A Phase IIIB Study to Evaluate the Use of Capivasertib in Combination With Fulvestrant in Patients With Advanced Breast Cancer Who Have Relapsed/Progressed on ET and CDK4/6 Inhibitor Reflecting Real World Clinical Practice in Spain

Key Inclusion Criteria Histologically confirmed HR+/HER2- breast cancer (primary or metastatic): * HR+ defined as ER+ with or without PRg+ * HER2- defined as IHC 0 or 1+, or IHC 2+/ISH- Patient with tumours harbouring at least one PIK3CA/AKT1/PTEN qualifying alteration detected by a validated test (including NGS on tissue, cell block, or if tissue/cell block is not available, on ctDNA, as per protocol requirements. If alteration is initially detected by a method other than NGS, NGS on tissue/cell block must be performed within 45 days unless not available, which must be documented.) Metastatic or locally advanced disease with radiological or objective evidence of recurrence or progression. Patients must have received treatment with an ET in combination with CDK4/6i and have: * Radiological evidence of breast cancer recurrence or progression while on, or within 12 months of the end of (neo)adjuvant treatment with an ET with CDK4/6i, OR * Radiological evidence of progression while on prior ET with CDK4/6i administered as a treatment line for locally advanced or metastatic breast cancer. Informed consent Eastern Cooperative Oncology Group (ECOG)/ World Health Organisation (WHO) performance status ≤ 2 at enrollment (not more than 20% of patients with ECOG PS2 will be allowed). Reproduction: * Women of childbearing potential (WOCBP) patients with ovarian suppression induced by LHRH agonist should agree to use 2 forms of highly effective methods of accepted contraception …