Real-World Treatment Patterns and Clinical Effectiveness of Palbociclib Plus an Aromatase Inhibitor as First-Line Therapy in Advanced/Metastatic Breast Cancer: Analysis from the US Syapse Learning Health Network

Curr Oncol. 2022 Feb 12;29(2):1047-1061. doi: 10.3390/curroncol29020089.


This retrospective single-arm study assessed real-world treatment patterns and clinical outcomes in patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced/metastatic breast cancer (A/MBC) who received palbociclib plus an aromatase inhibitor as first-line therapy in US community health systems. Using electronic health records from the Syapse Learning Health Network, 242 patients were identified as having received first-line palbociclib plus an aromatase inhibitor between 3 February 2015, and 31 July 2019 (data cutoff 1 February 2020) resulting in a minimum potential 6-month follow-up period. In total, 56.6% of patients had de novo A/MBC at initial breast cancer diagnosis, 50.8% had bone-only disease, and 32.2% had visceral disease. Median follow-up was 22.4 months. Disease progression (26.4%) and intolerance/toxicity (14.9%) were the main reasons for treatment discontinuation. The median (95% CI) real-world progression-free survival was 31.7 (27.9-not estimable (NE)) months and 2-year estimated overall survival (OS) rate was 78.0%. In total, 25.6% of patients died; however, OS data are limited by the small population size and insufficient follow-up time. These real-world effectiveness outcomes complement findings from other real-world studies and randomized controlled trials and support palbociclib plus an aromatase inhibitor as first-line therapy for HR+/HER2- A/MBC.

Trial registration: NCT04394247.

Keywords: HR+/HER2−; aromatase inhibitor; metastatic breast cancer; palbociclib; real-world data.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Combined Chemotherapy Protocols
  • Aromatase Inhibitors* / therapeutic use
  • Breast Neoplasms* / pathology
  • Female
  • Humans
  • Piperazines
  • Pyridines
  • Receptors, Estrogen / metabolism
  • Retrospective Studies
  • Treatment Outcome


  • Aromatase Inhibitors
  • Piperazines
  • Pyridines
  • Receptors, Estrogen
  • palbociclib

Associated data