postMONARCH is a Phase 3, global, multicenter, randomized, double-blind, placebo-controlledstudy in participants with HR+, HER2- advanced or metastatic breast cancer. This study willenroll adults who experienced disease progression on a CDK4 & 6 inhibitor and an AI in thefirst-line setting or relapse on/after a CDK4 & 6 inhibitor with ET in the adjuvant setting.

This is an international, multicenter, open-label, randomized, Phase 3 study in patients withlocally advanced, inoperable or metastatic triple-negative breast cancer (TNBC) who have not received previous therapy for advanced disease and whose tumors are either: PD-L1 negative at screening (defined using the PD-L1 IHC 22C3 assay as tumors with a combined positive score (CPS) < 10), OR PD-L1 positive at screening (defined using the PD-L1 IHC 22C3 assay as tumors with a CPS ≥ 10) if they previously received a checkpoint inhibitor in the adjuvant or neoadjuvant setting.

RATIONALE: Estrogen can cause the growth of breast cancer cells. Hormone therapy using tamoxifen citrate, goserelin acetate, leuprolide acetate, anastrozole, letrozole, or exemestane, may fight breast cancer by lowering the amount of estrogen the body makes. Everolimus may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. It is not yet know whether hormone therapy is more effective when given with or without everolimus in treating breast cancer. PURPOSE: This randomized phase III trial studies how well giving hormone therapy together with or without everolimus work in treating patients with breast cancer.

This randomized phase III trial studies how well doxorubicin hydrochloride and cyclophosphamide followed by paclitaxel with or without carboplatin work in treating patients with triple-negative breast cancer. Drugs used in chemotherapy, such as doxorubicin hydrochloride, cyclophosphamide, paclitaxel, and carboplatin, work in different ways to stop the growth of tumor cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. It is not yet known whether doxorubicin hydrochloride and cyclophosphamide is more effective when followed by paclitaxel alone or paclitaxel and carboplatin in treating triple-negative breast cancer.