Research On The Potential Cardiotoxic Effect And Mechanism Of Osimertinib

Background:Lung cancer is one of the most common malignant tumors in our country.At present,the morbidity and mortality of this disease occupy the first place among tumor diseases in China.Molecular targeted therapy is one of the main common methods for the treatment of lung cancer,which is not only safe but also effective.Non-small cell lung cancer（NSCLC）accounts for about 80%～85%of lung cancer.Osimertinib（AZD9291）is an oral but irreversible third-generation EGFR-TKI drug for patients who have previously been treated with an EGFR-TKI inhibitor or who have progressed after treatment.Targeted drugs for the treatment of adult patients with locally advanced or metastatic NSCLC with EGFR T790M mutation positive have been confirmed.The third generation of EGFR-TKI,Osimertinib,is coming into the picture because of resistance issues associated with taking first-and second-generation EGFR-TKI drugs.According to previous clinical trials and applications,the cardiotoxic effects of Osimertinib mainly include prolonged QT interval,decreased left ventricular ejection fraction（LVEF）/heart failure（HF）,atrial fibrillation（AF）and other conditions.However,the mechanism of cardiac toxicity by Osimertinib is not clearly explained.Purpose:The main purpose of this paper is to study the mechanism of cardiotoxic effects caused by Osimertinib,provide reference for rational drug use in clinical application and more comprehensive safety evaluation of drugs,minimize the adverse reactions caused by Osimertinib,and avoid unnecessary drug reduction or premature cessation of medication resulting in timely and effective treatment,further improve the efficacy of disease treatment and quality of life in the later period.Method:In terms of the overall heart,eligible guinea pigs were selected in this study.The guinea pig was sacrificed after isoflurane anesthesia.Its chest was opened,and the heart was quickly removed.The isolated heart was put on the Langendorff perfusion apparatus.Retrograde perfusion was performed through the aorta at an 8 ml/min flow rate with oxygenated K-H perfusate at 37℃under a constant flow rate.Multi-array electrical mapping system and synchronous electrocardiogram were used for recording.According to Osimertinib for pharmacokinetic,respectively take 0.8μM、2.4μM、7.2μM、24μM of guinea pigs in vitro drug testing,field potential signals and electrocardiogram signals under spontaneous rhythm and frequency stimulation were recorded before administration and after addition of different concentrations of Osimertinib.In terms of the ion channel,patch clamp technique was used in this study for further experiments.The slides with cultured cell were placed in the bath.The single cell was selected and adjusted to a clear field of view.Then,recording electrode was directed to the cell.The whole-cell configurations were established by applying moderate negative pressure to rupture the cell membrane after electrode contact the cell membrane surface and a giga-ohm seal was made.The electrophysiological signal recording was taken under a 6KHz filter.The stimulation protocol was made as follows.To recond the h ERG current,the cell was clamped at-80 mV,then was depolarized from-80 mV to+40 mV for 3000 ms,followed by repolarization to-40 mV for 2000 ms.To record the h ERG activation current,the cell clamps were first clamped at-80 mV,then depolarized from-50 mV depolarized to+50 mV by a 10m V step,each command voltage was lasted for 1000 ms.Finally the cell was repolarized to-40 mV for 2000 ms.To record the h ERG inactivation current,the cell was first clamped at-80 mV,then repolarized to+40m V,then the cell was depolarized from-130 mV to+40 mV with a 10m V step.Each command voltage was maintained for 3000 ms.The cell was finally repolarized to+40 mV and lasted for 1000 ms.To record the Nav1.5 current,the cell was first clamped at-120 mV,then depolarized from-120 mV to-15 mV for 100 ms.In order to have the channel about 20%inactivation,the clamp voltage was hold at-80to-90 mV for 100 ms.To make the channel about 50%inactivation,the clamp voltage was hold at about-70 mV for 100 ms.Result:1.Osimertinib lead to prolonged PR interval,QRS interval and QT interval,which are concentration-dependent.2.Osimertinib lead to decreased conduction of the left ventricle and left atrium,which are concentration-dependent.3.Osimertinib had a strong inhibitory effect on h ERG channel current,and the half inhibitory concentration(IC₅₀)was 2.21±1.29μM（n=9）.4.Osimertinib shifted the h ERG channel activation curve to the left,but the inactivation curve did not change significantly.5.Osimertinib had a strong inhibitory effect on Nav1.5 channel current,the IC₅₀under the no inactivation,20%of inactivation,and 50%of inactivation was 15.58±0.83μM（n=8）,3.24±0.09μM（n=8）,2.03±0.57μM（n=8）respectively.Conclusion:Osimertinib lead to prolonged PR interval,QRS interval and QT interval,and block h ERG channel and Nav1.5 channel at the ion channel level.But these effects were about four times higher than Css,max at the therapeutic dose to be statistically significant.In addition,simply blocking h ERG channels did not necessarily lead to prolonged QT interval,while blocking the Nav1.5 channel at the same time was associated with cardiovascular risk.Which may be one of the reasons for the decreased left ventricular ejection fraction,heart failure,prolonged QT interval,atrial fibrillation and other cardiovascular adverse reactions in some NSCLC patients.In addition,the prolongation of PR interval and atrioventricular block occurred when the therapeutic dose was about 1 times of the Css,max in human body.Therefore,caution should be exercised in clinical application,especially in patients with related underlying diseases,and attention should be paid to strengthening ECG monitoring.