Why carry out this study?

Limited data exist on the real-world treatment patterns and effectiveness of cyclin-dependent kinase (CDK) 4/6 inhibitors in patients with germline BRCA (gBRCA)-mutated breast cancer.

The current study addressed key evidence gaps surrounding the real-world outcomes of CDK4/6 inhibitor use in hormone receptor-positive, human epidermal growth factor receptor 2-negative metastatic breast cancer (mBC) by gBRCA status.

What was learned from the study?

The results of this real-world study suggest that treatment outcomes with CDK4/6 inhibitors may be worse in patients with mutated gBRCA (gBRCAm) mBC than in those with wild-type gBRCA mBC and unknown gBRCA status, suggesting potential differences in tumor biology.

The results highlight the unmet need in patients with gBRCAm requiring optimized treatment selection and sequencing; future exploration in larger samples of patients who have had biomarker testing is warranted.