A Study of Ipatasertib in Combination With Paclitaxel as a Treatment for Participants With PIK3CA/AKT1/PTEN-Altered, Locally Advanced or Metastatic, Triple-Negative Breast Cancer or Hormone Receptor-Positive, HER2-Negative Breast Cancer

Inclusion Criteria

• Women or men aged =>18 years with histologically documented triple-negative breast cancer (TNBC) or HR+/HER2- adenocarcinoma of the breast that is locally advanced or metastatic and is not amenable to resection with curative intent
• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1
• Adequate hematologic and organ function within 14 days prior to treatment initiation
• Histologically documented TNBC or HR+/HER2- adenocarcinoma of the breast that is locally advanced or metastatic and is not amenable to resection with curative intent
• Measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST) v1.1
• Eligible for taxane monotherapy, as per local investigator assessment (e.g., absence of rapid clinical progression, life-threatening visceral metastases, or the need for rapid symptom and/or disease control which may require combination chemotherapy)
• HR+/HER2- breast cancer that is not considered appropriate for endocrine-based therapy and meets one of the following: patient has recurrent disease =10 mg of prednisone per day or an equivalent dose of other anti-inflammatory corticosteroids or immunosuppressants for a chronic disease
• Unresolved, clinically significant toxicity from prior therapy, except for alopecia and Grade 1 peripheral neuropathy
• Uncontrolled clinical symptoms including pleural effusion, pericardial effusion, or ascites, tumor-related pain, hypercalcemia (or symptomatic hypercalcemia requiring continued use of bisphosphonate therapy)
• History of Type I or Type II diabetes mellitus requiring insulin
• Grade >=2 uncontrolled or untreated hypercholesterolemia or hypertriglyceridemia
• History of or active inflammatory bowel disease or active bowel inflammation
• Clinically significant lung disease (including pneumonitis, interstitial lung disease, idiopathic pulmonary fibrosis, cystic fibrosis, active infection/ history of opportunistic infections)
• Treatment with strong CYP3A inhibitors or strong CYP3A inducers within 2 weeks or 5 drug-elimination half-lives, whichever is longer, prior to initiation of treatment
• Grade >=2 peripheral neuropathy