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

Year: 2025

Type: article

Abstract: 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).

Source: The Breast

DOI: 10.1016/j.breast.2025.104448

Authors: Rachel M. Layman, Xianchen Liu, Benjamin Li, Lynn McRoy, Adam Brufsky

Institutions: The University of Texas MD Anderson Cancer Center, Pfizer (United States), UPMC Health System, UPMC Hillman Cancer Center, University of Pittsburgh Medical Center

Language: English

Topic: Advanced Breast Cancer Therapies

Subfield: Pulmonary and Respiratory Medicine

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $3,200