Delta NT-proBNP predicts cardiotoxicity in HER2-positive breast cancer patients treated with trastuzumab

Overall survival has improved significantly in patients with human epidermal growth receptor 2 (HER2)-positive breast cancer due to the use of the monoclonal antibody trastuzumab blocking HER2. However, patients may develop trastuzumab-induced cardiotoxicity (TIC) leading to congestive heart failure. Here we assessed whether analysing NT-proBNP and assessment of electrocardiography (ECG) could detect TIC during trastuzumab therapy. One hundred thirty-six patients undergoing adjuvant, neoadjuvant or palliative chemotherapy and HER2 blockade for HER2-positive breast cancer were prospectively assessed with echocardiography, ECG and N-terminal – pro hormone B-type natriuretic peptide (NT-proBNP) testing at baseline and at 6 and 12 months of trastuzumab therapy. TIC was defined as a left ventricular ejection fraction (LVEF) of less than 50% and a decline from baseline of ≥10 units. Six patients developed TIC under 12 months of trastuzumab therapy (incidence 4.4%). NT-proBNP increased from 198.8 ± 64.0 pg/ml to 678.7 ± 132.4 pg/ml (p p p p p Measuring changes in NTproBNP may be used to monitor patients for TIC under trastuzumab therapy. Patients with a cardiovascular risk profile are more at risk of developing TIC.