A Study Evaluating the Safety of Inavolisib and Fulvestrant With or Without Palbociclib in Participants With Advanced Breast Cancer (ABC) and Type 2 Diabetes

Other illness

• Metaplastic breast cancer
• Any history of Type 1 diabetes
• Any history of leptomeningeal disease or carcinomatous meningitis
• Known and untreated, or active central nervous system (CNS) metastases Participants with a history of treated CNS metastases are eligible
• Active inflammatory or conditions in either eye or history of idiopathic or autoimmune-associated uveitis in either eye
• Symptomatic active lung disease
• History of active bowel inflammation or active inflammatory bowel disease

Other

• Pregnant or breastfeeding, or intention of becoming pregnant during the study or within the time frame in which contraception is required
• Severe hyper- or hypoglycemia event within 6 months of initiation of study treatment

• Type 2 diabetes with laboratory fasting blood glucose \< 185 milligrams per deciliter (mg/dL) and HbA1c \<= 8% on any stable anti-hyperglycemic regimen excluding insulin short-term insulin dosing
• Eligible for triplet of inavolisib, fulvestrant and palbociclib: no prior systemic therapy for locally advanced unresectable or metastatic disease
• Confirmed diagnosis of HR+/HER2- breast cancer
• Confirmation of biomarker eligibility (detection of specified mutation(s) of PIK3CA via specified test)
• Measurable disease per Response Evaluation Criteria in Solid Tumors, Version 1.1 (RECIST v1.1)
• Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-1
• Adequate hematologic and organ function within 14 days prior to initiation of study treatment