Integration of pre‑existing cardiovascular comorbidity into CDK4/6 inhibitor selection for breast cancer.

Background: Cyclin-dependent kinase 4/6 (CDK4/6) inhibitors differ in cardiovascular (CV) safety. Ribociclib has been associated with a higher risk of CV adverse events compared to palbociclib and abemaciclib. Objectives: We examined patterns of CDK4/6 inhibitor selection among patients with breast cancer who had pre-existing cardiovascular disease (CVD) or cardiometabolic conditions (hypertension, hyperlipidemia, or diabetes). Design: We conducted a retrospective cohort study. Methods: Using 2017-2021 Merative MarketScan claims, we identified women ⩾18 years with breast cancer who initiated a first CDK4/6 inhibitor. The outcome was the type of CDK4/6 inhibitor. Primary factors were preexisting CVD and cardiometabolic risk factors measured in the prior 12 months. Multinomial logistic regression estimated unadjusted and adjusted odds of initiating palbociclib or abemaciclib versus ribociclib. Results: Among 5002 initiators (palbociclib Conclusion: Despite its potential higher risk of CV adverse events, ribociclib is more frequently prescribed to patients with breast cancer who have hypertension. Incorporating CV risk prediction into CDK4/6 inhibitor selection could help prevent costly CV complications.