A Study of PI3-Kinase Inhibitor GDC-0941 in Combination With Paclitaxel, With and Without Bevacizumab or Trastuzumab, and With Letrozole, in Participants With Locally Recurrent or Metastatic Breast Cancer

Inclusion Criteria:

• Confirmed adenocarcinoma of the breast with locally recurrent or metastatic disease

• Adequate organ and bone marrow function as assessed by laboratory tests

• Evaluable disease or disease measurable per RECIST

• Agreement to use an effective form of contraception for the duration of the study

Exclusion Criteria:

• History of malabsorption syndrome or other condition that would interfere with enteralabsorption

• Any condition requiring full-dose anticoagulants, such as warfarin, heparin, orthrombolytic agents

• Prior anti-cancer therapy (e.g., chemotherapy, biologic therapy, radiotherapy, orhormonal therapy) within 4 weeks or 5 half-lives (whichever is shorter) of the firstdose of study treatment

• Uncontrolled current illness

• Active small or large intestine inflammation (such as Crohn's disease or ulcerativecolitis)

• Clinically significant history of liver disease, including cirrhosis, current alcoholabuse, or current known active infection with human immunodeficiency virus (HIV),hepatitis B virus, or hepatitis C virus

• Known HIV infection

• New York Heart Association (NYHA) Class II or greater congestive heart failure

• Active ventricular arrhythmia requiring medication

• Pregnancy, lactation, or breastfeeding

• Known significant hypersensitivity to study drugs or excipients

• History of arterial thromboembolic disease within 6 months of first study treatment

• No more than two prior chemotherapy regimens for metastatic disease