What is the role of HER2-specific antibody immunity in patients with HER2-positive early breast cancer receiving chemotherapy plus trastuzumab?

Breast cancer is the most common malignancy among women worldwide and the leading cause of cancer death in many countries (1). In around 20% to 25% of breast cancer cases, there is an overexpression of HER2 or an amplification of its gene (HER2-positive subtype); HER2 is a transmembrane receptor implicated in tumor replication, invasion and dissemination (2). HER2-positive breast cancer is characterized by a worse prognosis, aggressive disease, higher mitotic index, worse nuclear grade and lymph nodes positivity (3).