Primary Outcome Measures
Stage 1: Percentage of Participants With Dose Limiting Toxicities [Time Frame: Day 1 up to Day 28 (for Stage 1 Arm A: Day 1 up to Day 35)] [Designated as safety issue: ]
Recommended Phase II Dose of GDC-0077 [Time Frame: Day 1 up to Day 28 (for Stage 1 Arm A: Day 1 up to Day 35)] [Designated as safety issue: ]
Percentage of Participants With Adverse Events and Serious Adverse Events [Time Frame: Day 1 up to 6 years] [Designated as safety issue: ]
Secondary Outcome Measures
Area Under the Concentration Time-Curve (AUC) from Time Zero to Infinity (AUCinf) of GDC-0077 [Time Frame: Predose (0-2 hours before dosing) on Cycle 1 Day 1 up to end of study (EOS; up to approximately 6 years); Cycle length=28 days (Cycle 1 of Stage 1 Arm A=35 days)] [Designated as safety issue: ]
AUC from Time Zero to Dosing Interval (AUC0-tau) of GDC-0077 [Time Frame: Predose (0-2 hours before dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days (Cycle 1 of Stage 1 Arm A=35 days)] [Designated as safety issue: ]
Half-Life of GDC-0077 [Time Frame: Predose (0-2 hours before dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days (Cycle 1 of Stage 1 Arm A=35 days)] [Designated as safety issue: ]
Maximum Plasma Concentration (Cmax) of GDC-0077 [Time Frame: Predose (0-2 hours before dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days (Cycle 1 of Stage 1 Arm A=35 days)] [Designated as safety issue: ]
Minimum Plasma Concentration (Cmin) of GDC-0077 [Time Frame: Predose (0-2 hours before dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days (Cycle 1 of Stage 1 Arm A=35 days)] [Designated as safety issue: ]
Time to Cmax (tmax) of GDC-0077 [Time Frame: Predose (0-2 hours before dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days (Cycle 1 of Stage 1 Arm A=35 days)] [Designated as safety issue: ]
Apparent Clearance (CL/F) of GDC-0077 [Time Frame: Predose (0-2 hours before dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days (Cycle 1 of Stage 1 Arm A=35 days)] [Designated as safety issue: ]
Accumulation Ratio (AR) of GDC-0077 at Steady-State [Time Frame: Predose (0-2 hours before dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days (Cycle 1 of Stage 1 Arm A=35 days)] [Designated as safety issue: ]
AUC of Palbociclib [Time Frame: Predose (0-2 hours before GDC-0077) dosing) on Cycle 1 Day 1 up to Cycle 6; Cycle length=28 days] [Designated as safety issue: ]
Cmax of Palbociclib [Time Frame: Predose (0-2 hours before GDC-0077) dosing) on Cycle 1 Day 1 up to Cycle 6; Cycle length=28 days] [Designated as safety issue: ]
AUC of Letrozole [Time Frame: Predose (0-2 hours before GDC-0077 dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days] [Designated as safety issue: ]
Cmax of Letrozole [Time Frame: Predose (0-2 hours before GDC-0077 dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days] [Designated as safety issue: ]
AUC of Fulvestrant [Time Frame: Predose (0-2 hours before GDC-0077 dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days] [Designated as safety issue: ]
Cmax of Fulvestrant [Time Frame: Predose (0-2 hours before GDC-0077 dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=28 days] [Designated as safety issue: ]
Percentage of Participants With Objective Response as Assessed by Response Evaluation Criteria in Solid Tumors (RECIST), Version 1.1 (v1.1) [Time Frame: Baseline up to occurrence of complete response (CR) or partial response (PR) on 2 consecutive occasions >/=4 weeks apart (up to approximately 6 years)] [Designated as safety issue: ]
Duration of Response, as Assessed by RECIST v1.1 [Time Frame: From first occurrence of a documented objective response (CR or PR) to disease progression or death from any cause, whichever occurs first (up to approximately 6 years)] [Designated as safety issue: ]
Percentage of Participants With Clinical Benefit as Assessed by RECIST v1.1 [Time Frame: Baseline up to disease progression or death from any cause, whichever occurs first (up to approximately 6 years)] [Designated as safety issue: ]
Progression Free Survival (PFS) as Assessed by RECIST v1.1 [Time Frame: Baseline up to disease progression or death from any cause, whichever occurs first (up to approximately 6 years)] [Designated as safety issue: ]
Change in Maximum Standard Uptake Value (SUV) of Tumor Regions of Interest (as assessed by [18] F-fluorodeoxyglucose-positron emission tomography) From Baseline to Approximately 2 Weeks of GDC-0077 Treatment [Time Frame: Baseline, Week 2] [Designated as safety issue: ]
AUC of Pertuzumab [Time Frame: Predose (0-2 hours before GDC-0077 dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=21 days] [Designated as safety issue: ]
Cmax of Pertuzumab [Time Frame: Predose (0-2 hours before GDC-0077 dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=21 days] [Designated as safety issue: ]
AUC of Trastuzumab [Time Frame: Predose (0-2 hours before GDC-0077 dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=21 days] [Designated as safety issue: ]
Cmax of Trastuzumab [Time Frame: Predose (0-2 hours before GDC-0077 dosing) on Cycle 1 Day 1 up to EOS (up to approximately 6 years); Cycle length=21 days] [Designated as safety issue: ]