < 45%
(p= 0.018, OR = 4.2) in response to adjuvant treatment with paclitaxel, cy-
clophosphamide and anthracyclines including doxorubicin [
231
]. The rs28714259 SNP
is found in the glucocorticoid receptor (GR) binding site and it was shown to decrease
Cancers 2023,15, 3290 15 of 53
its binding affinity
in vitro
and
in vivo
[
232
]. The SNP was identified in a randomized
phase III breast cancer trial ECOG-E5103 (cohort sample size n = 4994, tumor-derived DNA
from n = 3431, OR = 2.1; p= 9.25
×
10
−6
) and validated in two independent phase III
breast cancer trials, E1199 (cohort sample size n = 5052, tumor-derived DNA from n = 2906,
OR = 1.9
;p= 0.04) and BEATRICE (cohort sample size n = 2591, tumor-derived DNA from
n = 828, OR = 4.2; p= 0.018) [231].
The case group included breast cancer patients with CHF (as defined by the NYHA
class III or IV for BEATRICE or by the Common Toxicity Criteria version 2.0 for E1199) or
cases of cardiac events (decline in LVEF > 10% to LVEF < 50%). The control groups included
patients without CHF or other cardiac events (LVEF < 50% or drop by LVEF
≥
20% from
baseline (E5103) or LVEF < 45% (BEATRICE). Raw LVEF values were not available from
the E1199 trial. Association of the rs28714259 with CHF and drop in LVEF < 45% were
validated as part of E1199 and BEATRICE trials, respectively [
231
]. The predictive role
of this SNP was also validated by Gvaldin et al., 2021 [
233
], in a study of 256 patients of
which 235 patients had no CV complications and 21 patients experienced cardiac events. It
was shown that the rs28714259 SNP significantly increased the risk of cardiotoxicity and
the incidence of impaired LV contractility by 3.3-fold (95% CI (1.23–8.75), p= 0.002) and
6.6-fold (95% CI (1.92–22.75); p= 0.003), respectively. Cardiac events included a reduction
in LVEF > 10%, ECG abnormalities, arrhythmia, cardialgia, and pronounced dyspnea.
A recent publication by Wu et al., 2022 [
232
], revealed insights into the mechanisms
through which rs28714259 polymorphism may trigger cardiac failure in response to an-
thracyclines. It was shown that rs28714259 disrupts the GR-mediated protective signaling
pathway against doxorubicin-induced cardiotoxicity and reduction in cardiac contrac-
tility, dysregulates cardiac hypertrophy signaling, mitochondrial function, and glucose
metabolism, which interferes with cardiomyocyte survival following doxorubicin using
human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) in vitro [232].
Two studies investigated the role of the uridine glucuronosyltransferase 2B7 (UGT2B7)–
161 SNP C to T (C > T) (rs7668258) and the incidence of cardiotoxicity in Chinese breast
cancer patients [
234
,
235
]. UGT2B7 is a liver enzyme, which mediates drug elimination
through glucuronidation. Glucuronidation enhances the water solubility of lipophilic anti-
cancer agents and in turn, increases the clearance rate of these drugs and their toxic metabo-
lites from the body. UGT2B7 polymorphisms were shown to differentially regulate drug
metabolism and drug-associated toxicity [
236
]. Both studies [
234
,
235
], demonstrated that
the patients with UGT2B7-161 CC are at higher risk to experience cardiotoxicity compared
to the patients with UGT2B7-161 TT and UGT2B7-161 CT. Specifically, Li et al., 2022 [
235
],
included 50 post-operative HER2 breast cancer patients registered to receive trastuzumab
in combination with pertuzumab, without a diagnosis of severe cardiac complications
and/or hypertension, thoracic abnormalities or endocrine system diseases. Cardiotoxicity
was defined as a drop in LVEF by at least 10% and/or reduction in
LVEF < 53%
. However,
the time points assessed were limited including the baseline and
3 months
post-treatment.
Li et al., 2019 [
234
], included a total of 427 post-operative breast cancer patients scheduled
to receive epirubicin, cyclophosphamide followed by docetaxel. Concurrent treatment
with trastuzumab and docetaxel was administered in patients with HER2-positive breast
cancer. Cardiotoxicity was defined as the drop in LVEF by at least 10% from baseline
resulting in LVEF < 53% or clinical manifestation of acute coronary artery syndrome, CHF,
or arrhythmias. The follow-up period was for one-year post-treatment. Both studies re-
vealed that the UGT2B7-161 T allele is independently associated with low incidences of
cardiotoxicity compared to the CC genotype (p= 0.004). It was previously shown that
breast cancer patients with UGT2B7-161 TT or CT had increased epirubicin clearance rate
(median,
134.0 L/h
;p= 0.002) compared to the patients with UGT2B7-161 CC (median,
103.3 L/h) [
236
]. It is believed that UGT2B7-161 C>T, which is found on the promoter region
of UGT2B7, stimulates its transcription and enhances UGT2B7 enzymatic activity. This
then triggers glucuronidation of epirubicin and increases its clearance rate from the body,
hence protecting cardiac cells from potential epirubicin-induced cardiotoxicity [
234
,
236
].
Cancers 2023,15, 3290 16 of 53
However, both studies [
234
,
235
] had several limitations including selection bias as all
patients were Chinese from a single center, the small sample size, and the short period of
follow-up.
Nakano et al., 2019 [
223
], conducted GWAS to identify novel SNPs predicting trastuzumab-
induced cardiotoxicity in a total of 268 Japanese patients of which 11 cases experienced
cardiotoxicity and the remaining 257 controls had no incidences of cardiotoxicity. Car-
diotoxicity was defined as a reduction in LVEF < 45% or a drop by 10% from baseline
resulting in LVEF < 50%. GWAS revealed a total of 100 SNPs to be associated with car-
diotoxicity and which were further validated in a replication study, which included 14
cases with cardiotoxicity compared to 199 controls with no cardiotoxicity. Combined
results of both GWAS and the replication study identified five SNPs to be significantly
associated with a higher risk of trastuzumab-induced cardiotoxicity. These were the
following: rs9316695 (
pcombined = 6.00 ×10−6
, OR = 4.46, 95% CI (2.30–8.47)), rs28415722
(
pcombined = 8.88 ×10−5
, OR = 5.48, 95% CI (2.21–13.69)), rs7406710 (
pcombined = 1.07 ×10−4
,
OR = 6.64, 95% CI (2.19–27.01)), rs11932853 (p
combined
= 1.42
×
10
−4
, OR = 3.20, 95% CI
(1.70–6.23)) rs8032978 (p
combined
= 1.60
×
10
−4
, OR = 5.83, 95% CI (2.30–13.51)). A pre-
diction model developed using the five SNPs showed that the presence of these SNPs
could predict trastuzumab-induced cardiotoxicity at baseline (p= 7.82
×
10
−15
,
OR = 40
,
95% CI (15.6–102.3)). A follow-up study by the same authors, showed that the two pre-
viously identified SNPs, rs8032978 (p
combined
= 4.92
×
10
−5
, OR = 3.49) and rs7406710
(
pcombined = 5.50 ×10−5
, OR = 3.47) had a stronger association with trastuzumab-induced
cardiotoxicity compared to the remaining three SNPs, in a case–control cohort study consist-
ing of both Japanese (6 cases and 206 controls) and Singaporean (22 cases and 178 controls)
patients with HER2+ breast cancer treated with trastuzumab [
237
]. Cardiotoxicity was
defined as previously by Nakano et al., 2019 [
223
]. However, it is worth noting that the
strong association was evident only after a combined analysis with the previous study [
223
].
Otherwise, only similar trends of association to the five SNPs with trastuzumab-induced
cardiotoxicity were noted in this study, without significance, potentially due to the small
sample size [
237
]. Larger-scale validation studies need to be conducted to verify the
association of the selected SNPs with trastuzumab-induced cardiotoxicity.
3.3.2. MicroRNAs
MicroRNAs are endogenous small single-stranded non-coding RNAs (18–25 nu-
cleotides), implicated in various diseases including CV diseases such as CHF [
238
], acute
myocardial infarction [
239
,
240
] as well as metabolic disorders [
241
] and diabetes [
242
–
244
].
MicroRNAs can regulate protein expression post-transcriptionally via binding to protein-
coding messenger RNA (mRNA) [
245
]. Several studies have reported the potential of
using miRNAs as diagnostic biomarkers, primarily due to their direct association with
specific diseases [
244
,
246
,
247
], high sensitivity, and biochemical stability [
248
,
249
]. Studies
have demonstrated that the levels of circulating miRNAs are correlated with CTRCD [
250
]
(Table S2)
. A total of 15 prospective studies published during 2013–2023, revealed a total
of 445 differentially expressed miRNAs in breast cancer patients experiencing cardiotox-
icity compared to patients without cardiotoxicity. Specifically, from the 445 miRNAs,
229 miRNAs were found to be downregulated and 216 were upregulated in relation to
cardiotoxicity [
89
,
95
,
144
,
251
–
262
]. Sánchez-Sánchez et al., 2022 [
251
] revealed that miR-
4732-3p, one of the most promising cardioprotective microRNAs, was downregulated in the
blood samples of breast cancer patients following anthracycline treatment (* p< 0.05 vali-
dation study; ** p< 0.01 main study). MiR-4732-3p was the only miRNA identified by three
independent regression models (elastic net, Robinson and Smyth exact negative binomial
test, and random forest). The prospective observational study included patients with de-
clined cardiac function (n = 10 cases) during year 1 post-treatment with anthracycline-based
chemotherapy and patients without cardiac dysfunction (n = 10 controls). The findings
were validated by a second cohort (7 cases and 25 controls). Cardiotoxicity was defined
Cancers 2023,15, 3290 17 of 53
as a symptomatic reduction in LVEF by 5%, resulting in LVEF < 55%, or an asymptomatic
reduction in LVEF by 10% resulting in LVEF < 55%.
Significant upregulation of the circulating miRNAs, known to be implicated in cardiac
remodeling, cardiac dysfunction, and cardiomyocyte apoptosis, was recently demonstrated
in response to trastuzumab in combination with taxanes [
89
]. This is a prospective study of
a total of 17 HER2+ breast cancer patients treated with trastuzumab in combination with
paclitaxel or docetaxel (with or without carboplatin). A total of 17 healthy subjects were
included as the control group. Specifically, miR-1, miR-21, and miR-30e were statistically
significantly increased at 3 and 6 months of trastuzumab treatment compared to the baseline
and to the healthy controls (p< 0.05). MiR-34a and miR-133 showed significant upregulation
at 6 months as compared to the control (p< 0.05) and the control and baseline (p< 0.05),
respectively. Upregulated levels of cTnI and cTnT were noted in response to trastuzumab
and were strongly correlated with the increased levels of miR-34a (r = 0.3394 cTnI; r = 0.3882
cTnT), miR-21 (r = 0.4036 cTnI; r = 0.4744 cTnT), miR-133 (r = 0.5804 cTnI; r = 0.4242 cTnT),
miR-1 (r = 0.3235 cTnI; r = 0.4372 cTnT) and miR-30e (r = 0.3350 cTnI; r = 0.4920 cTnT) with
all at >99% CI. The authors concluded that the miRNA panel identified can be a promising
screening tool for the early identification of cardiotoxicity induced by trastuzumab-based
therapy. Cardiotoxicity was defined as LVEF reduction by
≥
5% resulting in LVEF < 55%
compared to baseline with symptomatic HF or as an asymptomatic HF with LVEF reduction
by
≥
10% to LVEF < 55% from baseline. In this study, there was no association between the
miRNA panel and LVEF reduction, potentially due to the small sample size and the low
incidences of cardiotoxicity. Despite the strong statistically significant data of the study, the
authors acknowledge the short follow-up time and the need to evaluate the miRNA panel
in the largest cohort with patients at a higher risk of CTRCD.
Upregulation of circulating miRNAs was also noted by Lakhani et al., 2021 [
95
] in
breast cancer patients (n = 17) at 3 and 6 months of anthracycline chemotherapy compared
to healthy subjects (n = 17). Specifically, increased levels of miR-423, miR-126, miR-34a,
and miR-29a were detected at 6 months as compared to the baseline (p< 0.05 or p< 0.01)
and healthy individuals (p< 0.01). MiR-499 levels were increased at 6 months as compared
to the control (p< 0.01), miR-126 levels were upregulated at 3 months as compared to the
control (p< 0.01), and baseline (p< 0.05) and miR423 levels were increased at month 3
as compared to the control (p< 0.01). The increased levels of miRNAs were positively
correlated with elevated troponins as follows: cTnI was strongly correlated with miR-29a,
miR34a, and miR-126 (r = 0.3052; r = 0.3163; r = 0.6164, respectively). Significant correlation
was observed between the hscTnT and miR-126, miR-423 and miR-499 (r = 0.4886; r = 0.3638,
r = 0.3959, respectively). In contrast to the previous study by the same research group [
89
],
no significant correlation was noted between troponin T and miR-34a nor miR-29a.
In addition, the levels of miR-3135b were significantly upregulated in breast cancer
patients with chemotherapy-induced cardiotoxicity (n = 33) (p= 0.0001) compared to
the patients without cardiotoxicity (n = 37) [
252
]. The upregulated levels of miR-3135b
were strongly correlated with changes in LVEF (r = 0.5, p= 0.0001). In addition, patients
with HF had significantly higher levels of miR-3135b (p< 0.05) compared to the control
group. Patients were treated with anthracycline-based regimens followed by treatment with
paclitaxel (67.4%) or docetaxel (26.1%) and cardiotoxicity was defined as a reduction in LVEF
< 50%. In this study, the levels of miR3135b prior to each treatment cycle were not evaluated
and hence further studies are needed to assess multiple time points during treatment.
The levels of miR-130a, known to be implicated in the regulation of cardiac pathology,
were progressively increased in HER2+ breast cancer patients with (p< 0.001) or without
cardiotoxicity (p< 0.001) during adjuvant treatment with epirubicin/cyclophosphamide
followed by docetaxel and trastuzumab [
144
]. However, in patients with cardiotoxicity, the
magnitude of increase in the miR-130a levels was greater in the cardiotoxicity patients at
all time points (all p< 0.05) assessed during treatment as revealed by a two-group com-
parison analysis. Importantly, baseline levels of miR-130a were negatively and positively
correlated with changes in LVEF and cTnI (p= 0.038, Spearman r =
−
0.245; p< 0.001;
Cancers 2023,15, 3290 18 of 53
Spearman
r = 0.414
, respectively), respectively. However, no correlation was evident with
NT-proBNP (p= 0.112, Spearman r = 0.019). Baseline levels of miR-130a (AUC = 0.783; 95%
CI (0.647–0.920)) distinguish patients who experience cardiotoxicity from patients without
cardiotoxicity. In this study, cardiotoxicity was defined by a reduction in LVEF by
≥
10%
and LVEF < 53% or HF defined as LVEF < 40% or BNP > 35 ng/L plus NT-proBNP >1
25 ng/L or acute coronary artery syndrome or severe arrhythmia. Despite the evidence
provided, the molecular mechanism through which miR-130a may trigger cardiac damage
and CTRCD, remains unknown and requires
in vitro
/
in vivo
experiments. Limitations
of the study include the small sample size and the potential bias that may have been
introduced due to variability in the LVEF measurements, which may have been different
according to the sonographer and the heart rate.
Evidence demonstrated that HER2+ breast cancer patients with low expression of
miR-222-3p showed complete response (31 out of 65 patients, 4.69%) (OR = 0.258, 95%
CI (0.070–0.958, p= 0.043)), disease-free survival (HR = 5.778, 95% CI (1.196–27.906),
p= 0.029
) and overall survival (p= 0.0037) [
253
]. Expression of serum miR-222-3p could
predict trastuzumab-induced cardiotoxicity (OR = 0.410, 95% CI (0.175-0.962), p= 0.040).
In this study, a total of sixty-five breast cancer patients were enrolled, derived from
two neoadjuvant
clinical trials (SHPD001 and SHPD002). All patients received neoad-
juvant paclitaxel and cisplatin followed by trastuzumab.
Interestingly, downregulation of the levels of miRNA-548 was noted in the PBMCs of
patients with dilated cardiomyopathy (DCM) (NYHA class II/III) (n = 44) but no changes
were noted in metastatic breast cancer patients with normal cardiac function or patients
with coronary artery disease (n = 10). This suggests that changes in miRNA548 expression
in PBMCs may be selective to DCM and hence it was suggested as a promising indicator of
early cardiac dysfunction [255].
3.3.3. Myeloperoxidase (MPO)
Myeloperoxidase (MPO) is a myeloid-lineage restricted enzyme with bactericidal
properties, found in the azurophilic granules of neutrophils [
263
], the main source of
MPO [
264
]. MPO is a component of the neutrophil extracellular traps (NETs) [
265
]. NETs
are produced by neutrophils and are composed of DNA structures, released as a result of
decondensed chromatin, histone proteins, and more than 30 granule proteins including
components with antibacterial activity such as neutrophil elastase, MPO, cathepsin G, and
peptidoglycan-binding proteins [
163
,
266
,
267
]. Evidence implicated NETs and NETs-related
factors such as dsDNA, MPO/DNA complexes with myocardial infarction, and serious
cardiac events [
268
]. Upon MPO activation, MPO by-products are extremely oxidizing
agents such as the hypochlorous acid, HCIO- resulting in molecular damage and can
be implicated in oxidative stress resulting in cellular damage [
163
,
269
,
270
]. Subsequent
studies detected elevated concentrations of neutrophil-specific genes including MPO in
patients who experienced doxorubicin-induced cardiotoxicity [
95
,
105
,
271
]. Consequently,
the utility of using MPO as a predictive biomarker of CTRCD was investigated in several
clinical studies [95,130,271,272] (Table S2).
MPO was one of the plasma biomarkers assessed as a potential novel indicator of
doxorubicin-induced cardiotoxicity in breast cancer patients in a study of 17 patients with
triple-negative breast cancer patients and 17 healthy individuals [
95
]. It was shown that
MPO was significantly elevated at 3 and at 6 months in patients receiving doxorubicin as
compared to the healthy control group (p< 0.01) and baseline (p< 0.01). Cardiotoxicity
was detected in a total of four patients (23.5%) at 6 months of treatment showing an LVEF
reduction of 8.1%, 7%, 9.3%, and 11.5%, respectively. Cardiotoxicity was defined by either
LVEF reduction of
≥
5% resulting in LVEF < 55% with clinical manifestation of CHF or by an
asymptomatic drop in LVEF by
≥
10% resulting in LVEF < 55% from baseline. A significant
positive correlation was noted between elevated levels of cTnI and cTnT with higher levels
of MPO (r = 0.3078 and r = 0.3240, respectively). These findings suggest that MPO can be
used as a promising biomarker for the detection of the early onset of anthracycline-related
Cancers 2023,15, 3290 19 of 53
cardiac dysfunction even before detected by echocardiographic assessment. However, the
small sample size in this study did not allow for the prediction of cardiotoxicity in a larger
population group.
Elevated circulating levels of MPO were detected in breast cancer patients treated
with anthracyclines (n = 192) as part of the CECCY trial with 1.3- and 1.5-fold increase at
3 months
(17.7 ng/mL (11.1, 31.1)) and 6 months (19.2 ng/mL (11.1, 37.8)) after initiation of
treatment, respectively, compared to the baseline (13.2 ng/mL (7.9, 24.8)). However, the
levels of MPO did not differentiate (p= 0.85) between the patients with decreased LVEF by
≥
10% (14.1 ng/mL (10.4, 25.5), n = 26) compared to the patients without a decrease in LVEF
(18.1 ng/mL (12.3, 39.1)), n = 148) at 3 months and 6 months (16.3 ng/mL (10.3, 35.6) and
20.5 ng/mL (10.5, 37.8), respectively), after initiation of anthracycline-based chemotherapy.
However, higher levels of baseline MPO above the median were associated with elevated
levels of cTnI (p= 0.041) during treatment (6, 9, and 12 months), indicative of myocardial
injury. The authors concluded that higher MPO levels prior to chemotherapy can be used
to identify patients with a higher probability to benefit from the cardioprotective effects of
carvedilol (p< 0.001) [
271
]. In this study, cardiotoxicity was defined as a drop in LVEF by
≥
10% at any point until 6 months when chemotherapy is completed. It is worth noting
that since there was no established cut-off value for MPO, similar cut-off values were
applied by the authors as described previously [
273
]. In addition, the low incidences
of cardiotoxicity observed in the CECCY trial may have underpowered the ability to
detect a potential association between MPO and the development of anthracycline-related
cardiac dysfunction.
MPO levels were significantly elevated in HER2+ breast cancer patients by 3 months of
treatment and were significantly associated with cardiotoxicity during the entire treatment
course of doxorubicin/trastuzumab with HR = 1.37 (95% CI (1.11–1.69); p= 0.02) [
98
].
The authors showed that persistent elevated MPO levels after the 3 months of treat-
ment can be used to predict patients at high risk of cardiotoxicity in response to dox-
orubicin/anthracycline treatment. A total of 78 patients with breast cancer were included
in this study and 23 patients developed 39 cardiac events over the treatment course. Car-
diotoxicity was defined in accordance with the Cardiac Review and Evaluation Committee
definition [
67
]. Similarly, another study showed higher serum levels of MPO at 3 months
of treatment compared to the baseline (p< 0.05) in a multicenter cohort of 78 HER2+ breast
cancer patients treated with adjuvant doxorubicin, taxanes, and trastuzumab [
105
]. Greater
predicted risk of cardiotoxicity was significantly associated with an increase in interval
change in the levels of MPO (HR = 1.36 per SD; 95% CI (1.04–1.79); p= 0.03). In particular,
the risk of cardiotoxicity by month 15 was 36.1% in patients with greater changes in the
levels of MPO (
∆
MPO > 422.6 pmol/L). Elevated changes in both cTnI and MPO increased
the probability of cardiotoxicity to 46.5%. Cardiotoxicity was defined in accordance with
the Cardiac Review and Evaluation Committee as previously described [67].
A total of 51 participants with ER+PR+HER2- or TNBC breast cancer were treated
with neoadjuvant (n = 36) or adjuvant (n = 15) doxorubicin in combination with cyclophos-
phamide in the study by Todorova et al., 2020 [
163
]. Abnormal LVEF was defined as a
reduction in LVEF by >10% or LVEF < 50%. Among 51 patients, 21 experienced asymp-
tomatic reduction in LVEF > 10% compared to baseline and the remaining 30 patients had
an LVEF decline of
≤
10%. Baseline MPO levels were significantly higher in patients with
abnormal LVEF (group 1) with a mean value (
±
SD) of 169
±
50.7 ng/mL compared to the
patients with normal LVEF (group 2) with a mean
±
SD of
132.6 ±45.6 ng/mL
(
p= 0.02
model 1; p= 0.01 model 2). MPO levels remained increased in group 1 (
mean ±SD
(
269.6 ±112.5 ng/mL
)) compared to group 2 (mean
±
SD (174.5
±
76.0)) after the first
cycle of chemotherapy (p= 0.007 model 1; p= 0.04 model 2) [
163
]. Overall, evidence
from this study further supports the utility of MPO as a promising predictor of cancer
therapy-induced cardiotoxicity, even at a baseline level. Gullo et al., 2019 [
93
], showed
that significantly increased serum MPO levels were detected in HER2-negative breast
cancer patients at 3 months (mean
±
SD (1.627
±
4.73), p< 0.05) of adjuvant treatment
Cancers 2023,15, 3290 20 of 53
with docetaxel and cyclophosphamide in combination with bevacizumab compared to the
baseline (
mean ±SD
(0.95
±
1.47)). However, the elevated levels of MPO were not differ-
entiated between the cardiotoxic (n = 12) versus non-cardiotoxic (n = 50) patients at either
the baseline or at
3 months
of treatment (difference in means 0.57, 95% CI (
−0.19, 1.34
),
p= 0.1637) [93].
3.3.4. Galectin-3 (Gal-3)
Galectin-3 (Gal-3) is a
β
-galactoside-binding protein, a member of the lectin family,
implicated in various pathophysiological processes including fibrosis, inflammation, ox-
idative stress [
274
] and is known to induce cardiac fibroblast proliferation and collagen
production and deposition [
275
]. During CHF, activated myocardial macrophages and car-
diac fibroblasts release Gal-3 [
275
,
276
]. Gal-3, as a marker of cardiac fibrosis, is considered
to be a promising predictor of the onset of CHF and related mortality in patients [277].
Recent studies investigated Gal-3 as a potential diagnostic biomarker for cancer
therapy-induced cardiac dysfunction in breast cancer patients [
92
,
136
,
149
,
271
,
278
,
279
]
(Table S2). A total of seven studies were included in this review, with five studies revealing
changes in the circulating levels of Gal-3 in response to treatment with cardiotoxic breast
cancer therapies [
92
,
105
,
149
,
271
,
279
]. The five studies included a total of 505 breast cancer
patients with Gulati et al., 2017 [
92
], showing significantly increased levels of Gal-3 in
patients treated with adjuvant anthracycline epirubicin combined with 5-FU and cyclophos-
phamide (median value 13.4 ng/mL (11.2, 16.0); p< 0.001) compared to baseline (median
value 12.1 ng/mL (10.4, 14.0)). However, there was no association between the elevated
levels of Gal-3 and the incidence of cardiotoxicity, which was defined as previously de-
scribed [
67
]. Similarly to Gal-3, no association with LV dysfunction was noted with either
of the other biomarkers assessed (cTnI, cTnT, BNP, NT-proBNP, CRP) as identified using
multivariable linear regression analysis, which corrected for age, BMI, blood pressure,
anthracycline dose and treatment with cardioprotective agents. The lack of association may
be due to the small number of patients included in the study and the fact that only one
patient showed a reduction in LVEF (from 62.7% to 51%) without HF and hence met the
criteria for cardiotoxicity. Additional limitations in the study were the lack of long-term
follow-up after adjuvant treatment.
In the study by Bulten et al., 2015 [
149
], increased levels of Gal-3 were significantly
(p< 0.05) associated with delayed planar whole-heart (WH) heart/mediastinum (H/M)
ratio measured by
123
I-met
α
iodobenzylguanidine (
123
I-mIBG) scintigraphy. This study
included 59 breast cancer survivors, 1 year after treatment with anthracyclines (docetaxel,
doxorubicin, and cyclophosphamide). In another study by Van Boxtel et al., 2015 [
279
],
abnormal levels of Gal-3 were detected in 7.3% of breast cancer patients (4 out of 55 patients)
after treatment with anthracyclines. Two of these patients had diminished LVEF or elevated
NT-proBNP, respectively. However, due to the small sample size, the role of Gal-3 as a
predictor of early onset of cardiotoxicity could not be sufficiently addressed. In addition,
increased Gal-3 levels were noted in patients during chemotherapy with a median difference
of 0.5 (
−
1.5 to 2.2) between baseline and 3 months, which was, however, non-statistically
significant (p= 0.14) [
105
]. The elevated levels of Gal-3 were not significantly associated
with the risk of cardiotoxicity (HR = 1.33, 95% CI (0.86–2.05); p= 0.195). Cardiotoxicity was
defined by a decline in LVEV of
≥
5% resulting in LVEF < 55% with clinical manifestation
of HF or by an asymptomatic decline in LVEF by ≥10% resulting in <55% [105].
A post hoc analysis by Wanderley et al., 2022 [
271
], of breast cancer patients included
in the CECCY trial, revealed that Gal-3 levels remained unchanged among the patients
with dropped LVEF of least 10% (n = 26; 10.4 ng/mL (8.5, 12.6)) compared to the patients
with no change in LVEF (n = 148; 10.3 ng/mL (7.6, 12.5)) at 6 months after initiation of
anthracycline treatment (p= 0.85). However, elevated levels of Gal-3 were noted in re-
sponse to anthracycline treatment with approximately 2- and 1.6-fold increases at 3 months
(
12.3 ng/mL
(9.8, 16.0)) and 6 months (10.3 ng/mL (8.2, 13.1)), respectively, compared to
the baseline (6.3 ng/mL (5.2, 9.6)) [
271
]. It is important to note that since there are no
Cancers 2023,15, 3290 21 of 53
established cut-off values for Gal-3, the authors followed a similar division performed in
previous studies [98,105].
In the remaining two studies, a total of 658 breast cancer patients were included
showing no changes in the levels of Gal-3 in patients receiving breast cancer therapies
including anthracyclines and/or trastuzumab nor an association with the development of
CTRCD in these patients [
98
,
136
]. Specifically, no significant differentiation in the levels of
Gal-3 was noted in a total of 580 breast cancer survivors treated with anthracycline-based
chemotherapy with a mean (SD) of 15.8 ng/L (7.5) compared to the control group of total
580 patients, who have not received anthracycline-driven therapy with a mean (SD) of
16.1 ng/L (7.8) [136].
The second study by Putt et al., 2015 [
98
], is a multicenter cohort of a total of
78 HER2+
breast cancer patients treated with adjuvant doxorubicin followed by taxanes and
trastuzumab. Cardiotoxicity was defined as a reduction in LVEF by
≥
5% to
LVEF < 55%
with HF or as an asymptomatic drop in LVEF of
≥
10% to LVEF < 55 [
67
]. A total of
23 patients
experienced a total of 39 cardiac events during month 15 of the study. There
were no significantly increased concentrations of Gal-3 at month 3 compared <