Mechanisms of gefitinib-induced QT prolongation

A biomimetic ion channel shortens the QT interval of type 2 long QT syndrome through efficient transmembrane transport of potassium ions

Potassium ion transport across myocardial cell membrane is essential for type 2 long QT syndrome (LQT2). However, the dysfunction of potassium ion transport due to genetic mutations limits the therapeutic effect in treating LQT2. Biomimetic ion channels that selectively and efficiently transport potassium ions across the cellular membranes are promising for the treatment of LQT2. To corroborate this, we synthesized a series of foldamer-based ion channels with different side chains, and found a biomimetic ion channel of K+ (BICK) with the highest transport activity among them. The selected BICK can restore potassium ion transport and increase transmembrane potassium ion current, thus shortening phase 3 of action potential (AP) repolarization and QT interval in LQT2. Moreover, BICK does not affect heart rate and cardiac rhythm in treating LQT2 model induced by E4031 in isolated heart as well as in guinea pigs. By restoring ion transmembrane transport tactic, biomimetic ion channels, such as BICK, will show great potential in treating diseases related to ion transport blockade. STATEMENT OF SIGNIFICANCE: Type 2 long QT syndrome (LQT2) is a disease caused by K+ transport disorder, which can cause malignant arrhythmia and even death. There is currently no radical cure, so it is critical to explore ways to improve K+ transmembrane transport. In this study, we report that a small-molecule biomimetic ion channel BICK can efficiently simulate natural K+ channel proteins on the cardiomyocyte and cure E4031-induced LQT2 in guinea pig by restoring K+ transport function for the first time. This study found that the potassium transmembrane transport by BICK significantly reduced the QT interval, which provides a conceptually new strategy for the treatment of LQT2 disease.

Impact of sequential (first- to third-generation) EGFR-TKI treatment on corrected QT interval in NSCLC patients

Objective

To evaluate the impact of sequential (first- to third-generation) epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment on top-corrected QT interval (top-QTc) in non-small cell lung cancer (NSCLC) patients.

Methods

We retrospectively reviewed the medical records of NSCLC patients undergoing sequential EGFR-TKI treatment at Shanghai Chest Hospital between October 2016 and August 2021. The heart rate (HR), top-QT interval, and top-QTc of their ECGs were extracted from the institutional database and analyzed. Logistic regression was performed to identify predictors for top-QTc prolongation.

Results

Overall, 228 patients were enrolled. Compared with baseline (median, 368 ms, same below), both first-generation (376 ms vs. 368 ms, p < 0.001) and sequential third-generation EGFR-TKIs (376 ms vs. 368 ms, p = 0.002) prolonged top-QT interval to a similar extent (p = 0.635). Top-QTc (438 ms vs. 423 ms, p < 0.001) and HR (81 bpm vs.79 bpm, p = 0.008) increased after first-generation EGFR-TKI treatment. Further top-QTc prolongation (453 ms vs. 438 ms, p < 0.001) and HR increase (88 bpm vs. 81 bpm, p < 0.001) occurred after treatment advanced. Notably, as HR elevated during treatment, top-QT interval paradoxically increased rather than decreased, and the top-QTc increased rather than slightly fluctuated. Moreover, such phenomena were more significant after treatment advanced. After adjusting for confounding factors, pericardial effusion and lower serum potassium levels were independent predictors of additional QTc prolongation during sequential third-generation EGFR-TKI treatment.

Conclusion

First-generation EGFR-TKI could prolong top-QTc, and sequential third-generation EGFR-TKI induced further prolongation. Top-QT interval paradoxically increased and top-QTc significantly increased as HR elevated, which was more significant after sequential EGFR-TKI treatment. Pericardial effusion and lower serum potassium levels were independent predictors of additional QTc prolongation after sequential EGFR-TKI treatment.

Research Progress on the Cardiotoxicity of EGFR-TKIs in Non-Small Cell Lung Cancer

OPINION STATEMENT

With the development of molecular biology and histology techniques, targeted therapy for non-small cell lung cancer (NSCLC) has emerged, which is highly effective and has marginal side effects. Epidermal growth factor receptor (EGFR) was the first driver gene discovered, whose three generations of therapeutic use have its characteristics and benefits in clinical practice. However, cardiovascular complications by EGFR-tyrosine kinase inhibitors (EGFR-TKIs) in preclinical studies have been increasingly reported, including heart failure, cardiomyopathy, and QT prolongation, among others. Cardiotoxicity of targeted drugs significantly affects the therapeutic effect of NSCLC and has become the second leading cause of death in NSCLC. The aim of the present review was to recognize the potential cardiotoxicity of third-generation targeted drugs in the treatment of NSCLC and their associated mechanisms to help clinicians identify and prevent it early in the treatment, minimize the cardiotoxicity of targeted drugs, and improve the therapeutic effect of patients.

The association between tyrosine kinase inhibitors and fatal arrhythmia in patients with non-small cell lung cancer in Taiwan

Objective

As a standard therapy, tyrosine kinase inhibitors (TKIs) improved survival in patients with non-small cell lung cancer (NSCLC) and epidermal growth factor receptor (EGFR) mutation. However, treatment-related cardiotoxicity, particularly arrhythmia, cannot be ignored. With the prevalence of EGFR mutations in Asian populations, the risk of arrhythmia among patients with NSCLC remains unclear.

Methods

Using data from the Taiwanese National Health Insurance Research Database and National Cancer Registry, we identified patients with NSCLC from 2001 to 2014. Using Cox proportional hazards models, we analyzed outcomes of death and arrhythmia, including ventricular arrhythmia (VA), sudden cardiac death (SCD), and atrial fibrillation (AF). The follow-up duration was three years.

Results

In total, 3876 patients with NSCLC treated with TKIs were matched to 3876 patients treated with platinum analogues. After adjusting for age, sex, comorbidities, and anticancer and cardiovascular therapies, patients receiving TKIs had a significantly lower risk of death (adjusted HR: 0.767; CI: 0.729-0.807, p < 0.001) than those receiving platinum analogues. Given that approximately 80% of the studied population reached the endpoint of mortality, we also adjusted for mortality as a competing risk. Notably, we observed significantly increased risks of both VA (adjusted sHR: 2.328; CI: 1.592-3.404, p < 0.001) and SCD (adjusted sHR: 1.316; CI: 1.041-1.663, p = 0.022) among TKI users compared with platinum analogue users. Conversely, the risk of AF was similar between the two groups. In the subgroup analysis, the increasing risk of VA/SCD persisted regardless of sex and most cardiovascular comorbidities.

Conclusions

Collectively, we highlighted a higher risk of VA/SCD in TKI users than in patients receiving platinum analogues. Further research is needed to validate these findings.

Enzastaurin cardiotoxicity: QT interval prolongation, negative inotropic responses and negative chronotropic action

Several clinical trials observed that enzastaurin prolonged QT interval in cancer patients. However, the mechanism of enzastaurin-induced QT interval prolongation is unclear. Therefore, this study aimed to assess the effect and mechanism of enzastaurin on QT interval and cardiac function. The Langendorff and Ion-Optix MyoCam systems were used to assess the effects of enzastaurin on QT interval, cardiac systolic function and intracellular Ca²⁺ transient in guinea pig hearts and ventricular myocytes. The effects of enzastaurin on the rapid delayed rectifier (I_Kr), the slow delayed rectifier K⁺ current (I_Ks), transient outward potassium current (I_to), action potentials, Ryanodine Receptor 2 (RyR2) and the sarcoplasmic/endoplasmic reticulum Ca²⁺ ATPase 2a (SERCA2a) expression and activity in HEK 293 cell system and primary cardiomyocytes were investigated using whole-cell recording technique and western blotting. We found that enzastaurin significantly prolonged QT interval in guinea pig hearts and increased the action potential duration (APD) in guinea pig cardiomyocytes in a dose-dependent manner. Enzastaurin potently inhibited I_Kr by binding to the human Ether-à-go-go-Related gene (hERG) channel in both open and closed states, and hERG mutant channels, including S636A, S631A, and F656V attenuated the inhibitory effect of enzastaurin. Enzastaurin also moderately decreased I_Ks. Additionally, enzastaurin also induced negative chronotropic action. Moreover, enzastaurin impaired cardiac systolic function and reduced intracellular Ca²⁺ transient via inhibition of RyR2 phosphorylation. Taken together, we found that enzastaurin prolongs QT, reduces heart rate and impairs cardiac systolic function. Therefore, we recommend that electrocardiogram (ECG) and cardiac function should be continuously monitored when enzastaurin is administered to cancer patients.

Angiotensin II type 1 receptor blockade attenuates gefitinib-induced cardiac hypertrophy via adjusting angiotensin II-mediated oxidative stress and JNK/P38 MAPK pathway in a rat model

Gefitinib is a tyrosine kinase inhibitor (TKI) of the epidermal growth factor receptor (EGFR), used for the treatment of advanced or metastatic non-small cell lung cancer. Recently, studies proved that Gefitinib-induced cardiotoxicity through induction of oxidative stress leads to cardiac hypertrophy. The current study was conducted to understand the mechanisms underlying gefitinib-induced cardiac hypertrophy through studying the roles of angiotensin II (AngII), oxidative stress, and mitogen-activated protein kinase (MAPK) pathway. Male Wistar albino rats were treated with valsartan, gefitinib, or both for four weeks. Blood samples were collected for AngII and cardiac markers measurement, and hearts were harvested for histological study and biochemical analysis. Gefitinib caused histological changes in the cardiac tissues and increased levels of cardiac hypertrophy markers, AngII and its receptors. Blocking of AngII type 1 receptor (AT1R) via valsartan protected hearts and normalized cardiac markers, AngII levels, and the expression of its receptors during gefitinib treatment. valsartan attenuated gefitinib-induced NADPH oxidase and oxidative stress leading to down-regulation of JNK/p38-MAPK pathway. Collectively, AT1R blockade adjusted AngII-induced NADPH oxidase and JNK/p38-MAPK leading to attenuation of gefitinib-induced cardiac hypertrophy. This study found a pivotal role of AngII/AT1R signaling in gefitinib-induced cardiac hypertrophy, which may provide novel approaches in the management of EGFRIs-induced cardiotoxicity.

A Novel Role of Arrhythmia-Related Gene KCNQ1 Revealed by Multi-Omic Analysis: Theragnostic Value and Potential Mechanisms in Lung Adenocarcinoma

The early diagnosis, prognostic prediction, and personalized therapy of lung adenocarcinoma (LUAD) remains a challenging issue. KCNQ1 (potassium voltage-gated channel subfamily Q Member 1) is implicated in long QT syndrome (LQTS) and cardiac arrhythmia, while its significance in LUAD remains unclear. In this study, we aimed to explore the significance of KCNQ1 in terms of clinical value, tumor immunity, underlying mechanisms, and a precision medicine approach by means of multi-omics analysis. The association of KCNQ1 with LUAD was first explored. Both altered variants and high expression of KCNQ1 in a TCGA-LUAD cohort indicated a favorable outcome. KCNQ1 levels had a negative correlation with tumor proliferation index Ki67 levels. siRNA-knockdown of KCNQ1 promoted the migration ability of lung cancer cells. KCNQ1 levels were decreased in LUAD tissue compared to normal tissue. A receiver operating characteristic (ROC) curve indicated good diagnostic efficiency of KCNQ1. High KCNQ1 is associated with an immunoactive profile of immune infiltration and immunomodulators and is involved in the inhibition of the cell cycle and DNA replication. Lapatinib was identified as a potent drug for LUAD in the context of low KCNQ1. This study unveiled the significance of KCNQ1 in diagnosis and prognosis and provided a corresponding precision medicine strategy for LUAD.