EPIK-B3: This phase III trial is trying to determine whether treatment with a combination of targeted therapy and chemotherapy is safe and effective for patients with advanced triple negative breast cancerA Phase III, Multicenter, Randomized, Double-blind, Placebo-controlled Study to Assess the Efficacy and Safety of Alpelisib (BYL719) in Combination With Nab-paclitaxel in Patients With Advanced Triple Negative Breast Cancer With Either Phosphoinositide-3-kinase Catalytic Subunit Alpha (PIK3CA) Mutation or Phosphatase and Tensin Homolog Protein (PTEN) Loss Without PIK3CA Mutation

Exclusion

• Participant has received prior treatment with any PI3K, mTOR or AKT inhibitor
• Participant has a known hypersensitivity to alpelisib, nab-paclitaxel or to any of their excipients
• Participant has not recovered from all toxicities related to prior anticancer therapies to NCI CTCAE version 4.03 Grade ≤1; with the exception of alopecia
• Participant has central nervous system (CNS) involvement which was not previously treated and/or was newly detected at screening
• Participant with an established diagnosis of diabetes mellitus type I or uncontrolled type II based on Fasting Plasma Glucose and HbA1c
• Participant has impairment of gastrointestinal (GI) function or GI disease that may significantly alter the absorption of the study drugs (e.g., ulcerative diseases, uncontrolled nausea, vomiting, diarrhea, malabsorption syndrome, or small bowel resection) based on investigator discretion
• Participant has a history of acute pancreatitis within 1 year prior to screening or past medical history of chronic pancreatitis
• Participant has currently documented pneumonitis/interstitial lung disease
• Participant has a history of severe cutaneous reactions, such as Steven-Johnson Syndrome (SJS), erythema multiforme (EM),Toxic Epidermal Necrolysis (TEN) or Drug Reaction with Eosinophilia and Systemic Syndrome (DRESS)
• Participant with unresolved osteonecrosis of the jaw

Other protocol-defined inclusion/exclusion criteria apply.