This study involves a two-part design. Part 1 is designed to determine the optimal dose of subcutaneous (SC) Perjeta, injected alone or mixed with Herceptin, that results in comparable exposure to intravenous (IV) Perjeta. Exposure between SC Perjeta and IV Perjeta will be compared using a compilation of pharmacokinetic (PK) parameters such as area under the concentration-time curve (AUC), maximum serum concentration (Cmax), time of maximum concentration (Tmax), and serum trough concentration (Ctrough). Part 2 is designed to confirm the dosing regimen in women with EBC on the basis of safety, tolerability, and PK assessments.