A Study to Evaluate the Efficacy and Safety of Giredestrant in Combination With Phesgo (Pertuzumab, Trastuzumab, and Hyaluronidase-zzxf) Versus Phesgo in Participants With Locally Advanced or Metastatic Breast Cancer (heredERA Breast Cancer)

This Phase III, randomized, two-arm, open-label, multicenter study will evaluate the efficacy and safety of giredestrant plus Phesgo compared with Phesgo after induction therapy with Phesgo plus taxane in participants with human epidermal growth factor receptor 2 (HER2)-positive, estrogen receptor (ER)-positive advanced breast cancer (metastatic or locally advanced disease not amenable to curative treatment) who have not previously received a systemic non-hormonal anti-cancer therapy in the advanced setting.