Microtubule Inhibitors and Cardiotoxicity

Nanobody-based immunotoxins: A precision tool in the treatment of solid tumors

Solid tumors, the main cause of cancer-related death, represent a significant therapeutic challenge due to the high-density microenvironment and intolerance to conventional treatments. Nanobody-based immunotoxins (NbITs) are an exciting candidate, combining the ultimate specificity of nanobodies (single-domain antibody fragments of camelid antibodies) and detrimental effects of the toxin. These nanobodies are small (one-tenth of conventional antibody size), thermostable with high specificity, high antigen binding affinity which give it the ability to penetrate into solid tumors. Specific delivery to tumor cells is achieved through conjugating nanobodies with cytotoxic agents of bacterial origin or synthetic drugs. This phenomenon is initially attracted to the cells by the antigen-antibody interaction that is further enhanced by receptor-mediated internalization and cytotoxic payload release that subdues essential cellular processes and, as a consequence, damages the cells. This review discusses the mechanisms that underlie the effectiveness of NbITs, such as tumor antigen recognition, toxin release, and cellular signaling pathways elicited by the internalized toxins. We also discuss the application of NbITs in treating cancers such as HER2-positive breast cancer and EGFR-overexpressing lung cancer, and other cancers, highlighting their ability to address limitations of conventional therapies. Key challenges in NbIT development, including stability, immunogenicity, and efficient delivery, are critically evaluated. Current advances such as the creation of bispecific nanobody constructs, optimization of linker strategies, as well as the incorporation of nanoparticle-based delivery systems are maximizing the therapeutic potential of these molecules. This review synthesizes recent progress and addresses current obstacles in NbIT development, showcasing their transformative potential as a targeted therapeutic approach for solid tumors. It also covers future opportunities to develop and advance this emerging treatment strategy.

The effects of sodium-glucose cotransporter-2 inhibitors in chemotherapy-induced cardiotoxicity and mortality in patients with cancer: a systematic review and meta-analysis

BACKGROUND

The effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors on reducing cardiovascular events in different subgroups of diabetic patients are under investigation. The current systematic review and meta-analysis investigated the effects of SGLT2 inhibitors on preventing cardiovascular events and mortality and their adverse events in patients with active cancer and diabetes undergoing cardiotoxic cancer treatment.

METHODS

We searched PubMed, Embase, Web of Science, and Scopus to find studies investigating the effects of SGLT2 inhibitors on patients with diabetes and confirmed cancer until 19 August 2024. Meta-analyses were conducted using the random-effects model to compare all-cause mortality, cancer-associated mortality, heart failure (HF) hospitalization, arrhythmia, and adverse event rates such as ketoacidosis, hypoglycemia, urinary tract infection, and sepsis between patients with or without SGLT2 inhibitors use. Risk ratios (RRs) with 95% confidence intervals (CI) were used to compare outcomes between SGLT2 inhibitors and non-SGLT2 inhibitors groups.

RESULTS

Eleven studies were included with 88,096 patients with confirmed cancer (49% male). Among the total population, 20,538 received SGLT2 inhibitors (age 61.68 ± 10.71), while 67,558 did not receive SGLT2 inhibitors (age 68.24 ± 9.48). The meta-analysis found that the patients who received SGLT2 inhibitors had a significantly lower mortality rate than those who did not receive SGLT2 inhibitors (RR 0.46, 95% CI 0.34 to 0.63, p-value < 0.0001). Similarly, the cancer-associated mortality rate was also lower (RR 0.29, 95% CI 0.27 to 0.30, p-value < 0.0001). Further analysis found that the SGLT2 inhibitor group had a lower rate of HF hospitalization, compared to controls (RR 0.44, 95% CI 0.27 to 0.70, p-value = 0.0007). Moreover, patients receiving SGLT2 inhibitors had a statistically lower rate of arrhythmia (RR 0.38, 95% CI 0.26 to 0.56, p-value < 0.0001). Finally, patients in the SGLT2 inhibitors group had a lower rate of adverse events (RR 0.51, 95% CI 0.42 to 0.62, p-value < 0.0001).

CONCLUSIONS

SGLT2 inhibitors are effective in reducing mortality (all-cause and cancer-associated), HF hospitalization, arrhythmia, and drug adverse events in patients with cancer. If confirmed in future studies, these agents could be a potentially ideal candidate to prevent cardiotoxicity of cancer therapies.

Mechanisms of mitotic inhibition in human aorta endothelial cells: Molecular and morphological in vitro spectroscopic studies

Mitotic inhibitors are drugs commonly used in chemotherapy, but their nonspecific and indiscriminate distribution throughout the body after intravenous administration can lead to serious side effects, particularly on the cardiovascular system. In this context, our investigation into the mechanism of the cytotoxic effects on endothelial cells of mitotic inhibitors widely used in cancer treatment, such as paclitaxel (also known as Taxol) and Vinca alkaloids, holds significant practical implications. Understanding these mechanisms can lead to more targeted and less harmful cancer treatments. Human aorta endothelial cells (HAECs) were incubated with selected mitotic inhibitors in a wide range of concentrations close to those in human plasma during anticancer therapy. The analysis of single cells imaged by Raman spectroscopy allowed for visualization of the nuclear, cytoplasmic, and perinuclear areas to assess biochemical changes induced by the drug's action. The results showed significant changes in the morphology and molecular composition of the nucleus. Moreover, an effect of a given drug on the cytoplasm was observed, which can be related to its mechanism of action (MoA). Raman data supported by fluorescence microscopy measurements identified unique changes in DNA form and proteins and revealed drug-induced inflammation of endothelial cells. The primary goal of mitotic inhibitors is based on the impairment of tubulin formation and the inhibition of the mitosis process. While all three drugs affect microtubules and disrupt cell division, they do so through different MoA, i.e., Vinca alkaloids inhibit microtubule formation, whereas paclitaxel stabilizes microtubules. To sum up, the work shows how a specific drug can interact with endothelial cells.

Palladium-Mediated Bioorthogonal System for Prodrug Activation of N-Benzylbenzamide-Containing Tubulin Polymerization Inhibitors for the Treatment of Solid Tumors

Bioorthogonal cleavage reactions have been developed as an intriguing strategy to enhance the safety of chemotherapeutics. Aiming to reduce the toxicity and improve the targeted release properties of the colchicine binding site inhibitors (CBSIs) based on previous work, a series of biologically inert prodrugs were further designed and synthesized through a bioorthogonal prodrug strategy. The therapeutic effects of prodrugs could be "turned-on" once combined with palladium resins. Particularly, prodrug 2b was 68.3-fold less cytotoxic compared to the parent compound, while its cytotoxicity was recovered in situ in the presence of palladium resins. Mechanism studies confirmed that 2b inhibited cell growth in the same manner as CBSIs. More importantly, in vivo efficacy studies demonstrated the efficient activation of 2b by palladium resins, resulting in significant inhibition of tumor growth (63.2%). These results suggest that prodrug 2b with improved safety and targeted release property catalyzed by a Pd-mediated bioorthogonal cleavage reaction deserves further investigation.

AMPK activation; a potential strategy to mitigate TKI-induced cardiovascular toxicity

The introduction of Tyrosine Kinase Inhibitors (TKIs) has revolutionised cancer treatment, yet concerns regarding cardiovascular toxicity have surfaced. This piece delves into the interplay between AMP-activated protein kinase (AMPK) signalling and TKI-induced cardiovascular toxicity. The study unravels the intricate relationship between AMPK activation and TKI-induced cardiovascular toxicity, aiming to ascertain whether AMPK can play a strategic role in mitigating adverse effects. Beyond unravelling mechanistic insights, the research sets the stage for future therapeutic approaches, envisioning AMPK activation as a pivotal connection for balancing effective cancer treatment with cardiovascular well-being. As research advances, the potential of AMPK activation not only addresses challenges in TKI-induced cardiovascular toxicity but also shapes the future landscape of personalised anticancer therapies. The article explores the mechanisms of TKI-induced toxicity, AMPK's impact on cardiovascular health, and the potential therapeutic implications of AMPK activation in alleviating TKI-associated toxicities.

Citrinin disrupts microtubule assembly in cardiac cells: Impact on mitochondrial organization and function

Citrinin (CTN) is a mycotoxin commonly present in various foods and feeds worldwide, as well as dietary supplements in Asian countries, but the risks and cellular mechanisms associated with its cardiotoxicity remains unclear. In this study, RNA-seq analysis of CTN-treated H9c2 cardiac cells demonstrated significant perturbations in pathways related to microtubule cytoskeleton and mitochondrial network organization. CTN disrupted microtubule polymerization and downregulated mRNA levels of microtubule-assembling genes, Map2 and Tpx2, in H9c2 cardiac cells. Additionally, CTN interfered with the distribution of mitochondrial network along the microtubules, leading to the accumulation of dysfunctional mitochondria characterized by elevated superoxide levels and reduced membrane potential. This disruption also caused the buildup of lysosomes and ubiquitinated proteins, which hindered waste clearance in microtubule-disassembled H9c2 cells. Molecular docking analysis indicated that CTN could bind to the colchicine binding site on β-tubulin, thereby mimicking the microtubule-disrupting effect of colchicine. This study provides morphological, transcriptomic, and mechanistic evidence to elucidate the cardiotoxic mechanisms of CTN, which involve the dysregulated microtubule network, subsequent mitochondrial mislocalization, and impaired proteolysis of damaged proteins/organelles in cardiac cells. Our findings may enhance the fundamental understanding and facilitate future risk assessment of CTN.

A Comprehensive Overview on Chemotherapy-Induced Cardiotoxicity: Insights into the Underlying Inflammatory and Oxidative Mechanisms

While oncotherapy has made rapid progress in recent years, side effects of anti-cancer drugs and treatments have also come to the fore. These side effects include cardiotoxicity, which can cause irreversible cardiac damages with long-term morbidity and mortality. Despite the continuous in-depth research on anti-cancer drugs, an improved knowledge of the underlying mechanisms of cardiotoxicity are necessary for early detection and management of cardiac risk. Although most reviews focus on the cardiotoxic effect of a specific individual chemotherapeutic agent, the aim of our review is to provide comprehensive insight into various agents that induced cardiotoxicity and their underlying mechanisms. Characterization of these mechanisms are underpinned by research on animal models and clinical studies. In order to gain insight into these complex mechanisms, we emphasize the role of inflammatory processes and oxidative stress on chemotherapy-induced cardiac changes. A better understanding and identification of the interplay between chemotherapy and inflammatory/oxidative processes hold some promise to prevent or at least mitigate cardiotoxicity-associated morbidity and mortality among cancer survivors.

Chemotherapy Induced Cardiotoxicity: A State of the Art Review on General Mechanisms, Prevention, Treatment and Recent Advances in Novel Therapeutics

As medicine advances to employ sophisticated anticancer agents to treat a vast array of oncological conditions, it is worth considering side effects associated with several chemotherapeutics. One adverse effect observed with several classes of chemotherapy agents is cardiotoxicity which leads to reduced ejection fraction (EF), cardiac arrhythmias, hypertension and Ischemia/myocardial infarction that can significantly impact the quality of life and patient outcomes. Research into possible mechanisms has elucidated several mechanisms, such as ROS generation, calcium overload and apoptosis. However, there is a relative scarcity of literature detailing the relationship between the exact mechanism of cardiotoxicity for each anticancer agent and observed clinical effects. This review comprehensively describes cardiotoxicity associated with various classes of anticancer agents and possible mechanisms. Further research exploring possible mechanisms for cardiotoxicity observed with anticancer agents could provide valuable insight into susceptibility for developing symptoms and management guidelines. Chemotherapeutics are associated with several side effects. Several classes of chemotherapy agents cause cardiotoxicity leading to a reduced ejection fraction (EF), cardiac arrhythmias, hypertension, and Ischemia/myocardial infarction. Research into possible mechanisms has elucidated several mechanisms, such as ROS generation, calcium overload, and apoptosis. However, there is a relative scarcity of literature detailing the relationship between the exact mechanism of cardiotoxicity for each anticancer agent and observed clinical effects. This review describes cardiotoxicity associated with various classes of anticancer agents and possible mechanisms. Further research exploring mechanisms for cardiotoxicity observed with anticancer agents could provide insight that will guide management.

New Concepts in Cardio-Oncology

Cancer and cardiovascular disease are the two major causes of morbidity and mortality in worldwide. Discovering new therapeutic agents for the management of breast cancer (BC) has increased the numbers of cancer survivors but with the risk of cardiovascular adverse events (CV-AEs). All drugs can potentially damage the cardiovascular system, with different types of clinical manifestations from ischemic myocardial disease to vasculitis, thrombosis or pericarditis. An early detection of CV-AEs guarantees an earlier treatment, which is associated with better outcomes. Cardio-oncology field enlarged its studies to improve prevention, monitoring and treatment of all cardiotoxic manifestations related to old or modern oncological agents. A multidisciplinary approach with a close partnership between oncologists and cardiologists is essential for an optimal management and therapeutic decision-making. The aim of this chapter is to review all types of cardiotoxic manifestations related to novel and old agents approved for treatment of BC patients including chemotherapy, anti-HER2 agents, cyclin-dependent kinase 4/6 inhibitors, PolyADP-ribose polymerase (PARP) inhibitors, antiangiogenic drugs and immunotherapy. We also focused our discussion on prevention, monitoring, treatment, and management of CV-AEs.

Discovery of Novel N-Heterocyclic-Fused Deoxypodophyllotoxin Analogues as Tubulin Polymerization Inhibitors Targeting the Colchicine-Binding Site for Cancer Treatment

Natural products are a major source of anticancer agents and play critical roles in anticancer drug development. Inspired by the complexity-to-diversity strategy, novel deoxypodophyllotoxin (DPT) analogues were designed and synthesized. Among them, compound C3 exhibited the potent antiproliferative activity against four human cancer cell lines with IC₅₀ values in the low nanomolar range. Additionally, it showed marked activity against paclitaxel-resistant MCF-7 cells and A549 cells. Moreover, compound C3 can inhibit tubulin polymerization by targeting the colchicine-binding site of tubulin. Further study revealed that compound C3 could arrest cancer cells in the G₂/M phase and disrupt the angiogenesis in human umbilical vein endothelial cells. Meanwhile, C3 remarkably inhibited cancer cell motility and migration, as well as considerably inhibited tumor growth in MCF-7 and MCF-7/TxR xenograft model without obvious toxicity. Collectively, these results indicated that compound C3 may be a promising tubulin polymerization inhibitor development for cancer treatment.

Cardio-oncology: Implications for Clinical Practice for Women

PURPOSE OF REVIEW

Clinical cardio-oncology considerations specific to women span across many areas and are particularly relevant for management of patients with sex-specific cancers, such as breast cancer.

RECENT FINDINGS

Major improvement in breast cancer survivorship over the last decade and the recognition of CV disease as the second leading cause of death among survivors point to the relevance of long-term cardiovascular (CV) safety. This review summarizes the CV effects associated with multimodality breast cancer treatments and contemporary approach to CV risk stratification, prevention, early detection, monitoring, and management at the time of cancer diagnosis, during and after completion of treatment. We highlight the growing role of a multidisciplinary, team-based approach for comprehensive CV and oncology care through the entire cancer treatment continuum, from diagnosis through survivorship.

Analysis and Validation of Differentially Expressed Ferroptosis-Related Genes in Regorafenib-Induced Cardiotoxicity

Background

Although tyrosine kinase inhibitors (TKIs) constitute a type of anticancer drugs, the underlying mechanisms of TKI-associated cardiotoxicity remain largely unknown. Ferroptosis is a regulated cell death form that implicated in several tumors' biological processes. Our objective was to probe into the differential expression of ferroptosis-related genes in regorafenib-induced cardiotoxicity through multiple bioinformatics analysis and validation.

Methods and Materials

Four adult human cardiomyocyte cell lines treated with regorafenib were profiled using Gene Expression Omnibus (GEO) (GSE146096). Differentially expressed genes (DEGs) were identified using DESeq2 in R (V.3.6.3). Then, Gene Ontology (GO) Enrichment Analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) Enrichment Analysis, and Gene Set Enrichment Analysis (GSEA) were used to explore DEGs' bioinformatics functions and enriched pathways. We intersected DEGs with 259 ferroptosis-related genes from the FerrDb database. Finally, the mRNA levels of differentially expressed ferroptosis-related genes (DEFRGs) were validated in regorafenib-cultured cardiomyocytes to anticipate the link between DEFRGs and cardiotoxicity.

Results

747,1127,773 and 969 DEGs were screened out in adult human cardiomyocyte lines A, B, D, and E, respectively. The mechanism by which REG promotes cardiotoxicity associated with ferroptosis may be regulated by PI3K-Akt, TGF-beta, and MAPK. GSEA demonstrated that REG can promote cardiotoxicity by suppressing genes and pathways encoding extracellular matrix and related proteins, oxidative phosphorylation, or ATF-2 transcription factor network. After overlapping DEGs with ferroptosis-related genes, we got seven DEFRGs and found that ATF3, MT1G, and PLIN2 were upregulated and DDIT4 was downregulated. The ROC curve demonstrated that these genes predict regorafenib-induced cardiotoxicity well.

Conclusion

We identified four DEFRGs which may become potential predictors and participate in the regorafenib-induced cardiotoxicity. Our findings provide possibility that targeting these ferroptosis-related genes may be an alternative for clinical prevention and therapy of regorafenib-related cardiotoxicity.

The microtubule cytoskeleton in cardiac mechanics and heart failure

The microtubule network of cardiac muscle cells has unique architectural and biophysical features to accommodate the demands of the working heart. Advances in live-cell imaging and in deciphering the 'tubulin code' have shone new light on this cytoskeletal network and its role in heart failure. Microtubule-based transport orchestrates the growth and maintenance of the contractile apparatus through spatiotemporal control of translation, while also organizing the specialized membrane systems required for excitation-contraction coupling. To withstand the high mechanical loads of the working heart, microtubules are post-translationally modified and physically reinforced. In response to stress to the myocardium, the microtubule network remodels, typically through densification, post-translational modification and stabilization. Under these conditions, physically reinforced microtubules resist the motion of the cardiomyocyte and increase myocardial stiffness. Accordingly, modified microtubules have emerged as a therapeutic target for reducing stiffness in heart failure. In this Review, we discuss the latest evidence on the contribution of microtubules to cardiac mechanics, the drivers of microtubule network remodelling in cardiac pathologies and the therapeutic potential of targeting cardiac microtubules in acquired heart diseases.

Targeting the tumor microenvironment by an enzyme-responsive prodrug of tubulin destabilizer for triple-negative breast cancer therapy with high safety

In response to the long-term potential toxicity concerns of tubulin destabilizer, an enzyme-responsive prodrug therapy for triple-negative breast cancer was developed based on the different β-glucuronidase levels between tumor and normal tissues in this study. All the prodrugs synthesized herein showed remarkable stability in phosphate buffer and bovine serum solution, among which 17a was found to be more susceptible to enzymatic cleavage. 17a exhibited excellent selectivity between the in vitro antiproliferative activities against β-glucuronidase-pretreated and -untreated cancer cells (IC₅₀ (+Enz) = 8.9-15.7 nM, IC₅₀ (-Enz) > 50 μM), along with favorable liver microsomal metabolic stability and improved aqueous solubility. Furthermore, as a candidate prodrug 17a showed potent antitumor efficacy in MDA-MB-231 xenograft mouse model without causing perceptible injury to organs. Importantly, 17a exhibited superior safety profiles with higher LD₅₀ value and no perceivable cardiotoxicity, which was a major dose-limiting adverse effect for the parent compound 1. These salient toxicity-reduced effects of 17a would merit further in-depth assessment of this compound for preclinical therapeutic usages.