Palbociclib’s Benefits in Metastatic Breast Cancer Assessed in Real-World Analysis

By: Celeste L. Dixon
Posted: Wednesday, March 8, 2023

In a real-world comparative effectiveness study of the CDK4/6 inhibitor palbociclib plus an aromatase inhibitor versus an aromatase inhibitor alone in nearly 3,000 postmenopausal women and adult men with hormone receptor–positive, HER2-negative metastatic breast cancer in the first-line setting, palbociclib was significantly associated with prolonged overall survival and other improved outcomes. The retrospective cohort study employed the Flatiron Health longitudinal database and is reportedly the largest of its kind to date, reported Angela DeMichele, MD, MSCE, of the University of Pennsylvania, Philadelphia, and colleagues during the Journal of Advanced Practitioner in Oncology conference JADPRO Live (Abstract JL1022E). This study’s findings continue to support palbociclib plus an aromatase inhibitor as a standard of care in the first-line treatment of this patient population.

The patients began treatment between February 2015 and March 2020, with more than 90% seeing physicians in the community versus academic setting. In the cohorts—1,324 patients taking palbociclib plus an aromatase inhibitor, and 1,564 receiving an aromatase inhibitor alone—34.8% had de novo metastatic breast cancer, 29.4% had lung or liver involvement, and 38.7% had bone-alone disease. In addition, noted the researchers, both baseline characteristics and the percentage of patients with different insurance plans were similar between the treatment groups.

Unadjusted and adjusted analyses consistently demonstrated that palbociclib plus an aromatase inhibitor was significantly associated with improved outcomes compared with an aromatase inhibitor alone, concluded Dr. DeMichele and co-investigators. For instance, analyses of prolonged median overall survival and real-world progression-free survival resulted in P values of .0001 and < .0001, respectively, after stabilized inverse probability treatment weighting. “Benefits were observed regardless of race and among patients with and without visceral or bone-only disease,” they stated.

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Journal of Advanced Practitioner in Oncology