Characterization of the Cardiotoxic Effects of Chemotherapies With Anthracyclines and Trastuzumab for Breast Cancer by Contrast-enhanced Cardiovascular Magnetic Resonance Imaging (CMR).

Study Focus and Design:

Breast cancer is one of the leading cancers among white and African American women; its incidence has increased from one in 20 in 1960 to one in eight today ARMSTRONG 2000. In Canada alone, approximately 22,000 women are diagnosed each year with breast cancer and over 5,000 die from it VERMA 2007. Surgery, radiation therapy and/or chemotherapy are the most commonly used treatment options. Anthracyclines, especially doxorubicin, are a class of chemotherapeutic agents with efficacy against a variety of solid tumors, including breast cancer. Unfortunately, cardiotoxic effects occur with cumulative doses and limit the clinical use of doxorubicin. The incidence of heart failure is less than 5% at doses below 500 mg/m2, but increases to 18% with doses of 500 - 550 mg/m2 and exceeds 30% at doses of more than 600 mg/m2 1-5. Although several mechanism have been proposed for the cardiotoxic effects, little is known about prevention and effective treatment of this drug-induced cardiomyopathy.

The human epidermal growth factor receptor 2 (HER-2), also known as ErbB2, is a member of the group of transmembrane tyrosine kinases and is involved in the regulation of cell proliferation GSCHWIND2004. In mice with genetic defects in ErbB2, the ventricle fails to undergo trabeculation CRONE 2002; mice with reduced expression of HER-2 develop a dilated cardiomyopathy.

Approximately one quarter of patients with breast cancer have increased expression of HER-2, which is associated with a poorer prognosis including positive lymph nodes, decreased hormone receptor expression and high proliferative rates.

Trastuzumab (Herceptin) is a monoclonal antibody against the extracellular domain of HER-2 CARTER1992 and was approved for treatment of patients with HER-2 positive metastatic breast cancer in the 1990´s VOGEL 2002. Later, trastuzumab was approved for the use following anthracycline-based chemotherapies to decrease disease progression and to improve survival. The combination of anthracyclines and trastuzumab in the adjuvant setting reduced the risk of breast cancer relapse by 50% and the risk of death from breast cancer by 33% PICCARD 2005 und ROMOND 2005.