Giredestrant plus Everolimus in Advanced Breast Cancer

BACKGROUND: Giredestrant and everolimus target the estrogen receptor (ER) pathway and the phosphatidylinositol 3-kinase (PI3K)-protein kinase B (AKT)-mammalian target of rapamycin (mTOR) pathway, respectively, which are implicated in endocrine-therapy resistance. METHODS: In this phase 3, open-label, randomized trial, we enrolled patients with ER-positive, human epidermal growth factor receptor 2 (HER2)-negative locally advanced or metastatic breast cancer who had disease progression or recurrence after receipt of a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor plus endocrine therapy. Patients were assigned, in a 1:1 ratio, to receive giredestrant plus everolimus (each given orally) or standard endocrine therapy (i.e., exemestane, fulvestrant, or tamoxifen) plus everolimus. The primary end point was investigator-assessed progression-free survival, evaluated first among patients with RESULTS: Overall, 373 patients underwent randomization, with 183 assigned to the giredestrant-everolimus group and 190 to the standard therapy-everolimus group. Among 207 patients with CONCLUSIONS: An all-oral giredestrant-everolimus regimen led to significantly longer progression-free survival than standard endocrine therapy-everolimus among patients with ER-positive, HER2-negative advanced breast cancer who had received a CDK4/6 inhibitor previously, mainly in patients with