Neoadjuvant breast cancer therapy and drug development.

Neoadjuvant treatment of breast cancer initially was limited to patients with locally advanced breast cancer in which downstaging was necessary. Now, neoadjuvant trials have become an increasingly common way to facilitate the rapid assessment of new cancer therapies. The appeal of neoadjuvant trials is that they provide the opportunity to study translational science, tumor biomarkers, and intermediate endpoints in response to systemic therapy within a shortened period. This review summarizes the data that contribute to our understanding of the association between pathological complete response and long-term outcomes, describes the implications of drug development and accelerated approval in neoadjuvant treatment of breast cancer, and provides a perspective on future neoadjuvant drug development.