Key clinical point: The addition of palbociclib to estrogen therapy for 1 year does not improve invasive disease-free survival (DFS) in high-risk patients with hormone-receptor–positive (HR+), human epidermal growth factor receptor (HER)-negative early breast cancer who had residual invasive disease after neoadjuvant chemotherapy.
Major finding: Palbociclib did not improve invasive DFS vs. placebo (stratified hazard ratio, 0.93; P = .525) after a median follow-up of 42.8 months. Incidences of grade 3-4 neutropenia and leukopenia were significantly higher in the palbociclib group. Eight fatal serious adverse events were reported.
Study details: A phase 3, double-blind, randomized PENELOPE-B study evaluated 1,250 high-risk patients with HR+, HER-negative early breast cancer who have residual invasive disease after neoadjuvant chemotherapy. Patients received estrogen therapy with either palbociclib or placebo.
Disclosures: The study was supported by Pfizer. The authors declared receiving consulting, honoraria, travel/accomodation expenses and research funding outside the study work. Some of the authors declared being employee of and/or stocks/ownership interests of various sources including Pfizer.
Source: Loibl S et al. J Clin Oncol. 2021 Apr 1. doi: 10.1200/JCO.20.03639.