LAUSR

Background: Chemotherapy regimens containing a combination of anti-Her2 antibodies are effective but can be associated with cardiac toxicity. Objectives: We evaluate the outcome with a particular focus on the cardiac function of patients with Her2 over-expressed breast cancer receiving Chemotherapy regimens combined with Trastuzumab and Pertuzumab in routine clinical practice settings. Design and methods: The initial cohort of patients who started Chemotherapy regimens in combination with Trastuzumab and Pertuzumab before September 2019 in four cancer units were reviewed retrospectively. All patients had regular measurements of left ventricular ejection fraction by Doppler ultrasound. Results: Sixty-seven patients were identified. Chemotherapy regimens in combination with Trastuzumab and Pertuzumab treatment were administered in the neoadjuvant and palliative settings in 28 (41.8%) and 39 (58.2%) patients, respectively. All patients underwent left ventricular ejection fraction assessment prior to starting Chemotherapy regimens in combination with Trastuzumab and Pertuzumab treatment and at 3 and 6 months later. Subsequently, left ventricular ejection fraction was measured at 9, 12, 15, 18, 21, and 24 months as long as patients are still receiving any of the treatment components. Compared to baseline, the mean left ventricular ejection fraction was not significantly different at any of the subsequent time points (range; decrease by 0.936% to increase by 1.087%: T-test P value not statistically significant for all comparisons). Trastuzumab and Pertuzumab administration was withheld temporarily for two patients due to clinically suspected cardiac toxicity which was excluded upon further investigations. In the neoadjuvant cohort, 82.3% of patients were relapse free at 3 years. The median progression-free survival was 20 months, and the median overall survival was 41 months in the palliative cohort. Conclusion: In this cohort describing our limited initial experience, dual anti-Her2 antibodies (Trastuzumab and Pertuzumab) combined with chemotherapy is effective and not associated with significant cardiac toxicity when the left ventricular ejection fraction is measured every 3 months. This may suggest that previous concerns about cardiotoxicity may have been overemphasized. Further studies investigating less frequent left ventricular ejection fraction monitoring may be warranted.