Integrated Testing Strategy for Simultaneous Detection of ESR-1 and gBRCA Mutations Via Liquid Biopsy in HR+/HER2- Metastatic Breast Cancer (mBC) Patients,

Participants must have a confirmed diagnosis of estrogen receptor-positive (ER+) and/or progesterone receptor-positive (PgR+) breast cancer through histological and/or cytological examination by the local laboratory Participants must exhibit HER2-negative breast cancer

or 2+). If IHC is 2+, a negative in situ hybridization (Fluorescent in situ hybridization (FISH), Chromogenic in situ hybridization (CISH), or Silver-enhanced in situ hybridization (SISH)) test is required by local laboratory testing.

Participants should be in an advanced or metastatic setting including both those prior to the initiation of treatment for metastatic disease and those who experienced progression following treatment with cyclin-dependent kinases (CDK)4/6 inhibitors. However, the primary tumor should be treated according to the standard of care.

Written informed consent must be signed and dated by the patient and the investigator prior to inclusion.