Study Assessing the Efficacy and Safety of Alpelisib + Nab-paclitaxel in Subjects With Advanced TNBC Who Carry Either a PIK3CA Mutation or Have PTEN Loss

Inclusion Criteria: * Participant has histologically confirmed diagnosis of advanced (loco-regionally recurrent and not amenable to curative therapy), or metastatic (stage IV) TNBC * Participant has either a measurable disease per RECIST 1.1 criteria or, if no measurable disease is present, then at least one predominantly lytic bone lesion or mixed lytic-blastic bone lesion with identifiable soft tissue component (that can be evaluated by CT/MRI) must be present. Part B1: Participants must have measurable disease * Participant has adequate tumor tissue to identify the PIK3CA mutation status (either carrying a mutation or without a mutation) and the PTEN loss status; both of which will determine whether the subject can be allocated to Part A - PIK3CA mutation regardless of PTEN status; or to Part B1 - PTEN loss or to Part B2 - PTEN loss without a PIK3CA mutation * Participant has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Participant has received no more than one line of therapy for metastatic disease * Participant has adequate bone marrow and organ function Exclusion Criteria: * 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 nervo…