The purpose of this study is to evaluate characteristics and clinical outcomes of patients with ER+ EC or ovarian cancer (OC) who have received a CDK4/6i+ET at our institution....For EC patients who started CDK4/6i+ET concurrently, their DOR was 11.7 months (IQR 7.7-24 months) with BRR of partial response (PR) (n=1), SD (n=2), and progressive disease (n=3). For OC, the TTF was 13.5 months (95% CI 5.4-not evaluable). All OC patients had CDK 4/6i added to their ET due to progression, with a median DOR on CDK4/6i+ET of 9.0 months (IQR 5.4-13.5 months).