Abstract 16720: Cardiovascular Toxicities of Cyclin Dependent Kinase (cdk) 4/6 Inhibitors in Metastatic Breast Cancer Patients

Introduction: Cyclin Dependent Kinase (CDK) 4/6 inhibitors are a novel class of cancer therapeutics which have significantly improved survival in patients with hormone receptor positive, HER2 negative metastatic breast cancer. There is little data regarding the epidemiology of cardiotoxicity with these therapies. Methods: Using the OneFlorida Data Trust , adult patients without prior cardiovascular disease who received at least one CDK 4/6 inhibitor between January 1, 2012 and December 31, 2018 were included in the analysis. CAEs identified from ICD 9/10 codes include: new hypertension (HTN); arrhythmias (excluding sudden cardiac death); new hypertension (HTN); heart failure/cardiomyopathy; ischemic heart disease, pericardial disease. Log-rank tests were performed to compare time to all-cause mortality in patients with or without CAE. Multivariable cox proportional hazard regressions were performed to estimate the hazard ratio (HR) and 95% confidence interval (CI) for mortality adjusting for age, gender, race, obesity, HTN, diabetes (DM) and hyperlipidemia (HLD). Results: A total of 1,035, predominantly female (96%) patients were included in the analysis. The mean age was 61±13 years, and CV risk factors were prevalent at baseline: obesity (17.1%), HTN (22.2%), DM (9.9%), HLD (10.5%). Cardiotoxicity occurred in 174 (16.8%) patients of which 30 (17.2%) died (p<0.001). There were 61 cases of arrhythmias with 15 (24.6%) deaths (p<0.001) and 97 cases of new HTN with 15 (15.5%) deaths (p<0.001). Unadjusted and adjusted HRs and 95% CIs for mortality are shown in the figure. Effects were similar across all CDK 4/6 inhibitors. Conclusions: Cardiotoxicity is common with CDK 4/6 inhibitors and are associated with overall increased mortality and arrhythmias and HTN accounting for a significant proportion of this finding. Patients taking CDK 4/6 inhibitors should be monitored for CAEs with aggressive risk mitigation strategies to minimize morbidity and mortality.