Clinical and Molecular Methods in Drug Development: Neoadjuvant Systemic Therapy in Breast Cancer as a Model

Neoadjuvant chemotherapy (NACT), neoadjuvant endocrine therapy (NAET), and neoadjuvant targeted therapy (NATT), more recently, have been adopted worldwide as standard of care in locally advanced and inoperable BC. These modalities, collectively called neoadjuvant systemic therapy (NAST), are also used for organ preservation and for mechanistic biological studies on drug response and resistance, drug development, and clinical trials. Furthermore, the response to NACT is a valuable indicator of long-term survival. In this work, the advantages and pitfalls of using NAST in BC for studying drug response and resistance for drug development and clinical trials are discussed as well as practical points on how to set up a NAST clinical trial in BC.