Study of Safety and Efficacy of Dapagliflozin + Metformin XR Versus Metformin XR in Participants With HR+, HER2-, Advanced Breast Cancer While on Treatment With Alpelisib and Fulvestrant

Key Inclusion Criteria: * Participant had a histologically and/or cytologically confirmed diagnosis of estrogen receptor positive (ER+) and/or progesterone receptor positive (PgR+) breast cancer by a local laboratory. * Participant had a PIK3CA mutation(s) present in the tumor prior to enrollment. * Participant had prior treatment with an endocrine-based treatment (e.g. letrozole, anastrozole, exemestane, fulvestrant, or oral SERD) and may have fallen into one of the following categories: 1. Relapsed with documented evidence of progression while on (neo) adjuvant endocrine-based therapy or within 12 months from completion of (neo) adjuvant endocrine-based therapy with no treatment for metastatic disease. 2. Relapsed with documented evidence of progression more than 12 months from completion of (neo) adjuvant endocrine-based therapy and then subsequently progressed with documented evidence of progression while on or after only one line of endocrine-based therapy for metastatic disease. 3. Newly diagnosed advanced breast cancer, then relapsed with documented evidence of progression while on or after only one line of endocrine-based therapy. Note: Participants with newly diagnosed endocrine-based treatment naïve advanced breast cancer were NOT included in the study. * Participants might or might not have received prior CDK4/6i therapy. If prior CDK4/6i therapy was administered, it may have been in the adjuvant or metastatic setting. * If female, the participant was postmenopausal. * Participant had an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. * Participant had adequate bone marrow and organ function. Key Exclusion Criteria: * Participant relapsed with documented evidence of progression more than 12 months from completion of (neo) adjuvant endocrine therapy with no treatment for metastatic disease. * Participant had more than 1 line of prior treatment in the metastatic setting. * Participant had received prior treatment with chemotherapy (except for neoadjuvant/adjuvant chemotherapy), any PI3K, Mammalian Target of Rapamycin (mTOR) or Protein Kinase B (Akt) inhibitor. * Participant had inflammatory breast cancer at screening. * Participants with an established diagnosis of diabetes mellitus type I or participants with type II diabetes mellitus requiring antihyperglycemic therapy. * Participant had a history of acute pancreatitis within 1 year of screening or a past medical history of chronic pancreatitis. * Participant had currently documented pneumonitis/interstitial lung disease. * Participant had a history of severe cutaneous reaction, such as Steven-Johnson Syndrome (SJS), erythema multiforme (EM), Toxic Epidermal Necrolysis (TEN) or Drug Reaction with Eosinophilia and Systemic Syndrome (DRESS).