Clinical and preclinical evidence of sex-related differences in anthracycline-induced cardiotoxicity

2-Methoxyestradiol ameliorates doxorubicin-induced cardiotoxicity by regulating the expression of GLUT4 and CPT-1B in female rats

The clinical usage of doxorubicin (DOX) is hampered due to cardiomyopathy. Studies reveal that estrogen (E2) modulates DOX-induced cardiotoxicity. Yet, the exact mechanism is unclear. The objective of the current study is to evaluate the influence of E2 and more specifically its metabolite 2-methoxyestradiol (2ME) on cardiac remodeling and the reprogramming of cardiac metabolism in rats subjected to DOX cardiotoxicity. Seventy-two female rats were divided into groups. Cardiotoxicity was induced by administering DOX (2.5 mg/kg three times weekly for 2 weeks). In some groups, the effect of endogenous E2 was abolished by ovariectomy (OVX) or by using the estrogen receptor (ER) blocker Fulvestrant (FULV). The effect of administering exogenous E2 or 2ME in the OVX group was studied. Furthermore, the influence of entacapone (COMT inhibitor) on induced cardiotoxicity was investigated. The evaluated cardiac parameters included ECG, histopathology, cardiac-related enzymes (creatine kinase isoenzyme-MB (CK-MB) and lactate dehydrogenase (LDH)), and lipid profile markers (total cholesterol (TC), triglyceride (TG), and high-density lipoprotein (HDL)). The expression levels of key metabolic enzymes (glucose transporter-4 (GLUT4) and carnitine palmitoyltransferase-1B (CPT-1B)) were assessed. Our results displayed that co-treatment of E2 and/or 2ME with DOX significantly reduced DOX-induced cardiomyopathy and enhanced the metabolism of the heart through the maintenance of GLUT4 and CPT-1B enzymes. On the other hand, co-treatment of DOX with OVX, entacapone, or FULV increased the toxic effect of DOX by further reducing these important metabolic enzymes. E2 and 2ME abrogate DOX-induced cardiomyopathy partly through modulation of GLUT 4 and CPT-1B enzymes.

Sex Differences in the Development of Anthracycline-Associated Heart Failure

BACKGROUND

Female sex is frequently cited as a risk factor for anthracycline cardiotoxicity based on pediatric data, but the role of sex in the development of cardiotoxicity has not been clearly established in adults.

OBJECTIVES

To assess the effect of female sex on the development of incident heart failure (HF) in adult patients treated with anthracyclines.

METHODS

This was a retrospective cohort study of 1525 adult patients with no prior history of HF or cardiomyopathy who were treated with anthracyclines between 1992 and 2019. The primary outcome was new HF within 5 years of the first dose of anthracyclines. The effect of sex was assessed using Cox proportional hazards and competing risk models.

RESULTS

Over a median (IQR) follow-up of 1.02 (0.30-3.01) years, 4.78% of patients developed HF (44 men and 29 women). Female sex was not associated with the primary outcome in a multivariable Cox proportional hazards model (HR 0.87; 95% CI 0.53-1.43; P = 0.58). Similar results were observed in a multivariable model accounting for the competing risk of death (HR 0.94; 95% CI 0.39-2.25; P = 0.88). Age, coronary artery disease and hematopoietic stem cell transplant were associated with the primary outcome in a multivariable Cox proportional hazards model. Age and body mass index were associated with the primary outcome in a multivariable competing risk model.

CONCLUSIONS

In this large, single-center, retrospective cohort study, female sex was not associated with incident HF in adult patients treated with anthracyclines.

CONDENSED ABSTRACT

Female sex is frequently cited as a risk factor for anthracycline cardiotoxicity based on pediatric data, but the role of sex in the development of cardiotoxicity has not been clearly established in adults. In this retrospective cohort study, we assessed the effect of female sex on the development of incident heart failure in adult patients treated with anthracyclines. Using Cox proportional hazards and competing risk regression models, we found that there was no association between female sex and heart failure after treatment with anthracyclines.

Doxorubicin induces deglycosylation of cancer cell-intrinsic PD-1 by NGLY1

Tumor cells can express the immune checkpoint protein programmed death-1 (PD-1), but how cancer cell-intrinsic PD-1 is regulated in response to cellular stresses remains largely unknown. Here, we uncover a unique mechanism by which the chemotherapy drug doxorubicin (Dox) regulates cancer cell-intrinsic PD-1. Dox upregulates PD-1 mRNA while reducing PD-1 protein levels in tumor cells. Although Dox shortens the PD-1 half-life, it fails to directly induce PD-1 degradation. Instead, we observe that Dox promotes the interaction between peptide-N(4)-(N-acetyl-beta-glucosaminyl)asparagine amidase (NGLY1) and PD-1, facilitating NGLY1-mediated PD-1 deglycosylation and destabilization. The maintenance of PD-1 sensitizes tumor cells to Dox-mediated antiproliferative effects. Our study unveils a regulatory mechanism of PD-1 in response to Dox and highlights a potential role of cancer cell-intrinsic PD-1 in Dox-mediated antitumor effects.

Sex-related differences in delayed doxorubicin-induced cardiac dysfunction in C57BL/6 mice

Cancer survivors may experience long-term cardiovascular complications due to chemotherapeutic drugs such as doxorubicin (DOX). The exact mechanism of delayed DOX-induced cardiotoxicity has not been fully elucidated. Sex is an important risk factor for DOX-induced cardiotoxicity. In the current study, we identified sex differences in delayed DOX-induced cardiotoxicity and determined the underlying molecular determinants of the observed sexual dimorphism. Five-week-old male and female mice were administered intraperitoneal injections of DOX (4 mg/kg/week) or saline for 6 weeks. Echocardiography was performed 5 weeks after the last dose of DOX to evaluate cardiac function. Thereafter, mice were sacrificed and gene expression of markers of apoptosis, senescence, and inflammation was measured by PCR in hearts and livers. Proteomic profiling of the heart from both sexes was conducted to determine differentially expressed proteins (DEPs). Only DOX-treated male, but not female, mice demonstrated cardiac dysfunction, cardiac atrophy, and upregulated cardiac expression of Nppb and Myh7. No sex-related differences were observed in DOX-induced expression of most apoptotic, senescence, and pro-inflammatory markers. However, the gene expression of Trp53 was significantly reduced in hearts of DOX-treated female mice only. The anti-inflammatory marker Il-10 was significantly reduced in hearts of DOX-treated male mice only, while the pro-inflammatory marker Il-1α was significantly reduced in livers of DOX-treated female mice only. Gene expression of Tnf-α was reduced in hearts of both DOX-treated male and female mice. Proteomic analysis identified several DEPs after DOX treatment in a sex-specific manner, including anti-inflammatory acute phase proteins. This is the first study to assess sex-specific proteomic changes in a mouse model of delayed DOX-induced cardiotoxicity. Our proteomic analysis identified several sexually dimorphic DEPs, many of which are associated with the anti-inflammatory marker Il-10.

Doxorubicin-induced cardiotoxicity and risk factors

Doxorubicin (DOX) is an anthracycline antibiotic widely used as a chemotherapeutic agent to treat solid tumours and hematologic malignancies. Although useful in the treatment of cancers, the benefit of DOX is limited due to its cardiotoxic effect that is observed in a large number of patients. In the literature, there is evidence that the presence of various factors may increase the risk of developing DOX-induced cardiotoxicity. A better understanding of the role of these different factors in DOX-induced cardiotoxicity may facilitate the choice of the therapeutic approach in cancer patients suffering from various cardiovascular risk factors. In this review, we therefore discuss the latest findings in both preclinical and clinical research suggesting a link between DOX-induced cardiotoxicity and various risk factors including sex, age, ethnicity, diabetes, dyslipidaemia, obesity, hypertension, cardiovascular disease and co-medications.

Dexrazoxane does not mitigate early vascular toxicity induced by doxorubicin in mice

Apart from cardiotoxicity, the chemotherapeutic agent doxorubicin (DOX) provokes acute and long-term vascular toxicity. Dexrazoxane (DEXRA) is an effective drug for treatment of DOX-induced cardiotoxicity, yet it remains currently unknown whether DEXRA prevents vascular toxicity associated with DOX. Accordingly, the present study aimed to evaluate the protective potential of DEXRA against DOX-related vascular toxicity in a previously-established in vivo and ex vivo model of vascular dysfunction induced by 16 hour (h) DOX exposure. Vascular function was evaluated in the thoracic aorta in organ baths, 16h after administration of DOX (4 mg/kg) or DOX with DEXRA (40 mg/kg) to male C57BL6/J mice. In parallel, vascular reactivity was evaluated after ex vivo incubation (16h) of murine aortic segments with DOX (1 μM) or DOX with DEXRA (10 μM). In both in vivo and ex vivo experiments, DOX impaired acetylcholine-stimulated endothelium-dependent vasodilation. In the ex vivo setting, DOX additionally attenuated phenylephrine-elicited vascular smooth muscle cell (VSMC) contraction. Importantly, DEXRA failed to prevent DOX-induced endothelial dysfunction and hypocontraction. Furthermore, RT-qPCR and Western blotting showed that DOX decreased the protein levels of topoisomerase-IIβ (TOP-IIβ), a key target of DEXRA, in the heart, but not in the aorta. Additionally, the effect of N-acetylcysteine (NAC, 10 μM), a reactive oxygen species (ROS) scavenger, was evaluated ex vivo. NAC did not prevent DOX-induced impairment of acetylcholine-stimulated vasodilation. In conclusion, our results show that DEXRA fails to prevent vascular toxicity resulting from 16h DOX treatment. This may relate to DOX provoking vascular toxicity in a ROS- and TOP-IIβ-independent way, at least in the evaluated acute setting. However, it is important to mention that these findings only apply to the acute (16h) treatment period, and further research is warranted to delineate the therapeutic potential of DEXRA against vascular toxicity associated with longer-term repetitive DOX dosing.

Doxorubicin-induced cardiovascular toxicity: a longitudinal evaluation of functional and molecular markers

AIMS

Apart from cardiotoxicity, the chemotherapeutic doxorubicin (DOX) induces vascular toxicity, represented by arterial stiffness and endothelial dysfunction. Both parameters are of interest for cardiovascular risk stratification as they are independent predictors of future cardiovascular events in the general population. However, the time course of DOX-induced cardiovascular toxicity remains unclear. Moreover, current biomarkers for cardiovascular toxicity prove insufficient. Here, we longitudinally evaluated functional and molecular markers of DOX-induced cardiovascular toxicity in a murine model. Molecular markers were further validated in patient plasma.

METHODS AND RESULTS

DOX (4 mg/kg) or saline (vehicle) was administered intra-peritoneally to young, male mice weekly for 6 weeks. In vivo cardiovascular function and ex vivo arterial stiffness and vascular reactivity were evaluated at baseline, during DOX therapy (Weeks 2 and 4) and after therapy cessation (Weeks 6, 9, and 15). Left ventricular ejection fraction (LVEF) declined from Week 4 in the DOX group. DOX increased arterial stiffness in vivo and ex vivo at Week 2, which reverted thereafter. Importantly, DOX-induced arterial stiffness preceded reduced LVEF. Further, DOX impaired endothelium-dependent vasodilation at Weeks 2 and 6, which recovered at Weeks 9 and 15. Conversely, contraction with phenylephrine was consistently higher in the DOX-treated group. Furthermore, proteomic analysis on aortic tissue identified increased thrombospondin-1 (THBS1) and alpha-1-antichymotrypsin (SERPINA3) at Weeks 2 and 6. Up-regulated THBS1 and SERPINA3 persisted during follow-up. Finally, THBS1 and SERPINA3 were quantified in plasma of patients. Cancer survivors with anthracycline-induced cardiotoxicity (AICT; LVEF < 50%) showed elevated THBS1 and SERPINA3 levels compared with age-matched control patients (LVEF ≥ 60%).

CONCLUSIONS

DOX increased arterial stiffness and impaired endothelial function, which both preceded reduced LVEF. Vascular dysfunction restored after DOX therapy cessation, whereas cardiac dysfunction persisted. Further, we identified SERPINA3 and THBS1 as promising biomarkers of DOX-induced cardiovascular toxicity, which were confirmed in AICT patients.

Tailored to a Woman's Heart: Gender Cardio-Oncology Across the Lifespan

PURPOSE OF REVIEW

Females outnumber males among long-term cancer survivors, primarily as a result of the prevalence of breast cancer. Late cardiovascular effects of cancer develop over several decades, which for many women, may overlap with reproductive and lifecycle events. Thus, women require longitudinal cardio-oncology care that anticipates and responds to their evolving cardiovascular risk.

RECENT FINDINGS

Women may experience greater cardiotoxicity from cancer treatments compared to men and a range of treatment-associated hormonal changes that increase cardiometabolic risk. Biological changes at critical life stages, including menarche, pregnancy, and menopause, put female cancer patients and survivors at a unique risk of cardiovascular disease. Women also face distinct psychosocial and physical barriers to accessing cardiovascular care. We describe the need for a lifespan-based approach to cardio-oncology for women. Cardio-oncology care tailored to women should rigorously consider cancer treatment/outcomes and concurrent reproductive/hormonal changes, which collectively shape quality of life and cardiovascular outcomes.

Anthracycline cardiotoxicity is exacerbated by global p38β genetic ablation in a sexually dimorphic manner but unaltered by cardiomyocyte-specific p38α loss

Severe cardiotoxic effects limit the efficacy of doxorubicin (DOX) as a chemotherapeutic agent. Activation of intracellular stress signaling networks, including p38 mitogen-activated protein kinase (MAPK), has been implicated in DOX-induced cardiotoxicity (DIC). However, the roles of the individual p38 isoforms in DIC remain incompletely elucidated. We recently reported that global p38δ deletion protected female but not male mice from DIC, whereas global p38γ deletion did not significantly modulate it. Here we studied the in vivo roles of p38α and p38β in acute DIC. Male and female mice with cardiomyocyte-specific deletion of p38α or global deletion of p38β and their wild-type counterparts were injected with DOX. Survival and health were tracked for 10 days postinjection. Cardiac function was assessed by echocardiography and electrocardiography and fibrosis by Picrosirius red staining. Expression and activation of signaling proteins and inflammatory markers were measured by Western blot, phosphorylation array, and chemokine/cytokine array. Global p38β deletion significantly aggravated DIC and worsened cardiac electrical and mechanical function deterioration in female mice. Mechanistically, DIC in p38β-null female mice correlated with increased autophagy, sustained hyperactivation of proapoptotic JNK signaling, as well as remodeling of a myocardial inflammatory environment. In contrast, cardiomyocyte-specific deletion of p38α improved survival of DOX30-treated male mice 5 days posttreatment but did not influence cardiac function in DOX-treated male or female mice. Our data highlight the sex- and isoform-specific roles of p38α and p38β MAPKs in DOX-induced cardiac injury and suggest a novel in vivo function of p38β in protecting female mice from DIC.NEW & NOTEWORTHY We show that p38α and p38β have distinct in vivo functions in a murine model of acute DIC. Specifically, although conditional cardiomyocyte-specific p38α deletion exhibited mild cardioprotective effects in male mice, p38β deletion exacerbated the DOX cardiotoxicity in female mice. Our findings caution against employing pyridinyl imidazole inhibitors that target both p38α and p38β isoforms as a cardioprotective strategy against DIC. Such an approach could have undesirable sex-dependent effects, including attenuating p38β-dependent cardioprotection in females.

Cardiovascular toxicities after anthracycline and VEGF-targeted therapies in adolescent and young adult cancer survivors

BACKGROUND

Cancer survival rates have been steadily improving in the adolescent and young adult (AYA) population, but survivors are at increased risk for cardiovascular disease (CVD). The cardiotoxic effects of anthracycline therapy have been well studied. However, the cardiovascular toxicity associated with newer therapies, such as the vascular endothelial growth factor (VEGF) inhibitors, is less well understood.

OBJECTIVE

This retrospective study of AYA cancer survivors sought to gain insight into their burden of cardiovascular toxicities (CT) following initiation of anthracycline and/or VEGF inhibitor therapy.

METHODS

Data were extracted from electronic medical records over a fourteen-year period at a single institution. Cox proportional hazards regression modeling was used to examine risk factors for CT within each treatment group. Cumulative incidence was calculated with death as a competing risk.

RESULTS

Of the 1,165 AYA cancer survivors examined, 32%, 22%, and 34% of patients treated with anthracycline, VEGF inhibitor, or both, developed CT. Hypertension was the most common outcome reported. Males were at increased risk for CT following anthracycline therapy (HR: 1.34, 95% CI 1.04-1.73). The cumulative incidence of CT was highest in patients who received both anthracycline and VEGF inhibitor (50% at ten years of follow up).

CONCLUSIONS

CT was common among AYA cancer survivors who received anthracycline and/or VEGF inhibitor therapy. Male sex was an independent risk factor for CT following anthracycline treatment. Further screening and surveillance are warranted to continue understanding the burden of CVD following VEGF inhibitor therapy.

Cellular Mechanisms Mediating Exercise-Induced Protection against Cardiotoxic Anthracycline Cancer Therapy

Anthracyclines such as doxorubicin are widely used chemotherapy drugs. A common side effect of anthracycline therapy is cardiotoxicity, which can compromise heart function and lead to dilated cardiomyopathy and heart failure. Dexrazoxane and heart failure medications (i.e., beta blockers and drugs targeting the renin-angiotensin system) are prescribed for the primary prevention of cancer therapy-related cardiotoxicity and for the management of cardiac dysfunction and symptoms if they arise during chemotherapy. However, there is a clear need for new therapies to combat the cardiotoxic effects of cancer drugs. Exercise is a cardioprotective stimulus that has recently been shown to improve heart function and prevent functional disability in breast cancer patients undergoing anthracycline chemotherapy. Evidence from preclinical studies supports the use of exercise training to prevent or attenuate the damaging effects of anthracyclines on the cardiovascular system. In this review, we summarise findings from experimental models which provide insight into cellular mechanisms by which exercise may protect the heart from anthracycline-mediated damage, and identify knowledge gaps that require further investigation. Improved understanding of the mechanisms by which exercise protects the heart from anthracyclines may lead to the development of novel therapies to treat cancer therapy-related cardiotoxicity.

Exposure to Doxorubicin Modulates the Cardiac Response to Isoproterenol in Male and Female Mice

Sex is a salient risk factor in the development of doxorubicin-induced cardiotoxicity. Sex differences in the heart's ability to respond to hypertrophic stimuli in doxorubicin-exposed animals have not been reported. We identified the sexual dimorphic effects of isoproterenol in mice pre-exposed to doxorubicin. Male and female intact or gonadectomized C57BL/6N mice underwent five weekly intraperitoneal injections of 4 mg/kg doxorubicin followed by a five-week recovery period. Fourteen days of subcutaneous isoproterenol injections (10 mg/kg/day) were administered after the recovery period. Echocardiography was used to assess heart function one and five weeks after the last doxorubicin injection and on the fourteenth day of isoproterenol treatment. Thereafter, mice were euthanized, and the hearts were weighed and processed for histopathology and gene expression analysis. Doxorubicin did not produce overt cardiac dysfunction in male or female mice before starting isoproterenol treatment. The chronotropic response to a single isoproterenol injection was blunted by doxorubicin, but the inotropic response was maintained in both males and females. Pre-exposure to doxorubicin caused cardiac atrophy in both control and isoproterenol-treated male mice but not in female mice. Counterintuitively, pre-exposure to doxorubicin abrogated isoproterenol-induced cardiac fibrosis. However, there were no sex differences in the expression of markers of pathological hypertrophy, fibrosis, or inflammation. Gonadectomy did not reverse the sexually dimorphic effects of doxorubicin. Additionally, pre-exposure to doxorubicin abrogated the hypertrophic response to isoproterenol in castrated male mice but not in ovariectomized female mice. Therefore, pre-exposure to doxorubicin caused male-specific cardiac atrophy that persisted after isoproterenol treatment, which could not be prevented by gonadectomy.

Effect of cumulative daunorubicin dose on cardiotoxicity after allogeneic stem cell transplantation

Cardiotoxicity after allogeneic stem cell transplantation (SCT) is associated with a high rate of mortality and worsening quality of life. The relation between daunorubicin dose and post- allogeneic stem cell transplantation (SCT) cardiotoxicity remains unclear. We retrospectively evaluated 171 patients with acute myeloid leukemia (AML) who underwent their first allogeneic SCT at our institution between 2005 and 2021. High-dose daunorubicin (50 mg/m²/day for 5 days) and cytarabine were usually used as induction therapy for AML. The median cumulative daunorubicin dose was 310 mg/m² (range, 0-950 mg/m²), and 43 patients received two courses of induction therapy with high-dose daunorubicin (daunorubicin doses of ≥500 mg/m²). Cardiotoxicity developed in 12 patients, and the cumulative incidence at 2 years after SCT was 7.1%. Univariable analysis revealed that female sex, left ventricular ejection fraction (LVEF) of < 60% before SCT, and daunorubicin doses of ≥ 500 mg/m² were associated with cardiotoxicity. Multivariable analysis showed that a daunorubicin dose of ≥ 500 mg/m² was an independent risk factor for cardiotoxicity. LVEF decline during the study was observed with an increase in the daunorubicin dose, and only a daunorubicin dose of ≥ 500 mg/m2 was associated with a pre-SCT decreased LVEF. Second induction therapy with high-dose daunorubicin is a risk factor for cardiotoxicity after SCT. This should be taken into consideration when determining reinduction therapies for SCT-eligible patients with relapsed or refractory AML.

Endothelial dysfunction as a complication of anti-cancer therapy

Recent strides in anti-cancer therapeutics have improved longevity and led to a growing population of cancer survivors, who are increasingly likely to die of other causes. Treatment-induced cardiotoxicity is a complication of several therapeutic agents with acute and long-term consequences for cancer patients. Vascular endothelial dysfunction is a precursor and hallmark of ischemic coronary disease and may play a role in anti-cancer therapy-induced cardiotoxicity. This review summarizes clinical evidence for endothelial dysfunction following anti-cancer therapy and extends the discussion to include the impact of therapeutic agents on conduit arteries and the microcirculation. We highlight the role of innate immune system activation and cross-talk between inflammation and oxidative stress as pathogenic mechanisms underlying anti-cancer therapy-induced vascular toxicity. Understanding the impact of anti-cancer agents on the vascular endothelium will inform therapeutic approaches to prevent or reverse treatment-induced cardiotoxicity and may serve as an important tool to predict, monitor, and prevent adverse cardiovascular outcomes in patients undergoing treatment.

Anthracycline-induced cardiotoxicity: targeting high-density lipoproteins to limit the damage?

Doxorubicin (DOX) is an anthracycline antibiotic frequently used against a wide range of cancers, including breast cancer. Although the drug is effective as a treatment against cancer, many patients develop heart failure (HF) months to years following their last treatment with DOX. The challenge in preventing DOX-induced cardiotoxicity is that symptoms present after damage has already occurred in the myocardium. Therefore, early biomarkers to assess DOX-induced cardiotoxicity are urgently needed. A better understanding of the mechanisms involved in the toxicity is important as this may facilitate the development of novel early biomarkers or therapeutic approaches. In this review, we discuss the role of high-density lipoprotein (HDL) particles and its components as possible key players in the early development of DOX-induced cardiotoxicity. HDL particles exist in different subclasses which vary in composition and biological functionality. Multiple cardiovascular risk factors are associated with a change in HDL subclasses, resulting in modifications of their composition and physiological functions. There is growing evidence in the literature suggesting that cancer affects HDL subclasses and that healthy HDL particles enriched with sphingosine-1-phosphate (S1P) and apolipoprotein A1 (ApoA1) protect against DOX-induced cardiotoxicity. Here, we therefore discuss associations and relationships between HDL, DOX and cancer and discuss whether assessing HDL subclass/composition/function may be considered as a possible early biomarker to detect DOX-induced cardiotoxicity.

Statins Protect Against Early Stages of Doxorubicin-induced Cardiotoxicity Through the Regulation of Akt Signaling and SERCA2

Background

Doxorubicin-induced cardiomyopathy (DICM) is one of the complications that can limit treatment for a significant number of cancer patients. In animal models, the administration of statins can prevent the development of DICM. Therefore, the use of statins with anthracyclines potentially could enable cancer patients to complete their chemotherapy without added cardiotoxicity. The precise mechanism mediating the cardioprotection is not well understood. The purpose of this study is to determine the molecular mechanism by which rosuvastatin confers cardioprotection in a mouse model of DICM.

Methods

Rosuvastatin was intraperitoneally administered into adult male mice at 100 μg/kg daily for 7 days, followed by a single intraperitoneal doxorubicin injection at 10 mg/kg. Animals continued to receive rosuvastatin daily for an additional 14 days. Cardiac function was assessed by echocardiography. Optical calcium mapping was performed on retrograde Langendorff perfused isolated hearts. Ventricular tissue samples were analyzed by immunofluorescence microscopy, Western blotting, and quantitative polymerase chain reaction.

Results

Exposure to doxorubicin resulted in significantly reduced fractional shortening (27.4% ± 1.11% vs 40% ± 5.8% in controls; P < 0.001) and re-expression of the fetal gene program. However, we found no evidence of maladaptive cardiac hypertrophy or adverse ventricular remodeling in mice exposed to this dose of doxorubicin. In contrast, rosuvastatin-doxorubicin-treated mice maintained their cardiac function (39% ± 1.26%; P < 0.001). Mechanistically, the effect of rosuvastatin was associated with activation of Akt and phosphorylation of phospholamban with preserved sarcoplasmic/endoplasmic reticulum Ca²⁺ transporting 2 (SERCA2)-mediated Ca²⁺ reuptake. These effects occurred independently of perturbations in ryanodine receptor 2 function.

Conclusions

Rosuvastatin counteracts the cardiotoxic effects of doxorubicin by directly targeting sarcoplasmic calcium cycling.

Doxorubicin-induced cardiotoxicity is mediated by neutrophils through release of neutrophil elastase

The mechanisms by which Doxorubicin (Dox) causes acute and late cardiotoxicity are not completely understood. One understudied area is the innate immune response, and in particular the role of neutrophils in Dox-induced cardiotoxicity. Here, using echocardiography, flow cytometry and immunofluorescence staining, we demonstrated increased infiltration of neutrophils that correlated with decreased heart function, disruption of vascular structures and increased collagen deposition in the heart after Dox treatment. Depleting neutrophils protected the heart from Dox-induced cardiotoxicity and changes in vascular structure. Furthermore, our data using neutrophil elastase (NE) knock-out mice and the NE inhibitor AZD9668 suggest that neutrophils cause this damage by releasing NE and that inhibiting NE can prevent Dox-induced cardiotoxicity. This work shows the role of neutrophils and NE in Doxorubicin-induced cardiotoxicity for the first time and suggests a new possible therapeutic intervention.

Pharmacological senolysis reduces doxorubicin-induced cardiotoxicity and improves cardiac function in mice

Many anticancer agents used in clinics induce premature senescence in healthy tissues generating accelerated aging processes and adverse side-effects in patients. Cardiotoxicity is a well-known limiting factor of anticancer treatment with doxorubicin (DOX), a very effective anthracycline widely used as antitumoral therapy in clinical practice, that leads to long-term morbidity and mortality. DOX exposure severely affects the population of cardiac cells in both mice and human hearts by inducing premature senescence, which may represent the molecular basis of DOX-induced cardiomyopathy. Here, we demonstrate that senescence induction in the heart contributes to impaired cardiac function in mice upon DOX treatment. Concomitant elimination of senescent cells with the senolytic Navitoclax in different formulations produces a significant decrease in senescence and cardiotoxicity markers together with the restoration of the cardiac function in mice followed by echocardiography. These results evidence the potential clinical use of senolytic therapies to alleviate cardiotoxicities induced in chemotherapy-treated patients.

Long-Term Outcomes among Adolescent and Young Adult Survivors of Acute Leukemia: A Surveillance, Epidemiology, and End Results Analysis

BACKGROUND

There is a growing population of adolescent and young adult (AYA, age 15-39 years) acute leukemia survivors in whom long-term mortality outcomes are largely unknown.

METHODS

The current study utilized the Surveillance, Epidemiology, and End Results (SEER) registry to assess long-term outcomes of AYA acute leukemia 5-year survivors. The impact of diagnosis age, sex, race/ethnicity, socioeconomic status, and decade of diagnosis on long-term survival were assessed utilizing an accelerated failure time model.

RESULTS

A total of 1,938 AYA acute lymphoblastic leukemia (ALL) and 2,350 AYA acute myeloid leukemia (AML) survivors diagnosed between 1980 and 2009 were included with a median follow-up of 12.3 and 12.7 years, respectively. Ten-year survival for ALL and AML survivors was 87% and 89%, respectively, and 99% for the general population. Survival for AYA leukemia survivors remained below that of the age-adjusted general population at up to 30 years of follow-up. Primary cancer mortality was the most common cause of death in early survivorship with noncancer causes of death becoming more prevalent in later decades of follow-up. Male AML survivors had significantly worse survival than females (survival time ratio: 0.61, 95% confidence interval: 0.45-0.82).

CONCLUSIONS

AYA leukemia survivors have higher mortality rates than the general population that persist for decades after diagnosis.

IMPACT

While there have been improvements in late mortality, long-term survival for AYA leukemia survivors remains below that of the general population. Studies investigating risk factors for mortality and disparities in late effects among long-term AYA leukemia survivors are needed.

Sex and Gender Differences in Anticancer Treatment Toxicity: A Call for Revisiting Drug Dosing in Oncology

The practice of oncology has dramatically changed in the last decade with the introduction of molecular tumor profiling into routine tumor diagnostics and the extraordinary progress in immunotherapies. However, there remains an unmet need to explore personalized dosing strategies that take into account the patient's sex and gender to optimize the balance between efficacy and toxicity for each individual patient. In this mini-review, we summarize the evidence on sex and gender differences in toxicity of anticancer therapies and present data on dose reduction and dose discontinuation rates for selected chemotherapies and targeted therapies. Finally, we propose the investigation of body composition (specifically fat-free muscle mass) as a viable approach for personalized treatment dosage.

Sex Differences in Risk of Severe Adverse Events in Patients Receiving Immunotherapy, Targeted Therapy, or Chemotherapy in Cancer Clinical Trials

PURPOSE

Women have more adverse events (AEs) from chemotherapy than men, but few studies have investigated sex differences in immune or targeted therapies. We examined AEs by sex across different treatment domains.

METHODS

We analyzed treatment-related AEs by sex in SWOG phase II and III clinical trials conducted between 1980 and 2019, excluding sex-specific cancers. AE codes and grade were categorized using the Common Terminology Criteria for Adverse Events. Symptomatic AEs were defined as those aligned with the National Cancer Institute's Patient-Reported Outcome-Common Terminology Criteria for Adverse Events; laboratory-based or observable/measurable AEs were designated as objective (hematologic v nonhematologic). Multivariable logistic regression was used, adjusting for age, race, and disease prognosis. Thirteen symptomatic and 14 objective AE categories were examined.

RESULTS

In total, N = 23,296 patients (women, 8,838 [37.9%]; men, 14,458 [62.1%]) from 202 trials experiencing 274,688 AEs were analyzed; 17,417 received chemotherapy, 2,319 received immunotherapy, and 3,560 received targeted therapy. Overall, 64.6% (n = 15,051) experienced one or more severe (grade ≥ 3) AEs. Women had a 34% increased risk of severe AEs compared with men (odds ratio [OR] = 1.34; 95% CI, 1.27 to 1.42; P < .001), including a 49% increased risk among those receiving immunotherapy (OR = 1.49; 95% CI, 1.24 to 1.78; P < .001). Women experienced an increased risk of severe symptomatic AEs among all treatments, especially immunotherapy (OR = 1.66; 95% CI, 1.37 to 2.01; P < .001). Women receiving chemotherapy or immunotherapy experienced increased severe hematologic AE. No statistically significant sex differences in risk of nonhematologic AEs were found.

CONCLUSION

The greater severity of both symptomatic AEs and hematologic AEs in women across multiple treatment modalities indicates that broad-based sex differences exist. This could be due to differences in AE reported, pharmacogenomics of drug metabolism/disposition, total dose received, and/or adherence to therapy. Particularly large sex differences were observed for patients receiving immunotherapy, suggesting that studying AEs from these agents is a priority.

Cardiac SIRT1 ameliorates doxorubicin-induced cardiotoxicity by targeting sestrin 2

Although it is known that the expression and activity of sirtuin 1 (SIRT1) significantly decrease in doxorubicin (DOX)-induced cardiomyopathy, the role of interaction between SIRT1 and sestrin 2 (SESN2) is largely unknown. In this study, we investigated whether SESN2 could be a crucial target of SIRT1 and the effect of their regulatory interaction and mechanism on DOX-induced cardiac injury. Here, using DOX-treated cardiomyocytes and cardiac-specific Sirt1 knockout mice models, we found SIRT1 deficiency aggravated DOX-induced cardiac structural abnormalities and dysfunction, whereas the activation of SIRT1 by resveratrol (RES) treatment or SIRT1 overexpression possessed cardiac protective effects. Further studies indicated that SIRT1 exerted these beneficial effects by markedly attenuating DOX-induced oxidative damage and apoptosis in a SESN2-dependent manner. Knockdown of Sesn2 impaired RES/SIRT1-mediated protective effects, while upregulation of SESN2 efficiently rescued DOX-induced oxidative damage and apoptosis. Most importantly, SIRT1 activation could reduce DOX-induced SESN2 ubiquitination possibly through reducing the interaction of SESN2 with mouse double minute 2 (MDM2). The recovery of SESN2 stability in DOX-impaired primary cardiomyocytes by SIRT1 was confirmed by Mdm2-siRNA transfection. Taken together, our findings indicate that disrupting the interaction between SESN2 and MDM2 by SIRT1 to reduce the ubiquitination of SESN2 is a novel regulatory mechanism for protecting hearts from DOX-induced cardiotoxicity and suggest that the activation of SIRT1-SESN2 axis has potential as a therapeutic approach to prevent DOX-induced cardiotoxicity.

Myocardial Extracellular Volume Fraction Measured by Cardiac Magnetic Resonance Imaging Negatively Correlates With Cardiomyocyte Breadth in a Healthy Porcine Model

Background

The extracellular volume fraction (ECV) derived from cardiac magnetic resonance imaging (MRI) is extensively used to evaluate myocardial fibrosis. However, due to the limited histological verification in healthy individuals, it remains unclear whether the size of cardiomyocytes may play a potential role in the physiological changes of ECV. The aim of this study was to examine the association between cardiomyocyte size and myocardial ECV by using a healthy porcine model.

Methods

Sixteen domestic healthy pigs were anesthetized and underwent cardiac MRI with mechanical controlled breathing. Intravenous contrast medium was introduced at a dose of 0.2–0.25 mmol/kg. The interventricular septum ECV was calculated using an established MRI procedure, which was based on the pre- and post-contrast T1 values of the heart and individual blood hematocrit. The cardiomyocyte breadth (CmyB) in cross section was measured by hematoxylin and eosin staining to reflect the cardiomyocyte size.

Results

Data were successfully acquired from 14 pigs. The CmyB was obtained from the myocardial tissues corresponding to the region of interest on cardiac MRI. The mean ± SD of the ECV was 0.253 ± 0.043, and the mean ± SD of the CmyB was 10.02 ± 0.84 μm. The ECV exhibited a negative correlation with the CmyB (r = −0.729, p = 0.003).

Conclusion

The myocardial ECV detected by cardiac MRI is negatively correlated with the CmyB in healthy pigs, demonstrating that the size of cardiomyocytes is potentially associated with the ECV under physiological conditions.

Physiologically Based Pharmacokinetic Modelling and Simulation to Predict the Plasma Concentration Profile of Doxorubicin

Doxorubicin (DOX) is still an important anticancer agent despite its tricky pharmacokinetics (PK) and toxicity potential. The advent of systems pharmacology enables the construction of PK models able to predict the concentration profiles of drugs and shed light on the underlying mechanisms involved in PK and pharmacodynamics (PD). By utilizing existing published data and by analysing two clinical case studies we attempt to create physiologically based pharmacokinetic (PBPK) models for DOX using widely accepted methodologies. Based on two different approaches on three different key points we derived eight plausible models. The validation of the models provides evidence that is all performing as designed and opens the way for further exploitation by integrating metabolites and pharmacogenomic information.

Mitochondrial-Targeted Therapy for Doxorubicin-Induced Cardiotoxicity

Anthracyclines, such as doxorubicin, are effective chemotherapeutic agents for the treatment of cancer, but their clinical use is associated with severe and potentially life-threatening cardiotoxicity. Despite decades of research, treatment options remain limited. The mitochondria is commonly considered to be the main target of doxorubicin and mitochondrial dysfunction is the hallmark of doxorubicin-induced cardiotoxicity. Here, we review the pathogenic mechanisms of doxorubicin-induced cardiotoxicity and present an update on cardioprotective strategies for this disorder. Specifically, we focus on strategies that can protect the mitochondria and cover different therapeutic modalities encompassing small molecules, post-transcriptional regulators, and mitochondrial transfer. We also discuss the shortcomings of existing models of doxorubicin-induced cardiotoxicity and explore advances in the use of human pluripotent stem cell derived cardiomyocytes as a platform to facilitate the identification of novel treatments against this disorder.

Differential cardiotoxic electrocardiographic response to doxorubicin treatment in conscious versus anesthetized mice

INTRODUCTION

Doxorubicin (DOX), an anticancer drug used in chemotherapy, causes significant cardiotoxicity. This study aimed to investigate the effects of DOX on mouse cardiac electrophysiology, in conscious versus anesthetized state.

METHODS

Male and female C57BL/6 mice were injected with saline, 20 or 30 mg/kg DOX. ECGs were recorded 5 days post-injection in conscious and isoflurane anesthetized states. ECGs were analyzed using a custom MATLAB software to determine P, PR, QRS, QTc, and RR intervals as well as heart rate variability (HRV).

RESULTS

ECGs from the same mouse demonstrated P wave and QTc shortening as well as PR and RR interval prolongation in anesthetized versus conscious saline-treated mice. ECG response to DOX was also modulated by anesthesia. DOX treatment induced significant ECG modulation in female mice alone. While DOX20 treatment caused decrease in P and QRS durations, DOX30 treatment-induced QTc and RR interval prolongation in anesthetized but not in conscious female mice. These data suggest significant sex differences and anesthesia-induced differences in ECG response to DOX. HRV measured in time and frequency domains, a metric of arrhythmia susceptibility, was increased in DOX20-treated mice compared to saline.

CONCLUSIONS

This study for the first time identifies that the ECG response to DOX is modulated by anesthesia. Furthermore, this response demonstrated stark sex differences. These findings could have significant implications in clinical diagnosis of DOX cardiotoxicity.

Pulmonary circulation-mediated heart targeting for the prevention of heart failure by inhalation of intrinsically bioactive nanoparticles

Heart failure is a serious clinical and public health problem. Currently there is an unmet demand for effective therapies for heart failure. Herein we reported noninvasive inhalation delivery of nanotherapies to prevent heart failure.

Methods: A reactive oxygen species (ROS)-scavenging material (TPCD) was synthesized, which was processed into antioxidative and anti-inflammatory nanoparticles (i.e., TPCD NP). By decoration with a mitochondrial-targeting moiety, a multilevel targeting nanotherapy TTPCD NP was engineered. Pulmonary accumulation of inhaled TPCD NP and underlying mechanisms were examined in mice. In vivo efficacies of nanotherapies were evaluated in mice with doxorubicin (DOX)-induced cardiomyopathy. Further, an antioxidative, anti-inflammatory, and pro-resolving nanotherapy (i.e., ATTPCD NP) was developed, by packaging a peptide Ac2-26. In vitro and in vivo efficacies of ATTPCD NP were also evaluated.

Results: TPCD NP alleviated DOX-induced oxidative stress and cell injury by internalization in cardiomyocytes and scavenging overproduced ROS. Inhaled TPCD NP can accumulate in the heart of mice by transport across the lung epithelial and endothelial barriers. Correspondingly, inhaled TPCD NP effectively inhibited DOX-induced heart failure in mice. TTPCD NP showed considerably enhanced heart targeting capability, cellular uptake efficiency, and mitochondrial localization capacity, thereby potentiating therapeutic effects. Notably, TPCD NP can serve as bioactive and ROS-responsive nanovehicles to achieve combination therapy with Ac2-26, affording further enhanced efficacies. Importantly, inhaled TPCD NP displayed good safety at a dose 5-fold higher than the efficacious dose.

Conclusions: Inhalation delivery of nanoparticles is an effective, safe, and noninvasive strategy for targeted treatment of heart diseases. TPCD NP-based nanotherapies are promising drugs for heart failure and other acute/chronic heart diseases associated with oxidative stress.

Risk Factors of Daunorubicine Induced Early Cardiotoxicity in Childhood Acute Lymphoblastic Leukemia: A Retrospective Study

Background:

Daunorubicine, a type of anthracycline, is a drug commonly used in cancer chemotherapy that increases survival rate but consequently compromises with cardiovascular outcomes in some patients. Thus, preventing the early progression of cardiotoxicity is important to improve the treatment outcome in childhood acute lymhoblastic leukemia (ALL).

Objective:

The present study aimed to identify the risk factors in anthracycline-induced early cardiotoxicity in childhood ALL.

Methods:

This retrospective study was conducted by observing ALL-diagnosed children from 2014 to 2019 in Dr. Soetomo General Hospital. There were 49 patients who met the inclusion criteria and were treated with chemotherapy using Indonesian Childhood ALL Protocol 2013. Echocardiography was performed by pediatric cardiologists to compare before and at any given time after anthracycline therapy. Early cardiotoxicity was defined as a decline of left ventricle ejection fraction (LVEF) greater than 10% with a final LVEF < 53% during the first year of anthracycline administration. Risk factors such as sex, age, risk stratification group, and cumulative dose were identified by using multiple logistic regression. Diagnostic performance of cumulative anthracycline dose was evaluated by receiver operating characteristic (ROC) curve.

Results:

Early anthracycline-induced cardiotoxicity was observed in 5 out of 49 patients. The median cumulative dose of anthracycline was 143.69±72.68 mg/m². Thirty-three patients experienced a decreasing LVEF. The factors associated with early cardiomyopathy were age of ≥ 4 years (PR= 1.128; 95% CI: 1.015-1.254; p= 0.001), high risk group (PR= 1.135; 95% CI: 1.016-1.269; p= 0.001), and cumulative dose of ≥120 mg / m² (CI= 1.161; 95% CI:1.019-1.332).

Conclusion:

Age of ≥ 4 years, risk group, and cumulative dose of ≥120 mg/m² are significant risk factors for early cardiomyopathy in childhood ALL.

CYP1B1 as a therapeutic target in cardio-oncology

Cardiovascular complications have been frequently reported in cancer patients and survivors, mainly because of various cardiotoxic cancer treatments. Despite the known cardiovascular toxic effects of these treatments, they are still clinically used because of their effectiveness as anti-cancer agents. In this review, we discuss the growing body of evidence suggesting that inhibition of the cytochrome P450 1B1 enzyme (CYP1B1) can be a promising therapeutic strategy that has the potential to prevent cancer treatment-induced cardiovascular complications without reducing their anti-cancer effects. CYP1B1 is an extrahepatic enzyme that is expressed in cardiovascular tissues and overexpressed in different types of cancers. A growing body of evidence is demonstrating a detrimental role of CYP1B1 in both cardiovascular diseases and cancer, via perturbed metabolism of endogenous compounds, production of carcinogenic metabolites, DNA adduct formation, and generation of reactive oxygen species (ROS). Several chemotherapeutic agents have been shown to induce CYP1B1 in cardiovascular and cancer cells, possibly via activating the Aryl hydrocarbon Receptor (AhR), ROS generation, and inflammatory cytokines. Induction of CYP1B1 is detrimental in many ways. First, it can induce or exacerbate cancer treatment-induced cardiovascular complications. Second, it may lead to significant chemo/radio-resistance, undermining both the safety and effectiveness of cancer treatments. Therefore, numerous preclinical studies demonstrate that inhibition of CYP1B1 protects against chemotherapy-induced cardiotoxicity and prevents chemo- and radio-resistance. Most of these studies have utilized phytochemicals to inhibit CYP1B1. Since phytochemicals have multiple targets, future studies are needed to discern the specific contribution of CYP1B1 to the cardioprotective and chemo/radio-sensitizing effects of these phytochemicals.

The Determining Role of Mitochondrial Reactive Oxygen Species Generation and Monoamine Oxidase Activity in Doxorubicin-Induced Cardiotoxicity

Aims: Doxorubicin cardiomyopathy is a lethal pathology characterized by oxidative stress, mitochondrial dysfunction, and contractile impairment, leading to cell death. Although extensive research has been done to understand the pathophysiology of doxorubicin cardiomyopathy, no effective treatments are available. We investigated whether monoamine oxidases (MAOs) could be involved in doxorubicin-derived oxidative stress, and in the consequent mitochondrial, cardiomyocyte, and cardiac dysfunction. Results: We used neonatal rat ventricular myocytes (NRVMs) and adult mouse ventricular myocytes (AMVMs). Doxorubicin alone (i.e., 0.5 μM doxorubicin) or in combination with H₂O₂ induced an increase in mitochondrial formation of reactive oxygen species (ROS), which was prevented by the pharmacological inhibition of MAOs in both NRVMs and AMVMs. The pharmacological approach was supported by the genetic ablation of MAO-A in NRVMs. In addition, doxorubicin-derived ROS caused lipid peroxidation and alterations in mitochondrial function (i.e., mitochondrial membrane potential, permeability transition, redox potential), mitochondrial morphology (i.e., mitochondrial distribution and perimeter), sarcomere organization, intracellular [Ca²⁺] homeostasis, and eventually cell death. All these dysfunctions were abolished by MAO inhibition. Of note, in vivo MAO inhibition prevented chamber dilation and cardiac dysfunction in doxorubicin-treated mice. Innovation and Conclusion: This study demonstrates that the severe oxidative stress induced by doxorubicin requires the involvement of MAOs, which modulate mitochondrial ROS generation. MAO inhibition provides evidence that mitochondrial ROS formation is causally linked to all disorders caused by doxorubicin in vitro and in vivo. Based upon these results, MAO inhibition represents a novel therapeutic approach for doxorubicin cardiomyopathy.

Consideration of Sex as a Biological Variable in the Development of Doxorubicin Myotoxicity and the Efficacy of Exercise as a Therapeutic Intervention

Doxorubicin (DOX) is an anthracycline antibiotic used to treat a wide variety of hematological and solid tumor cancers. While DOX is highly effective at reducing tumor burden, its clinical use is limited by the development of adverse effects to both cardiac and skeletal muscle. The detrimental effects of DOX to muscle tissue are associated with the increased incidence of heart failure, dyspnea, exercise intolerance, and reduced quality of life, which have been reported in both patients actively receiving chemotherapy and cancer survivors. A variety of factors elevate the probability of DOX-related morbidity in patients; however, the role of sex as a biological variable to calculate patient risk remains unclear. Uncertainty regarding sexual dimorphism in the presentation of DOX myotoxicity stems from inadequate study design to address this issue. Currently, the majority of clinical data on DOX myotoxicity come from studies where the ratio of males to females is unbalanced, one sex is omitted, and/or the patient cohort include a broad age range. Furthermore, lack of consensus on standard outcome measures, difficulties in long-term evaluation of patient outcomes, and other confounding factors (i.e., cancer type, drug combinations, adjuvant therapies, etc.) preclude a definitive answer as to whether differences exist in the incidence of DOX myotoxicity between sexes. This review summarizes the current clinical and preclinical literature relevant to sex differences in the incidence and severity of DOX myotoxicity, the proposed mechanisms for DOX sexual dimorphism, and the potential for exercise training to serve as an effective therapeutic countermeasure to preserve muscle strength and function in males and females.

Diagnosis, Prevention, Treatment and Surveillance of Anthracycline-Induced Cardiovascular Toxicity in Pediatric Cancer Survivors

Advances in pediatric cancer therapies have dramatically improved the likelihood of survival. As survivors are aging, however, we are now understanding that treatment carries a significant risk of cardiovascular toxicity, which can develop immediately, or even many years after completing therapy. Anthracycline derivates are some of the most commonly used agents in pediatric oncology treatment protocols, which have a dose-dependent correlation with the development of cardiac toxicity. As we learn more about the mechanisms of toxicity, we are developing prevention strategies, including improvements in surveillance, to improve early diagnosis of heart disease. Current survivorship surveillance protocols often include screening echocardiograms to evaluate systolic function by measuring the ejection fraction or fractional shortening. However, these measurements alone are not enough to capture early myocardial changes. The use of additional imaging biomarkers, serum biomarkers, electrocardiograms, as well as cholesterol and blood pressure screening, are key to the early detection of cardiomyopathy and cardiovascular disease. Medical treatment strategies are the same as those used for heart failure from other causes, but earlier recognition and implementation can lead to improved long term outcomes.

Aerobic exercise training attenuates doxorubicin-induced ultrastructural changes in rat ventricular myocytes

AIMS

To investigate the effects of aerobic exercise training on cardiomyocyte ultrastructure, oxidative stress, and activation of protein synthesis pathways in a model of cardiomyopathy induced by doxorubicin (Dox).

MAIN METHODS

Male Sprague Dawley rats were randomly assigned to Control (saline, sedentary), Dox/sedentary (DoxSed), or Dox/exercise (DoxEx) groups. Saline or Dox were injected i.p. for 10 days (1 mg/kg/d). Aerobic exercise training was performed for 9 wks (starting with drug administration) on a treadmill, 5 d/wk, 30 min/d at 60% of maximum velocity. After euthanasia, the left ventricle (LV) was dissected, and processed for microscopy or frozen for Western blot and kinetic measurement of antioxidant enzymes activity.

KEY FINDINGS

Dox resulted in a mortality of 31.2% of sedentary animals, whilst all animals from both Control and DoxEx groups survived. DoxSed animals presented increased LV connective tissue deposition alongside with massive sarcomeric disorganization with dissolution of myofibrils and wavy Z-lines. There was an increase in oxidative damage and a reduction in the activation of both Akt and ERK pathways in LV from DoxSed compared to Control group. Aerobic training caused notable changes in myocardial structure with reduced fibrosis and preservation of myofibrils integrity and sarcomere organization. This was associated with reduced LV oxidative damage and increased activity of antioxidant enzymes, and an increase in the activation of PI3K-Akt pathway.

SIGNIFICANCE

Aerobic exercise training was effective in preventing mortality caused by Dox and in preserving LV ultrastructure, partially via activation of the physiological protein synthesis pathway, PI3K-Akt, and reducing oxidative stress.

Telomerase therapy attenuates cardiotoxic effects of doxorubicin

Doxorubicin is one of the most potent chemotherapeutic agents. However, its clinical use is restricted due to the severe risk of cardiotoxicity, partially attributed to elevated production of reactive oxygen species (ROS). Telomerase canonically maintains telomeres during cell division but is silenced in adult hearts. In non-dividing cells such as cardiomyocytes, telomerase confers pro-survival traits, likely owing to the detoxification of ROS. Therefore, we hypothesized that pharmacological overexpression of telomerase may be used as a therapeutic strategy for the prevention of doxorubicin-induced cardiotoxicity. We used adeno-associated virus (AAV)-mediated gene therapy for long-term expression of telomerase in in vitro and in vivo models of doxorubicin-induced cardiotoxicity. Overexpression of telomerase protected the heart from doxorubicin-mediated apoptosis and rescued cardiac function, which was accompanied by preserved cardiomyocyte size. At the mechanistic level, we observed altered mitochondrial morphology and dynamics in response to telomerase expression. Complementary in vitro experiments confirmed the anti-apoptotic effects of telomerase overexpression in human induced pluripotent stem cell-derived cardiomyocytes after doxorubicin treatment. Strikingly, elevated levels of telomerase translocated to the mitochondria upon doxorubicin treatment, which helped to maintain mitochondrial function. Thus, telomerase gene therapy could be a novel preventive strategy for cardiotoxicity by chemotherapy agents such as the anthracyclines.

p38δ genetic ablation protects female mice from anthracycline cardiotoxicity

The efficacy of an anthracycline antibiotic doxorubicin (DOX) as a chemotherapeutic agent is limited by dose-dependent cardiotoxicity. DOX is associated with activation of intracellular stress signaling pathways including p38 MAPKs. While previous studies have implicated p38 MAPK signaling in DOX-induced cardiac injury, the roles of the individual p38 isoforms, specifically, of the alternative isoforms p38γ and p38δ, remain uncharacterized. We aimed to determine the potential cardioprotective effects of p38γ and p38δ genetic deletion in mice subjected to acute DOX treatment. Male and female wild-type (WT), p38γ-/-, p38δ-/-, and p38γ-/-δ-/- mice were injected with 30 mg/kg DOX and their survival was tracked for 10 days. During this period, cardiac function was assessed by echocardiography and electrocardiography and fibrosis by Picro Sirius Red staining. Immunoblotting was performed to assess the expression of signaling proteins and markers linked to autophagy. Significantly improved survival was observed in p38δ-/- female mice post-DOX relative to WT females, but not in p38γ-/- or p38γ-/-δ-/- male or female mice. The improved survival in DOX-treated p38δ-/- females was associated with decreased fibrosis, increased cardiac output and LV diameter relative to DOX-treated WT females, and similar to saline-treated controls. Structural and echocardiographic parameters were either unchanged or worsened in all other groups. Increased autophagy, as suggested by increased LC3-II level, and decreased mammalian target of rapamycin activation was also observed in DOX-treated p38δ-/- females. p38δ plays a crucial role in promoting DOX-induced cardiotoxicity in female mice by inhibiting autophagy. Therefore, p38δ targeting could be a potential cardioprotective strategy in anthracycline chemotherapy.NEW & NOTEWORTHY This study for the first time identifies the sex-specific roles of the alternative p38γ and p38δ MAPK isoforms in promoting doxorubicin (DOX) cardiotoxicity. We show that p38δ and p38γ/δ systemic deletion was cardioprotective in female but not in male mice. Cardiac structure and function were preserved in DOX-treated p38δ-/- females and autophagy marker was increased.

Cell Therapy Improves Cardiac Function in Anthracycline-Induced Cardiomyopathy Preclinical Models: A Systematic Review and Meta-Analysis

Although anthracycline (ANT)-based treatment strongly contributes to cancer survivorship, the use of these agents is limited by the risk of cardiotoxicity. For those patients who evolve to heart failure, myocardial regenerative approaches are of particular interest, and a growing body of preclinical studies has been investigating the use of cell therapy for ANT-induced cardiomyopathy (AIC). However, since animal models and modalities of cell therapy are highly heterogeneous between studies, the efficacy of cell therapy for AIC is not clear. Thus, we conducted a systematic review and meta-analysis of experimental studies reporting the use of cell therapy with mesenchymal stromal cells (MSC) or bone marrow mononuclear cells (BMMNC) in animal models of AIC with regard to global cardiac function. The Medline, EMBASE, and Web of Science databases were searched from inception to November 2019. Two reviewers independently extracted data on study quality and the results of left ventricular ejection fraction (LVEF) and fractional shortening (FS) obtained by echocardiography. The quality of outcomes was assessed using the Cochrane, Collaborative Approach to Meta-Analysis and Review of Animal Data from Experimental Studies (CAMARADES), and SYRCLE bias risk tools. Pooled random-effects modeling was used to calculate pooled mean differences (MD) and 95% confidence intervals (CIs). Twenty-two studies comprising 381 small animals (rabbits and rodents) were included. A pooled meta-analysis of all treatments showed that cell therapy increased LVEF by 9.87% (95% CI 7.25-12.50, P < 0.00001) and FS by 7.80% (95% CI 5.68-9.92, P < 0.00001) in small animals with AIC. Cell therapy with MSC/BMMNC is effective to mitigate the deleterious effects of ANT on cardiac function in preclinical models. Nevertheless, due to the small number of studies and considerable heterogeneity, future translational studies must be designed to diminish between-study discrepancies and increase similarity to the clinical landscape.

Sex-Related Differences in Dilated Cardiomyopathy with a Focus on Cardiac Dysfunction in Oncology

PURPOSE OF REVIEW

The aim of this report is to describe the main aspects of sex-related differences in non-ischemic dilated cardiomyopathies (DCM), focusing on chemotherapy-induced heart failure (HF) and investigating the possible therapeutic implications and clinical management applications in the era of personalized medicine.

RECENT FINDINGS

In cardio-oncology, molecular and multimodality imaging studies confirm that sex differences do exist, affecting the therapeutic cardioprotective strategies and, therefore, the long-term outcomes. Interestingly, compelling evidences suggest that sex-specific characteristics in drug toxicity might predict differences in the therapeutic response, most likely due to the tangled interplay between cancer and HF, which probably share common underlying mechanisms. Cardiovascular diseases show many sex-related differences in prevalence, etiology, phenotype expression, and outcomes. Complex molecular mechanisms underlie this diverse pathological manifestations, from sex-determined differential gene expression to sex hormone interaction with their receptors in the heart. Non-ischemic DCM is an umbrella definition that incorporates several etiologies, including chemotherapy-induced cardiomyopathies. The role of sex as a risk factor for cardiotoxicity is poorly explored. However, understanding the various features of disease manifestation and outcomes is of paramount importance for a prompt and tailored evaluation.

Lack of sexual dimorphism in a mouse model of isoproterenol-induced cardiac dysfunction

Sex-related differences in cardiovascular diseases are highly complex in humans and model-dependent in experimental laboratory animals. The objective of this work was to comprehensively investigate key sex differences in the response to acute and prolonged adrenergic stimulation in C57Bl/6NCrl mice. Cardiac function was assessed by trans-thoracic echocardiography before and after acute adrenergic stimulation (a single sub-cutaneous dose of isoproterenol 10 mg/kg) in 15 weeks old male and female C57Bl/6NCrl mice. Thereafter, prolonged adrenergic stimulation was achieved by sub-cutaneous injections of isoproterenol 10 mg/kg/day for 14 days in male and female mice. Cardiac function and morphometry were assessed by trans-thoracic echocardiography on the 15th day. Thereafter, the mice were euthanized, and the hearts were collected. Histopathological analysis of myocardial tissue was performed after staining with hematoxylin & eosin, Masson's trichrome and MAC-2 antibody. Gene expression of remodeling and fibrotic markers was assessed by real-time PCR. Cardiac function and morphometry were also measured before and after isoproterenol 10 mg/kg/day for 14 days in groups of gonadectomized male and female mice and sham-operated controls. In the current work, there were no statistically significant differences in the positive inotropic and chronotropic effects of isoproterenol between male and female C57Bl/6NCrl. After prolonged adrenergic stimulation, there was similar degree of cardiac dysfunction, cardiac hypertrophy, and myocardial fibrosis in male and female mice. Similarly, prolonged isoproterenol administration induced hypertrophic and fibrotic genes in hearts of male and female mice to the same extent. Intriguingly, gonadectomy of male and female mice did not have a significant impact on isoproterenol-induced cardiac dysfunction as compared to sham-operated animals. The current work demonstrated lack of significant sex-related differences in isoproterenol-induced cardiac hypertrophy, dysfunction, and fibrosis in C57Bl/6NCrl mice. This study suggests that female sex may not be sufficient to protect the heart in this model of isoproterenol-induced cardiac dysfunction and underscores the notion that sexual dimorphism in cardiovascular diseases is highly model-dependent.

Toxicity and Pharmacogenomic Biomarkers in Breast Cancer Chemotherapy

Breast cancer (BC) is one of the most prevalent types of cancer worldwide with high morbidity and mortality rates. Treatment modalities include systemic therapy, in which chemotherapy is a major component in many cases. Several chemotherapeutic agents are used in combinations or as single agents with many adverse events occurring in variable frequencies. These events can be a significant barrier in completing the treatment regimens. Germline genomic variants are thought of as potential determinants in chemotherapy response and the development of side effects. Some pharmacogenomic studies were designed to explore germline variants that can be used as biomarkers for predicting developing toxicity or adverse events during chemotherapy in BC. In this review, we reassess and summarize the major findings of pharmacogenomic studies of chemotherapy toxicity during BC management. In addition, deficiencies hampering utilizing these findings and the potential targets of future research are emphasized. Main insufficiencies in toxicity pharmacogenomics studies originate from study design, sample limitations, heterogeneity of selected genes, variants, and toxicity definitions. With the advent of high throughput genotyping techniques, researchers are expected to explore the identified as well as the potential genetic biomarkers of toxicity and efficacy to improve BC management. However, to achieve this, the limitations of previous work should be evaluated and avoided to reach more conclusive and translatable evidence for personalizing BC chemotherapy.

The Role of AMPK Activation for Cardioprotection in Doxorubicin-Induced Cardiotoxicity

Doxorubicin is a commonly used chemotherapeutic agent for the treatment of a range of cancers, but despite its success in improving cancer survival rates, doxorubicin is cardiotoxic and can lead to congestive heart failure. Therapeutic options for this patient group are limited to standard heart failure medications with the only drug specific for doxorubicin cardiotoxicity to reach FDA approval being dexrazoxane, an iron-chelating agent targeting oxidative stress. However, dexrazoxane has failed to live up to its expectations from preclinical studies while also bringing up concerns about its safety. Despite decades of research, the molecular mechanisms of doxorubicin cardiotoxicity are still poorly understood and oxidative stress is no longer considered to be the sole evil. Mitochondrial impairment, increased apoptosis, dysregulated autophagy and increased fibrosis have also been shown to be crucial players in doxorubicin cardiotoxicity. These cellular processes are all linked by one highly conserved intracellular kinase: adenosine monophosphate-activated protein kinase (AMPK). AMPK regulates mitochondrial biogenesis via PGC1α signalling, increases oxidative mitochondrial metabolism, decreases apoptosis through inhibition of mTOR signalling, increases autophagy through ULK1 and decreases fibrosis through inhibition of TGFβ signalling. AMPK therefore sits at the control point of many mechanisms shown to be involved in doxorubicin cardiotoxicity and cardiac AMPK signalling itself has been shown to be impaired by doxorubicin. In this review, we introduce different agents known to activate AMPK (metformin, statins, resveratrol, thiazolidinediones, AICAR, specific AMPK activators) as well as exercise and dietary restriction, and we discuss the existing evidence for their potential role in cardioprotection from doxorubicin cardiotoxicity.

Cardiovascular adverse events in patients with non-Hodgkin lymphoma treated with first-line cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or CHOP with rituximab (R-CHOP): a systematic review and meta-analysis

BACKGROUND

Patients treated for non-Hodgkin lymphoma are at risk of cardiovascular adverse events, with the risk of heart failure being particularly high. A regimen of cyclophosphamide, doxorubicin, vincristine, and prednisone, with (R-CHOP) or without (CHOP) rituximab is the standard first-line treatment for aggressive non-Hodgkin lymphoma, and doxorubicin and cyclophosphamide are both associated with left ventricular dysfunction. The aim of this systematic review and meta-analysis was to evaluate the cardiovascular toxicity of this regimen.

METHODS

We systematically searched PubMed, EMBASE, and the Cochrane Library from database inception to June 3, 2019, for clinical trials and observational studies in adult patients with non-Hodgkin lymphoma (diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, peripheral T-cell lymphoma, and non-Hodgkin lymphoma not otherwise specified) that received first-line treatment with R-CHOP or CHOP. Studies reporting on cardiovascular adverse events and treatment-related cardiovascular mortality were included. Abstracts and articles not written in English were excluded. The main outcomes were the proportion of patients with grade 3-4 cardiovascular adverse events and heart failure. Meta-analyses of one-sample proportions were done in all patients receiving CHOP or R-CHOP. Subgroup analyses on summary estimates were done to determine the effect of number of CHOP or R-CHOP cycles, cycle interval, age, and sex.

FINDINGS

Of 2314 identified entries, 137 studies (21 211 patients) published between April, 1984, and June, 2019 were eligible (9541 patients treated with CHOP, 11 293 patients treated with R-CHOP, 377 both regimens used in the study; median follow-up 39·0 months [IQR 25·5-52·8]). From the included studies, 85 subgroups were treated with CHOP, 76 with R-CHOP, and in four studies both CHOP and R-CHOP were used without a subdivision in separate groups. The pooled proportion for grade 3-4 cardiovascular adverse events, based on 77 studies (n=14 351 patients), was 2·35% (95% CI 1·81-2·93; heterogeneity test Q=326·21; τ²=0·0042; I²=71·40%; p<0·0001). For heart failure, the pooled proportion, based on 38 studies (n=5936 patients), was 4·62% (2·25-7·65; heterogeneity test Q=527·33; τ²=0·0384; I²=95·05%; p<0·0001), with a significant increase in reported heart failure from 1·64% (95% CI 0·82-2·65) to 11·72% (3·00-24·53) when cardiac function was evaluated post-chemotherapy (p=0·017). 53 (39%) of 137 studies were rated as having high risk of bias for incomplete outcome data and 54 (39%) for selective reporting.

INTERPRETATION

The considerable increase of reported heart failures with cardiac monitoring, indicates that this complication often remains undiagnosed in patients with non-Hodgkin lymphoma who received first-line R-CHOP or CHOP. Our findings are of importance to raise awareness of this complication among clinicians treating patients with non-Hodgkin lymphoma and stresses the need for cardiac monitoring during and after chemotherapy. Prompt initiation of treatment for heart failure in the presymptomatic phase can mitigate the progression to more advanced heart failure stages.

FUNDING

None.

Sexual Dimorphism in Doxorubicin-induced Systemic Inflammation: Implications for Hepatic Cytochrome P450 Regulation

Doxorubicin (DOX) is an effective chemotherapeutic agent used to treat a wide variety of malignancies. In addition to its multi-organ toxicity, DOX treatment has been shown to induce systemic inflammation in patients and experimental animals. Inflammation alters the expression of hepatic cytochrome P450 (CYP) enzymes, which play important roles in drug metabolism and DOX-induced toxicity. Significant sex differences have been reported in DOX-induced toxicity; however, sex differences in DOX-induced systemic inflammation and the potential effects on hepatic CYP expression have not been determined. In the current work, male and female C57Bl/6 mice were administered DOX (20 mg/kg by intraperitoneal injection), and groups of mice were sacrificed 24 and 72 h after DOX administration. DOX elicited a systemic inflammatory response in both male and female mice, but the inflammatory response was stronger in male mice. DOX altered the expression of hepatic CYP isoforms in a sex-dependent manner. Most notably, inhibition of Cyp2c29 and Cyp2e1 was stronger in male than in female mice, which paralleled the sex differences in systemic inflammation. Therefore, sex differences in DOX-induced systemic inflammation may lead to sexually dimorphic drug interactions, in addition to contributing to the previously reported sexual dimorphism in specific DOX-induced organ toxicity.

Sexual dimorphism of acute doxorubicin-induced nephrotoxicity in C57Bl/6 mice

Doxorubicin (DOX) is a chemotherapeutic agent that has been reported to cause nephrotoxicity in rodent models and to a lesser degree in cancer patients. Female rodents have been shown to be protected against several features of DOX-induced nephrotoxicity. Nevertheless, the underlying mechanisms of this sexual dimorphism are not fully elucidated. Therefore, in the current study, we investigated the sex and time-dependent changes in pathological lesions as well as apoptotic and fibrotic markers in response to acute DOX-induced nephrotoxicity. We also determined the effect of acute DOX treatment on the renal expression of the sexually dimorphic enzyme, soluble epoxide hydrolase (sEH), since inhibition of sEH has been shown to protect against DOX-induced nephrotoxicity. Acute DOX-induced nephrotoxicity was induced by a single intra-peritoneal injection of 20 mg/kg DOX to male and female adult C57Bl/6 mice. The kidneys were isolated 1, 3 and 6 days after DOX administration. Histopathology assessment, gene expression of the apoptotic marker, BAX, protein expression of the fibrotic marker, transforming growth factor-β (TGF-β), and gene and protein expression of sEH were assessed. DOX administration caused more severe pathological lesions as well as higher induction of the apoptotic and fibrotic markers in kidneys of male than in female mice. Intriguingly, DOX inhibited sEH protein expression in kidneys of male mice sacrificed at 3 and 6 days following administration, suggesting that induction of sEH is not necessary for acute DOX-induced nephrotoxicity. However, DOX-induced inhibition of renal sEH in male mice may protect the kidney from further DOX-induced injury in a negative feedback mechanism. We also observed lower constitutive expressions of TGF-β and sEH in the kidney of female mice which may contribute, at least in part, to sexual dimorphism of DOX-induced nephrotoxicity.