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William J. Gradishar, MD, FACP, FASCO


Real-World vs PALOMA-2 Results With Palbociclib and Aromatase Inhibitors in Breast Cancer

By: Amanda E. Ruffino, BA
Posted: Monday, December 4, 2023

Filipa Alves da Costa, PhD, of the Portuguese Oncology Institute Francisco Gentil, Lisbon, and colleagues examined the real-world effectiveness of the CDK4/6 inhibitor palbociclib in combination with aromatase inhibitors for patients with advanced breast cancer. The study aimed to assess the effectiveness of palbociclib with aromatase inhibitors and compare it with the efficacy reported in the clinical trial PALOMA-2. The researchers found that treatment demonstrated a mean progression-free survival of 28.8 months when administered to patients with characteristics similar to those in the PALOMA-2 trial. The investigators published their findings in Breast Cancer Research.

This retrospective cohort study included 131 patients who began palbociclib treatment in Portugal and were registered in the National Oncology Registry. Progression-free survival was the primary outcome, and secondary outcomes included time to palbociclib failure, overall survival, time to next treatment, and the proportion of patients discontinuing treatment because of adverse events.

Results showed a median progression-free survival of 19.5 months, with 1- and 2-year progression-free survival rates of 67.9% and 42.0%, respectively. A sensitivity analysis suggested a slight increase in median progression-free survival reaching 19.8 months when excluding patients not following the recommended dose. Among patients meeting criteria similar to those in PALOMA-2, the mean progression-free survival increased to 28.8 months, with a time to palbociclib failure of 19.8 months. Median overall survival was not reached, and the time to next treatment was 22.5 months. However, when palbociclib was administered to patients outside the PALOMA-2 criteria, particularly those with less-favorable prognoses such as visceral disease, “the benefits were inferior, even though still favorable,” according to the study authors. Approximately 10.7% of patients discontinued palbociclib because of adverse events.

Disclosure: For full disclosures of the study authors, visit

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