HER2+ Breast Cancer Targeted Therapy: Neoadjuvant Therapy and New Drugs

Abstract

5-20 % of breast cancer patients are diagnosed with overexpression of the HER2 (human epidermal receptor type 2) gene. This amplification is associated with an aggressive type of cancer, poor prognosis, and bad clinical outcomes. Neoadjuvant therapy is a standard treatment used to reduce the size of the tumor in HER2+ breast cancer and make it suitable for surgery. By down-regulating the tumor, neoadjuvant therapy was shown to effectively increase the pathologic complete response (pCR) and to reduce the scope of surgery. This paper reviews different types of drugs that are used as neoadjuvant agents for HER2+ targeted therapy. We will mention many clinical trials that led to the advancement in this treatment and will highlight different combinations between chemotherapy drugs and targeted HER2+ drugs to compare the efficiency and pCR of these combinations. Although chemotherapy plus HER2+ targeted therapy was shown as the most suitable neoadjuvant treatment, Metastatic breast cancer (MBC) is still a pending problem that is not solved by the previous treatments. For this purpose, we will also tackle the most recent drugs (tyrosine kinase inhibitor drugs, monoclonal antibody drugs, and antibody-drug conjugates) that are being tested for their efficiency on MBC. Although FDA-approved medications had improved the efficacy or reduced the side effects of HER2+ therapy in a particular way, neither of these therapies resulted in a major change in the industry and neither led to a final solution for MBC.