Inclusion Criteria:

- Female adult patients

- Histologically or cytologically confirmed adenocarcinoma of the breast, with
measurable or non-measurable locally recurrent or metastatic disease

- Human epidermal growth factor receptor 2 (HER2)-negative and HR (estrogen receptor
and/or progesterone receptor)-positive disease as defined by local guidelines

- Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1

- Adequate hematologic and end organ function

- Women of childbearing potential must agree to remain abstinent or to use two adequate
methods of contraception, including at least one method with a failure rate of < 1%
per year, during the treatment period and for at least 30 days after the last dose of
study treatment or 6 months after discontinuation of paclitaxel, whichever is longer

Exclusion Criteria:

- Prior non-capecitabine chemotherapy for locally recurrent or metastatic disease

- Prior treatment with a PI3K inhibitor for advanced or metastatic breast cancer

- History of intolerance to a taxane-containing therapy

- History of clinically significant cardiac or pulmonary dysfunction

- History of malabsorption syndrome or other condition that would interfere with
enteral absorption

- Clinically significant history of liver disease

- Active autoimmune disease or active inflammatory disease

- Immunocompromised status

- Need for current chronic corticosteroid therapy

- Pregnancy, lactation, or breastfeeding

- Current severe, uncontrolled systemic disease

- Known untreated or active central nervous system (CNS) metastases