Palbociclib for Residual High-Risk Invasive HR-Positive and HER2-Negative Early Breast Cancer-The Penelope-B Trial.

Purpose: About one third of patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative breast cancer who have residual invasive disease after neoadjuvant chemotherapy (NACT) will relapse. Thus, additional therapy is needed. Palbociclib is a cyclin-dependent kinase 4 and 6 inhibitor demonstrating efficacy in the metastatic setting.