Study: NCT03493854

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

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: FDC of Pertuzumab and Trastuzumab SC
Description: The FDC of pertuzumab and trastuzumab 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: Trastuzumab IV
Description: Trastuzumab will be administered as an 8-mg/kg IV loading dose and then 6 mg/kg IV maintenance dose Q3W.

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Trastuzumab SC
Description: After surgery (from Cycle 9 onwards), participants in Arm A will be allowed to switch from trastuzumab IV to trastuzumab SC, at the discretion of the investigator, in the countries where trastuzumab SC is routinely used. For participants who switch, a fixed dose of 600 mg trastuzumab SC (irrespective of the patient's weight) will be administered in the adjuvant phase.

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).

Intervention type: RADIATION
Group type: EXPERIMENTAL
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).

Intervention type: DRUG
Group type: ACTIVE_COMPARATOR
Intervention: Hormone Therapy
Description: For hormone receptor positive breast cancer, tamoxifen or aromatase inhibitors will be allowed as adjuvant hormone therapy for postmenopausal participants and with ovarian suppression or ablation for premenopausal participants in countries where it has been registered for this indication. Its use must be consistent with the registered label. Hormone therapy is given after chemotherapy and surgery during adjuvant HER2-targeted therapy.

Intervention type: DRUG
Group type: EXPERIMENTAL
Intervention: Hormone Therapy
Description: For hormone receptor positive breast cancer, tamoxifen or aromatase inhibitors will be allowed as adjuvant hormone therapy for postmenopausal participants and with ovarian suppression or ablation for premenopausal participants in countries where it has been registered for this indication. Its use must be consistent with the registered label. Hormone therapy is given after chemotherapy and surgery during adjuvant HER2-targeted therapy.