PALLAS: adjuvant palbociclib with endocrine therapy vs. endocrine therapy alone for HR+/HER2- early breast cancer

Abstract No : Presentation LBA12

Indication : Breast cancer

Intervention : Palbociclib

Company : Pfizer

Technology : CDK4/6 Inhibitor


5,760 pts (median age 52 years) were randomized and included in the analysis; 1,013 (17.6%) had stage IIA disease and 4,729 (82.1%) stages IIB/III. 4,754 (82.5%) had received prior chemotherapy. At IA2, after a median follow-up of 23.7 months (351 events), iDFS was similar between the two arms, with 3-year iDFS of 88.2% for P and ET, and 88.5% for ET alone (HR 0.93, 95% confidence interval 0.76-1.15), crossing a pre-specified futility boundary. No benefit from P was observed within clinicopathologic subgroups. Grade 3 or 4 neutropenia was more common with P (61.3% vs 0.4%) but febrile neutropenia was uncommon (1.0%). Other all-grade toxicities occurring more often with P included leukopenia, fatigue, thrombocytopenia, anemia, upper respiratory tract infection, and alopecia. 42.2% of pts discontinued P prior to the planned 2 year duration, primarily due to adverse even


Within the PALLAS trial, at IA2, two years of adjuvant palbociclib with ET did not improve iDFS compared to ET alone. Ongoing long-term follow-up and additional clinical and translational analyses will explore the effect of P in this patient population.