Abemaciclib plus fulvestrant vs fulvestrant alone for HR+, HER2- advanced breast cancer following progression on a prior CDK4/6 inhibitor plus endocrine therapy: Primary outcome of the phase 3 postMONARCH trial.

作者：Kevin M. Kalinsky, Giampaolo Bianchini, Erika Paige Hamilton, Stephanie L. Graff, Kyong Hwa Park, Rinath M. Jeselsohn, Umut Demırcı, Miguel Martín, Rachel M. Layman, Sara A. Hurvitz, Sarah LeNoir Sammons, Peter Andrew Kaufman, Montserrat Muñoz-Mateu, Ling‐Ming Tseng, Holly M. Knoderer, Bastien Nguyen, Yanhong Zhou, Elizabeth E. Ravenberg, Lacey M. Litchfield, Seth Andrew Wander · 发表于：Journal of Clinical Oncology · 年份：2024 · DOI：10.1200/jco.2024.42.17_suppl.lba1001 · 被引用次数：77 · 研究领域：Advanced Breast Cancer Therapies

LBA1001 Background: The combination of CDK4/6 inhibitors (CDK4/6i) + endocrine therapy (ET) is the standard first line treatment for HR+, HER2- advanced breast cancer (ABC). While disease progression occurs in nearly all patients (pts) with ABC, the optimal treatment for pts who experience progression on a CDK4/6i + ET remains uncertain. Real-world evidence suggests that use of abemaciclib after disease progression on a prior CDK4/6i prolongs progression-free survival (PFS) in ABC; however, Phase 2 trials with other CDK4/6i have generated mixed results. Here we present the primary outcome analysis for the Phase 3 postMONARCH trial (NCT05169567) of fulvestrant + abemaciclib or placebo in pts with HR+, HER2- ABC following disease progression on prior CDK4/6i + ET. Methods: postMONARCH was a global, double-blind, placebo-controlled study with pts randomized 1:1 to abemaciclib + fulvestrant or placebo + fulvestrant. Eligible pts had disease progression on a CDK4/6i + AI as initial therapy for ABC or relapse on/after a CDK4/6i + ET as adjuvant therapy for early breast cancer. No other prior treatment for ABC was permitted. Primary endpoint was investigator-assessed PFS; secondary endpoints included PFS by blinded independent central review (BICR), overall survival (OS), objective response rate (ORR), and safety. Assuming a hazard ratio (HR) of 0.7, the study had ~80% power to detect superiority for abemaciclib, with a cumulative 2-sided type I error of 0.05. Kaplan-Meier method wa...