Pharmacokinetics and Pharmacogenomics of Ribociclib in Race-based Cohorts

The aim is to determine the pharmacological and biochemical association between ribociclib exposure and CYP3A variants in African American/Blacks and Non-Hispanic White patients. The investigators hypothesize that patients treated with ribociclib who are CYP3A5 poor metabolizers may be exposed to higher levels of ribociclib than CYP3A5 intermediate or normal metabolizers. The findings could allow clinicians to tailor treatments to maintain therapeutic doses while limiting toxicities.