Study Assessing the Efficacy and Safety of Treatment With Alpelisib Plus Fulvestrant Versus Placebo Plus Fulvestrant in Chinese Men and Postmenopausal Women With Advanced Breast Cancer

Key Inclusion Criteria: * Participant has adequate tumor tissue for the analysis of PIK3CA mutational status by a Novartis designated laboratory. One new or recent biopsy (collected at screening if feasible) or archival tumor block or slides (3 slides minimum from a surgical specimen, or 7 slides minimum from a core needle biopsy) must be provided. It is recommended to provide a tumor sample collected after the most recent progression or recurrence. * Chinese man or postmenopausal woman ≥ 18 years of age * Participant has identified PIK3CA mutation (as determined by a Novartis designated laboratory) * Participant has a histologically and/or cytologically confirmed diagnosis of ER+ and/or PgR+ breast cancer by local laboratory. * Participant has HER2-negative breast cancer defined as a negative in situ hybridization test or an IHC status of 0, 1+ or 2+. If IHC is 2+, a negative in situ hybridization (FISH, CISH or SISH) test is required by local laboratory testing * Participant has either * Measurable disease, i.e., at least one measurable lesion as per RECIST 1.1 criteria (a lesion at a previously irradiated site may only be counted as a target lesion if there is clear sign of progression since the irradiation) OR * If no measurable disease is present, then at least one predominantly lytic bone lesion must be present (Participants with no measurable disease and only one predominantly lytic bone lesion that has been previously irradiated are eligible if there is documented ev…