A correlative study of cardiac biomarkers and left ventricular ejection fraction (LVEF) from N9831, a phase III randomized trial of chemotherapy and trastuzumab as adjuvant therapy for HER2-positive breast cancer

Abstract

579 Background: N9831 and other clinical trials have demonstrated the additive survival benefit of trastuzumab (H) therapy with chemotherapy for patients with resected HER-2 positive breast cancer. Cardiac toxicity (CTox) is increased by this strategy. Prediction of or early detection of CTox is important. Methods: 95 patients provided informed consent. Brain natriuretic peptide (BNP), C-reactive protein (CRP), troponin T (TnT) and I (TnI), TNF-alpha, IL-1b, and IL-6 were to be drawn at baseline, after initiation of doxorubicin/cyclophosphamide (AC), after initiation of paclitaxel (T), and after the initiation of H (may have been given concurrently with T). 67 patients with at least a baseline sample, a post-treatment sample, and a baseline and subsequent evaluation of LVEF were studied. No patient in this group had a grade 3 decline in LVEF. Only 3 of these patients did not receive H. Values above the 99th percentile were considered abnormal for troponin. 40 ng/ml was considered elevated for BNP. Results: Values of CRP, TNF-alpha, IL- 6 and IL1b changed in very few patients and without a discernible pattern. For further evaluation of BNP, TnI, and TnT, 2 definitions of CTox were tested: 1. a >10% drop in LVEF from baseline (n=27) and 2. a drop in LVEF of 10–15% to less than the institutional lower limit of normal (LLN) OR a >15% decline in LVEF (n=14). No pre-treatment marker appeared to predict a > 10% decline in LVEF (definition 1). For patients fulfilling definition 2, pre-treatment BNP > 40 was seen in 21% of patients vs 8% of normals (nls) (p= 0.18) and an abnormal TnI (>0.04) was seen in 21% vs 6% of nls (p=0.10). Only doubling of BNP appeared promising as a serial marker of CTox using definition 2 (27% vs 7% for nls (p = 0.09). Conclusions: Baseline BNP and TnI and serial measures of BNP may be promising for further investigation for the prediction and detection of treatment-related CTox. Due to limitations of the study including the small numbers of patients analyzed, the difficulty in defining CTox, and the variation in the timing of sample procurement and assessment, these data are considered exploratory. Supported by CA-25224, CA-2115, CA 38926, CA31946. No significant financial relationships to disclose.