We have recently launched a clinical trial that will study the tolerability and preliminary efficacy of rogaratinib, fulvestrant, and palbociclib in FGFR1-positive (by RNAscope and/or FISH) HR+ breast cancer patients that have progressed to first line CDK4/6 inhibitor plus aromatase inhibitor in order to address the role of this driver of HR+ breast cancer aggressiveness. The gene discussed is CDK4; the disease is breast carcinoma.