Real-world palbociclib dose modifications and clinical outcomes in patients with HR+/HER2− metastatic breast cancer: A Flatiron Health database analysis

Purpose: To examine the associations of palbociclib dose modifications with clinical outcomes of patients with HR+/HER2− metastatic breast cancer (MBC) treated with first-line (1L) palbociclib + aromatase inhibitor (AI) in routine practice. Methods: Using the Flatiron Health Analytic Database, we co...

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Main Authors: Rachel M. Layman, Xianchen Liu, Benjamin Li, Lynn McRoy, Adam Brufsky
Format: Article
Language:English
Published: Elsevier 2025-06-01
Series:Breast
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Online Access:http://www.sciencedirect.com/science/article/pii/S0960977625004655
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author Rachel M. Layman
Xianchen Liu
Benjamin Li
Lynn McRoy
Adam Brufsky
author_facet Rachel M. Layman
Xianchen Liu
Benjamin Li
Lynn McRoy
Adam Brufsky
author_sort Rachel M. Layman
collection DOAJ
description Purpose: To examine the associations of palbociclib dose modifications with clinical outcomes of patients with HR+/HER2− metastatic breast cancer (MBC) treated with first-line (1L) palbociclib + aromatase inhibitor (AI) in routine practice. Methods: Using the Flatiron Health Analytic Database, we conducted a retrospective analysis of HR+/HER2− MBC patients who started 1L palbociclib + AI February 2015–March 2020. Kaplan−Meier analyses were used to estimate treatment duration, real-world progression-free survival (rwPFS), and overall survival (OS) by palbociclib dose adjustments (any change in palbociclib daily dose while on treatment) and dose reductions (starting dose <125 mg/day or dose reduced while on treatment). Cox proportional hazard regression models were performed to compute unadjusted/adjusted hazard ratios (HRs). Results: Of 1302 patients with documented starting dose, 524 (40.2 %) had palbociclib dose adjustments; 778 (59.8 %) had none. Median treatment duration was significantly longer in patients with dose adjustments versus those with none (27.4 vs 21.4 months; adjusted HR = 0.80 [95 % CI, 0.69–0.93]; P = 0.004). Patients with and without dose adjustments showed similar median rwPFS (20.5 vs 19.6 months; adjusted HR = 0.89 [95 % CI, 0.76–1.04]; P = 0.133). Median OS was significantly prolonged in patients with versus without dose adjustments (57.8 vs 51.4 months; adjusted HR = 0.73 [95 % CI, 0.59–0.89]; P = 0.002). Similar findings were observed in patients with and without dose reductions. Conclusions: In this real-world study, rwPFS in HR+/HER2− MBC patients was maintained irrespective of dose adjustments. However, dose adjustments were associated with extended treatment duration and OS. Clinical trial registration: NCT05361655 (ClinicalTrials.gov)
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spelling doaj-art-a4008cc1ef8d46a88991a0a25bdcd24e2025-08-20T02:30:55ZengElsevierBreast1532-30802025-06-018110444810.1016/j.breast.2025.104448Real-world palbociclib dose modifications and clinical outcomes in patients with HR+/HER2− metastatic breast cancer: A Flatiron Health database analysisRachel M. Layman0Xianchen Liu1Benjamin Li2Lynn McRoy3Adam Brufsky4The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX, 77030, USA; Corresponding author. The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX, 77030, USA.Pfizer Inc, 66 Hudson Yards, New York, NY, 10001, USA; Corresponding author. Pfizer Inc, 66 Hudson Yards, New York, NY, 10001, USA.Pfizer Inc, 66 Hudson Yards, New York, NY, 10001, USAPfizer Inc, 66 Hudson Yards, New York, NY, 10001, USADepartment of Medicine, Division of Hematology/Oncology, UPMC Hillman Cancer Center, University of Pittsburgh Medical Center, 5115 Centre Ave, Pittsburgh, PA, 15232, USAPurpose: To examine the associations of palbociclib dose modifications with clinical outcomes of patients with HR+/HER2− metastatic breast cancer (MBC) treated with first-line (1L) palbociclib + aromatase inhibitor (AI) in routine practice. Methods: Using the Flatiron Health Analytic Database, we conducted a retrospective analysis of HR+/HER2− MBC patients who started 1L palbociclib + AI February 2015–March 2020. Kaplan−Meier analyses were used to estimate treatment duration, real-world progression-free survival (rwPFS), and overall survival (OS) by palbociclib dose adjustments (any change in palbociclib daily dose while on treatment) and dose reductions (starting dose <125 mg/day or dose reduced while on treatment). Cox proportional hazard regression models were performed to compute unadjusted/adjusted hazard ratios (HRs). Results: Of 1302 patients with documented starting dose, 524 (40.2 %) had palbociclib dose adjustments; 778 (59.8 %) had none. Median treatment duration was significantly longer in patients with dose adjustments versus those with none (27.4 vs 21.4 months; adjusted HR = 0.80 [95 % CI, 0.69–0.93]; P = 0.004). Patients with and without dose adjustments showed similar median rwPFS (20.5 vs 19.6 months; adjusted HR = 0.89 [95 % CI, 0.76–1.04]; P = 0.133). Median OS was significantly prolonged in patients with versus without dose adjustments (57.8 vs 51.4 months; adjusted HR = 0.73 [95 % CI, 0.59–0.89]; P = 0.002). Similar findings were observed in patients with and without dose reductions. Conclusions: In this real-world study, rwPFS in HR+/HER2− MBC patients was maintained irrespective of dose adjustments. However, dose adjustments were associated with extended treatment duration and OS. Clinical trial registration: NCT05361655 (ClinicalTrials.gov)http://www.sciencedirect.com/science/article/pii/S0960977625004655Advanced breast cancerClinical outcomesCyclin-dependent kinase 4/6 inhibitorDose modificationsHR+/HER2−Metastatic breast cancer
spellingShingle Rachel M. Layman
Xianchen Liu
Benjamin Li
Lynn McRoy
Adam Brufsky
Real-world palbociclib dose modifications and clinical outcomes in patients with HR+/HER2− metastatic breast cancer: A Flatiron Health database analysis
Breast
Advanced breast cancer
Clinical outcomes
Cyclin-dependent kinase 4/6 inhibitor
Dose modifications
HR+/HER2−
Metastatic breast cancer
title Real-world palbociclib dose modifications and clinical outcomes in patients with HR+/HER2− metastatic breast cancer: A Flatiron Health database analysis
title_full Real-world palbociclib dose modifications and clinical outcomes in patients with HR+/HER2− metastatic breast cancer: A Flatiron Health database analysis
title_fullStr Real-world palbociclib dose modifications and clinical outcomes in patients with HR+/HER2− metastatic breast cancer: A Flatiron Health database analysis
title_full_unstemmed Real-world palbociclib dose modifications and clinical outcomes in patients with HR+/HER2− metastatic breast cancer: A Flatiron Health database analysis
title_short Real-world palbociclib dose modifications and clinical outcomes in patients with HR+/HER2− metastatic breast cancer: A Flatiron Health database analysis
title_sort real world palbociclib dose modifications and clinical outcomes in patients with hr her2 metastatic breast cancer a flatiron health database analysis
topic Advanced breast cancer
Clinical outcomes
Cyclin-dependent kinase 4/6 inhibitor
Dose modifications
HR+/HER2−
Metastatic breast cancer
url http://www.sciencedirect.com/science/article/pii/S0960977625004655
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