CDK4/6 Inhibition and Radiation as a Treatment Strategy to Improve Local Disease Control in Breast Cancers With Poor Prognoses

RB loss mitigates CDK4/6 inhibitor-mediated radiosensitization of both ER+ and TNBC cells. Loss of RB expression prevents CDK4/6i-mediated radiosensitization, suggesting that RB expression may be a valuable clinical biomarker to predict efficacy of CDK4/6i + RT in future clinical trials. Our data also provide the preclinical rationale for CDK4/6i with RT not just in ER+ BC, but also in women with TNBC that express RB.