Researchers from Tempus studied the mutational landscape of patients with metastatic breast cancer. Partners in the study included: Northwestern University’s Robert H. Lurie Comprehensive Cancer Center; Baylor University’s Dan L. Duncan Comprehensive Cancer Center; Cedar Sinai’s Samuel Oschin Comprehensive Cancer Center; and University of Pittsburgh’s Hillman Cancer Center.

CDK4/6 inhibitors (CDK4/6i), such as palbociclib, ribociclib, and abemaciclib, in combination with antiestrogens, have revolutionized the treatment of ER+/HER2- metastatic breast cancer (MBC). Although most patients initially respond, almost all eventually progress, and ER+ MBC remains incurable. There is an urgent need to understand the molecular processes that drive resistance in order to improve survival. The researchers utilized a large real-world dataset to compare the mutational landscapes of HR+/HER2- MBC samples in which CDK4/6 inhibitor (CDK4/6i) treatment was initiated ≥6 months prior to biopsy to describe variations in tumor biology associated with exposure to each CDK4/6i. They also compared mutations detected by solid tumor sequencing and liquid biopsy to better understand each assay’s ability to identify relevant alterations in this population.

This study was presented at the San Antonio Breast Cancer Symposium in December 2022.