Efficacy of CDK4/6 Inhibitor Plus Aromatase Inhibitor versus Fulvestrant in Chinese Patients with Hormone Receptor-Positive and Human Epidermal Growth Factor Receptor 2-Negative (HR+/HER2-) Advanced Breast Cancer.

Authors

Yujing Tan, Cheng Zeng, Jiuda Zhao, Weihong Zhao, Hanfang Jiang, Jiani Wang, Fei Ma

Published in

Breast cancer (Dove Medical Press). Volume 18. Pages 574628. Epub Jun 23, 2026.

Abstract

The multicenter, real-world study aims to explore the clinical efficacy of the cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) plus aromatase inhibitor (AI) versus fulvestrant (FUL) in Chinese patients with hormone receptor-positive and human epidermal growth factor receptor 2-negative (HR+/HER2-) advanced breast cancer (ABC).
We retrospectively collected clinicopathological data of cancer patients receiving CDK4/6i from four cancer centers in China. Clinical benefit rate (CBR), objective response rate (ORR), and progression-free survival (PFS) were compared between AI- and FUL-combined therapy.
A total of 315 patients with HR+/HER2- ABC were qualified. 188 (59.7%) patients received AI+CDK4/6i, and 127 (40.3%) patients received FUL+CDK4/6i therapy. In the overall population, the median PFS was 16.8 months versus 14.9 months for AI+CDK4/6i and FUL+CDK4/6i (p=0.34, HR=0.87, 95% CI=0.64-1.17). ORR (19.7% versus 24.4%, p=0.33) and CBR (69.7% versus 77.2%, p=0.16) were comparable between the two treatment regimens. For patients receiving post-first-line (1L) therapy, CBR for FUL+CDK4/6i therapy was 69.1%, which was significantly higher than 52.6% for AI+CDK4/6i therapy (p=0.04). Among ET-resistant subgroups, FUL+CDK4/6i achieved a higher CBR of 70.1% compared with 56.2% for AI+CDK4/6i (p = 0.008). In other subgroups, including patients receiving 1L CDK4/6i, who had a favorable response to ET, with/without liver metastasis at first relapse, the median PFS, ORR, and CBR showed no statistical difference (all p>0.05).
In general, both AI and FUL combinations are effective alternatives, irrespective of the CDK4/6i treatment line, liver metastasis at first relapse, or endocrine sensitivity. Further studies are expected.

PMID:
42371538
Bibliographic data and abstract were imported from PubMed on 29 Jun 2026.

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