Targeted Neoadjuvant Therapies in HR+/HER2−Breast Cancers: Challenges for Improving pCR
Translational Oncology Laboratory, Avera Cancer Institute, Sioux Falls, SD 57105, USA
Author to whom correspondence should be addressed.
Academic Editor: Didier Picard
Received: 25 November 2020 / Revised: 20 January 2021 / Accepted: 21 January 2021 / Published: 26 January 2021
A high pathological complete response in the neoadjuvant setting is directly associated with a better overall response. A favorable prognosis is achieved when preoperative chemo or endocrine therapy succeeds in achieving a high pathological complete response (total eradication of tumors in the breast and the lymph nodes). Approximately 70% of breast cancers are ER-positive. The growth and progression of ER-positive breast cancers are critically dependent on estrogen receptor signaling. Although endocrine therapies (tamoxifen, an aromatase inhibitor, and fulvestrant) in ER-positive breast cancers are the backbone of adjuvant setting, the efficacy of such therapies in terms of achieving a pathological complete response is not encouraging in the neoadjuvant setting. Similar results are observed following targeted therapies in a neoadjuvant setting. Reviewing the literature in the context of different therapies of ER-positive breast cancers in the neoadjuvant setting, here we propose two hypothetical strategies to induce apoptosis based on the background of genomic alterations in the tumor tissues.