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 <=5 years of being on
adjuvant endocrine therapy or if patient with de novo metastatic disease have
progressed within 6 months of being on first line endocrine therapy.

- Consent to submit a formalin-fixed, paraffin-embedded tumor (FFPE) tissue block or
freshly cut unstained, serial tumor slides from the most recently collected tumor
tissue for central molecular analysis

- Confirmation of biomarker eligibility using an appropriately validated molecular assay
at a diagnostic laboratory, Clinically Laboratory Improvement Amendments (CLIA) or
equivalently accredited i.e., valid results from either central testing or local
testing of tumor tissue or blood demonstrating PIK3CA/AKT1/PTEN-altered status

Exclusion Criteria:

- Treatment with approved or investigational cancer therapy within 14 days prior to
treatment initiation

- Any previous chemotherapy for inoperable locally advanced or metastatic TNBC or
HR+/HER2- adenocarcinoma of the breast (patients receiving neo/adjuvant chemotherapy
eligible provided they have at least a 12 month disease-free interval)

- History of or known presence of brain or spinal cord metastases

- Malignancies other than breast cancer within 5 years prior to treatment initiation
(except for appropriately treated carcinoma in situ of the cervix, non-melanoma skin
carcinoma, or Stage I uterine cancer)

- Prior treatment with an Akt inhibitor (prior PI3K or mTOR inhibitors are allowed)

- History of malabsorption syndrome or other condition that would interfere with enteral
absorption or results in the inability or unwillingness to swallow pills

- Active infection requiring systemic anti-microbial treatment (including antibiotics,
anti-fungals, and anti-viral agents)

- Known human immunodeficiency virus (HIV) infection

- Known clinically significant history of liver disease consistent with Child-Pugh Class
B or C, including active viral or other hepatitis, current drug or alcohol abuse, or
cirrhosis

- Major surgical procedure, open biopsy, or significant traumatic injury within 28 days
prior to initiation of treatment (or anticipated need during study)

- Pregnant or breastfeeding, or intending to become pregnant during the study

- Clinically significant cardiac dysfunction (including NYHA Class II/III/IV heart
failure, left ventricular ejection fraction [LVEF] <50%, active ventricular arrhythmia
requiring medication, history of myocardial infarction within 6 months of treatment
initiation, clinically significant electrocardiogram [ECG] abnormalities).

- Need for chronic corticosteroid therapy of >=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