OT1-02-13: Cardiac Biomarkers on Trastuzumab (Cabot Trial): Determining the Cardiac Biomarker Profile in Breast Cancer Patients Receiving Adjuvant Trastuzumab Therapy.
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AbstractBackgroundTrastuzumab is a humanized anti-HER2 monoclonal antibody that has demonstrated a 50% reduction in the risk of HER2+ breast cancer recurrence. This benefit is at the risk of possible cardiac dysfunction. Detecting trastuzumab-related cardiotoxicity based on physical examination and assessment of left ventricular ejection fraction (LVEF) by serial echocardiography or multi gated acquisition (MUGA) scan, has low diagnostic sensitivity and low predictive power in detecting subclinical myocardial injury. There is interest in developing simple, non-invasive, and cost-effective tools for early identification of trastuzumab-related cardiotoxicity. Use of easily detectible cardiac biomarkers in blood, such as cardiac troponins (cTnT and cTnI) and natriuretic peptides (NPs), are being evaluated. Kavsak et al. have studied a high-sensitivity cTn (hs-cTn) assay that is 10-fold more sensitive, and may be able to identify evolving injury earlier when compared to the conventional cTn assays. B-type natriuretic peptide (BNP) has been established as an indicator for heart failure. Pro-BNP is secreted from the cardiac ventricles in response to increased pressure and volume and is divided into NT-pro-BNP and BNP. The longer half-life of NT-proBNP may make it a more accurate predictor of ventricular stress.Trial design: This is a pilot single institution, prospective cohort study of 25 patients. Breast cancer patients will be seen at the Juravinski Cancer Centre, Hamilton, Canada. Biomarkers will be collected at baseline, then days 1 and 2 of every 21 day cycle for the first 3 months, then every 42 days for the next 3 months. LVEF will be measured at baseline and then every 3 months while on trastuzumab.Eligibility criteria: Patients with stage I-III, HER2 positive (3+ by immunohistochemistry or FISH+) breast cancer receiving adjuvant trastuzumab therapy. Patients who have received prior trastuzumab therapy or are unable to provide informed consent will be excluded.Specific aims: To determine the biological profile of cardiac biomarkers — cTnT, hs-cTn, and NT-proBNP — in patients on adjuvant trastuzumab; and, to determine if elevations in these biomarkers correlate with LVEF.Statistical methods: A convenient sample size of 25 patients will be entered into this pilot study. The minimum of 20 patients is a requirement by the Clinical Laboratory Standards Institute (CLSI) to formally accept existing reference ranges for the cardiac biomarkers to be used in the HER2 breast cancer population (National Committee for Clinical Laboratory Standards (NCCLS)).Present accrual and target accrual: 8 patients have enrolled to date.Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT1-02-13.
