Cardiotoxicity: trastuzumab and cancer survivors

Effects of trastuzumab and trastuzumab emtansine on corrected QT interval and left ventricular ejection fraction in patients with metastatic (HER2+) breast cancer

BACKGROUND

Trastuzumab and trastuzumab emtansine are specific antibody and antibody-drug conjugates used in the treatment of human epidermal growth factor receptor 2 (HER2) positive metastatic breast cancer. The aim of this study was to test their effect on the QTc interval duration and left ventricular ejection fraction (LVEF) in our patients, two parameters used in evaluation of cardiotoxicity. From May 2015 to October 2017, 26 patients with preserved LVEF were included in the study. All of them were previously treated with standard paclitaxel and cisplatin-based chemotherapy regimens. Electrocardiogram (ECG) was recorded just before each trastuzumab dose application and six months after the last dose. Echocardiography with LVEF measurement was performed several days before the application of the initial dose, and six months after the last cycle. Later, 24 patients with metastatic disease received additional treatment with trastuzumab emtansine after six months and the same ECG and echocardiography protocol was performed again. Due to reduction in LVEF, two patients were discontinued from additional treatment.

RESULTS

A statistically significant QTc prolongation was found after each drug dose application, with an increase in mean QTc duration with every successive application, reaching the peak QTc values just before the fifth cycle of treatment. The QTc interval returned to its initial value six months after the last cycle (p < 0.001). These results were similar for both drugs. Mean LVEF before both treatment protocols was significantly higher compared to LVEF value after the treatment. LVEF before trastuzumab emtansine treatment was non-significantly higher than LVEF after trastuzumab treatment.

CONCLUSION

Trastuzumab and trastuzumab emtansine cardiotoxicity manifested as a significant and progressive QTc prolongation after successive drug applications, reaching the peak value just before the fifth cycle of both drugs. Both medications also caused statistically significant but asymptomatic LVEF reduction. Complete reversibility of cardiotoxic effects of both drugs was confirmed by QTc interval and LVEF normalisation after the treatment discontinuation.

Heme oxygenase-1 regulates mitochondrial quality control in the heart

The cardioprotective inducible enzyme heme oxygenase-1 (HO-1) degrades prooxidant heme into equimolar quantities of carbon monoxide, biliverdin, and iron. We hypothesized that HO-1 mediates cardiac protection, at least in part, by regulating mitochondrial quality control. We treated WT and HO-1 transgenic mice with the known mitochondrial toxin, doxorubicin (DOX). Relative to WT mice, mice globally overexpressing human HO-1 were protected from DOX-induced dilated cardiomyopathy, cardiac cytoarchitectural derangement, and infiltration of CD11b+ mononuclear phagocytes. Cardiac-specific overexpression of HO-1 ameliorated DOX-mediated dilation of the sarcoplasmic reticulum as well as mitochondrial disorganization in the form of mitochondrial fragmentation and increased numbers of damaged mitochondria in autophagic vacuoles. HO-1 overexpression promotes mitochondrial biogenesis by upregulating protein expression of NRF1, PGC1α, and TFAM, which was inhibited in WT animals treated with DOX. Concomitantly, HO-1 overexpression inhibited the upregulation of the mitochondrial fission mediator Fis1 and resulted in increased expression of the fusion mediators, Mfn1 and Mfn2. It also prevented dynamic changes in the levels of key mediators of the mitophagy pathway, PINK1 and parkin. Therefore, these findings suggest that HO-1 has a novel role in protecting the heart from oxidative injury by regulating mitochondrial quality control.

Insights into cardio-oncology: Polypharmacology of quinazoline-based α1-adrenoceptor antagonists

New uses of cardiovascular drugs with proven experience are emerging, including for treating cancer. Quinazoline is a compound made up of two fused six member simple aromatic rings, benzene and pyrimidine rings, with several biological effects. Cardiologists first used quinazoline-based α₁-adrenoceptor antagonists prazosin, doxazosin, and terazosin; currently available data support their use as safe, well tolerated, and effective add-on therapy in uncontrolled hypertension with additional favourable metabolic effects. Recent findings highlight the anticancer effects of quinazoline-based α₁-adrenoceptor antagonists, indicating that they may have a significant role in uncontrolled hypertensive cancer patients without signs of ischemia.