Abstract 178P
Background
Nowdays patients with Her2 positive breast cancer are usually treated with trastuzumab. Nevertheless, around 10-20% of patients develop cardiotoxicity. The purpose of this study is to analyze the association of the HER2 Ile655Val A>G polymorphism with trastuzumab-induced cardiotoxicity and the possible correlation with the efficacy of the treatment, so we asses if there is any impact in the survival.
Methods
We determined the HER2 655 A>G was genotyping using TaqMan SNP technology polymorphism in 93 patients treated with trastuzumab in our center. (The cost of the test is 60 euros). The cardiotoxicity was defined as a decrease of the left ventricular ejection fraction (LVEF) from baseline more than 10%, to develop a LVEF inferior to 40% or the presentation of clinical manifestation of heart insufficiency.
Results
Genotype frequencies of HER2/neu 655 met Hardy-Weinberg equilibrium (p=0.363). Logistic regression analysis adjusted by hormonal status and anthracycline treatment showed significant differences between AG vs. AA (OR=3.00, CI95% 1.07-8.41, P=0.037) or AG vs. AA+GG (OR=3.21, CI95% 1.15-8.96, P=0.026) for developing cardiotoxicity. Association between Her2/neu Ile655Val polymorphism and disease-free survival or overall survival was not found. We did not find differences in baseline LVEF in patients who developed cardiotoxicity vs. those who did not. However, in cardiotoxicity group, the symptomatic patients had a baseline LVEF significantly lower than non-symptomatic patients (57.7 vs. 66.1, p <0.028).
Conclusions
HER2 655 A>G polymorphism is significantly associated with higher risk of trastuzumab-induced cardiotoxicity but not with less efficacy in terms of survival. So, we recommend to perform this test to all the patients who are going to receive trastuzumab, to provide a closer follow up to the patients that present this polymorphism.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.