Abstract Body (Do not enter title and authors here): Introduction
In a major paradigm shift of management of high-risk early-stage triple negative breast cancer (TNBC), the KEYNOTE-522 trial showed evidence to suggest that the addition of the immune checkpoint inhibitor (ICI) pembrolizumab to current standard-of-care chemotherapy leads to greater clinical efficacy than that of chemotherapy alone. However, the addition of an ICI carries with it the risk of immunotherapy-related cardiotoxicities. This raises concern for additive risks for cardiotoxicity for patients with high-risk early-stage TNBC receiving both anthracycline and ICI.

Hypothesis
Management of high-risk early-stage TNBC with a treatment regimen consisting of anthracycline and ICI will have no increase in cardiotoxicity when compared to those receiving anthracycline alone.

Aims
The purpose of this study is to identify if the combination of anthracycline and ICI in the management of high-risk early-stage TNBC is associated with greater cardiotoxicity than that of those on anthracycline alone.

Methods
Patients with TNBC were identified within the electronic health record system at our institution. Cohorts were created based on management strategy: anthracycline with ICI and anthracycline without ICI. Patient demographics, comorbidities, functional status, medications, cardiac imaging, management, and outcomes were analyzed retrospectively. Cohorts were then compared for analysis of time to adverse cardiac event. An alpha value of 0.05 was used to determine statistical significance.

Results
A total of 385 patients with TNBC were included in the study, with 312 receiving anthracycline without ICI and 73 receiving anthracycline with ICI. Baseline characteristics between the two cohorts were well balanced with no significant differences in prevalence of comorbidities. There were no significant differences in incidence of general cardiac events, heart failure, acute coronary syndrome, cardiac arrhythmias, and pericardial effusion between these two cohorts following each respective treatment regimen. Furthermore, there was no significant difference in time to cardiac events between the two groups.

Conclusion
There appears to be no significant differences in cardiac events between patients with TNBC on anthracycline with ICI and those on anthracycline without ICI. Given no significant differences in cardiotoxicity, these findings further favor use of an ICI in management of high-risk early-stage TNBC and serve to reduce clinician hesitancy.