Study: NCT04024462

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Pertuzumab IV
Description: Pertuzumab will be administered as a fixed non-weight-based loading dose of 840-milligrams (mg) IV and then a 420-mg IV maintenance dose Q3W.

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Trastuzumab IV
Description: Trastuzumab will be administered as an 8-milligram per kilogram of body weight (mg/kg) IV loading dose and then 6 mg/kg IV maintenance dose Q3W.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Pertuzumab and Trastuzumab FDC SC
Description: The pertuzumab and trastuzumab fixed-dose combination for subcutaneous administration (PH FDC SC) will be administered SC at a fixed non-weight-based dose. A loading dose of 1200 mg SC pertuzumab and 600 mg SC trastuzumab is then followed by a maintenance dose of 600 mg SC pertuzumab and 600 mg SC trastuzumab Q3W.

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Doxorubicin
Description: Doxorubicin 60 milligrams per meter squared of body surface area (mg/m\^2) will be administered IV on Day 1 of each cycle of treatment (as part of AC Q3W) for Cycles 1-4.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Doxorubicin
Description: Doxorubicin 60 milligrams per meter squared of body surface area (mg/m\^2) will be administered IV on Day 1 of each cycle of treatment (as part of AC Q3W) for Cycles 1-4.

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Cyclophosphamide
Description: Cyclophosphamide 600 mg/m\^2 will be administered IV on Day 1 of each cycle of treatment (as part of AC Q3W) for Cycles 1-4.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Cyclophosphamide
Description: Cyclophosphamide 600 mg/m\^2 will be administered IV on Day 1 of each cycle of treatment (as part of AC Q3W) for Cycles 1-4.

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Docetaxel
Description: Docetaxel 75 mg/m\^2 will be administered IV on Day 1 of Cycle 5. At the investigator's discretion the dose may be escalated to 100 mg/m\^2 IV for Cycles 6-8 (Q3W) provided no dose-limiting toxicity occurs.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Docetaxel
Description: Docetaxel 75 mg/m\^2 will be administered IV on Day 1 of Cycle 5. At the investigator's discretion the dose may be escalated to 100 mg/m\^2 IV for Cycles 6-8 (Q3W) provided no dose-limiting toxicity occurs.

Intervention type: PROCEDURE
Group type: ACTIVE_COMPARATOR
Intervention: Surgery
Description: Participants in both cohorts are scheduled to undergo surgery after 8 cycles of neoadjuvant therapy. Participants may undergo breast-conserving surgery or mastectomy according to routine clinical practice.

Intervention type: PROCEDURE
Group type: EXPERIMENTAL
Intervention: Surgery
Description: Participants in both cohorts are scheduled to undergo surgery after 8 cycles of neoadjuvant therapy. Participants may undergo breast-conserving surgery or mastectomy according to routine clinical practice.

Intervention type: RADIATION
Group type: ACTIVE_COMPARATOR
Intervention: Post-Operative Radiotherapy
Description: If indicated, radiotherapy is given after chemotherapy and surgery, during adjuvant HER2-targeted therapy and hormone therapy (for hormone-receptor positive disease).