Biomarkers of palbociclib response in hormone receptor-positive advanced breast cancer from the PARSIFAL trial

Abstract Currently, there are no clinically actionable biomarkers to predict patient to cyclin-dependent kinases 4 and 6 inhibitors (CDK4/6i) plus endocrine therapy for hormone receptor (HR)[+]/ human epidermal growth factor receptor 2 (HER2)[-] advanced breast cancer (ABC). Herein, we report an exp...

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Main Authors: Joan Albanell, Angelo Gámez Pozo, Carlos L. Arteaga, Meritxell Bellet, Federico Rojo, Abel González, Beatriz Bellosillo, Violeta Serra, Petra Gener, José Antonio Guerrero, Eileen Shimizu, Mario Mancino, Jose Rodríguez-Morató, Leonardo Mina, José Manuel Pérez-García, Javier Cortés, Antonio Llombart-Cussac
Format: Article
Language:English
Published: Nature Portfolio 2025-06-01
Series:npj Breast Cancer
Online Access:https://doi.org/10.1038/s41523-025-00777-0
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Summary:Abstract Currently, there are no clinically actionable biomarkers to predict patient to cyclin-dependent kinases 4 and 6 inhibitors (CDK4/6i) plus endocrine therapy for hormone receptor (HR)[+]/ human epidermal growth factor receptor 2 (HER2)[-] advanced breast cancer (ABC). Herein, we report an exploratory biomarker substudy (transFAL) from a subset of patients included in PARSIFAL, a phase II randomized clinical trial that evaluated first-line palbociclib plus fulvestrant or letrozole for HR[+]/HER2[−] ABC. No definitive biomarkers were discovered, however, worse outcomes were found with CDK6 postivity (p = 0.008), ER negativity (p = 0.008), high Ki67 (p = 0.04), and TP53 mutation (p = 0.04). ctDNA density (p = 0.036) and number of mutations (p = 0.033) at baseline were significantly higher for resistant patients. Our study reveals future directions to explore in the goal to determine biomarkers of response to CDK4/6i.
ISSN:2374-4677