Abstract ED04-02: Combination endocrine therapy following progression on first-line therapy

Assessing genomic status is critical to make treatment decisions in patients who have experienced disease progression following a CDK 4/6 inhibition with endocrine therapy. Three trials have evaluated CDK 4/6 inhibition with endocrine therapy through progression and show that switching CDK 4/6 inhibitor results in modest efficacy while continuing the same CDK 4/6 inhibitor is not effective. The optimal therapy for patients whose tumors have a PI3-kinase mutation is alpelisib and fulvestrant. Other PIK3-ca inhibitors have not shown efficacy to date. Everolimus with endocrine therapy is an effective second line approach. Emerging data demonstrate efficacy of AKT inhibition with endocrine therapy. Several other agents are in clinical development. Citation Format: R. O'Regan. Combination endocrine therapy following progression on first-line therapy [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr ED04-02.