Key clinical point: Addition of palbociclib to adjuvant endocrine therapy (ET) vs. ET alone failed to improve invasive disease-free survival (IDFS) in patients with early-stage hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2−) breast cancer.
Major finding: At the median follow-up of 23.7 months, 3-year IDFS was similar for palbociclib + ET and ET alone groups (88.2% vs. 88.5%; hazard ratio, 0.93; log-rank P = .51). Serious adverse events occurred in 12.4% of patients on palbociclib + ET vs. 7.6% on ET alone.
Study details : Findings are from the second interim analysis of the ongoing phase 3 PALLAS trial that randomly allocated 5,760 patients with stage II-III HR+ and HER2− breast cancer to receive either 2 years of palbociclib in addition to ongoing standard adjuvant ET (n = 2,883) or ongoing standard adjuvant ET alone (n = 2,877).
Disclosures: PALLAS trial was cosponsored by the Alliance Foundation Trials and the Austrian Breast and Colorectal Cancer Study Group, in collaboration with Eastern Cooperative Oncology Group, the National Surgical Adjuvant Breast and Bowel Project, the German Breast Group, and the Breast International Group, with funding from Pfizer. The lead author reported receiving personal fees from Eisai, Lilly, and Novartis. Some of the coinvestigators reported ties with various pharmaceutical companies including Pfizer.
Source: Mayer EL et al. Lancet Oncol. 2021 Jan 15. doi: 10.1016/S1470-2045(20)30642-2 .