Impact of BRCA2 pathogenic variants on outcomes to first-line CDK4/6 inhibitors plus endocrine therapy in HR-positive/HER2-negative metastatic breast cancer.
BRCA2 carriers with breast cancer show poorer response to standard hormone-plus-CDK4/6 treatment, signaling need for tailored first-line strategies.
In 233 HR+/HER2- metastatic breast cancer patients treated with first-line CDK4/6 inhibitor plus endocrine therapy, germline BRCA2 PV carriers (n=67) had significantly shorter progression-free survival (median 11 vs 27 months; aHR 2.73) compared to matched controls, with RB1 LOH detected in most BRCA2 tumors before treatment. These findings from a multicenter Spanish cohort with IPTW adjustment suggest BRCA2 germline carriers—particularly those with endocrine-sensitive disease—may need alternative first-line strategies beyond CDK4/6i+ET.
What the study was
- Study design
- retrospective multicenter case-control
- Population
- HR+/HER2- metastatic breast cancer patients treated with first-line CDK4/6i+ET (Spanish multicenter cohort)
- Sample size
- 233
- Category
- Genomics/Precision Medicine
- Maturity
- Validated
- Journal
- ESMO Open
Why it surfaced
Clinically actionable precision oncology data showing BRCA2 germline PVs predict substantially poorer response to the current standard first-line therapy in HR+/HER2- MBC; RB1 LOH as proposed mechanism provides a testable biomarker; impacts treatment selection for a large, well-defined breast cancer subgroup.
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