Association Between BMI and the Efficacy and Safety of CDK4/6 Inhibitors in HR+/HER2− Advanced Breast Cancer: A Multicenter Retrospective Propensity Score Matched Cohort Study (CAMELIA)

ABSTRACT

The prognostic value of body mass index (BMI) in hormone receptor‐positive (HR+), human epidermal growth factor receptor 2‐negative (HER2−) advanced breast cancer treated with CDK4/6 inhibitors remains unclear. We evaluated the association of baseline BMI with efficacy and safety outcomes in a multicenter retrospective real‐world cohort of 588 patients. Propensity score matching (1:3) was used to balance baseline characteristics between patients with BMI ≥ 25 kg/m ² and BMI < 25 kg/m ² . Survival was assessed using Kaplan–Meier and Cox regression analyses, with sensitivity analyses using BMI cutoffs of 23 and 24 kg/m ² . After matching, 113 patients with BMI ≥ 25 kg/m ² and 339 with BMI < 25 kg/m ² were analyzed. With a median follow‐up of 21.5 months, BMI ≥ 25 kg/m ² was associated with longer progression‐free survival (PFS, 16.77 vs. 12.93 months; HR 0.737, 95% CI 0.554–0.981; p  = 0.036), which remained significant after multivariable adjustment (HR 0.705; p  = 0.021). Sensitivity analyses confirmed consistent PFS results across BMI thresholds. No differences were observed in overall survival (OS) or objective response rate (ORR). Adverse event profiles were comparable between groups. BMI ≥ 25 kg/m ² was independently associated with improved PFS, supporting that BMI may have prognostic relevance in this population.