This study will evaluate the safety of inavolisib in combination with fulvestrant, with or without palbociclib, in participants with PIK3CA-mutated, HR+, HER2-negative ABC and type 2 diabetes.
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)
Pregnant or breastfeeding, or intention of becoming pregnant during the study or within the time frame in which contraception is required
Metaplastic breast cancer
Any history of Type 1 diabetes
Severe hyper- or hypoglycemia event within 6 months of initiation of study treatment