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

Inclusion Criteria:

Participant has a histologically and/or cytologically confirmed diagnosis of estrogen receptor positive (ER+) and/or progesterone receptor positive (PgR+) breast cancer by local laboratory
Participant has a PIK3CA mutation(s) present in tumor prior to enrollment

Participant has prior treatment with an endocrine-based treatment (i.e. letrozole, anastrozole, exemestane, fulvestrant or oral SERD) and may be:

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
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
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 will NOT be included in the study.

Participants may or may 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, then the participant is postmenopausal
Participant has an Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
Participant has adequate bone marrow and organ function

Exclusion Criteria:

Participant who 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 has received prior treatment with chemotherapy (except for neoadjuvant/adjuvant chemotherapy), any PI3K, Mammalian Target of Rapamycin (mTOR) or Protein Kinase B (Akt) inhibitor
Participant has 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 has a history of acute pancreatitis within 1 year of screening or a past medical history of chronic pancreatitis
Participant has currently documented pneumonitis/interstitial lung disease
Participant has 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)

Other inclusion/exclusion criteria may apply