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

          -  Measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST)
             v1.1

          -  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:

          -  Valid results from central molecular analysis confirming PIK3CA/AKT1/PTEN-altered
             status in tumor tissue by next-generation sequencing (NGS)

        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

          -  Participants with HR+/HER2- breast cancer for whom endocrine-based therapy is
             considered an appropriate option per local clinical guidelines (i.e. participants
             should not be considered eligible for endocrine-based treatment)

          -  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 antibiotics

          -  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

          -  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