Background: Palbociclib is the first-in-class cyclin-dependent kinase 4/6 inhibitor approved in the United States in combination with an aromatase inhibitor (AI) or fulvestrant for treating patients with hormone receptor–positive (HR+), human epidermal growth factor receptor 2–negative (HER2–) advanced or metastatic breast cancer (mBC) as initial or later-line endocrine therapy. More than 80,000 patients have been treated in the United States with palbociclib since its approval in February 2015, but data on real-world palbociclib utilization are limited.
Objective: The objective of this study was to describe real-world population characteristics, utilization patterns (reported earlier), and clinical outcomes in patients who initiated treatment with palbociclib using an oncology electronic health record (EHR) database.
Methods: A retrospective analysis of EHR was conducted using de-identified patient data from the Flatiron Health Analytic database. The Flatiron provider network comprises over 265 community cancer clinics and 3 academic cancer centers across 2500 clinicians and more than 2.0 million active patients with cancer in the United States. Adults with mBC and a record of initiation of palbociclib (index) on or after February 2015 and before August 2017 were selected. First line of therapy in the metastatic setting was assigned by Flatiron using business rules to evaluate systemic treatment before and after palbociclib initiation. A subset who were treated with a palbociclib regimen was further analyzed by chart level extraction to report objective response rate (ORR), stable disease rate, and landmark progression free-survival (PFS) at 6, 12, and 18 months.
Results: 171 female patients were selected with palbociclib in combination with an endocrine partner as first-line therapy in the metastatic setting. Most were ECOG status 0 (23.4%) or 1 (33.5%), Caucasian (66.7%), and age >50 years (59.1%). The median follow-up post index was 12.7 months. Patients were treated primarily in community practice (86.6%). ORR was 44.5%, stable disease rate was 39.1%, resulting in the clinical benefit rate of 83.6%. PFS at 6, 12, and 18 months were 80.0%, 67.1%, and 54.7%, respectively.
Conclusions: A palbociclib-containing regimen shows real-world effectiveness consistent with clinical trial data in this cohort of HR+, HER2– advanced or metastatic breast cancer patients. ORR, stable disease rate, clinical benefit rate, and PFS are demonstrated in first-line use of palbociclib in a large oncology EHR.
Note: Reused with permission from the Miami Breast Cancer Conference. This abstract was accepted and previously presented at the 2018 Meeting. All rights reserved.
